Cadmium Exposure in the Swedish Environment

Home , Agriculture in Sweden, Cadmium stearate, Siljan (lake), Vulnerable area

d-Sf #807/4*3 - /V6 KEM Bses No 1/98 received JUS 2 919% OST l Cadmium exposure in the Swedish environment

FOREIGN sales PROHIBITED

Exemption Substances Project

THE SWEDISH NATIONAL CHEMICALS INSPECTORATE DISCLAIMER

Portions of this document may be illegible electronic image products. Images are produced from the best available original document. Cadmium exposure in the Swedish environment

Part I Cadmium in Sweden - environmental risks

Part II Cadmium in goods - contribution to environmental exposure

Part III Cadmium in fertilizers, soil, crops and foods - the Swedish situation ISSN: 0284-1185 Order No. 360 598 Printed by: Printgraf, Stockholm, March 1998 Publisher: Swedish National Chemicals Inspectorate© Order address: P.O. Box 1384, S-171 27 Solna, Sweden Telefax 46 8-735 52 29, e-mail [email protected] Part I Cadmium in Sweden - environmental risks

Helena Parkman and Ake Iverfeldt, Swedish Environmental Research Institute, Hans Borg and Goran Lithner, Institute for Applied Environmental Research - Laboratory for Aquatic Environmental Chemistry Contents Summary $ Sammanfattning 8

1. Introduction 11

2. Naturally occurring cadmium 12

2.1. Background concentrations in Sweden 12

3. Sensitivity in the Swedish environment 15

3.1 Poor soils and sensitivity to acidification 16 3.2 The Baltic Sea, something between a lake and a sea 19

4. Cadmium in air 20

4.1 Concentrations 20 4.2 Deposition 21

5. Cadmium in terrestrial ecosystems 23

5.1 Concentrations and mobility 23 5.1.1 Forest soil 23 5.1.2 Agricultural soils 27 5.2 Accumulation in and effects on soil organisms 29 5.3 Accumulation and effects in higher terrestrial organisms 31 5.4 Accumulation and effects in plants 35 5.5 Conclusions - effects in the terrestrial environment 37

6. Cadmium in aquatic ecosystems 38

6.1 Concentrations 39 6.1.1 Rivers and lakes 40 6.1.2 Groundwater 45 6.1.3 Seas 45 6.2 Accumulation in, and effects on aquatic organisms 48 6.2.1 Factors affecting bioaccumulation and effects 48 6.2.2 Effects on aquatic organisms 53 6.1.4 Effect studies on organisms captured in Swedish environments 55 6.3 Conclusions- effects of cadmium in Swedish aquatic environments 56

7. Cadmium in the Urban environment 57

8. Temporal trends 60

9. Overall conclusions 64

10. References 68

10.1 Personal communications 76

11. Appendix n Summary

The present report aims at assessing possible effects of cadmium in the Swedish environment.

Swedish soils and soft freshwater systems are, due to a generally poor buff ering capacity, severely affected by acidification. In addition, the low salin ity in the Baltic Sea imply a naturally poor organism structure, with some important organisms living close to their limit of physiological tolerance. Cadmium in soil is mobilised at low pH, and the availability and toxicity of cadmium in marine systems are enhanced at low salinity. The Swedish envi ronment is therefore extra vulnerable to cadmium pollution.

The average concentrations of cadmium in the forest mor layers, agricul tural soils, and freshwaters in Sweden are enhanced compared to ‘back ground concentrations ’, with a general increasing trend from the north to the south-west, indicating strong impact of atmospheric deposition of cadmium originating from the central parts of Europe. In Swedish sea water, total cadmium concentrations, and the fraction of bioavailable ‘free’ cadmium, generally increases with decreasing salinity.

Decreased emissions of cadmium to the environment have led to decreasing atmospheric deposition during the last decade. The net accumulation of cadmium in the forest mor layer has stopped, and even started to decrease. In northern Sweden, this is due to the decreased deposition, but in southern Sweden the main reason is increased leakage of cadmium from the topsoil ’s as a consequence of acidification. As a result, cadmium in the Swedish environments is undergoing an extended redistribution between different soil compartments, and from the soils to the aquatic systems.

Cadmium concentrations measured in surface layers of forest soils and peatlands (up to 2 mg Cd kg"' dw) in southern Sweden are close to critical concentrations at which effects on microbiological activity occur. Measured concentrations in soil solution and data on toxicity to microorganisms in water indicate that cadmium concentrations in forest soil pore water may reach hazardous concentrations. When calculating the risk for effects according to the EU Technical Guidance Document, it is indicated that also the concentrations measured in Swedish agricultural soils might affect soil living organisms.

There is some evidence for chronic effects (kidney dysfunction) in certain mammals (bank voles) close to a point source in northern Sweden. 5 The effects occur at kidney cadmium concentrations > 4 mg Cd kg'* wet weight. Kidney cadmium concentrations above this level have also been found in a considerable number of bank voles captured in southern Sweden, indicating that these animals might suffer from kidney dysfunction as well, due to accumulation of cadmium from diffuse sources.

Some plants in Sweden, especially certain trees, accumulate cadmium to concentrations that might be hazardous to the plants themselves and maybe also to birds and herbivorous mammals feeding on them.

Lakes in southern Sweden are severely damaged by acidification and many species have disappeared. Since both the total concentrations and the amount of free (ionic) cadmium, increases at low pH, chronic effects of cadmium may add to other effects caused by the acidification. Cadmium concentrations in a large number of the acidified lakes in southern Sweden, exceed the reported LOEC (0.17 pg Cd L*l) for freshwater organisms, and can reach concentrations >0.3 pg Cd L" 1. Concentrations in acidified rivers are mostly below 0.1 pg L" 1.

The Baltic Sea is severely affected by many different pollutants. The eu trophication, with large areas of the bottom being anoxic as a result, is probably the most harmful factor to the biota. However, the effects of dif ferent stress factors often add to each other. Therefore, the cadmium in the Baltic Sea may imply extra stress for certain organisms. Organisms in the seas surrounding Sweden accumulates more cadmium at lower salinity, and the concentrations in certain organisms (e.g. Baltic Herring) are also in creasing over time. Cadmium concentrations in water of the Swedish seas (0.02-0.05 pg L" *) do not exceed reported LOECs, while LOECs for sedi ment-dwelling organisms are exceeded in certain areas of the Baltic Proper.

Generally, the diffuse contamination of cadmium in urban soils is not re markably high, e.g. concentrations in parks in Stockholm usually represent an enhancement less than four times the average concentration in Swedish agricultural soils. Still effects on biota may occur in certain areas.In indus trial areas, the concentrations in soil is sometimes markedly enhanced, e.g. > 30 times in the areas around the RonnsMrsverken smelters. Such high concentrations may affect soil organisms, and the uptake in plants. Accumu lation in plants may cause risks for both the plants themselves, as well as for birds and mammals feeding on them.

Little is known about the long-term effects of cadmium leakage from old landfills, as well as from those in use.

6 More than 23 tonnes of cadmium is annually deposited on landfills in Sweden today. About 1 % of this amount leaches to ground and surface waters.

Water bodies in urban areas are often highly disturbed and also enriched with cadmium, to concentrations exceeding LOECs for aquatic organisms. However, it is impossible to distinguish effects of cadmium from the effects of other pollutants, and disturbing factors, prevailing in these environments.

All inputs of cadmium, through atmospheric deposition, with fertilisers, with sludge or as diffuse leakage from articles of consumption, will put extra pressure on the Swedish environment, and should therefore be avoided.

7 Sammanfattning

Foreliggande rapport syftar till att sammanfatta tillstandet i den svenska miljon, med avseende pa forekomst och effekter av kadmium.

Framst tva faktorer gor den svenska miljon speciellt kanslig for extra tillskott av kadmium. Dels innebar berggrundens laga vittringshastighet i Sverige att manga sjoar bar ultramjukt vatten och att de fiesta jordama bar lag buffertkapacitet. Detta medfbr att den pagaende forsumingen av mark och vatten i Sverige dkar mobiliteten av kadmium, samt att mark- och vattenlevande organismer redan paverkas av forsumingen och darmed &r mindre toleranta for kadmiumexponering. Dels medfbr den laga salthalten i Ostersjdn att ekosystemet ar utarmat och att manga organismer lever nara sin fysiologiska toleransniva, samt att biotillgangligheten av kadmium ar hogre jamfort med i rent marina system.

Uppmatta halter av kadmium i skogsmark, akerjord och sotvatten ar forhojda i forhallande till bakgrundsvarden, med en generell trend av okande halter fran norr till sydvast. Detta visar pa stark paverkan fran deposition av lufttransporterat kadmium, och forsurande amnen fran Mel- laneuropa. I sydvastra Sverige ar haltema forhojda 6-8 ganger i skogsmark- ens marlager, och upp till 30 ganger i de sura sjoamas vatten (pH runt 4.5), jamfort med de generella bakgrundsvardena (0.17 mg Cd kg" Us respektive 0.01 p.g Cd L"l). I de svenska havsomradena okar kadmiumhalten generellt med minskande salthalt.

Begransningar av kadmiumutslapp till miljon har medfort att depositionen av kadmium i Sverige har minskat med ca 50 % under de senaste tva artion- dena. Netto-ackumulationen av kadmium i skogens marlager har upphort i de fiesta omraden i Sverige. I de nordligaste delama ar detta troligen en direkt effekt av den minskade depositionen, medan den huvudsakliga or- saken till detta i sodra Sveriga, ar att forsumingen har medfort ett okat utlackage av kadmium fran markens bvre skikt. Pa grund av forsumingen pagar for narvarande en omfattande omfordelning av kadmium, fran mark ens ytskikt till djupare jordlager och sa smaningom till avrinningsvatten och sjoar. Detta aterspeglas i forhojda kadmiumhalter i sma backar och sura sjoar i sodra Sverige. Vattendrag i de mindre forsurade omradena i Norrland uppvisar minskande kadmiumhalter.

8 De toxikologiska data som firms angaende effekter av kadmium i mark och markvatten ar fa och inte direkt applicerbara pa svenska jordar. Uppmatta koncentrationer av kadmium i skogs- och torvmark (upp till 2 mg Cd kg' Idw) och i surt markvatten (5 pg Cd L'l) i sodra Sverige ar dock sa pass hoga att effekter pa mikrobiologisk aktivitet kan befaras. Riskkarakteriser- ing enligt vagledningsdokumentet i EU:s program for existerande amnen styrker denna farhaga. Enligt samma riskbedomningsmetodik, tillampad pa jordbruksmark, kan det inte uteslutas att aven de halter som uppmatts i svenska jordbruksjordar utgor en risk for marklevande organismer.

De kroniska effekter som pavisats pa njurfunktionen hos skogssork i nar- heten av Ronnskarsverken, kan hero av den kadm iumexponering de utsatts for. Skadoma tycks uppsta vid halter i njure > 4 mg kg'l vs, halter som aven uppmatts i skogssork fangad i Skane. Det ar alltsa mojligt att denna typ av effekter aven forekommer hos djur i sodra Sverige, till fbljd av exponering for kadmium fran diffusa kallor.

Upptaget av kadmium i vaxter okar generellt vid minskande pH. Vissa trad (speciellt salg), buskar och svampar i Sverige ackumulerar kadmium till halter som kan vara skadliga for vaxtema sjalva, och som kan innebara ett hot mot vaxtatande faglar och daggdjur.

Manga sjoar i sodra Sverige ar kraftigt paverkade av forsumingen, vilket bl.a. lett till utarmning av flora och fauna. Samtidigt okar bade totalkoncen- trationen av kadmium och andelen kadmium i jonform (fritt kadmium) vid minskande pH i vattnet. Forekomst av kroniska effekter av kadmium ar darfor mest trolig i fbrsurade sjoar dar biotillgangligheten av kadmium ar stor och dar organismema dessutom kan vara paverkade av lagt pH. I manga av de fbrsurade sjoama i sodra Sverige ar kadmiumhalten i vatten hogre an lagsta uppmatta effektkoncentration for sotvattensorganismer (LOEC, 0.17 pg Cd L'l). Halter > 0.3 pg Cd L"1 har uppmatts i de sura sjoama, medan halten i sura backar och alvar ar < 0.15 pg L'L

Ostersjon ar kraftigt paverkad av manga olika fororeningar. Eutrofieringen, som medfort att en stor del av bottnama ar syrefria, ar troligen den faktor som har storst negativ inverkan pa Ostersjdns organismer. Andra stressfak- torer, sasom forhojda kadmiumhalter, kan innebara extra pafrestningar. I svenska havsomradena med lagre salthalt okar dessutom tillgangligheten av kadmium for organismema, vilket t.ex. aterspeglas i haltema i stromming och blamussla som ar hogre i Ostersjon an i Kattegatt. Haltema i stromming fran Ostersjon har okat under det senaste artiondet.

9 Kadmiumhalten i vatten i de svenska haven (0.02 - 0.05 gg L" 1) overskrider ej tillgangliga LOEC for vattenlevande organismer, medan LOEC for sedi- mentorganismer overskrids i sediment i vissa delar av egentliga Ostersjon.

Generellt sett ar kadmiumhalten i mark inte extremt hog i urbaniserade om raden, paverkade av diffusa utslappskallor. Till exempel har halter < 0.5-0.9 mg kg'Its uppmatts i Stockholms parker, dar det hogsta vardet representerar knappt fyra gangers fdrhojning jamfort med medelhalten i jordbruksmark. Inom begransade omraden i staden ar haltema dock sa hdga att effekter pa biota kan befaras. I vissa industriomraden, sasom runt Ronnskarsverken, ar markens kadmiumhalt forhojd >30 ganger, till koncentrationer (>15 mg kg' Its) som troligen innebar skadliga effekter pa markorganismer och sma daggdjur. Upptaget i vaxter i dessa omraden kan innebararisker saval for vaxtema sjalva som for djur som ater av dem.

I dag deponeras mer an 23 ton kadmium arligen pa soptippar i Sverige. Ungefar 1 % av denna mangd lacker till grund- och ytvatten. Kunskapen ar dalig angaende effekten av detta lackage, speciellt som en forandring av sammansattningen av det deponerade materialet forvantas i framtiden (mindre organiskt material).

Storstademas vattensystem ar ofta kraftigt stdrda av olika fororeningar. Kadmiumhaltema overskrider ofta LOEC-varden for akvatiska organismer. Det gar ej att urskilja effekter av kadmium fran effekter av andra kraftigare stomingar, sasom syrgasfria bottnar till foljd av eutrofieringen. Eventuella forbattrade syrgasfbrhallanden kan innebara att det kadmium som ackumul- erats i bottnarna blir tillgangligt, och darmed utgor en risk for aterkoloniser- ande organismer.

Alla ytterligare tillskott av kadmium; via atmosfarisk transport och deposi tion, via godsel, via spridning av rotslam, eller via emission fran produkter, innebar en okad belastning av svenska miljder, dar effekter av kadmium redan kan forekomma.

10 1. Introduction

The forest ecosystem in Sweden is an important natural resource for biodi versity, for recreational purposes, and for the Swedish economy. The many lakes and the beautiful archipelagos are popular recreational areas for Swedes, but also for many other Europeans. The legal right to enter private land and freely pick berries and fungi, attracts many Europeans. These val ues and the concept of sustainable development implies the long-term pro tection of this environment.

The Swedish forest ecosystems are affected by several environmental men aces. For instance, acidification has damaged forests and caused diminishing fauna and flora in several lakes in south-western Sweden. In addition, high mercury concentrations in fish has led to recommendations from the authorities of a restricted consumption of fish caught in a large number of remote forest lakes.

Increased atmospheric deposition of air-borne heavy metals, during the last century, has resulted in an increased load of these metals in soils. In general, the acid rain increases the leakage, the mobility and the biological uptake of the accumulated metals.

Even though the anthropogenic emissions of cadmium (Cd) in Sweden have decreased markedly during the last two decades, cadmium concentrations in some terrestrial and aquatic organisms show increasing trends. One reason for this is that the accumulated cadmium is mobilised, and with that has become more available, as a consequence of acidification. Another reason is that cadmium still is added to agricultural soils with fertilisers and through atmospheric deposition.

The present report aims at assessing possible effects of cadmium in the Swedish environment. Reviews prepared for and from the OECD Cadmium Workshop, held in Sweden in, 1995, is cited in the assessment without checking the source references. Very recent Swedish data, not yet published in scientific journals, are taken from summaries by Bergback and Johansson (1996) and Hedlund (1997). This report does not include exposure and ef fects on humans, the cadmium fluxes in the technosphere, or the effects of cadmium in fertilisers and accumulation in crops. (However, effects on or ganisms exposed to cadmium in agricultural soils, are considered.) These subjects are assessed in Berglund et al. (1997), Bergback (1997), and Hell- strand and Landner (1997), respectively.

11 2. Naturally occurring cadmium

The average abundance of cadmium in the Earth ’s crust is 0.1-0.15 mg kg~l (Eggenerg & Waberg, 1997), but the concentrations in individual rock types can vary over four orders of magnitude (0.02-200 mg Cd kg*l) (Garrett, 1995). The distribution and mobility of cadmium in the biotic and abiotic environments is closely associated with the behaviour of calcium and zinc (ibid.). Calcium and zinc are essential micronutrient for plants as well as animals and man. Cadmium partly derives its toxicological properties from its similarities with these elements.

In remote areas not influenced by ore bodies, surface soil concentrations of cadmium typically range between 0.1 and 0.4 mg kg~l. Levels of up to 4.5 mg kg"l have been found in volcanic soils (summarised in OECD, 1995b). Most undisturbed soils contain cadmium levels in the range of 0.01 to 2.0 mg kg"l, with a calculated world-wide mean of 0.5 mg kg~l (Eggenerg & Waberg, 1997).

2.1. Background concentrations in Sweden

The epithet ‘background concentrations ’ is commonly used, but the defini tion can be either pre-industrial concentrations or current concentrations in remote areas. The former definition is usually used for sediment concentra tions, while the latter is used for water and soil concentrations. In 1987, SEP A (Swedish Environmental Protection Agency) estimated concentra tions from remote areas in Sweden (Table 1). Other more recently discussed background estimates are briefly summarised below.

The regions and water-bodies referred to in this report are specified in Figure 1.

12 Table 1. Estimated concentrations of cadmium in remote areas in Sweden reported bySEPA (1987) (summarised by Hedlund, 1997). media concentration

Air 0.1 (ng m'J)

Lake water, not acidified 0.01 (Ugl/)

Sea water 0.01-0.03 WL')

Surficial ground water <0.01 (pgL')

Lake sediments 0.3-0.6 (mg kg"1 dw)

Marine sediments 0.1-0.5 (mg kg'1 dw)

Forest soils, humic layer 0.4 (mg kg"1 dw)

Agricultural soil 0.15 (mg kg'1 dw)

13 Kiruna

NORTHERN SWEDEN Bothnian Bay ,

:mea« 'Gulf of Bothnia swSden FINLAND

Bothnian Sea

CENTRAL SWEDEN

Gulf of Finland

Baltic Sea Skagerrak \ R SOUTHERN Webc %" SWEDEN Vf P J North Kattegat V N Sea

Baltic Proper

Figure 1. Regions and water-bodies in Sweden, referred to in the report.

As a result of long-range transport of airborne pollution, all water bodies are more or less influenced by anthropogenic activities.

14 However, remote parts of northern Sweden and Finland is relatively unaf fected, and fresh water data from this area have been used to provide an overall picture of current background concentrations. The data range be tween 0.005 and 0.01 pg L'l (SEPA, 1993). A median value for cadmium in Swedish groundwater was estimated to 0.02 pg L'l by Ledin et al (1989, cited in SEPA 1993). True background values for Baltic Sea water are es pecially difficult to determine since all the different basins are connected, and are more or less affected by discharges from anthropogenic activities. The present background range is 0.01 -0.03 pg L" 1.

Concentrations in ‘pre-industrial ’ sediment layers, below 20 cm depth, in lakes are 0.3-0.6 mg kg'l dry weight (dw) in south-western Sweden (Johansson 1980), and 0.1-0.4 in middle and northern Sweden (Johansson, 1989). A generalised background concentration of 0.4 mg Cd kg'l dry weight was therefore proposed for Swedish lake sediments (SEPA, 1993).

In the Baltic Sea, concentrations in ‘pre-industrial ’ sediment layers (10-20 cm) are 0.4 mg Cd kg'l dry weight for the Bothnian Bay, 0.1 for the Bothnian Sea, and 0.3 mg kg'l dry weight for the western Baltic Proper. In Skagerack outside the Swedish west coast, the concentration is 0.17 mg kg'l dry weight (Borg & Jonsson, 1996; SEPA, 1993).

Cadmium concentrations in Swedish soils vary naturally depending on the parent material (see Hellstrand & Landner, 1997). Johansson et al. (1995) have recently recalculated the background concentration in forest soil and came up with a value of 0.17 mg kg'l dry weight. 3. Sensitivity in the Swedish environment

Linkage of the exposure and effects on ecosystems depends on the bioavail ability of cadmium. The bioavailability and/or effects vary between envi ronments due to differences in soil properties, climate, salinity, microbial activity, species composition, synergistic effects from other stress factors, etc. Therefore, environmental factors are important to consider in determin ing the availability of cadmium for plant and animal uptake, or its capacity to be transformed to other environmental compartments.

15 3.1 Poor soils and sensitivity toacidification

Sedimentary bedrock dominates in Central Europe, while, in Sweden, sedimentary bedrock only occurs in the southern-most part (Skane) and in some limited areas in the central (around the lake Siljan, in the county of Skaraborg, on the islands of Oland and Gotland) and northern-most parts (the high mountains). The bedrock in Sweden as well as in Finland and Canada, is mainly magmatic. During the last glacial period, most areas of these countries were covered with ice, and the soils were scraped of with the ice movements. This, the shorter time span when biological production of soil has occurred, and the slow weathering of magmatic rocks, has led to thin soil layers in these areas compared to most of Central Europe.

As a consequence, most Swedish soils are weakly buffered, have a low pH, and are vulnerable to the effects of acidification, and hence the addition of acidic fertilisers (Figure 2). In addition, the combination of relatively high precipitation and low temperature in south-western Sweden results in a surplus of precipitation over evaporation. This causes an efficient washout of base cations from the soil and tends to reduce the buffer capacity of the soil (Hellstrand & Landner, 1997). Figuer 2. Relative sensitivity to acidification in the European soils (the darker the more sensitive). Modifiedfrom Chadwick & Kuylenstierna (1990), with permission from Stockholm Environment Institute

17 The forest soils in Sweden are podsols of moraine origin, with a marked organic surface layer, the mor layer. The decomposition rate of the mor layer is very slow, the half-life of the carbon being estimated to 250 to 300 years (Andersson etal., 1991). The metal concentrations measured in the mor layer are thus the result of the accumulated deposition over decades or centuries.

Figure 3. The Swedish pH situation in a) humic layer of forest soils (map from Internet, the Swedish University of Agricultural Science) b) lake water (unpublished data from the Swedish Monitoring Programme, A. Willander, pers com.).

18 Most of the forest areas are coniferous, which further contributes to a lowered pH in the soils. The acidic situation in the Swedish mor layer is demonstrated in Figure 3a. The atmospheric deposition of acidifying substances together with the poor buffering capacity in the Swedish soil, and hence the generally soft character of Swedish waters, has led to acidification of lakes (Figure 3b) and groundwater. In the winter 1990, about 15 000 of the 84 000 Swedish lakes (> 1 ha) had pH values below 5.5 (Bernes, 1991). Most of the acidic lakes were less than 10 ha. In autumn 1995 lakes larger than 4 ha were monitored and it was estimated that about 10 % of the Swedish lakes of that size (56 000 lakes in total) had pH < 6, while 2.5 % had pH < 5 (unpublished data from the National monitoring Program; A. Willander, pers. com.). The medium pH value was 6.8. On reason for the appearent difference between the two investigations is the sampling date, i.e. pH is usually lower during winter. Another reason is that lakes with an area between 1 and 4 ha not were included in the latter study, concomitant with the fact that low pH is more frequently measured in smaller lakes.

Many Swedish lakes and water-courses have ultra soft water, with a hardness below 0.5 meq L'l defined as base cation content (<25 mg CaCOg ), which may increase the toxicity of cadmium (Bernes, 1991).

Lowered pH affects e.g. osmoregulation in the animals, a stress factor leav ing less energy for growth, reproduction and tolerance to other pollutants. Organisms at all trophic levels are affected. For instance, several fish spe cies disappear when pH reaches below 5.5 (Herrman et al., 1993).

3.2 The Baltic Sea, something between a lake and a sea

The Baltic Sea is a semi-enclosed and markedly stratified sea, and consti tutes one of the largest brackish water areas in the world: It has a stable, low salinity and practically no tides. A large supply of freshwater from the rivers mainly in the north, in combination with the denser salt water entering the Baltic Sea from the North Sea, causes a stratification in salinity as well as a salinity gradient from the Bothnian Bay (having a salinity of 2-3 %o) to the Danish sounds (15-20 %o) (Kautsky & Andersson, 1997).

There is a large input of eutrophicating substances into the Baltic Sea, which causes oxygen depletion in the bottom waters of stratified areas. About 100 000 km2 of the deeper bottom substrate of the Baltic Proper and the Gulf of Finland lacks macrofauna owing to anoxic conditions (Elmgren, 1989).

19 Another important factor to consider for the Swedish seas is the difference in residence time for water in the different basins, ranging from 25-30 years in the Baltic Proper to some weeks in Skagerack (SEPA, 1991).

Organisms in the Baltic Sea are strongly affected by the salinity gradient. The harsh environment has lead to fewer and smaller species than in seas or freshwaters (Kautsky & Andersson, 1997). Experiments have shown that common species, such as blue mussels (Mytilusedulis), bladderwrack (.Fucus vesiculosus) and amphipods (Gammarus spp), live close to their limit of physiological tolerance. Increased stress in the form of pollutants bring the organisms even closer to, or above this limit. The vulnerability of the Baltic Sea ecosystem is further increased by the fact that the accumula tion and toxicity of certain pollutants increases as salinity decreases (Kautsky & Tedengren, 1992). 4. Cadmium in air

4.1 Concentrations

Cadmium concentrations in air are usually less than 1 ng nr 3 in remote, uninhabited areas. Cadmium released to the atmosphere (mainly from combustion of coal) is predominantly associated with aerosols and fine particles, and will be transferred to other environmental compartments via wet or dry deposition (OECD, 1995b). The estimated yearly emissions to the atmosphere from the whole of Europe was about 900 tonnes, in the beginning of the 1990 ’s (Pacyna, 1994). In 1990, cadmium emissions from point sources in Sweden was estimated to less than 5 tonnes, while the total airborne deposition of cadmium in Sweden was about 20 tonnes, indicating large contributions from transboundary transported cadmium (OECD, 1995b).

According to a review of airborne cadmium levels in Europe (WHO, 1987 cited in Hutton, 1995), annual means in rural areas ranged from <1 to 5 ng m*3, compared with 5-15 ng nr 3 in urban areas, and 15-50 ng nr 3 in industrialised areas. However, most of the references used in the review were dated from the early 1970s.

More recent measurements (late 1980s) in rural areas of Central Europe showed concentrations between 0.1 and 0.8 ng m*3(summarised by Jensen & Bro-Rasmussen, 1990; Hutton, 1995). Kruger and Petersen (1993) modelled yearly average cadmium concentrations in air 1985, in European rural areas. 20 Estimated concentrations for central Europe ranged from about 0.15 to 2.5 ng m"3. The modelled averages for northernmost Sweden were about 0.02 ng nr 3, while the concentrations in the southernmost part were 5-10 times higher (0.2 ng nr 3 in Skane).

4.2 Deposition

Hutton (1995) summarised cadmium deposition data from 1986, reported for the EC countries. The deposition in remote areas was 0,05-3 g ha-l-y-1 and in urban areas 1,5-100 g ha -1y-1. In 1992, the average cadmium deposition in Sweden was 0,1 g ha-ly 1 in the northern parts and 0,5 g ha-lyl in the southern parts (OECD, 1995b).

The wet deposition in Sweden was in 1996, about 0.5-0.6 g ha -1 in the southern part, about 0.4 g ha" 1 in central Sweden, and about 0.15 g ha -1 in the northern part (the location of the sampling stations are shown in Figure 21) (unpublished data from the National Monitoring Program; K. Kindbom, IVL, pers. com.).

21 Figure 4. Concentrations of cadmium in mosses sampled in northern Europe in 1990 (From Rhiiling, 1994).

22 Moss analysis, as a means of surveying atmospheric heavy metal deposition, is based on the fact that carpet forming mosses obtain most of their supply of chemical substances directly from the deposition (Rhiiling, 1994). The concentrations of pollutants in mosses are therefore an indirect measure of atmospheric deposition. The cadmium concentrations in mosses have been monitored in Sweden every fifth year since 1975, and in the later investiga tions, the examined area has been expanded to include the whole Scandi navia and other parts of Europe.

Results from the moss analyses express a regional trend with increasing cadmium concentrations going from the north to the south. The concentra tions were below 0.2 mg kg'l in northern Scandinavia, 0.4-0.5 mg kg'l in south-western Sweden and > 2 mg kg'l in the industrial areas of southern Poland (Figure 4) (Rhiiling, 1994).

The marked south-north gradients in cadmium concentrations illustrates the strong influence of transboundary atmospheric transport of cadmium from central Europe. However, moss analyses and cadmium concentrations in wet deposition show that cadmium deposition in Sweden has decreased during the last two decades (section 8).

The deposition and build up of cadmium in soils represents a major source of environmental exposure to cadmium (OECD, 1995). 5. Cadmium in terrestrial ecosystems

5.1 Concentrations and mobility

5.1.1 Forest soil

Concentrations of cadmium in the mor layer of forest soils were monitored in 1983-84 (Andersson et al., 1991). The concentrations showed a large- scale pattern with the highest values in southern Sweden and decreasing concentrations towards the north, the same pattern as for concentrations in deposition and mosses.

Regional averages of cadmium concentrations in the mor layer ranged between 1.0 mg kg'l in the south and 0.4 mg kg'l in the north. About 2 mg Cd kg'ldw has been measured in surface layers (0-20cm) of peatlands (J. Eriksson in Bergback & Johansson, 1996).

23 Locally enhanced cadmium concentrations in forest soils are attributed to larger point sources, such as the Ronnskar smelters. The concentrations in mor layer are > 5 mg kg"l dry weight, within a distance of 15 km from the Ronnskar smelters (SEPA, 1993).

Historical records and background concentrations in sediments were used, together with the present levels in soils in remote areas in northern Sweden, to estimate background levels and enrichment factors for cadmium in forest soils. In the southern half of Sweden, the concentrations are 3-5 times background levels. The enrichment decreases to the north, but even in the northern-most part of Sweden the soil content is somewhat affected by long- range atmospheric transport and deposition of cadmium, probably by a factor of about 2 (Figure 5a) (Johansson et al., 1995). There are indications of enriched concentrations also in the B-horizon of the soils (15-25 cm below surface), in southern Sweden (M. Olsson, & A. Alriksson, in Bergback & Johansson, 1996).

Recent data indicate that cadmium concentrations in mor layer of Swedish forest soils at present are decreasing in most areas (B. Bergkvist in Berg back & Johansson, 1996) (Figure 5b). In northern Sweden, decreasing concentrations in the mor layer is probably a result of the decreased atmos pheric deposition. In southern Sweden, acidification has caused increased leakage rates of cadmium from soil surface layers which, together with de creased deposition, results in net outflow of cadmium from the mor layers. This indicates that cadmium is leaching from surface soils to deeper soil layers, and finally to the runoff water.

24 Figure 5. a) Relative increases in the concentrations of cadmium in mor layer of forest soils based on an estimated background concentration of 0.17 mg kg1 dw (Johansson et al., 1995). b)Yearly change (%) of total cadmium in Swedish forest mor layer. Positive values means net accumulation of cadmium in the mor layer while negative values indicates that the outflow of cadmium from the mor layer exceeds the accumulation (B. Bergkvist in Bergback & Johansson, 1996)

Cadmium is more weakly bound to soil particles than most other heavy metals, and soil pH is the principal factor controlling the stability and solubility of cadmium in the soil environment (OECD, 1995b; Butcher et al., 1992). This is exemplified in the diagram below, showing adsorption isotherms of different metals onto amorphous oxyhydroxides at varying pH (Figure 6). Almost no cadmium is adsorbed at pH < 5.5 and at pH as high as 7 only 40 % is adsorbed (Butcher et al., 1992).

25 % metal adsorbed

Figure 6. Effects of pH on sorption of uncomplexed metals onto amorphous oxyhydroxide systems (modifiedfrom Butcher et al. 1992)

This effect is also seen in the Swedish environment, where cadmium in soil solutions is low (< 0.5 pg L'l) as long as soil pH is > 5. At pH < 4.5 the cadmium content in the soil solution often increases dramatically, reaching concentrations around 5 pg L~1 (Figure 7) (Bergqvist et al, 1989; B. Bergqvist, pers. com.).

Cd=e(9.634-2.146pH)

|2=0.41

Figure 7. Cadmium and pH in soil solution from profiles (0-50 cm) of Swedish forest soils (unpublished data from B. Bergqvist, pers. com.)

26 The pH in soil solution is often lowest in the upper parts of a drainage area, while it increases in lower parts where the ground water level reaches the soil surface (outflow area). In such areas dissolved cadmium precipitates and accumulates and therefore constitute zones where cadmium may reach especially high concentrations. This was shown in a small catchment in Smaland (Sweden) where soil cadmium concentrations in the upper, more acidic (pH-3.8), part of the area was 0.7 mg kg" ' dry weight and increased to about 2 mg kg~l dry weight in an outflow area (pH=4.4) (J. Eriksson in Bergback & Johansson, 1996).

The studies of Swedish forest soils, summarised above, indicate that a large- scale redistribution of cadmium is occurring.

Cadmium in surface soils is mobilised due to acidification, and is transported to deeper soil layers, run-off, and lake waters.

5.1.2 Agricultural soils

High cadmium concentrations in crops have lead to more attention being paid to cadmium in agricultural soils. The relations between cadmium in soil, crops and fertilisers is extensively reviewed in Hellstrand and Landner (1997).

Hellstrand and Landner (1997) tabulated averages of cadmium concentrations found in normal agricultural topsoil ’s from EC member states. The values ranged from 0.06 (Finland) to 0.44 mg kg'l dry weight (UK).

In Sweden, the present average cadmium content in agricultural soils is about 0.26 mg Cd kg'* dry weight, with more than 5 % of the measured concentrations being higher than 0.49 mg kg"* dry weight (Hellstrand & Landner, 1997). A concentration of 0.2 mg Cd kg"l dry weight corresponds to about 0.6 kg Cd ha"l in the topsoil (Landner et al., 1996). During the 20th century, the cadmium content in Swedish agricultural topsoils has risen with about 30 %. In the uppermost 100 cm of the soil layer total cadmium currently increases with 0.01-0.03 % per year (Hellstrand and Landner, 1997).

Cadmium concentrations in drainage water from cultivated soils from seven different areas in Sweden, ranged between 0.027 and 1.11 pg L*1 (Johnsson, 1995). Draining measures of sulfidic soils (such as in certain areas of central Sweden) as well as replantation of agricultural soil with coniferous forests,

27 decreases soil pH and hence increases the mobility of Cd. As a result, cadmium concentrations in soil solution may increase.

Most European countries which have estimated net cadmium budgets for agricultural soil, have ascertained that this balance is positive, i.e. that cadmium is accumulating in the soil (Pearse, 1995). Only Finland has almost succeeded in achieving equilibrium, through managing cadmium inputs (fertilisers with low cadmium content, reduced air emissions) to the soils (Pearse, 1995). The load of cadmium to arable land in Sweden has to be reduced on average by 70 % in order to achieve a balance between input and output in the soil (Hellstrand & Landner, 1997).

Hellstrand and Landner (1997) estimated that the average cadmium influx with P-fertilisers to arable land in Sweden was 0.20 g ha* 1 year 1, account ing for 38 % of the total influx. In 1990, the average cadmium input to agri cultural soils in the EC countries, only from phosphate fertilisers, was about 2.5 g Cd ha* 1 year" 1, although the most dominating sources of influx was other than phosphate (Landner et al, 1996).

Waste problems in society can, in the long term, only be solved by recycling. Therefore, nutrients in urban sewage sludge should be returned to agricultural land, provided that the sludge is of a quality that not give rise to adverse effects. Today ’s input of cadmium on agricultural land through sewage sludge or manure only applies to a relatively small percentage of the total agricultural land in the EU countries. However, a long-term application of sludge to soil may result in a marked increase in cadmium contents of soil and plants (OECD, 1995b).

Compared with normal commercial fertilisers, addition of sewage sludge doubles the rate of cadmium increase in soils (Andersson 1991, cited in SEPA, 1993). However, due to the high contents of organic material, cadmium added with sludge is probably less available than cadmium added with fertilisers.

Local point-sources may affect cadmium concentration also in agricultural soils. In the vicinity of the Ronnskar smelters, a 3 to 10 times increase (compared to background levels) have been registered at a distance of 20 km from the smelting works (SEPA, 1993).

28 5.2 Accumulation in and effects on soil organisms

Few data are available from relevant studies on effects of metals on soil organisms. Tyler (1992) reviewed the available literature in order to esti mate critical concentrations (lowest concentrations for measurable adverse effects) for cadmium in forest mor layers. Microbial activity, measured as soil respiration and soil enzymes activity, were the mostsensitive parameters for forest mor layers, with critical soil concentration estimates between 3.5 and 7 mg kg' 1 dry weight. These critical concentrations should be regarded as upper limits, which under no circumstances should be exceeded (Tyler, 1992). Tyler concludes that a five-fold increase of cadmium concentrations in the mor layers of the Swedish forest soils may have inhibitory effects on soil biological activity. This applies regardless of the initial concentration in the soil (Tyler, 1992).

According to Johansson et al. (1995) enrichment of this order exists in southern Sweden and in large areas surrounding the Ronnskar smelters (Figure 5a). Marked inhibition (>10%) of soil biological processes has also been observed at distances up to 30 km from the smelters. These effects can however not specifically be addressed to cadmium contamination, since the area is severely polluted by other metals as well.

Cadmium, added to soil with nutrient broth, at a concentration of 0.5 mg L" 1 inhibited the growth of the bacterium Alcaligenes faecalis (Prahalad & Seenayya in WHO, 1992). Data on toxic cadmium concentrations for micro organisms in true soil solution is, however, lacking. A comparison with data for lake water could be relevant, although soil solutions are usually more acidic. Waara (1992) found that cadmium was very toxic to cellulose degra dation processes, when added to lake waters from different Swedish lakes. A 50 % inhibition was found at a cadmium concentration of about 3 pg L'l. Concentrations above this level have been measured in acidic forest soil solution (Figure 7).

Reduced breakdown of leaf litter and recycling of nutrients has also been attributed to metal pollution in the field, and cadmium appears to be the most potent metal at inhibiting litter degradation (WHO, 1992). Cadmium affects fungi, some species being eliminated after exposure to cadmium in soil. There is selection for resistant strains after low exposure to cadmium in soil (ibid.). Many (macro- and micro-) fungi are tolerant to metal exposure and can accumulate metals to very high concentration, up to twenty percent of the mycelian dry weight (Krantz-Rulcker, 1993). In laboratory Thricho- derma harzianum accumulated cadmium to approximately 50 mmol kg'l (~ 29 5 g kg~l) solid mycelium. For some fungi species, decreased pH results in increased cadmium accumulation (ibid.).

Witter (1992) reviewed the literature on toxicity of heavy metals in agricul tural soils. There were only a few studies available on effects of cadmium, and there was a high disparity between the studies. Most of the studies were carried out at neutral pH, which is not generally relevant for Swedish soils. In addition, critical concentrations estimated from laboratory tests does not take into account that populations of terrestrial organisms may develop tol erance to metals after long-term exposure. From laboratory studies (summarised in Appendix I) a LOEC value for cadmium exposure to micro organisms in agricultural soil was estimated to 2 mg Cd kg"l soil (total soil concentration 2.2 mg Cd kg~l, relative increase 14-fold). The observed ef fect was a reduction of the microbial nitrogen fixation.

Terrestrial invertebrates vary considerably in their sensitivity to cadmium. For instance, 9-week LC$QS for two different species of collembola (Orchesella sincta and Platynothrus peltifer) were 179 and 817 mg Cd kg"l soil, respectively. The NOECs (No Effect Concentration) for the same species were 4.7 and 2.9 mg kg~l soil (Van Straalen et al. 1989, in WHO 1992). The lowest available LOEC for exposure to cadmium in soil was found for grasshopper (Aiolopolus thalassinus), for which a significant reduction (15 %) in egg hatching was observed when exposed to 1.2 mg Cd kg~l sandy soil (dw) (Schmidt et al., 1991, in CEPA, 1994).

If applying the principles of the Technical Guidance Document (TGD, 1996) to estimate the risk for cadmium to cause negative effects in soils, the variation in sensitivity between organisms can be taken into account.

A Predicted No Effect Concentration (PNEC) can be determined from the lowest available LOEC, which was 1.2 mg Cd kg" 1 soil (dw) for grass hopper. According to the TGD a LOEC can be used to derive a NOEC with the following procedure: if the effect percentage of the LOEC is >10 and <20 %, NOEC can be calculated as LOEC/2. When applying this on the grasshopper-study a NOEC of 0.6 mg Cd kg" 1 soil is obtained. The lowest assessment factor of 10 can be applied since long term studies are available for at least three trophic levels, resulting in a PNEC of 0.06 mg Cd kg" 1 soil.

Due to the complex nature of the soil matrix the bioavailability of cadmium is highly variable and difficult to determine. According to the TGD it is important that both PEC and PNEC are based on similar levels of availabil ity. Partition coefficients (Kp) can be used to estimate the availability in

30 soils. However, in the monitored Swedish soils Kp data for cadmium are lacking. It may be assumed that if the cadmium is likely to have been added in an acid-soluble form and the pH of the soil is low (acidic), a significant fraction of the cadmium could be bioavailable. Andersson (1992) estimated that 40 % of cadmium in Swedish agricultural topsoils can be classified as easily soluble in the sence that this fraction would be soluble and mobile if soil pH drops below pH 5. Therefore, in the following calculations, PEC is estimated by multiplying total cadmium concentrations, measured in the field, by a factor of 0.4.

The PEC/PNEC ratio for average agricultural soil concentrations is 0.26 0.4/0.06 = 1.7. In 5 % of the agricultural soil the PEC/PNEC ratio is (at least) 0.49 0.4/0.06 = 3.3. Since these quotients are >1 it can not be ex cluded that effects of cadmium occur in Swedish agricultural soils. If the same assumptions are made for forest soil mor layers in southern Sweden, with an average cadmium concentration of 1 mg kg~l, a PEC/PNEC ratio of 1 0.4/0.06 = 6.7 is obtained.

Finally, some invertebrates can take up and store cadmium to very high levels (5000 mg/kg body weight) without apparent negative effects, however, they may pose a threat to predators.

5.3 Accumulation and effects in higher terrestrial organisms

Terrestrial mammals and birds are exposed to heavy metals mainly from their food. The food choice is therefore a crucial factor for accumulation and effects in these animals.

For instance, the capacity of certain fungi to accumulate cadmium to very high concentrations (section 5.2), might pose a threat to (macro-) fungi consuming organisms, e.g. roe deers. This potential threat, and a possible relation with the acidification in the Swedish environments, has to our knowledge not been investigated.

However, herbivorous mammals are generally less exposed to metals than small mammals feeding on invertebrates that inhabit surface soils (Ma, 1994). The general trend for cadmium concentrations in animals with different feeding regimes is as follows: small mammals feeding on soil organisms>omnivores> herbivores > predators (Nyholm, et al. 1996).

31 Most (> 80 %) of the body-burden of cadmium is in the liver and kidneys where it accumulates through time bound to metallothionein (MT) (Scheu- hammer, 1991). Being the critical organ of chronic cadmium toxicity, the kidney cadmium concentration offers an adequate estimate of the internal cadmium dose. Notice that the kidney concentrations discussed below, sometimes are reported per dry weight (dw) and sometimes per wet weight (ww).

In 1973-1976, cadmium was measured in the kidney of animals (moose, roe deer, reindeer, hare, badger and hedgehog) that were found dead in the nature (Frank, 1986). Cadmium concentrations ranged between 0.07 and 8.8 mg kg"l wet weight, with the highest concentration measured in badger (Meles meles). The badger represents an omnivorous terrestrial mammal, frequently found close to inhabited regions.

Free-living bank voles (Clethrionomus glareolus), captured in a gradient from the Ronnskar smelters, showed signs of toxic effects typical for kidney dysfunction, in voles with enhanced cadmium concentrations in the kidney (30-40 times) (Leffler & Nyholm, 1996). These effects appeared at kidney concentrations of 4 mg Cd kg" 1 wet weight, and were not found in bank voles from a reference station (Figure 8 ). One may argue that the area around Ronnskar is polluted with other metals, e.g. arsenic, mercury, and lead, which might have contributed to the effects in the bank voles. However, cadmium was the only element showing significantly different kidney concentrations in voles from the different sampling sites (Figure 8 ).

Kidney cadmium concentrations > 4 mg Cd kg" 1 wet weight have also been found in a considerable number of bank voles captured in southern Sweden, indicating that these animals might suffer from kidney dysfunction as well, due to accumulation of cadmium from diffuse sources (Nyholm et al., 1996).

Also the concentrations of cadmium and lead in liver of young pied flycatcher (Ficedula h. hypoleuca) in southern Sweden were in the same range as concentrations measured close to the Ronnskar smelters, where marked effects on reproduction and development among the flycatchers have been observed (Jonsson et al. 1994; Nyholm, 1993).

32 UProt foig 24h" 1 g-1b.w.)

1000 -

i x Cd-R (M-g g'1}

X = Vindeln □ = Burdn

UProt (pg 24b"" 1 g"’b.w.) = 135.6 + 24.1 * Cd-R {pg g-'); R2 = 0.22; p<0.023; N=23

Figure 8. Relation between proteinuria (UProt) and kidney cadmium concentration (Cd-R) in bank voles sampled at Vindeln and Burdn (90 and 4 km respectively from the Ronnskar smelters) (from Lejfler & Nyholm, 1996).

Cadmium enriched crops could be hazardous to seed-feeding birds. A diet dose of 4 mg Cd kg-1 have been proven to affect the behaviour of ducklings (OECD, 1995b). Concentrations measured in wheat grain, and other crops in Sweden, ranged between 0.008 and 0.207 mg kg-1 (summarised in Hellstrand & Landner, 1997), indicating that cadmium in Swedish crops does not affect the behaviour of seed-feeding birds. However, other chronic effects, such as kidney dysfunction, might be possible.

When the effects of local point-sources are ignored, large-scale geogra phical trends appear for cadmium-accumulation in biota: cadmium con centrations in liver of pied flycatcher nestlings were twice as high in southern Sweden (Skane) as in the inland of northern Sweden. Similar gradients were found for bank vole (Figure 9), common shrew (Sorex arcmeus), and starling (Sturnus v. vulgaris) (Nyholm et al., 1996).

33 R6n nska rsve rke n

0.35

0.3

0.25

0.2 fc

0.15 t

0.1

0.05

Vasterbotten

0.15

0.1 S 1 0.05>

skAne

Figure 9. Mean concentrations of cadmium (mg kg-^ww) in kidney of bank vole and in liver of piedflycatcher, sampled in southern Sweden (Skane), northern Sweden (Vasterbotten), and close to the Ronnskarsverken smelters. Data from Nyholm et al. (1996).

34 Lithner et al. (1995) measured cadmium in kidney of common shrew captured in two taiga regions in southern and northern Sweden (Boaberg and Vindeln, respectively) during 1986. The shrew kidney contained 1.5-2.1 times more cadmium in Boaberg than in Vindeln. In Boaberg, the average concentration was 17 mg kg'l dry weight (n=14) and the maximum concen tration 30 mg kg'l dry weight. This maximum value is 4 times lower than the critical concentration (105-120 mg kg'ldw), when kidney dysfunction appears in laboratory rats. Considerable regional differences for yearly increase of cadmium in moose (Alces alces) kidney were observed in Sweden in the beginning of the 1980s (Mattsson 1991, cited in Jonsson et al, 1994). The highest value (2.98 mg Cd (kg ww)'l y 1) was measured in southern-most Sweden and the lowest (0.88 mg Cd (kg ww)'ly 1) in the northern-most part, and the accumulation rate correlated with the degree of soil acidification. Cadmium concentrations in moose kidney sampled in central Sweden (Grimsd and Sigtuna) during 1980-1996, ranged between 0.5 and 6.1 mg kg'l wet weight (Hedlund, 1997; Stenman, 1997). For comparison, kidney-cadmium concentrations as high as 50 mg kg'l wet weight have been reported for moose and deer from Ontario and Quebec (Scheuhammer, 1991). (Kidney function/dysfunction was not investigated).

5.4 Accumulation and effects in plants

The fact that cadmium is more weakly bound to soil particles, compared to most other metals, makes it more readily available for uptake by plants (SEPA, 1993). There are also indications that plants accumulate more cadmium in acidified areas. One of the most important ways of decreasing cadmium uptake by plants is to maintain soil pore water pH above 6.5 (Johnston & Jones, 1995). However, pH in the B-horizon of the Swedish forest soils are with a few exceptions below 5.5 (SEPA 1991). In agricul tural areas throughout Sweden more than 50% of analysed soil samples have pH values < 6 (Hellstrand & Landner, 1997).

Concentrations of cadmium in moss at control sites in Europe are generally less than 2 mg kg'l dry weight, while concentrations near smelters are up to 30 mg kg' 1 dry weight. Plants that readily accumulate cadmium are Sam- bucus, Salix and Vaccinium. High levels on bark suggest that perennial structures accumulate more cadmium than short-lived organs (in review by Crowder, 1991). Cadmium accumulation in different tree species is largely varying. Recent results from a Swedish field study indicate that spruce and lodge pole pine (Pinus contorta) accumulated more cadmium than common pine (Pinus silvestris) and birch (Betula verrucosa).

35 In an area, dominated by Pinus contorta, the trees contained three times the amount of cadmium in the mor layer (per square meter ground) (A. Alriksson & H. Eriksson, cited in Bergback & Johansson, 1996). Johnsson (1995) summarised measured cadmium concentrations in trees and crops in Sweden. Wood of poplar (Populus sp) and sallow (Salix sp ) showed the highest concentration potentials, and extremely high values (1147 and 7.7 mg kg'* dw, respectively) were measured in trees from metal polluted areas. The concentrations in these species, growing in low contaminated areas, were 0.4- 3.3 mg kg"* dry weight. Other investigated trees all had con centrations below 1 mg kg" 1 dry weight in woody parts. The highest con centration reported in an earlier review of concentrations in wood and foliage of plants from southern Sweden was 1.5 mg kg"* (Balsberg Pahlsson, 1985). Higher concentrations (4.8 mg kg"*), that were close to the critical concentrations discussed below were reported for roots (ibid.).

Symptoms of toxicity in plants include reduced growth with chloriosis and necrosis. Thresholds of toxicity vary, but are generally not more than 10 mg kg" * dry weight (in the plant tissue) and for several species critical concen trations in shoots and foliage have been set to 4-5 mg kg'* dry weight. In culture, 62 pg L"* and 5 uM (550 pg L" *) cadmium inhibited root growth of alder (Alnus rubra) and spruce (Picea abies) respectively. Increased turgor pressure and transpiration was observed in plants exposed to 10 pg Cd L" * (in reviews by Balsberg Pahlsson, 1985 and Crowder, 1991). Most toxicity data are from laboratory studies, where cadmium was added to the nutrient solution. No field observations of such effects have been reported (OECD, 1995b).

However, it can not be excluded that cadmium in soil solution in acidified coniferous forests in Sweden occasionally reach levels close to the lowest observed effect concentration (10 pg L**) for cadmium-effects on plants (compare Figure 7).

The high accumulation rate of cadmium in sallow has lead to ideas that growing of this species could be a biological method to clean metal contaminated soils (Johnsson, 1995). The produced sallow could then be used for bioenergy. On the other hand, the predicted future increase of the use of biomass as a source of energy, together with the planned restoration of the mineral nutrient balance in forest soils by recycling the wood ashes, have led to concern for increased cadmium accumulation in the forest soils. Temporally increased cadmium concentrations in soil solution from 0.1 to 0.7-1.7 pg L"1 was reported after addition of 3-6 ton ha"* granulated woodash. 36 The concentrations in the mor layer 4 years after addition of 2, 7, and 10 ton ha~l granulated woodash had increased by 17, 56, and 194 %, respectively (Lundborg, 1994).

5.5 Conclusions - effects in the terrestrial environment

Based on measured cadmium concentrations in the soils, and the critical enhancement levels estimated by Tyler (1992) and Witter (1992), it is likely that chronic effects on soil organisms occur in certain areas in Sweden, especially in forest soils in southern Sweden and in agricultural and forest soils close to point sources. In addition, it can not be excluded that the general large-scale enhancement that is reported for cadmium in Swedish agricultural soils have effects on soil organisms.

The main exposure route of cadmium to plants and probably to most soil fauna is via the soil pore water. Measured concentrations in soil solution and data on toxicity to microorganisms in water indicate that cadmium concen trations in forest soil pore water in Sweden may reach hazardous concentra tions. Acidification, and measures such as draining and replantation of for est and agricultural soils, causes increased concentrations and mobilisation of hydrogen ions as well as cadmium in the soil solution. The consequense of this is a large-scale redistribution of cadmium from surface to deeper soil layers, and runoff water. The cadmium also becomes more available to or ganisms, due to solubilisation and changed chemical speciation in water. This may increase the risk of toxic effects of cadmium to soil organisms and plants. In addition, other acidification factors such as high concentrations of hydrogen and aluminium ions, may have put the organisms under constant physiological stress, making them more vulnerable to cadmium. However, data on toxic cadmium concentrations under such conditions are lacking.

Plants, especially trees, take up cadmium via the roots from the deeper soil layers. Increasing accumulation of cadmium in trees is therefore to be expected as long as acidification proceeds and the cadmium pool is not exhausted. Certain trees, accumulate cadmium to levels that might be toxic for the plants themselves. Today ’s cadmium accumulation in trees may also cause problems when recycling wood ashes from biomass burning.

Since the concentrations of cadmium are especially high in bark structures of plants, increased attention should be paid to herbivorous mammals (moose, hare and roe deer) that feed on branches and brushwood.

37 This concern is supported by the fact that the concentrations in these animals are increasing despite the fact that deposition has decreased.

Certain fungi can accumulate cadmium to very high concentrations, and acidification of soils may enhance the accumulation rate. Therefore, it can not be excluded that cadmium in fungi may pose a threat to animals feeding on fungi, especially in acidified areas.

Kidney dysfunction, possibly due to cadmium accumulation, exist in mammals close to point sources at kidney concentrations > 4 mg Cd kg" 1 wet weight. Kidney cadmium concentrations > 4 mg Cd kg" 1 wet weight have also been found in a considerable number of bank voles captured in southern Sweden, indicating that these animals might suffer from kidney dysfunction as well, due to accumulation of cadmium from diffuse sources. 6. Cadmium in aquatic ecosystems

Generally, cadmium may exist in water as the hydrated ion (Cd2+*6 H2O), as inorganic complexes with COg2-, OH", Cl", or SO42- ligands, bound in colloids or as organic complexes with humic acids (OECD, 1995b). The dissolved fraction, by means of in situ dialysis, of the total cadmium content in humic water is usually greater than 50 %, at pH-values below 7. This places cadmium in the same category as extremely mobile elements like zinc and nickel. The dissolved fraction increases further in acidified waters, in which also the total concentrations are elevated.

38 Dissolved Cd fraction Dissolved Cu fraction • TOC * 5.0 mg/t 6 TOC «5.0 mg/1 © 100 Pa-0.661 * 100 © • « o® a o \ ® 0 • i/ \ ° • y*a i j ■so T / 3 50 ' * J r.-0,7606*" 1 h • \ t ^k5 S.C 6.0 20 15 10 5 5.0 6.0 to 'is to s 7.0 TOC eg/l PH TOC mg/1 PH

Dissolved Pb fraction Dissolved Al fraction C'.I 1%) > •100 O -too ® if I \ r*-Q,750$ \® {o onlyt T P,-0.578 •* h a r,-0.6137** P 6>- so . X

T ij : 1 * .•VH j J > ^kS 5.0 6.0 20 15 10 i 4,5 5.0 6.0 to 15 10 5 7J0 TOC eg/1 PH TOC mg/1 pH

Figure 10. Influence of pH and TOC (total organic carbon) on the dialysable fractions of Cd, Pb, Cu andAl in 17 oligotrophic forest lakes (< 2 km?, hardness 0.14-0.53 meq L~f in Sweden. The dialysable fraction (< 2.4 nm) consists offree ionic species, inorganic complexes and possibly some low molecular weight organic complexes. The symbols with standard deviations represent mean values of 3-4 parallel measurements. Levels of significance: * = p < 0.05, ** = p < 0.01 (from Borg & Andersson, 1984).

In Swedish oligotrophic lakes, about 60-100 % of the cadmium is dissolved (separated by in situ dialysis, pore-size 2.4 nm) at pH 6.0-4.5 and about 10- 60 % at pH 7-6. The dialysable fraction is not determined by the organic content of the water (TOC), as is the case for other metals (Borg & Andersson, 1984). No significant correlation was found between the dialysable cadmium fraction and TOC (Figure 10). In Dutch rivers, where pH is generally higher, the dissolved fraction range between 9 and 34 % of the total cadmium concentration (Hutton, 1995). Cadmium can substitute for calcium when calcite is formed, a mechanism that may scavenge cadmium from the water phase (Tesoriero & Pankow, 1996) and/or decrease the bioavailability of cadmium in calcite rich areas, such as the Netherlands.

6.1 Concentrations

Aritmethic means of total concentrations of cadmium in different categories of water are shown in Figure 11.

39 Cadmium in water (jjg/L)

-LOEC freshw. % ,1 - ,08 ,06 sgs ,04 if S£S NSea ,02 g T S^M $ Rivers

,01 ▼ Marine ,008 w Aliarrt 0 Lakes ,006 T ,004 # Brackish Figure 11. Total cadmium concentrations in different categories of water, expressed as arithmetic means. Lowest observed effect level (LOEC) for cadmium in freshwater is indicated. (Sw = Sweden, Fi = Finland, N = north, S = south, M = middle) (forest lakes: Borg, 1984 & Verta et al, 1990; rivers: Swedish Monitoring Program; Baltic Sea, North Sea and North Atlantic: Kremling et al, 1987).

6.1.1 Rivers and lakes

Background concentrations measured in various lakes and streams in Northern Sweden ranged between 0.005 and 0.01 fig L" 1, while the mean concentrations measured in some watercourses draining into the seas around Sweden ranged from 0.009 to 0.022 gg L"1 (SEPA, 1993).

Cadmium concentrations in river and lake waters in Sweden increase from north to south, as does acidification and air-bom cadmium. Negative correlations between cadmium and pH in Swedish river and lake waters are observed (Figure 12).

40 Northern Sweden * Riven

3 0.08.

a 0.06.

0.3 -r

Southern Sweden

0.2-

r 0.08-

S 0.06-

0.04-

0.02-

0.00-1

Figure 12. Concentrations of Figure 12. Concentrations cadmium in relation to pH in a) of cadmium in relation to waters from brooks and rivers in pH in b) Lake water from northern and southern parts of south-western Sweden Sweden (n=1153). 10, 50 and 90 (modifiedfrom SEPA, percentiles are shown in the 7993 ; graphs (from Johansson et a/7995)

In southern-most acidified areas, pH is likely to be the most causative factor for high cadmium concentrations in water, making cadmium levels in thou sands of acidified lakes as high as 0.1-0.3 pg L"1 (Lithner & Borg, 1995; Johansson et al., 1995; SEPA, 1993). At pH 5, cadmium concentrations exceeds regional background concentra tions by a factor 4-8 (Figure 11) (Lithner & Borg, 1995). In 1995 cadmium was measured in water from about 1 200 lakes, with lake areas > 4 ha (within the Swedish Monitoring Programme). The evaluation of the data is not yet completed, still, a medium cadmium concentrations has been esti mated to 0.015 pg L~l. The concentrations in lakes with pH <5.5 mostly range between 0.02 and 0.17 pg L~l, but concentration > 0.3 pg L~1 occa sionally occurs (A. Willander, pers. com.). For comparison, concentrations up to 4 pg L" 1 have been measured in small lakes in Swedish mining areas (SEPA, 1993).

The major reason for higher concentrations in acidified lakes is probably increased leakage from soils in the catchment areas. Since 1986, cadmium concentrations have been monitored in different types of watercourses throughout Sweden (G. Aim, unpublished data). From these data it is clear that, cadmium concentrations are comparatively high, coincident with very low pH values, in small forest brooks in south-western (acidified) Sweden (Figure 13). There are significant negative correlations (p<0.001, linear regression) between pH and cadmium concentrations in these brooks. Due to high variability in the data over the years, no general temporal trends are ascertained (section 8 ).

0.06 -r T 6

j ■Cd xpH ~|

Figure 13. Cadmium and pH (mean ± sd) in different types of watercourses in northern (N) and southern (S) Sweden, 1986-1995 (G. Aim, pers. com., data from the Swedish Monitoring Programme)

42 Borg et al. (1989) monitored the concentrations of different fractions of cadmium (total, particulate, filterable, and dialysable cadmium) in five soft- water forest lakes with differing pH (average 4.85-6.61) in southern Swe den. Most of the cadmium in water was in the dialysable form, especially in the more acidic lakes (Figure 14a). It was also cadmium in this fraction that increased with decreasing pH, resulting in increased total cadmium levels. The fixation of cadmium to the sediment (sedimentation) also decreased at pH below 5 (Borg et al., 1989), increasing the residence time of cadmium in the water phase (Figure 14b). Decreased pH in the sediment pore water may also cause increased leakage of cadmium from the sediments to the water phase. The two later mechanisms should cause decreased cadmium concen trations in surface sediments, compared to concentrations in deeper sedi ment layers deposited during less acidic conditions. Johansson (1980) also found lower concentrations in surface sediments (0-1 cm) compared to in subsurface layers (1-3 cm) in acidic forest lakes.

43 a) 8.10 □ CdT 8.88- H edp

B CdF

1,0.06- fit CdD . / L8.04-

0.02-

0.00- Lake: 2011 2812

PH: 6.St 6.15 5.45 5.25 4.85

Lake: 2011 2012 2013 2014 2015

Figure 14. a) Cadmium fractions (CdT = total, CdP = particulate, CdF = filtrable, CdD = dialysable; mean values and standard deviation) in lake waters from lakes with different pH.

b) Sedimentation of cadmium, as percentage of total input. The lakes are situated in Aneboda, Sweden and were sampled during 1981-1984. Each bar represent one year (modifiedfrom Borg et al, 1989).

In the late 1970s, cadmium concentrations in sediments of remote Swedish lakes were surveyed, (Johansson 1980, 1989). Assuming that concentrations in surface sediments (0-1 cm) reflect the load during the last 10-20 years, and that deeper sediments (ca. 20 cm) reflect preindustrial concentrations, then cadmium in southern part of Sweden were on average 3-10 times higher in newly deposited than in preindustrial sediments.

44 The corresponding figures for the northern areas were 1-3 times. Cadmium concentrations measured in surface sediments of forest lakes in southwes tern Sweden (measured 1977) were 1-6 mg kg'l while the concentrations in central and northern Sweden (measured 1979) were 0.4-2.4 mg kg'l dry weight. In Sweden, cadmium in sediments has not been monitored syste matically after that.

In Belgium, in the late 1980s, total concentrations around 0.1 pg L~1 were measured in surface waters (OECD, 1995b). OECD reported total cadmium concentrations between 0.1 to 1.02 pg L" 1, measured in EC Member state rivers in 1991 (Hutton, 1995). Several of these rivers are severely affected by anthropogenic activities.

Sediment concentrations of cadmium between 0.1 and 34 mg kg'l dry weight were reported from European lakes, the highest concentration found in Ketelmeer, the Netherlands. The highest concentration reported for European river sediments, 11.8 mg kg'l, was from the lower Rhine (Hutton, 1995; OECD, 1995b).

Compared to these figures, total cadmium concentrations in Swedish lakes and rivers are fairly low. However, most of the Swedish lakes are not directly affected by Cd discharges, as is probably the case with several of the European watercourses. The low pH and the soft waters in the Swedish lakes and rivers increases the residence time and the dissolved fraction of cadmium compared to waters in most of Europe. Jensen and Bro-Rasmussen (1990) summarised typical concentrations of dissolved cadmium in European lakes, ranging between 0.004 and 0.036 pg L'l, and the highest values were from Swedish lakes.

6.1.2 Groundwater

Concentrations of cadmium in groundwater in Sweden have been monitored since 1978 until today. No significant trends have been observed during this period (partly due to high detection limit, 0.05 pg L'l) (Hedlund 1997). An earlier investigation of groundwater in Sweden during 1985-87 showed cad mium concentrations ranging between 0.006 and 0.1 pg L'l (SEPA, 1993).

6.1.3 Seas

The concentration of cadmium in the seas surrounding Sweden decreases with increasing salinity, with cadmium concentration ranging from 0.03- 0.04 pg L'l in the Baltic Sea, 0.025 pg L'l in the Kattegatt to 0.02 pg L'l

45 in the North Sea (Figure 15) (SEPA, 1991). Total cadmium concentrations in open sea water are typically 0.005-0.02 pg L"1 (Pearse, 1995; OECD, 1995b). The concentration profile with depth resembles that of nutrients, that is surface depletion and deep water enrichment.

The ’’dissolved ” fraction of cadmium, operationally defined by filtration, in surface water of the Baltic Proper, is as high as 90% of the total cadmium concentration (Jensen & Bro-Rasmussen, 1990), which indicates a high mobility of the metal (Lithner & Borg, 1995). The high mobility in the Bal tic Proper is also reflected by relatively long residence times of cadmium (5- 6 yrs), 20 times the residence time for lead (Lithner & Borg, 1995). Typical dissolved cadmium concentrations measured in European open and coastal seawater are 0.005 pg L"1 for the Mediterranean Sea, about 0.02 pg L'l in the waters surrounding Great Britain, and 0.045-0.290 pg L'l at the Belgian and Dutch coasts (data summarised in Jensen & Bro-Rasmussen, 1990).

Cd pgL'l 0.04

10 20 30 Salinity %o Baltic Sea Kattegatt North Sea

Figure 15. Cadmium concentrations (figL'l) in relation to salinity (%o) in surface waters of seas around Sweden (from SEP A, 1991).

The concentrations of cadmium in surface sea sediments deviates from background concentrations mainly in the southern areas in the Bothnian Bay which is affected by the Ronnskar smelters, the western Bothnian Sea, af fected by the Dalalven river discharge, and in the northern open Baltic. Proper influenced by large-scale anthropogenic emissions (Figure 16) (Borg & Jonsson, 1996). The mean concentrations in surface sediments in the three basins are 0.94, 0.31 and 2.9 mg kg'l dry weight respectively (Table 2), and extreme values up to 10 mg kg'l dry weight are found. 46 The concentrations in the Bothnian Bay and Bothnian Sea correspond to approximately a tree-fold increase compared to background levels, while the increase in the northern open Baltic Proper is about 10 times, while some extreme values exceed the background levels about 50 times.

Besides the anthropogenic load, the oxic/anoxic conditions in the Baltic Sea affect the fluxes of cadmium from the water to the sediments and from solid phases in the sediment to pore water and overlaying water. Low amounts of cadmium in anoxic bottom water and elevated cadmium concentrations and drastic increases towards the sediment surface in laminated sediments at anoxic sites in the Baltic Proper (e.g. Gotland deep), appears to be deter mined by scavenging with iron sulphides (Dyrssen & Kremling, 1990, Borg & Jonsson, 1996). Studies in the Kiel Bight also indicates that there is a reduced accumulation rate of anthropogenic cadmium in oxic sediments compared to anoxic sediments (Lapp & Balzer, 1993). This demonstrates how the sediments serve as a sink for anthropogenic cadmium at anoxic conditions, but may imply a threat to the environment as oxygen conditions improve and cadmium may be released from the sediments.

Figure 16. Cadmium in surficial sediments (0-1 cm), sampled during 1986- 89 in the Baltic Sea. One unit on the scale on the bars corresponds to 0.5 mg kg-ldw (Borg & Jonsson, 1996).

47 Jensen & Bro-Rasmussen (1990) summarised cadmium concentrations measured in marine sediments in Europe. The data ranged from 0.04 mg kg' 1 in the River Ebro delta to 6.8 mg kg"l in the Baltic Sea.

6.2 Accumulation in, and effects on aquatic organisms

6.2.1 Factors affecting bioaccumulation and effects

Cadmium is readily accumulated by many organisms, particularly by micro organisms and certain invertebrates for which the bioconcentration factors (expressed on dry weight basis) are in a factor of thousands. For instance, the bioconcentration factor in invertebrates from humic waters in the Ronn- skar area (Sweden), varied from 65 000 (on dry weight basis) in Asellus aquaticus (detritivore) to 27 000 in Sialis lutaria (predator) (Lithner el al., 1995). This support a generally accepted hypothesis that cadmium does not biomagnify in aquatic food chains. However, conflicting evidences exist about this theory, and it is suggested that cadmium may biomagnify in specific marine food chains (CWQG, 1996).

Some aquatic macrophyte species bioconcentrate cadmium, with accumulation factors as high as 10 000 (Myriophyllum) (Crowder, 1991), and for aquatic moss (Fontinalis antipyretica) the bioaccumulation factor can reach 24 000.

Generally, the concentrations in planktonic invertebrate species are corre lated with cadmium concentrations in water, a dose-response relationship (Wren & Stephenson, 1991). By studying lakes in deposition gradients of air-borne metals from the Ronnskar smelters, it was possible to investigate dose-response relationships under realistic conditions (in situ) (Lithner et al, 1995). Linear relationships were observed between cadmium in biota and cadmium in water. Cadmium in liver of Eurasian Perch (Perea fluviatilis) showed the closest correlation with cadmium in water, and exhib ited an extremely high bioconcentration factor of 164 000 (maximum Cd concentration in liver was 30 mg kg" ' dw), which is 20-40 times more than found in fish experimentally exposed to cadmium in water (Lithner & Borg, 1995). Such difference in bioconcentration factors indicates that food might be an important uptake-route for cadmium in fish (Lithner et al., 1995). An- dersson and Gabring (1988) also stressed the importance of food as a source for cadmium accumulation in fish, especially in recovering environments where concentrations in water have decreased while concentrations in sedi ment, the habitat for many food organisms, still are high.

48 Most toxicological data are based on laboratory studies with organisms only exposed to cadmium in water (Lithner & Borg, 1995).

Regional differences were observed in occurrence of cadmium in Swedish freshwater pike (Bjorklund, 1986, cited in SEPA, 1993). Cadmium concen trations in pike liver from southern Sweden, and the Bergslagen area of central Sweden, varied between 0.5 and 1.7 mg kg'l dry weight. Further north, concentrations were lower than 0.2 mg kg~l.

Environmental factors affect the uptake and, therefore, the toxic impact of cadmium on aquatic organisms. The toxicity is aggravated by inorganic species of cadmium being extremely soluble and mobile, in comparison with the speciation of other hazardous metals, such as lead and mercury (Lithner & Borg, 1995).

The organic material in the water generally decrease the uptake and toxic effect by binding cadmium and reducing its availability to organisms (OECD, 1995b). However, some organic matter may have the opposite effect. For instance, addition of lipophilic chelating agents together with CdCl2 increased cadmium accumulation, relative to exposure only to CdCl2 (Gottofrey, 1990).

The effects of pH on cadmium accumulation is somewhat contradictory. Levels of cadmium in invertebrates increase with a decrease in pH down to 5.5. A further reduction in pH inhibits the cadmium uptake (Wren & Stephenson, 1991). Reduced uptake of cadmium in fish has also been demonstrated at pH levels below 5 (SEPA, 1993). In the Rdnnskar area, cadmium accumulation in aquatic bryophytes increased 10-fold from pH 5 to pH 6, expressed as bioconcentration factor (BCF) (Lithner et al, 1995). Also decreased toxic effects at decreasing pH have been reported (Wren & Stephenson, 1991). The reason for this is probably competition with hydro gen ions where transport occurs via the cell membrane in fish gills (SEPA, 1993). The net result may nevertheless be increased concentrations, and possibly toxicity, of cadmium in organisms in acidified areas, since acidifi cation causes enhanced cadmium concentrations in the water. This was shown in a Canadian field study where the mean concentrations in fish (Lepomis gibbosum) from circumneutral lakes, were 0.02-0.07 mg kg"l dry weight, while the concentrations in acidic lakes (pH 5.1-6.0) were 0.08-0.61 mg kg"l (Wiener, 1983 cited in Ahgren & Norrgren 1996).

49 The net negative effect of low pH on cadmium accumulation is also indi cated in two Swedish studies, in which the effects of liming on cadmium concentrations in lake water, fish and invertebrates were investigated. The annual means of pH in one of the studied lakes, varied between 5.6 an 5.9 before liming (monitored during 4 years) and between 6.7 and 7.2 after liming (12 years) (Andersson & Holm, 1995). The corresponding annual means for cadmium in water during the same periods were 0.09-0.18 and 0.020-0.085 pg L"l, respectively. Cadmium concentrations in liver of small (50 g) perch were lowered by 27 % within 4 years after liming and 38 % within 12 years. The decrease in actual concentrations was from 7 (before liming) to 4.3 mg kg"l dry weight (12 years after liming). In the other study (Andersson & Borg, 1988), decreasing cadmium concentrations in lake water, pike liver, and sediment-dwelling midge larvae (Chironomus anthracinus) were observed after liming.

Increasing salinity, or water hardness, decreases the uptake and toxicity of cadmium. Probably, this is the reason why freshwater organisms frequently are affected by cadmium at lower total concentrations than marine orga nisms. Increased bioavailability of cadmium due to decreased salinity is partly the result of a higher proportion of cadmium in ionic form. In sea water the chloride ion plays a key role for the bioavailability by forming complexes with cadmium, which exhibit lower bioavailability than the free cadmium ion (Cd2+). In open sea waters the free ion typically makes up less than 5 % of the total concentration and this fraction might be further reduced by complexation with dissolved organics and suspended solids. In the Baltic Sea, the calculated fraction of free cadmium ions increases as salinity decreases, from 10-15 % of total cadmium in the North Baltic Proper to 50 % in the Bothnian Sea, and 70-95 % in the Bothnian Bay. The Bothnian Bay and the Bothnian Sea might therefore be comparable with lakes as far as cadmium concentrations and complexation with chlorides are concerned (Lithner & Borg, 1995). It has also been shown that cadmium desorbes from particulate material during transition from fresh to more saline waters. Hence, another mechanism that has been proposed for higher accumulation rates in low salinity waters, is that plankton may gain in adsorption capacity as salinity decreases. Organisms (e.g. fish) feeding on plankton may thus be exposed to increasing levels of bioavailable cadmium (Bignert, 1997).

50 Table 2. Concentrations of cadmium measured in water, sediment, bladderwrack (Fucus vesiculosus), blue mussel (Mytilus edulis), zooplankton and Baltic herring/herring (Clupea harengus) in Swedish waters during the 1980s. (Modified summary of data from SEP A, 1993 and Hedlund, 1997).

Area Water Sedi Bladder- Blue Zoo Herring (M9 L-1) ment wrack mussel plankton liver (mg kg-1 (mg kg-1 (mg kg-1 (mg kg-1 (mg kg-1 dw) dw) dw) dw) dw)

Rivers to the 0.009 Bothnian bay

Bothnian Bay 0.03 0.9 1.8 1.0-2.4

Bothnian Sea 0.3-0.5 5-13 7.4-10.8 2.6 0.5-1.5

Baltic Proper 0.03-0.04 2.9 2-9 2.5-6.3 2.0 1.5-2.0

Kattegat! 0.2 0.8-1.6 1.5 0.3-0.8

Skagerack 0.7-3.0

North Sea 0.02

N. Atlantic 0.004- 0.008

51 jjg/gTS

100%-

50 % -

30 Sal-

Bothnian Bay Bothnian Sea Baltic Sea Seas weetot Sweden

Figure 17. Diagram showing how the concentration of cadmium in organisms and how the calculated relative proportion of the cadmium ion (as percentage of the total concentration) varies with salinity (SEPA, 1993).

The concentrations of cadmium in common sea mussels (Mytilusedulis ) is six times higher in the Bothnian Sea than it is in the Skagerack and Kattegatt, while the concentrations in Baltic herring (Clupea harengus) and zooplankton is approximately doubled (SEPA, 1993) (Table 2, Figure 17). This geographical trend is partly due to higher cadmium concentrations in the water, but salinity and as a consequence cadmium in ionic form, is probably a more important factor, possibly in combination with salinity stress. The cadmium concentrations in liver of herring from the Baltic Sea also show a general increasing trend since the 1980s (section 8).

52 6,2.2 Effects on aquatic organisms

Cadmium is toxic to a wide range of aquatic microorganisms and inverte brates, the main effect being on growth and reproduction. Manifested re sponses of certain organisms to cadmium exposure are observed at water concentrations lower than 1 pg L" 1.

The acute toxicity is variable, even between closely related species e.g. the 48-hours acute toxicity level of cadmium for invertebrates ranged from 3.6 to 34 600 pg L"1 (data summarised in Wren & Stephenson, 1991; CWQG, 1996), and is related to the concentration of free ionic cadmium. Cadmium ions causes impaired growth in blue-green algae at 0.1-1 pg L'l, expressed as the free C

Among fishes, salmonids are particularly susceptible to cadmium, and the most vulnerable life-stages are the embryo and early larvae stages (OECD, 1995b). In a 46-days study of Atlantic salmon (Salmo salar), significant reduction in body weight and fork length were observed at cadmium con centrations of 0.47 pg L'l (CWQG, 1996). Spry & Weiner (1991) con cluded from studies of early life stages of different fish exposed to cad mium, that maximum acceptable toxicant concentrations (MATC, 5 60d) was lowest for salmonids and ranged from 0.7 to 6.7 pg L'l.

Selected toxicity data for freshwater and marine organism are summarised in Appendix II and III, respectively.

Zinc may increase the toxicity of cadmium (OECD, 1995b). One possible mechanism, is that zinc quickens the intracellular cadmium turnover, which results in an increased transfer of cadmium from the gill cells to the circulatory system (Wicklund, 1990). Zinc and cadmium acted synergistically on the mortality of juvenile minnows (ibid.)

53 The gills are considered the most important organ for cadmium accumu lation from the water by freshwater fish. The uptake via the gills, has been proposed to occur by facilitated diffusion through calcium channels in the apical membranes of epithelial cells in the gills (Wicklund, 1990).

Probably, cadmium also inhibit calcium uptake from the water causing hypocalcaemia in fish (OECD, 1995b), which can explain that spinal malformations have been observed for cadmium-exposed fish (Pearse, 1995).

On the other hand, high concentrations of calcium and/or zinc in the water protect fish and invertebrates from cadmium uptake and toxicity by com peting at uptake sites (OECD, 1995b ;Wren & Stephenson, 1991). This is considered in Canada, where the Water Quality Guidelines (1996) recom mend the following critical concentrations, related to water hardness; 0.01 pg L'l for soft water (0-30 mg L'l, CaCOg), 0.03 for moderate water hardness (90 mg L'l, CaCOg) and 0.06 pg L'l for very hard water (>210 mg L'l, CaCOg). The concentration of calcium ions is lower in the Baltic Sea than in a marine environments (Kautsky & Andersson, 1997).

Cadmium is probably also taken up in receptor cells in the olfactory mucosa (Gottofrey, 1990). Cadmium accumulated mainly in the olfactory organs of brown trout and pike, which were exposed via water to radioactive tracers of CdCl2 (Gottofrey, 1990; Gottofrey & Tjalve, 1991). Other studies, cited by Gottofrey (1990), have shown that cadmium and other heavy metals are strong inhibitors of the olfactory functions in fish, and that cadmium has a potent noxious effect on the olfactory epithelium in fish. The olfactory sense is important to fish, since various chemical stimuli affect their behavioural pattern. One example is the salomonids typical migration back to their native rivers (Hare, 1994). As far as we know, it has not been investigated if such functions in fish, dependent of the olfactory organs, are affected at the cadmium concentrations found in the environment. However, it has been shown that humans have lost some of their olfactory sense when exposed to cadmium in their work (H. Tjalve, pers. com.).

The Ontario Ministry of Environment estimated NOEC for cadmium in sediment to be 0.6 mg kg'l, with a LOEC at 1 mg kg'l (Baudo et al., 1990). They also assigned a limit of tolerance level to 10 mg kg'l. Long and Morgan (1990) surveyed data on biological effects of sediment-sorbed contaminants, mainly from marine systems in the US. Chemical concen trations observed or predicted to be associated with biological effects were sorted, and the lower 10 percentile in the data were identified as an Effect 54 Range-Low (ER-L). The ER-L for cadmium was approximately found at 5 mg kg'l, a concentration at which the benthic community composition was apparently affected.

6.1.4 Effect studies on organisms captured in Swedish environments

Sjobeck et al. (1984) found strong indications of disturbed carbohydrate metabolism and white blood cell pattern in perch inhabiting waters in River Eman (southern Sweden). The water in the system, affected by discharge from a battery industry, was soft (50 mg CaCOg L'l) and the cadmium concentration in the water was 0.1-0.2 ug L*l. Cadmium has also been shown to induce synthesis of metallothioneins (MT) in perch of River Eman, probably as a means of detoxification (Olsson & Haux, 1986). This process may hence be considered as a continues stress response. Cadmium may also have indirect toxic effects on growth and reproduction of fish, by allocating resources from these functions to the synthesis of MT.

a e A lege Rsq = 0,2755

# 1984 Rsq = 0,2324

Figure 18. Number of phytoplankton taxa plotted vs cadmium in lake water in the Ronnskdr area (Lithner & Borg, 1995).

In the Ronnskar area, the diversity of phytoplankton was negatively correlated with the water cadmium content, and not so much with other physicochemical parameters (pH, Al, Fe, Mn, humics, N, P, Zn, Cu, Pb, As, Ni, Cr, Co). 55 The cadmium concentration in the water ranged between 0.004 and 0.4 pg L'l (Figure 18). Blue mussels from the North Sea and from the Baltic Sea were exposed to 10 pg L'l cadmium for up to 14 days. Under the cadmium exposure North Sea mussels produced high levels of a stress pro tein, HSP70, and had low concentrations of cadmium. Baltic Sea mussels had low levels of HSP70 and accumulated three times the tissue concen tration of cadmium as North Sea mussels. Also, North Sea mussels had lower mortality rates, oxygen consumption, nitrogen excretion, and energy expense than the Baltic Sea mussels (Brown et al., 1995)

In long term microcosm experiments, the embryogenesis of amphipods (Pontoporeia affirtis) captured in the Baltic Sea, was disturbed at exposure to 5 pg Cd L'l (Sundelin, 1989).

6.3 Conclusions- effects of cadmium in Swedish aquatic environments

The Swedish aquatic environments are especially vulnerable to cadmium pollution, compared to most other EC states. In soft freshwater, the acid rain, together with the poor buffering capacity in soils and water lead to: 1) increased concentrations of cadmium in surface and lake water, 2) increased bioavailability due to increased fractions of free ionic cadmium 3) acid-stressed organisms which are less tolerant to pollutants such as cadmium.

In the Baltic Sea the low salinity (compared to other seas) lead to: 1) increased fraction of free ionic cadmium and hence increased bioavailability 2) salinity-stressed organisms which are less tolerant to pollutants.

When considering the data above it is probable that chronic effects occur in certain organisms in the Swedish aquatic environments.

In the southern-most acidified areas of Sweden, atmospheric deposition of transboundary transported cadmium and acidifying substances are likely to be the most causative factors for high water-concentrations, resulting in cadmium levels between 0.05 and 0.3 pg L'l, in thousands of acidified lakes. The LOEC observed for Daphnia magna (0.17 pg L'l) is exceeded in several of these lakes. Also sediment concentrations in many lakes, espec ially in southern Sweden, exceed estimated LOECs.

56 Therefore, it is likely that certain negative effects of cadmium exist in Swedish freshwaters environment. This conclusion is emphasised if the assessment factors according to TGD is applied, taking into account species variation.

Effects are likely to occur on lower organisms (plankton and benthic fauna) as well as on fish. Effects on fish might involve disturbed carbohydrate metabolism, spinal malformations, reduced growth, behavioural changes, etc.

Toxic effects of cadmium arise at lower concentrations in freshwater systems compared to in marine environments. The salinity of the water in the Baltic Sea range from being almost freshwater in the Bothnian Bay, to fairly low salinity (as compared to other seas) in the Baltic Proper. The fraction of free ionic cadmium in the water increases as salinity decreases. Cadmium at a certain concentration in the Baltic Sea is therefore probably more toxic than is indicated by available toxicity data for marine organisms. In addition, total cadmium concentrations are higher in the Baltic Sea com pared to concentrations in the seas west of Sweden. This indicate that if toxic effects of cadmium occur in the Swedish seas, they would most likely initially occur in the Bothnian Sea and the Baltic Proper, or in coastal areas with locally enhanced concentrations of cadmium. Cadmium concentrations in the sea sediments are highest in the Baltic Proper, where the concen trations exceed LOEC in both coastal and deep sea areas. The average cadmium concentrations measured in Swedish sea water does not exceed LOECs reported for neither marine nor freshwater organisms. However, the occurrence of cadmium in the Baltic Sea might imply extra stress for its sensitive fauna and flora. 7. Cadmium in the Urban environment

Large amounts of cadmium in urban areas originates from diffuse leakage from articles of consumption. Sooner or later this cadmium reaches the soils, and finally the waters surrounding the urban areas. The accumulated amount of cadmium used in products in Sweden to date is about 5000 tonnes (Bergback et al., 1994 ). To put this amount into perspective, it is equivalent to the total amount of cadmium in the top layer (0-5 cm) of all Swedish soil (Pearse, 1995). The release of only a small fraction of this amount may cause serious impact, if and when it reaches the environment. Deposition on landfills is one of the major routes by which cadmium in products can reach the environment. Landfills already contain large amount of cadmium and more is likely to be added from a variety of sources. 57 Little data are available on long-term fate of cadmium in landfills, e.g. 50 years or longer.

As rain water percolates through the deposited material, metals among other pollutants are liberated/solubilised and transported from the landfill, in dis solved or particulate form. The cadmium concentrations in leakage water are low compared to municipal sewage water. Cadmium concentrations measured in leakage water from six different landfills in Sweden ranged between 0.09 and 1.39 pg L_1 (Oman & Wennberg, 1997), concentrations within the range found in acidified forest soils. However, since large amounts of water passes through a landfill, the total amount of cadmium loss with the leakage water might be considerable. About 4000 landfills exists in Sweden, of which 300 are used today. The leakage water from about 100 of those are connected to municipal sewage plants, and about 50 have their own treatment works (C. Oman, IVL, pers. com.). More than 23 tonnes cadmium is annually deposited on landfills in Sweden today, and about 1 % of this amount leaches to ground and surface waters (Pearse, 1995). Concern exist about the future management of landfills. Deposition of organic material, and hence the sorption sites for metals, will be mini mised probably resulting in increased leakage rates of metals.

The fluxes of cadmium in the technosphere is described more in detail by Bergback (1997).

Very little is known about the biological effects in the urban areas. Concern for children accidentally ingesting surface soil, initiated an investigation of metal concentrations in parks of the City of Stockholm and surrounding communities in 1993 (Berglund et al. 1994). Most samples showed cad mium concentrations below the detection limit (0.5 mg kg'l) and the maximum value found was 0.9 mg kg*l dry weight, corresponding to less than a 4-fold enhancement compared to average concentrations in Swedish agricultural soils. An earlier (1988) pilot study at two spots in the city resulted in levels of 2 and 6 mg kg~l. Cadmium at these higher concen trations probably affects soil organisms (compare section 5.2). It is also possible that some plants and trees have accumulated cadmium concen trations that might be toxic to the plants themselves, or to birds or insects that feed on seeds and foliage (section 5.4). Effects on smaller mammals might also occur, like in the surroundings of the Ronnskar area (5.3).

58 Cadmium Cd

Stockholm

Figure 19. Cadmium levels of surface sediments in water bodies surrounding Stockholm (from Blomqvist & Larsson, 1996).

Very high concentrations of cadmium were measured in surface sediments from water-bodies in the central parts of Stockholm and from lakes surroun ding Stockholm (Ostlund & Palm, 1995; Blomqvist & Larsson, 1996). The highest value was 14 mg kg'l, which corresponds to a contamination factor of 50 (Blomqvist & Larsson, 1996). This can be compared with concen trations measured close to local point sources such as the Oxelosunds steelworks and the Ronnskar smelters, 20 and 39 mg kg-*, respectively (SEPA, 1993). Most of the Stockholm samples (Figure 19) where within a concentration range, 1-5 mg kg‘l dry weight, where biological effects might occur. However, the macrofauna has almost totally disappeared due to anoxic bottom conditions. If the input of oxygen consuming, eutrophicating substances decreases, oxic conditions in the recipient may improve and organisms may recolonize the bottoms. Toxic effects of cadmium might then occur in the bottom fauna and their predators.

59 Cadmium may also start to leach from the sediments, resulting in enhanced concentrations in the watermass. 8. Temporal trends

Analyses of cadmium in moss indicate that the atmospheric deposition of cadmium in Sweden has decreased by about 50 % during the last two decades (Figure 20).

1970 1975 1980 1985 1990

Figure 20. Changes in average cadmium concentrations in mosses from different parts of Sweden 1970-1990 (data from A. Rhuling, in Hedlund, 1997)

The yearly deposition during the last decade varies strongly, according to measurements of cadmium in wet deposition (Figure 21). There was a marked peak in cadmium deposition in 1988-89 which was also seen for sulphate and vanadium, elements that are strongly correlated to the burning of fossil fuels. However, there is still a general decreasing trend, which is significant in Svartedalen (linear regression, p <0.05) (K. Kindbom, IVL, pers com., data from the National Monitoring Program).

60 1" o a ■

year

Bredkalen

84 86 88 90

150 - Aspvreten

100 -

150 - Svartedalen 84 86 88 90 92 94

100 •

84 86 88 90 92 94 150 -

100 -

84 86 88 90 92 94

Figure 21. Variations in the yearly wet deposition of cadmium at four stations in Sweden (K. Kindbom, pers. com. data from the Swedish Monitoring Programme).

Since 1988, cadmium is monitored in some larger rivers and in smaller brooks in Sweden (Hedlund, 1997; G. Aim, pers. com, unpublished data). Concentrations as well as the yearly transport indicates decreasing cadmium transport at least in some rivers in the north No decreasing trends are ascer tained in southern Sweden (G. Aim, pers. com), probably as a result of increased leaching from the soils due to acidification.

61 The high deposition during the late 1980s is reflected by increased concentrations in the brooks (Figure 22).

Agriculture in Sweden is currently in a transitional period, implying that large areas of arable land are used for replanting of forests. Plantation of coniferous trees on light soil with poor buffering capacity probably lead to a progressive decline in pH towards pH 4, also in former agricultural areas (SEPA, 1993). This will result in a progressive liberation of the soluble fraction, about 50 % of the cadmium store (corresponding to 200-300 g ha' 1). This mobilised cadmium can be redistributed in the soil and/or leach out into surface water or ground water (ibid.).

a) b)

,005 * OCOO^M*

1867 1988 1989 1990 1991 1992 1998 1994 1995 1996 1997 1886 1866 1980 1992 1964 1996 1998

Figure 22. Temporal trends of cadmium concentrations in a) river Vindelalven (N. Sweden) and

b) a smaller brook in southern Sweden. Note the different scales. (Unpublished data from the National Monitoring Program, G. Aim, pers. com.).

Data on cadmium in organisms are generally too few and too variable to permit any conclusions about temporal trends. An exception is cadmium concentrations in liver of Baltic Herring (Clupea harengus) during 1980- 1996. The concentrations in herring from the Bothnian Sea and the Baltic Proper did significantly increase by 5-7 % a year, whereas concentrations in samples from the Bothnian Bay and the Kattegatt did not (Figure 23) (Bignert, 1997). No conclusions regarding temporal trends can be drawn from available data on freshwater fish, data being to scarce and unsystema tically sampled and reported.

62 Starlings are used as indicators of the environmental state in agricultural areas. Since the 1980s, significant decreases in cadmium concentrations were found at 2 of 8 investigated areas. In the other areas, no general changes were proven (Odsjo, 1995).

Figure 23. Time trends of cadmium concentrations (mg kg'^dw) in liver of herring sampled at Harufjarden in the Bothnian Bay, at Angskarsklubb in the Bothnian Sea, at Landsort and Utlangan in the Baltic Proper, and at Fladen in the Kattegatt (modifiedfrom Bignert, 1997).

63 9. Overall conclusions

Swedish biotopes are especially vulnerable to additional stress factors, such as cadmium pollution, since:

1) the predominance of magmatic bedrock and the thin soil layers imply low buffering capacity, which has resulted in that soil and freshwater systems already are severely affected by acidification.

2) the low salinity in the Baltic Sea imply a naturally poor organism structure, with some important organisms living close to their limit of physiological tolerance.

The concentrations of cadmium in forest and agricultural soils, freshwaters, and the seas surrounding Sweden are enhanced compared to ‘background concentrations ’. Generally, the enrichment (above background) in soils and freshwater increases from the north to the south-west. This indicates a strong impact of deposition of atmospheric cadmium, originating from central Europe.

In seas surrounding Sweden, the cadmium concentrations in water generally increases with decreasing salinity, while the concentrations in the sediments are highest in the Baltic Proper. The fraction of bioavailable, free cadmium ions increases with decreasing salinity, and is therefore higher in the Baltic Sea compared to other seas.

Decreased emissions of cadmium to the environment have led to decreasing atmospheric deposition during the last decade. However, the enrichment of cadmium in the Swedish environment is still critical in certain areas.

In the mor layer of forest soils the enrichment is 3-5 fold in the southern half of Sweden. Recent studies indicate that the net accumulation of cadmium in the forest soils has stopped, and even started to decrease. In northern Sweden this is probably due to the decreased deposition, but in southern Sweden the main reason may be an increased leakage of cadmium from the soils as a consequence of acidification. The acidification has resulted in increased mobility of the accumulated cadmium. In agricultural soils, cadmium is still accumulating, but acidification and changes in the use of land will probably increase the leakage rate of cadmium also from arable land. This means that cadmium in the Swedish environments is probably undergoing an extended redistribution between different soil compartments, and from the soils to the aquatic systems.

64 Generally in Europe, such extended leakage and redistribution is more likely to be hindered by calcium rich soils and presence of deeper soil layers.

The increased mobilisation, described above, is probably the reason why cadmium concentrations in brooks in south-western Sweden are not decreasing, although deposition has decreased. Rivers of less acidified areas show decreasing concentrations.

Today, the high cadmium concentrations measured in forest soils and soil solutions in southern Sweden, are close to the lowest effect concentrations reported for microorganisms and invertebrates in laboratory studies, which implies that chronic effects might already occur in forest soils. When apply ing risk assessment factors according to TGD on concentrations measured in agricultural soils, as well as in forest soils, PEC/PNEC ratios of >1 is de termined in both cases, indicating risk for effects also in agricultural soils.

There is some evidence for chronic effects (kidney dysfunction) in certain mammals (bank voles) close to a point source in northern Sweden. The effects occur at kidney cadmium concentrations > 4 mg Cd kg" 1 wet weight. Kidney cadmium concentrations above this level have also been found in a considerable number of bank voles captured in southern Sweden, indicating that these animals might suffer from kidney dysfunction as well, due to accumulation of cadmium from diffuse sources.

Some plants in Sweden, especially certain trees, accumulate cadmium to concentrations that might be hazardous to the plants themselves and maybe also to birds and herbivorous mammals feeding on them.

The accumulation in plants may also hinder the recycling of biomass for energy use.

Cadmium that leaks from the soils, ends up in rivers, lakes and finally in the seas. Lakes in southern Sweden are already severely damaged by acidi fication and many species have disappeared. The main reason for this is probably not cadmium, but since cadmium increases in acidified waters (both as total concentrations and as amount free ion) chronic effects of cadmium may add to the other acidification effects. The cadmium concen trations in a large number of the acidified lakes in southern Sweden exceed LOEC for freshwater organisms. Probable cadmium effects (disturbed carbohydrate metabolism, and white blood cell pattern , etc.) have been observed in fish from a contaminated river with cadmium concentrations in water similar to those found in acidified lakes.

65 Such chronic effects and others, e.g. behavioural changes, are however difficult to prove.

Organisms in the seas surrounding Sweden accumulates more cadmium at lower salinity. The concentrations in herring from the Baltic Proper and the Bothnian Sea are also increasing over time. However, no observable effects due to the increased cadmium concentrations, have been reported.

The cadmium concentrations in water of the Baltic Sea usually do not exceed estimated LOECs, while LOECs for sediment-dwelling organisms are exceeded in certain areas of the Baltic Proper. However, the Baltic Sea is heavily contaminated, and also severely affected, by many different pollu tants. The eutrophication, with large areas of the bottom being anoxic as a result, is probably the most harmful factor to the biota. As in the case of acidified lakes, the effects of different stress factors often add to each other. Therefore, the cadmium in the Baltic Sea may imply extra stress for certain organisms.

Generally, the diffuse contamination of cadmium in urban soils is not re markably high, e.g. concentrations in parks in Stockholm usually represent an enhancement less than four times the average concentration in Swedish agricultural soils. Still effects on biota may occur in certain areas. The con centrations in soil can be markedly enhanced in industrialised areas, and may affect the soil organisms and the uptake in plants. Accumulation in plants may cause risks for both the plants themselves, as well as for birds and mammals feeding on them.

Large amounts of cadmium are accumulated in landfills. Little is known about the long-term effects of cadmium leakage from old landfills, as well as from those in use.

Water bodies in urban areas are often highly disturbed and also enriched with cadmium, to concentrations exceeding LOECs for aquatic organisms. The most important disturbing factor in these systems is probably low oxy gen condition, which causes almost total deficiency of certain organism levels, such as bottom-dwelling invertebrates. However, if the oxygen conditions in the bottoms recover, it is likely that the accumulated cadmium become available, and pose a threat to recolonising organisms.

In conclusion, although the deposition of cadmium and, recently, concen trations in forest surface soils have started to decrease, the concentrations in certain selected aquatic organisms (i.e. Baltic Herring) increases.

66 A possible recovery from enhanced cadmium concentrations in water, plants and fauna, is counteracted by the acidification of the Swedish soils, which increases the mobility and availability of the accumulated cadmium. The effects are most pronounced in southern Sweden, where the impact is high of air-borne cadmium and acidifying substances, originating from the European continent.

Therefore, all inputs of cadmium, through atmospheric deposition, with fertilisers, with sludge or as diffuse leakage from articles of consumption, will put extra pressure on the Swedish environment, already affected by stress from cadmium and other factors.

67 10. References

Andersson, A., 1992. Trace elements in agricultural soils - fluxes, balances, and background values, Swedish EPA, report 4077.

Andersson, A., Nilsson, A., & Hakansson, L., 1991. Metal concentrations of the mor layer. Swedish EPA, report 3990, 95 ppg.

Andersson, L., & Gabring, S., 1988. Food related cadmium uptake in fish (Fodorelaterat kadmiumupptag i fisk). Project Report No. 15 from the Stuy Programme in Ecotoxicology, Institution of Zoophysiology, Uppsala University, Sweden (in Swedish).

Andersson, P., & Borg, H., 1988. Effects of liming on the distribution of cadmium in water, sediment, and organisms in a Swedish lake. Can. J. Fish. Aquat. Sci., Vol 45, 1154-1162.

Andersson, P., & Holm, K., 1995. Cadmium in water and perch {Perea fluviatilis) liver in limed L. Stensjon in Tyresta National Park in Sweden. Water, Air, and Soil Pollution. Vol 85, 805-810.

Balsberg Pahlsson, A.-M., 1985. Effects of cadmium and copper on plants - a literature review (Effekter av kadmium och koppar pa vaxter - En litteraturdversikt). Swedish EPA, report nr 1996, 97 ppg (In Swedish)

Baudo, R., Giesy, J., & Muntau, H., 1990. Sediments: Chemistry and toxicity of in-place pollutants. Lewis Publishers, Inc., ISBN 0-87371-252-8, 405 ppg.

Bergback, B., Anderberg, S., & Lohm, 1994: Accumulated environmental impact: the case of cadmium in Sweden. The Science of the Total Environment 145, 13-28.

Bergback, B. & Johansson, K., 1996. Metals in the Urban and Forest Environment (Metaller i Stad och Land), progress report. Swedish EPA, report No 4677. (in Swedish).

Bergback, B., 1997. Cadmium in goods - contribution to exposure of the environment. Report prepared for the National Chemicals Inspectorate, Solna, Sweden (vol 2, present report).

68 Bergkvist, B., Folkesson, L., & Berggren, D., 1989. Fluxes of Cu, Zn, Pb, Cd, Cr, and Ni in temperate forest ecosystems. A literature review. Water, Air, and Soil Pollution. Vol 47, 198-216.

Berglund, M., Fahlgren, L., Freland, M., & Vahter, M., 1994. Metals in soils in Stockholm City and its municipalties - occurrence and health risks for children (Metal ler i mark i Stockholms innerstad och kranskommuner- forekomst och halsorisker for bam). Inst, for Environmental Medicine, Karolinska Institute, Solna, Sweden, report No. 2/94. (In Swedish)

Berglund, M., Blinder, C. G., Jarup, L. (editor), Nordberg; G., & Vahter, M., 1997. Health effects of cadmium exposure - a review of the literature and a risk estimate. . Report prepared for the National Chemicals Inspectorate, Solna, Sweden (in press).

Bernes 12, 1991. Acidification and liming of Swedish waters (Forsuming och kalkning av svenska vatten). Svedish ERA. ISBN 91-620-1108-1. (In Swedish).

Bignert, A., 1997. Comments concerning the national Swedish contaminant monitoring programme in marine biota. Annual report to the Swedish ERA.

Blomqvist, S, & Larsson, U., 1996. Metal levels of aquatic bottom sediments at Stockholm. Final research report for the Swedish EPA

Borg. H., 1984. Background concentrations of trace metals in Swedish fresh-waters (Bakgrundshalter av metaller i svenska sdtvatten). Swedish EPA, PM 1817. (In Swedish).

Borg. H., & Andersson, P., 1984. Fractionation of trace metals in acidified fresh waters by in situ dialysis. Verb. Intemat. Verein. Limnol. Vol 22, 725- 729.

Borg, H., Andersson, P., & Johansson, K., 1989. Influence of acidification on metal fluxes in Swedish forest lakes. The science of the total environment, Vol 87/88, 241-253.

Borg, H., & Jonsson, P., 1996: Large-scale metal distribution in Baltic Sea sediments. Marimne Pollution Bulletine, Vol. 32, 8-21.

Brown, D.C., Bradley, B.P.,, Tedengren, M., 1995. Genetic and environmental regulation of HSP70 expression. Mar. Environ. Res. Vol 39, 181-184. 69 Butcher, S.S., Charlson, R.J., Orians, G.H., Wolfe, G.V., 1992. Global, Geochemical Cycles. International Geophysics Series, vol. 50. Academic Press Limited, London, ISBN 0-12-147685-5,

CEPA, 1994. Canadian Environmental Protection Act. Cadmium and its compounds. ISBN 0-662-22046-3, 97 ppg.

Chadwick, M.J., & Kuylenstiema, 1990. The relative sensitivity of ecosystems in Europe to acidic depositions. Stockholm Enivronment Institute.

CWQG, 1996. Canadian Water Quality Guidelines, Appendix XXI on Cadmium, Updates, May 1996.

Crowder A., 1991. Acidification, metals and macrophytes. Environmental Pollution. Vol 71, 171-203.

Dyrssen, D., & Kremling, K., 1990. Increasing hydrogen sulfide concentration and trace metal behavior in the anoxic Baltic waters. Marine Chemistry, vol. 30, 193-204.

Elmgren, R. 1989. Man's impact on the ecosystem of the Baltic Sea: Energy flow today and at the turn of the century. Ambio 18, 326-332.

Eggenerg, U., Waberg, H.N., 1997. Characterization and long term behavior of cadmium in landfills. Prepared for Federal Office of Environment, Forests and Landschap, Switzerland.

Frank, G., 1986. In search of biomonitors for cadmium: cadmium content of wild Swedish fauna during 1973-1976. The Science of the Total Environment, vol. 57, 57-65.

Garrett, G. R, 1995. Geological Survey of Canada. Issue Paper on the workshop on Cadmium Sources Workshop , Stockholm 16th- 18th October.

Gottofrey, 1990. The disposition of cadmium, nickel, mercury and methylmercury in fish and effects of lipophilic metal chelation. Doctoral Thesis from the Swedish University of Agricultural Sciences, Uppsala, Sweden, ISBN: 91-576-4401-2, 71 pp.

Gottofrey, J., & Tjalve, H., 1991. Axonal transport of cadmium in the olfactory nerve of the pike. Pharmacology & Toxicology, vol. 69, 242-252.

70 Hara, T.J., 1994. Olfaction and gustation in fish: an overview. Acta physiol. Scand. Vol. 152, 207-217.

Hellstrand S., & Landner, L., 1997. Cadmium in feertilizers, soil, crops and foods —the Swedish situation. The National Chemicals Inspectorate, Solna, Sweden, (vol 3, present report).

Herrman, J., Degerman, E., Gerhardt, A., Johansson, C., Lingdell, P.-E., & Muniz, I. P., 1993. Acid-stress effects on stream biology. AMBIO. Vol 22, 298-307.

Hutton, M., 1995. Sources, Environmental Levels, Exposure to Humans. Issue Paper on the workshop on Cadmium Sources Workshop, Stockholm 16th- 18th October.

Jensen, A., & Bro-Rasmussen, F., 1990. Review of environmental fate and exposure of cadmium in the European environment. University of Denmark, report no 90.102, 121 ppg.

Johansson, K., 1980. (Heavy metals in acidic forest lakes (Tungmetaller i sura skogssjoar). Swedish EPA, report PM 1359: 69pp. (In Swedish).

Johansson, K., 1989. Metals in sediment of lakes in northern Sweden. Water, air and Soil Pollution, 47. 441-455.

Johansson, K., Bringmark, E., Lindevall & Willander, A., 1995. Effects of acidification on the concentrations of heavy metals in running waters in Sweden. Water, Air and Soil Pollution, vol. 85, 779-784.

Johansson, K., 1995. Cadmium and other heavy metals in Swedish forest soils. Issue Paper on the workshop on Cadmium Sources Workshop, Stockholm 16th- 18th October.

Johansson, K., Andersson, A., & Andersson, T., 1995. Regional accumulation pattern of heavy metals in lake sediments and forest soils in Sweden. Sci. Total Environ. Vol 160/161, 373-380.

Johnsson, L., 1995. Heavy metals in trees and energy crops (Tungmetaller i trad och energigrodor). Report from Vattenfall Utveckling AB, Project Bioenergy, Report No 1995/5. (In Swedish)

71 Johnston, A.J. & Jones,. K.C., 1995. The origin and fate of cadmium in soil. Issue Paper on the workshop on Cadmium Sources Workshop, Stockholm 16th-18th October.

Jonsson, M., Odsjo, T., Nyholm, E., Galgan, V., Pettersson, L., & Johansson, K., 1994. Mercury, lead and cadmium in terrestrial mammals and birds (Kvicksilver, bly och kadmium i terrestra daggdjur och faglar). SEP A, report nr 4379, 45 ppg (in Swedish).

Kautsky, N. & Tedengren, M., 1992. Salinity, pollutants and the life in the Baltic Sea (Salthalt, fororeningar och livet i Ostersjon). In: Ostersjon- ett hav i forandring. Naturvetenskapliga forskningsradets arsbok 1992. Swedish Science Press, Uppsala, ISBN 91-546-0336-3-6, 141 ppg. (In Swedish).

Kautsky, N. & Andersson, S., 1997. The Baltic Sea environment, and its sensitivity to pollutants with emphasis on organic tin compounds

Krantz-Riilcker, C., 1993. Effects of fungi on the distribution of metals in soil systems. Doctoral Thesis from Linkoping Studies in Arts and Sciencer, nr 96, Linkoping 1993.

Kremling, K., Briiggman, L., & Jensen, A., 1987. Trace metals in the Baltic. In: First periodic assessement of the state of the marine environment of the Baltic Sea 1980-85. Baltic Sea Environ. Proced. No. 17B, 82-96.

Kruger; O., & Petersen; G., 1993. Europaweite Depositionen von Schwefel - und Stickstoffverbindungen und Schwermetallen im EMEP-Gitter. GKSS 93/E/105. GKSS- Forschungszentrum GmbH, D-21502 Geestacht.

Landner, L., Folke, J., Olsson Oberg, M., Mikaelsson, H., 1996. Cadmium in Fertilizers. Report prepared for the OECD Cadmium Workshop, Sweden 16-20 October 1995 by the European Environmental Research Group Inc. on commission by The National Chemicals Inspectorate, Pm Nr 8/96.

Lapp, B., & Balzer, W., 1993. Early diagenesis of trace metals used as indicator of past productivity changes in coastal sediments. Geochimica and Cosmochimica Acta, vol. 57, 4639-4652.

Leffler, P.E. & Nyholm, N.E. 1996. Nephrotox Effects in Free-living Bank Voles in a Heavy Metal Polluted Environment. Ambio Vol. 25 No. 6 Sept. 1996. The Royal Swedish Academy of Sciences.

72 Lithner, G., 1989. A system for classification of lakes and water-courses. (Bedomningsgrunder for sjoar och vattendrag) Backgruond document 2, Metals. Swedish EPA, report No. 3628, 80 ppg. (In Swedish).

Lithner, G. & Borg, H., 1995. Cadmium in the aquatic environment - a Nordic perspective. Issue Paper on the workshop on Cadmium, Stockholm 16th- 18th October, 1995.

Lithner, G., Holm, K., Homfeldt, B., & Odsjo; T., 1995. Comparison of metal concentrations among common shrews (Sorex araneus) in southern and in northern Sweden (Jamforelse av metallhalter hos vanlig nabbmus {Sorex araneus) i sodra och norra Sverige). Institute of Applied Environmental Research (ITM), Report No. 35, 23 ppg. (In Swedish).

Long, E. R., & Morgan, L.G., 1990, The potential for biological effects of sediment-sorbed contaminants tested in the national status and trends program. National Oceanic and Atmospheric Administration, Technical Memorandum NOS OMA 52, Seattle, Washington, 173 ppg.

Lundborg, a., 1994. Forest fuels, ashes and ecology (Skogsbransle, aska och ekologi). Vattenfall Utveckling AB, Vallingby, Report No. 1994/6. ISSN 1100-5130. (In Swedish)

Ma, W.-C., 1994. Methodological principles of using small mammals for ecological hazard assessement of chemical soil pollution, with examples on cadmium and lead. In: Ecotoxicology of Soil Organisms. Eds. M.H. Donker, H. Eijsackers & F. Heimbach. Lewis Publ. Chelsea, USA, 373-382.

Nyholm, N.E.I., 1993. Heavy metal tissue levels, impact on breeding and nestling developement in natural populations of Pied Flycatcher (Aves) in the pollution gradient from a smeltwr. In: Ecotoxicology of soil organisms: Donker, Eijsackers & Heimbach; Eds. Lewis Publ. 373-382.

Nyholm, E., Galgan, V., Jonsson, M., Momer, T., Odsjo, T., and Petersson, L., 1996. Effects of atmospheric deposition of metals on terrestrial birds and mammals in the forest ecosystem (Effekter av storskaligt luftnedfall av metaller pa terrestra faglar och daggdjur i skogslandskapet). Final report from the project 802-040-94-Ff, Swedish EPA, Sweden. (In Swedish).

Odsjo, T., 1995. Time series off DDT- and PCB-substances, Hg, CD, Pb, Cu, and Zn in starling {Sturnus vulgaris) from reference areas in Sweden. Report from the Swedish Monitoring Programme in Terrestrial Biota, Contaminant Research Group at the Swedish Museum of Natural History. 73 OECD, 1995. Chairmans report of the cadmium working group meeting, Saltsjobaden, Sweden 20th -21st October. ENV/MC/CHEM/RD(96)2.

OECD, 1995b. Risk reduction monograph No.5: Cadmium - Background and national experience with reducing risk. OECD/GD(94)97.

OECD, 1995c. Chairmans report of the cadmium working group meting, Saltsjobaden, Sweden 16th-20th October. ENV/MC/CHEM/RD(96)1.

Olsson, P.-E., & Haux, C., 1986. Increased hepatic metallothionein content correlates to cadmium accumulation in environmentally exposed Perch {Pereafluviatilis). Aquat. Toxicol. Vol 9, 231-242..

Pacyna, J., M., 1994. Emissions of heavy metals in Europe. In: Background document for the EMEP workshop on European monitoring, modelling and assesement of heavy metals and persitent organic pollutants, Beekebergen, The Netherlands, 3-6 may, 1994.

Pearse, J., 1995. Cadmium - Some aspects of risk reduction. Consultant ’s report prepared for the OECD Cadmium Workshop, Sweden, 16-20 October 1995.

Rhuling, A., 1994. Atmospheric heavy metal deposition in Europe - estimation based on moss analysis. Report from the Nordic Council of Ministers: Nord 1994:9, ISBN 92 9120 427 7, 53 ppg.

Scheuhammer, A.M., 1991. Effects of acidification on the availability of toxic metals and calcium in wild birds and mammals. Environmental Pollution. Vol 71,329-375.

Schmidt, G.H., Ibrahim, N.H., & Abdallah, M.D., 1991. Toxicological studies in the long-term effects of heavy metals, Hg, Cd, Pb, in soil on the development of Aiolopus Thalassiunus. Fabr. Salatoria: Acrididae. Sci. Tot. Environ. 107: 109-133.

Sjobeck, M.-L., Haux, C., Larsson, A., & Lithner, G., 1984. Biochemical and hematological studies on Perch, Perea fluviatilis, from the cadmium contaminated River Eman. Ecotox. Environ. Safety. Vol 8 , 303-312.

Spry, D.J., & Wiener, J.G., 1991. Metal bioavailability and toxicity to fish in low-alkalinity lakes: a critical review. Environmental Pollution. Vol 71, 243-304.

74 Stenman, U., 1997. Uptake of cadmium in kidney and liver of moose from the surroundings of Sigtuna (Upptag av kadmium i njure och lever av alg i Sigtunatrakten). Student's woork report, the Technical Programme, Marsta Gymnasium, Sweden. (In Swedish).

Sundelin, B., 1989. Ecological effect assessment of pollutants using Baltic benthic organisms. Doctoral thesis at the University of Stockholm. ISBN 91-87272-18-0.

SEP A, 1987. Cadmium in the environment - a classification system (Kadmium i miljdn, bedomningsgrunder). Swedish EPA, report No. 3317, ISBN 91-620-3317-4, 76 ppg. (In Swedish).

SEPA, 1991. Metals in seas surrounding Sweden (Metaller i svenska havsomraden) Swedish EPA, report 3696, ISBN 91-620-6-3696-3, 86 ppg. (In Swedish).

SEPA, 1993: Metals and the environment. Swedish EPA, report 4245, ISBN 91-620-4245-9, 187 ppg.

Tesoriero, A. J., & Pankow, J. F., 1996. Solid solution partitioning of Sr2+, Ba2+, and Cd2+ to calcite. Geochimica et Cosmochimica Acta, Vol 60, 1053-1063.

TGD, 1996. Technical Guidance Document in support of the Commission Regulation (EC) 1488/94 on risk assessment for existing substances.

Tyler, G., 1992. Critical concentrations of heavy metals in the mor horizon of Swedish forests. Swedish Environmental Protection Agency. Report 4078..

Verta, M., et al., 1990. Trace metals in Finnish headwater lakes - effects of acidification and airborne load. In: Acidification in Finland. (ED: Kauppi et al.) Springer Verlag, Berlin, Heidelberg, 1990.

Waara, K.-O., 1992. Impacts of heavy metals on certain microbial processes in lake water. Acta Universitatis Upsaliensis. Comprehennsive Summaries of Uppsala Dissertations from the Faculty of Science, report nr 386.

WHO, 1992. Cadmium - Environmental aspects. Environmental Health Criteria 135. World Health Organization, Geneva. 280ppg.

75 Wicklund, A., 1990. Metabolism of cadmium and zink in fish. Acta. Univ. Ups., Comprehensive Summeries of Uppsala Dissertations from the Faculty of Science, 250. 31pp. ISBN 91-554-2530-5.

Witter, E., 1992. Heavy metal concentrations in agricultural soils critical to microorganisms. Swedish EPA, report 4079, 44 ppg.

Wren, C.D., & Stephenson, G.L., 1991. The effect of acidification on the accumulation and toxicity of metals to freshwater invertebrates. Environmental Pollution. Vol 71, 205-241.

Oman, C., & Wennberg, L., 1997. Development of methods for characterisation of leakage water from waste deposits (Utveckling av metoder for karaktarisering av lakvatten fran avfallsupplag). Report from the Swedish Environmental Research Institute (IVL), Stockhom, Sweden. (In Swedish)

Ostlund, P., & Palm, V., 1995. Meatals, lead isotopes, and denitrification potential in sediments from Stockholm (Metaller, blyisotoper och denitrifikationspotential i sediment runt Stockholm stad). Report from the Swedish Environmental Research Institute (IVL), Stockhom, Sweden, 28 ppg. (in Swedish).

10.1 Personal communications

Gunilla Aim, Swedish University of Agricultural Science. Department of Environmental Assesement.

Bo Bergqvist, University of Lund, Department of Plant Ecology.

Karin Kindbom, Swedish Environmental Research Institute, Gothenburg, Sweden.

Hans Tjalve, Swedish University of Agricultural Science, Department of Pharmacology and toxicology.

Anders Willander, Swedish University of Agricultural Science. Department of Environmental Assesement.

Cecilia Oman, Swedish Environmental Research Institute; Stockholm, Sweden.

76 11. Appendix

Appendix 1: Tabulated laboratory toxicity data for cadmium in agricultural soils, modified from Witter (1992). The references are given in the original report.

Appendix II: Examples from the literature on toxicity data for freshwater organisms from summaries by CWQG (1996), SEPA (1993), Wren and Stephenson (1991), Lithner (1989), and Spry and Weiner (1991).

Appendix III: Examples from the literature on toxicity data for freshwater organisms from summaries by CWQG (1996) and SEPA (1993).

77 APPENDIX I, page 1 of 3 Laboratory studies. Cadmium Cd Cd Cd in Reference DEL Soil type pH Parameter total added crease type 1.1 0.1 i.i Eivazi 1990 LOEL clay High N mineral. 63.5 61.7 35.3 McKenney & LOEL clay Not N mineral. Vriesacker, 1985 known 50.5 50.0 101.0 Stadelmann & LOEL loam Low C mineral. Santschi- Fuhrimann, 1987 7.8 Reber, 1989 LOEL loam Low C mineral. 2.7 Reber, 1989 LOEL loam Neutral C mineral. 16.2 16.0 107.7 Coppola et al., LOEL loam Neutral Microbial 1988 population 0.4 0.3 5.0 Wilson, 1977b LOEL loam Neutral N mineral. 1.1 0.1 1.1 Eivazi, 1990 LOEL loam Neutral N mineral. 0.6 0.6 8.0 Wilson, 1977b LOEL loam Neutral N mineral. 400.0 Chang & LOEL loam Neutral N mineral. Broadbent, 1982 4.2 4.0 27.7 Coppola et al., LOEL loam Neutral N mineral. 1988 8.8 8.7 125.3 Chang & LOEL loam Not C mineral. Broadbent, 1981 known 560.0 Lighthart et al., LOEL Not Neutral C mineral. 1983 known 50.0 Kahn & Frankland. LOEL Not Not C mineral. 1984 known known 20.0 Rogers & Li, 1985 LOEL Not Not enzyme known known 2.6 Reber, 1989 LOEL sand Neutral C mineral. 150.4 150.0 376.0 Doelman & LOEL sand Neutral C mineral. Haanstra, 1984 95.4 95.0 238.5 Doelman & LOEL sand Neutral enzyme Haanstra, 1986 55.2 54.1 50.2 McKenney& LOEL sand Neutral? N mineral. Vriesacker, 1985 500.0 Morrisey, 1985 LOEL loam Not N mineral. known 29.0 Walter & LOEL Not Low C mineral. Stadelmann, 1979 known 29.0 Walter & LOEL Not Low Microbial Stadelmann, 1979 known population 500.0 Bewley& Stotzky, LOEL Not Low N mineral. 1983c known 58.0 Walter & LOEL Not Low N mineral. Stadelmann, 1979 known 562.0 Tabatabai, 1977 LOEL Not Not enzyme known known 10.0 Cornfield, 1977 LOEL sand Low C mineral. APPENDIX I. page 2 of 3 Laboratory studies. Cadmium Cd Cd Cd in Reference OEL Soil type PH Parameter total added crease type 10.0 Naidu & Reddy, LOEL clay High N mineral. 1988 2.2 2.0 14.3 Coppola et al., 1988 LOEL clay Neutral N mineral. 281.0 Juma & Tabatabai, LOEL loam Neutral enzyme 1977 0.1 1.0 Zibilske & Wagner, LOEL loam Neutral Microbial 1982 popu-lation 10.0 Bollag & Barabasz, LOEL loam Neutral N mineral. 1979 100.0 Chang & Broadbent, LOEL loam Neutral N mineral. 1982 2810.0 Stott et al., 1985 LOEL Not Neutral enzyme known 281.0 Al-Khafaji & LOEL Not Neutral enzyme Tabatabai, 1977 known 562.0 Liang & Tabatabai, LOEL Not Neutral N mineral. 1977 known 55.4 55.0 138.5 Haanstra & LOEL sand Neutral C mineral. Doelman, 1984 50.0 Wilke & Keuffel, LOEL sand Neutral enzyme 1988 1.0 0.0 1.0 Eivazi 1990 NOEL clay High N mineral. 12.4 10.6 6.9 McKenney & NOEL clay Not N mineral. Vriesacker, 1985 known 2.0 1.5 4.0 Stadelmann & NOEL loam Low C mineral. Santschi-Fuhrmann, 1987 560.0 Stott et al. 1985 NOEL loam Neutral enzyme 8.2 8.0 54.3 Coppola et al., 1988 NOEL loam Neutral Microbial popu lations 1.0 Zibilske & Wagner, NOEL loam Neutral Microbial 1982 popu lations 0.2 0.1 2.0 Wilson, 1977b NOEL loam Neutral N mineral. 2.2 2.0 14.3 Coppola et al., 1988 NOEL loam Neutral N mineral. 1.0 0.0 1.0 Eivazi 1990 NOEL loam Neutral N mineral. 200.0 Chang & Broadbent, NOEL loam Neutral N mineral. 1982 0.2 0.1 2.8 Wilson, 1977b NOEL loam Neutral N mineral. APPENDIX I. page 3 of 3

Cd Cd Cd in Reference OEL type Soil type PH Parameter total added crease 10.0 Kahn & NOEL loam? Neutral C mineral. Frankland, 1984 ? 8.9 7.8 8.1 McKenney & NOEL sand Neutral N mineral. Vriesacker, 1985 ? 5.1 Walter & NOEL Not Low C mineral. Stadelmann, 1979 known 15.0 Walter & NOEL Not Low Microbial Stadelmann, 1979 known populations 1000.0 Bewley & Stotzky, NOEL Not Low N mineral. 1983c known 29.0 Walter & NOEL Not Low N mineral. Stadelmann, 1979 known 16.2 16.0 107.7 Coppola et al., NOEL clay Neutral Microbial 1988 populations 50.0 Mateoz & NOEL loam High enzyme Carcedo, 1988 562.0 Frankenberg & NOEL loam? Neutral enzyme Tabatabai, 1981 ? 56.0 Lighthart et al., NOEL Not Neutral C mineral. 1983 known 3.0 Wilke, 1988 NOEL sand Low enzyme APPENDIX II. page 1 of 3 Acute toxicity data for fresh-water organisms Species Life Test Hardness Criterion Effect Reference stage con level dition (mg CaCOVL) (pg Cd/L)

Invertebrates Daphnia s <100 48-h LC50 9.9-166 Wren & magna Stephenson, 1991 s 100-200 48-h LC50 34-58 s >200 48-h LC50 178-319 48-h LC50 3.60 CWQG, 1996 Daphnia s 53.5-106 48-h LC50 7-268.2 Wren & pulex Stephenson, 1991 Cerio- s 100-240 48-h LC50 27.3-184 Wren & daphnia Stephenson, 1991 reticulata Hyalella ss 20 96-h LC50 85.00 Wren & azteca Stephenson, 1991 s pH=5 96-h LC50 12.00 s pH=5.5 96-h LC50 16.00 s pH=6 96-h LC50 33.00 130 42d LC50 0.53 CWQG, 1996 Gammarus 96-h LC50 7.60 CWQG, 1996 fossarum Anodonta 96-h LC50 9.00 CWQG, 1996 imbicillis

Fish Salmonids LC10-50 0.8-1.4 CWQG, 1996 Salmo adult 82-132 96h- LC50 6.60 Lithner, 1989 gairdneri Ochor- fry 96-h& 168- <0.5 CWQG, 1996 chynchus h. LC50 mykiss Onchor- early <25 >7d. LC50 <0.5-3 Spry & Weiner, chynchus life 1991 tshawy- stages tscha s = static, ss = semi static, ft = flow through APPENDIX II. page 2 of 3 Cronic toxicity data for fresh-water organisms Species Life Test Hardness Criterion Effect Reference stage con- level dition (mg CaCOVL) ft* g Cd/L)

Algae Tabellaria s 14-d mor- 1-10 CWQG, flocculosa phology 1996 changes & growth inhibition Selenastrum s growth 6.00 CWQG, capricorn- inhibition 1996 turn Spirulina s reduced final 9.00 CWQG, platensis & yield 1996- Nostoc linckia

Blue-green impaired 0.1-1 SEPA, 1993 algae growth

Macrophytes Lemna inhibited 10.00 CWQG, minora photo- 1996 synhesis

Invertebrates Daphnia ft. ss 90-240 NOEC 0.32-0.5 Wren & magna Stephenson, 1991 ft. ss 90-240 LOEC 0.5-4.2 48.5 LOEL. 21-d. 0.17 CWQG, 16% reproduct 1996 ive impairment Daphnia ss 42-240 NOEC 1.00 Wren & pulex Stephenson, 1991 ss 42-240 LOEC 0.2-0.5 ss 42-240 MATC 3.8-7.5 _ _ LOEC. 14d. 0.20 CWQG, 16% reproduct 1996 ive impairment Ceriodaphnia ss 55-79 NOEC 3.40 Wren & reticulata Stephenson, 1991 ss 55-79 LOEC 7.20 LOEC. 7d, 0.20 CWQG, 16% reproduct 1996 ive impairment APPENDIX II. page 3 of 3

Cronic toxicity data for fresh-water organisms Species Life Test Hardness Criterion Effect Reference stage con level dition (mg CaCOVL) (dsCd/L)

Fish Salmonids early life stages <60d, 0.7-6.7 Spry&Weiner, MATC, 1991 survival and growth Salmo alevin 46d. 11% 0.47 CWQG, 1996 salar body weight red., 6% fork length red. s = static, ss = semi static, ft = flow through APPENDIX III. page 1 of 2

Acute toxcity data for marine organisms Species Sal Life Criterion Effect Reference inity stage level (%) (gg Cd/L)

Invertebrates Mysidopsis bahia 96-h LC50 14.7-16 CWQG, 1996 Mysidposis bahia 2 96-h LC50 29 SEPA, 1993 Acartia tonsa 2.1 96-h LC50 380 -”- Crangon septem- 96-h LC50 320 CWQG, spinosa 1996 Homarus americanus 96-h LC50 78 Neomysic americanus 2 96-h LC50 20 SEPA, 1993

Marine and estaurine fish Scorpaeinchthys 24- LC50 310 CWQG, marmoratus 1996 Pagrus major 96-h LC50 200-500 Mugil cephalus 96-h LC50 700 Phoxinus phoxinus larvae 56-d LC50 100 Cyprinodon varieg. 70-d LC50 420 Meidia men. 2 96-h LC50 15600 SEPA, 1993 2 96-h LC50 6400 APPENDIX III. page 2 of 2

Chronic toxicity data for marine organisms Species Sal Life Criterion Effect Reference inity stage level (%) (pgCd/L)

Algae Cylindrothea growth inhibition 5 CWQG, closterium 1996 Most other algal growth inhibition 5-50 CWQG, species 1996

Invertebrates Mysidopsis bahia LOEL, 20d, 17% 1.2 CWQG, surv. red; 26% 1996 red. in fecundity Acartia tonsa 96-h reduction in 78 CWQG, feeding and 1996 fecundity Diporeia affinis abn. egg devel. 6.3 CWQG, and red. biomass 1996

Marine and estaurine fish Allorchestes abn. egg devel. 11 CWQG, compressa and red. biomass 1996 Meiofauna 0.7 460 d, abnormal 6* SEPA, 1993 eggs Pontoperia aff. 0.7 105 d, abnormal 6* SEPA, 1993 eggs Other groups of invertebrates red. survival and 15-26000 CWQG, (echinoderms. polychatet) reproduction 1996

Marine and estaurine fish Mugil cephalus larvae reduced survival 50 CWQG, (>10%) 1996 *Note: 6pg/l is the lowest dose, which means that the zero effect cannot be specified with greater accuracy than 0.02-6 pg/1 Part II Cadmium in goods - contribution to environmental exposure

Bo Bergback and Ame Jonsson, Kalmar Universitet, Department of Natural Science Contents

Abstract 4 Sammanfattning 5

1. Introduction 6

2. The use of cadmium in Sweden i

3. Accumulated amounts of Cd in the Swedish anthroposphere io 4. Cadmium in the urban environment n 4.1 A case study of Stockholm 11

5. Calculation of consumption emissions is 5.1 Consumptive uses and losses of Cd in the United States, 1880-1980 16 5.2 Consumption emission factors - a general discussion 17 5.3 Consumption emission factors for Cd 20

6. Calculations of emissions in Sweden 1940-1990 22 6.1 Production emissions 22 6.2 Consumption emissions 23 6.2.1 Consumption emissions - the simple method 23 6.2.2 Consumption emissions - an alternative method 24 6.3 Total emissions 25

7. Conclusions 27 8. Glossary 28 9. References 29 Abstract

Since the turn of this century, technological development has drastically increased the industrial consumption of metals. The total amount of Cd used in Sweden since 1940 is approximately 5000 tonnes, including alloys, fertilizers and impurities in zinc.

The stock of Cd in goods in the Swedish anthroposphere is dominated by NiCd-batteries. However, when one considers the degree of exposure to corrosion, Cd stabilizers are dominant.

Emissions of Cd from industrial plants and other point sources have been historically important. However, these point source emissions must be seen in relation to the increasingly significant fugitive ’’consumption emissions ”, from the use and/or end-use of various goods.

In this study, methods of reconstructing the flows of cadmium (Cd) and estimating the emissions over time are discussed. This is done through stu dies of the development of production, technology, trade and the longe-vity of metals in Swedish society. This last part in the chain will form the "con sumption emissions" calculated from emission factors giving the proportion of the cadmium content in a good that eventually will reach the environ ment. The main accumulation of metals in the anthroposphere occurs in urban areas where the influx of metals is greatest. Urban areas probably represent "hot spots" as far as this type of environmental impact is concerned.

Extreme Cd concentrations in surface sediments in central Stockholm indi cate an ongoing release of Cd from the anthroposphere. The sources are so far unknown, i.e. this Cd flow to the biosphere cannot be explained in terms of deposition or emissions from point sources. Approximately 40 tonnes of Cd in goods are exposed to corrosion in varying degrees. This stock is domi nated by Cd in stabilizers and pigments, and as impurities in Zn.

4 Sammanfattning

Under 1900-talet har den industriella konsumtionen av metaller okat drama- tiskt. Den totalt anvanda kadmiummangden i Sverige sedan 1940 ar ca 5000 ton, inklusive Cd i legeringar, handelsgodsel och som fbrorening i zink. Ackumulerade Cd-mangder i produkter i den svenska antroposfaren domineras av NiCd-batterier. Utifran exponeringsgrad for korrosion ar dock mangden Cd i stabilisatorer dominerande.

Historiskt har Cd-utslapp fran industriverksamhet varit betydande. Dessa punktutslapp maste dock sattas i relation till allt mer betydelsefulla diffusa ’’konsumtionsutslapp ” fran produkter i anvandning och som avfall.

I delta arbete diskuteras metoder att rekonstruera Cd-floden och att upp- skatta olika typer av utslapp over tid. Delta genomfors genom studier av utveckling av produktion, teknologi och handel, samt livslangd av metaller i det svenska samhallet. ’’Konsumtionsutslapp ” beraknas utifran emissions- faktorer vilka ger den del av Cd-innehallet i en produkt som slutligen nar miljdn. Den huvudsakliga ackumulationen av metaller i antroposfaren sker i stader dar inflodet av metaller ar storst. Stader kan anses vara ’’hot spots ” for denna typ av miljopaverkan.

Extremt hoga Cd-koncentrationer i ytsediment i centrala Stockholm indikerar en pagaende frigorelse av Cd fran antroposfaren. Kallor ar hittills o- kanda, dvs delta Cd-flode kan inte forklaras med deposition eller utslapp fran punktkallor. Ca 40 ton Cd i olika produkter ar exponerade for korrosion av vaxlande grad. Denna upplagrade mangd domineras av Cd i stabilisatorer och pigment samt som fbrorening i zink.

5 1. Introduction

The enormous variety of chemicals used during the last century has resulted in large amounts of substances, materials and goods ^ accumulated in the anthroposphere ^.

Since the turn of this century, technological development has drastically increased the industrial consumption of metals. The present flow of most heavy metals through society exceeds the natural amounts circulating in the biosphere (Nriagu, 1990). Once dispersed in the environment, the metals cannot be degraded but will accumulate in soil or sediment sinks. Thus, the environmental effects of heavy metal pollution tend to be permanent.

In this study, methods of reconstructing the flows of cadmium (Cd) and estimating the emissions over time are presented. This is done through studies of the development of production, technology, trade and the longe vity of metals in Swedish society. This last part in the chain will form the "consumption emissions" calculated from emission factors giving the pro portion of the cadmium content in a good that will eventually reach the environment.

There is an obvious risk that these "fugitive" fluxes will increase as metals accumulate in society. The main accumulation of metals in the anthroposphere occurs in urban areas where the influx of metals is greatest. Urban areas probably represent "hot spots" as far as this type of environmental impact is concerned. In this study, the flow and accumulation of cadmium in the anthroposphere and biosphere of Stockholm are discussed.

1 C.f glossary 2 C.f glossary 6 2. The use of cadmium in Sweden

In the 20th century, five principal uses of cadmium have dominated: (i) in pigments, (ii) in stabilizers, (iii) in Ni-Cd batteries, (iv) as protective plating on steel and (v) in various alloys (Table I). Since the early 1980s the use of cadmium in pigments, stabilizers and plating has been restricted in Sweden by legislation.

Sulphide of cadmium is used extensively in pigments. It can produce colours from very light yellow, through orange and light red to deep maroon, either on its own or with varying amounts of cadmium selenide. In Sweden, about 90% of cadmium pigments have been used in plastics, mainly polythene, polystyrene and polyvinyl chloride (PVC). Most of the remaining 10% were used in glass and ceramics. Today a small but impor tant amount of Cd is used in artists' paint.

Organic cadmium salts (notably cadmium stearate and cadmium benzoate) have been used as stabilizers mainly for PVC plastics. These stabilizers protect plastics from degradation caused by heat and light.

There are two distinct categories of Ni-Cd storage batteries: the open, pocket type (Jungner type) and the sealed, sintered plate type. The bulk of cadmium metal imports into Sweden are used in the production of Jungner- type batteries. However, approximately 90% of these batteries have been exported. The domestic use of cadmium for this application has been esti mated at 20 tonnes yr 1 in the mid-1980s. Earlier domestic use has then been calculated according to the net cadmium metal consumption.

The use of the sintered plate type of Ni-Cd rechargeable cells in portable appliances and tools increased dramatically in the 1980s. Between 1985 and 1990 the yearly increase in consumption was approximately 30%. Consum ption culminated in the early 1990s.

Electroplating of various metals has been one of the most important uses of metallic cadmium, where it provides a coating that is resistant to corrosion by alkalis, salt water or the atmosphere. In the early 1970s the consumption of cadmium for this use was 40 tonnes yr 1, but in the 1980s it was reduced significantly to 2 tonnes yr 1.

Cadmium has an extensive use in alloys. For example, cadmium is alloyed with copper to improve its strength and wear resistance (e.g. car radiators).

7 The consumption of cadmium in domestically produced alloys was approxi mately 10-40 tonnes yr 1 between 1940 and 1990. However, most of this amount has been exported in the form of various goods. Thus, the total amount of cadmium in alloys used in Sweden can be estimated at 5-20 tonnes yr 1, i.e. 250 to 1000 tonnes for the whole period. The import of cadmium in alloyed goods has not been considered due to the lack of reli able data. The Swedish consumption of zinc in the mid-1980s was approxi mately 50000 tonnes yr'l. The total amount of zinc used in Sweden in the period 1940 to 1990 was 2.1 million tonnes. As there has been no produc tion in Sweden, all zinc has been imported, in more recent decades mainly as electrolytic zinc with an average cadmium content of 0.001%. This amounts to a total of 20 tonnes of cadmium for the period 1940 to 1990. In a study of zinc production in the U.S. in 1968, an average content of 0.01% was found when considering different types of zinc processed (special high 0.002 - prime western 0.025%) (Fulkerson & Goeller, 1973). For Sweden this would amount to a total of 200 tonnes of cadmium for the period studied.

Finally, the amount of cadmium added to agricultural soils as impurities in phosphorus fertilizers has been calculated at 280 tonnes (1940-1990) or 370 tonnes (1900-1990).

In Table 1 the ’’new ” use or consumption of Cd per year has been calculated for 1940 to 1995. The Cd ban from the early 1980s is well reflected on the use of pigments, stabilizers and plating. However, the total amount of Cd is still at a level corresponding to the 1970s, due to an extraordinary increase in the use of NiCd-batteries.

8 Table I. Estimated consumption of cadmium in Sweden 1940-1995, (tyr'l) Pigments Stabili NiCd- batterie Plating zers Jungner Sintplate

1940 - - 3 - 20

1945 - - 5 - 20 1950 0.3 1 12 - 25 1955 1 2 10 - 30 1960 3 6 12 - 35 1965 6 13 17 - 40 1970 13 29 16 1 40 1975 18 40 25 6 30 1980 7 30 21 18 20 1985 0.5 9 20 24 2 1990 0.5 2 11 90 2 19951 0.5 0 20 73 0.5 Total 240 660 790 930 1290 (1940-1995) Grand total 3910

Fertilizers 280 1. Alloys. Estimated use 250-10001. Impurities in zinc. Estimated use 20-2001. iLohm et al., (1996)

9 3. Accumulated amounts of Cd in the Swedish anthroposphere

The total amount of Cd used in Sweden since 1940 is approximately 5000 tonnes, including alloys, fertilizers and impurities in zinc. Assuming that the longevity of the different goods categories is below 20 years, the present amount of Cd accumulated in the anthroposphere of Swe den will be in the magnitude of 1800 tonnes. If only 10 years (1986 to 1995) are considered the accumulated amounts of Cd decrease to approximately 900 tonnes. The distribution of the use of different goods categories over time is shown in Table II.

Table II. Estimated consumption ofCd in different goods in Sweden, 1976 to 1995, (t/ 5 yr)

1976-80 1981-85 1986-90 1991-95 Total Pigments 63 19 3 3 88 Stabilizers 175 98 28 5 306 NiCd-batteries, Jungner 115 100 78 78 371 NiCd-batteries, sint.plate 60 105 285 408 858 Plating 125 55 10 6 195 Total 538 377 404 500 1820

The total amount of Cd in alloys has been estimated at 5-20 tonnes per year, i.e. 100-400 tonnes for the last 20 years. For the same time period mostly electrolytic zinc has been used with an average cadmium content of 0.001%. Thus, the total amount of Cd in Zn used in the last 20 years is in the magnitude of 20 tonnes. The recycling of open Jungner batteries has been high (>90%). For the sealed, sintered plate batteries the recycling rate be fore 1990 was approximately 10 to 20 percent. In the mid 1990s, various campaigns have increased the rate to more than 30%. For the other goods categories recycling has been negligible.

10 4. Cadmium in the urban environment

The total amount of Cd used in the Swedish anthroposphere is approxi mately 5000 tonnes (c.f. Table II, alloys and impurities in Zn included). The major part of this Cd has been used in urban areas.

4.1 A case study of Stockholm

In 1994 the Swedish Environmental Protection Agency (SEPA) started a new research programme "Metals in the Urban and Forest Environment - Ecocycles and Critical Loads, 1994/95-1998/99". The purpose of the sub- programme "Metals in the urban environment" is to produce data to use when deciding which metal fluxes should be given priority for closure and which ones should be prevented in the urban environment.

Stockholm has been chosen as the subject of this study and one major scope of the research is to focus on the fugitive "consumer emissions" from the use of goods containing heavy metals. One major project within SEPA's re search program is "Metal metabolism - analysis of accumulated environ mental impact in urban areas", Linkoping University. The first part of this project is focused on collecting information about flows and stocks of metals in Stockholm. The time period studied is the 20th cen tury and the metals are cadmium, chromium, copper, lead, mercury, nickel and zinc. Here, official statistics on a national, regional and local level are used and contacts are established with industrial/sector representatives from production/ construction. This part has been going on for two years giving a good overview of the major flows. However, this work will continue especi ally to enlarge the information of goods with large flows/stocks and an ex pected high "release factor" of metals from the anthroposphere to the bio sphere.

In the second part of the project, flow schemes and a flow model are con structed. The aim is to implement a model that synthesises flows and stocks in the anthroposphere with flows and stocks in the biosphere. Information of metal flows from the anthroposphere, e.g. by corrosion, and metal concen trations in different sinks will be provided by other research groups working within the SEPA's programme. The model should be a tool for scenarios of environmental impact for different measures. This part of the project has just started, but will continue to be a major task during the coming years.

11 The stock of metals in Stockholm has thus been calculated. For Cd, 120 tonnes are in use today (1995) in various goods. Scaling up to the national level, this would correspond to approximately 1 200 tonnes accumulated within the Swedish anthroposphere. This is in agreement with the discussion in section 3.

The metal stock has been divided into different categories e.g. ■ sector of use (household, infrastructure, buildings, vehicles, industry) ■ exposure of the goods to different corrosive environments, e.g. air, water and soil.

The distribution on different sectors of use is shown in Figure 1.

Alleys

Rgrents

Rating

Batteries, open

Inpurities inZn

Batteries sealed

Stabilizers Cdtorre

0 10 20 30

Blnfhastructire ■Buildngs D Households i Industry S Wides:

Figure 1. Cd in goods distributed on categories of use, Stockholm 1995. From Bergbdck & Johansson (1996).

Cd in stabilizers and sealed batteries constitutes 50 % of the total amount accumulated in the anthroposphere in Stockholm. The stabilizers are used mainly in the infrastructure and in buildings, while the batteries are assumed to be shared equally between households and the industry sector. The major part of Cd in goods is in a protected environment with a negli gible exposure to corrosion, e.g. indoor plastics or batteries in various appli ances. However, approximately 40 tonnes are exposed to corrosion in vary ing degrees. Cd-containing goods in vehicles, buildings and infrastructure exposed to air, water and soil are presented in Table III:

Table III. Amounts of Cd (tonnes) in goods exposed to corrosion in air, soil and water, Stockholm 1995. From Lohm et al. (1996). Air/ Vehicles alloys 2 plastics, stabilizers and pigments 4 plating 6

Air/ Buildings Impurities in Zn, roofs etc. 6

Water/ Buildings Impurities in Zn, brass 7

Soil/ Infrastructure Stabilizers 12

These categories of use represent large areas of exposure and constitute a stock for the potential release of Cd to the biosphere. Stabilizers represent an important part of this exposed stock.

At present there is a lack of reliable data to calculate the release of Cd from goods in different corrosive environments. Ongoing studies within the SEPA's research programme will in the near future increase our knowledge of Cd emission rates both from metallic surfaces and various materials (plastics, concrete etc.). However, there are strong indications of a Cd re lease from the anthroposphere of Stockholm , e.g. the corrosion rate of Cd metal in an atmospheric environment is relatively high (5-22 g/m^ yr) (Persson & Kucera, 1996) and there is a high Cd content in waste water from car washes (Jonsson et al., 1991). The major amounts of Cd in a car are found in the metal parts, i.e. plated surfaces and alloys (Flyhammar 1995, Baccini & Brunner, 1991).

The strongest indication of an ongoing release of Cd from the anthro posphere is the elevated Cd concentrations in sediments in central Stock holm. Here, extreme values of 14 ppm have been found (Blomqvist & Larsson, 1996 and Bergback & Johansson, 1996). This corresponds to an enrichment factor3 of 50 (normalised to Scandium), i.e. the concentration is 50 times that which can be expected from the surrounding bedrock. Even

3 C.f. glossary 13 when calculated on the median concentration (n= 85), an enrichment factor of 10 indicates a strong anthropogenic impact. This impact seems to originate from the city since Cd concentrations decrease with distance from the central parts of Stockholm. Further, these samples are from surface sediments, i.e. they represent recent Cd flows from the anthroposphere.

These Cd flows, reflected in the sediment cannot be explained by emissions from industry, waste water treatment plants or other known sources includ ing deposition. As mentioned before, a flow model is under construction that synthezises the anthroposphere with the biosphere. A first run of this flow model indicates a significant contribution by various goods to the total flow of Cd.

14 5. Calculation of consumption emissions

One major scope with the Stockholm study is to calculate the metal release from various goods to the biosphere. This will be done through specific factors giving the ’’corrosion rate” of goods in different environments, i.e. atmospheric corrosion for roofs or vehicles, corrosion in tap water system or corrosion in soil for PVC plastics. As mentioned before, at present there is a lack of reliable data to calculate the release of Cd from goods.

A rough estimation of the metal release from goods in use or as waste may be made from ’’consumption emission factors” (Tarr & Ayres, 1990). The consumption emission factor‘d gives the proportion of heavy metal in a spe cific good that will be released into the environment. The emission is then accounted for a decade as a function of the actual use of the good. Con sumption emission45 includes the release of metal from a good in use and from the waste fraction. In order to clarify the method of calculation some points must be stressed:

■ The starting point is the net consumption per decade of Cd in a specific good. ■ The aim is to estimate the proportion of Cd that eventually will reach the biosphere. No time scale is given. ■ This proportion is given by a consumption emission factor. ■ In the most simple application, the calculated consumption emissions are accounted for in the same decade as the actual use. Obviously this is not true for all goods.

In the following sections the calculation of consumption emissions with these emission factors will be discussed.

4 C.f. glossary 5 C.f. glossary 15 5.1 Consumptive uses and losses of Cd in the United States, 1880-1980.

One example of this method of calculation, with all simplifications, is found in Ayres & Ayres (1994). Here, an historical reconstruction of US emissions of some heavy metals to the environment, resulting from dissipative con sumptive uses, is presented. Emission factors as presented in section 5.2 were used for calculations. For Cd, the emissions from consumptive uses have been dominated by losses from plating and coating, paints and pig ments and from stabilizers, mostly in urban areas. Production emissions6 have been calculated for metallurgical operations and for fossil fuel com bustion (Table IV).

Table IV. Calculated US Cd emissions from production and consumption, 1880 to 1980 (tonnes). From Ayres & Ayres, 1994. 1880 1920 1940 1960 1980 Production, metallurgical low 194 164 136 114 24 high 239 410 350 253 31

Production, fossil fuel* 55 243 156 193 302

Consumption 0 34 714 894 228

Total low 249 441 1006 1201 554 high 294 687 1220 1340 561

1 fossil fuel combustion

The importance of the calculated consumption emissions is obvious from the 1940s. However, the used emission factors must be analyzed before it is possible to assess the reliability of these calculations. This will be done in the following section.

6 C.f. glossary 16 5.2 Consumption emission factors - general discussion

The consumption emission factors are, of course, tentative and should be considered more as indicators of magnitude than absolute values. Obviously, more knowledge of total flows for various goods in society is urgently needed. In the long run, however, an upper limit of consumption emissions is given by the total amount of metals used.

Tarr & Ayres (1990) give emission factors for different metals in relation to various uses. Some examples are shown in Table V.

Table V Consumption related emission factors for cadmium, chromium and lead (c.f Tarr & Ayres, 1990)

Cadmium Chromium Lead Metallic use^ 0.001 0.001 0.005 Plating and coating^ 0.15 0.02 - Batteries^ 0.02 0.01 0.2 Paint and pigments^ 0.5 0.5 0.5 Chemical uses, embodied^ 0.15 0.05 0.8 1. For Cd and Cr in alloys. For lead also as pure metal. Losses can be as sumed to be due primarily to wear and corrosion. 2. Protective surfaces deposited by dip coating, e.g. electroplating or chemical bath. Losses in use are mainly due to wear and abrasion or flaking. 3. Includes lead coated cables. Discarded equipment goes mainly to land fills or incinerators. Lead batteries and the pocket type of nickel-cad mium batteries are recycled to a much higher degree than the sintered plate type of nickel-cadmium batteries. 4. Paints and pigments are lost primarily by weathering (e.g. for metal- protecting paints), by wear, or by disposal of painted dyes or pigmented objects. Lead oxides have been considered to be extra resistant (emission factor 0.1). A factor of 0.5 is rather arbitrarily assumed for all other paints and pigments. 5. Chemical uses embodied in final goods: fuel additives (Pb), stabilizers (Cd) in plastics and chromium salts embodied in tanned leather. 17 There are three major shortcomings with the use of emission factors as de fined by Tarr & Ayres (1990):

■ The time perspective, i.e. the release is a function of the consumption within a decade. Obviously, the time period of release will be strongly related to the type of good. ■ Degree of exposure to corrosive environment for the good. Here, the same factor is used for a good in all environments. ■ Lack of differentiation of the factor for a category of good, i.e. pigments on a metal surface have the same factor as pigments in plastics (c.f. sec tion 5.3).

The emission factor gives the proportion of heavy metal in a specific good that will be released into the environment. The emission is then accounted for a decade as a function of the actual use of the good. Clearly, this is a simplification as the release from a good is often slow and may go on for more than one decade. To follow the development of consumption emis sions over time, it would be more accurate to calculate accumulated emis sions, i.e. the remaining parts of the heavy metal in a good (from earlier decades) are added to the use in one specific decade. A simple example shows the difference in calculated emissions whether accumulation is considered or not: Assume a constant use of metal (10 t per decade) and an emission factor of 0.1. In Table VI the accumulated emissions have been calculated per decade by adding the remaining amounts from previous decades to the actual use.

18 Table VI. Calculation of accumulated emissions. Emission factor=0.1 (E), Amount of "new" use = 10 tonnes per decade (A). Total Emission amount accumu used lated Decade 1 2 3 4 5..... 1 k

1 10 10 1 2 9 10 19 1.9 3 8.1 9 10 27 2.7 4 7.3 8.1 9 10 34 3.4 5 6.6 7.3 8.1 9 10 41 4.1

' n (0.9)n-lf0 . (0.9)n "k10

In short, the consumption emission (C.E.) can be calculated from

n C.E.= E(l-E)n -kA»E eq. 1 k=l compared to eq.2 where no accumulation is considered

C.E. = A • E eq.2 i.e. the consumption emission according to eq. 2 is a linear function of the amount used, while in eq. 1 the relation between the emission and amounts used is more complex. This is especially true when the emission factor (E) is small as the importance of (1-E)n 'k then will increase. However, the cal culation of accumulated emissions assumes a slow and constant release of metal from the good. Further, when studying total emissions released during a time period, the method with accumulated emissions probably demands other emission factors than those given by Tarr & Ayres (1990).

The emission factors used in eq. 2 are used for a specific good, regardless of the exposed area or degree of corrosive environment, which obviously is another simplification. In the Stockholm study, the stock of each good is distributed over four degrees of exposure: to air, water or to soil, and fi nally goods that are protected.

19 Each type of exposure then corresponds to a specific emission factor, ranging from close to zero (protected) up to close to 1 for goods with a high potential for metal release in the most corrosive environment. To identify these specific emission factors, a large number of data will be needed on the different categories of uses and corrosion rates. This is one major task for the Stockholm project for the next few years.

However, at present the simpler method of calculation given in eq. 2 has to be used because of lack of data for the more specific emission factors. Even if this method includes extreme simplifications, there are still obvious ad vantages:

■ straightforward calculations, easy to discuss/assess ■ a quick way to identify major flows, which then may be studied in more detail ■ trends in consumption emission may easily be analyzed as the net inflow per time period is used as a starting point. ■ the release of Cd from a good in use or as waste are included in the emission factors. Thus, the total flow from a specific good can be calcu lated for and then accounted for the actual time period (e.g. decade).

5.3 Consumption emission factors for Cd

For Cd the factors given by Tarr & Ayres (1990) range from 0.001 (alloys) to 0.5 (pigments), i.e. the calculated release from the good will be from 0.1 up to 50 percent of the cadmium content. Thus, the factors give the total amount of Cd released from various goods that will ever reach the envi ronment from a specific use and time period.

For metallic uses (alloys) a factor of 0.001 indicates that 99.9% of the Cd consumption for a specific decade will remain in the anthroposphere for ever. This is obviously an underestimation of the release for the emissions from alloys and Cd impurities in Zn.

For NiCd-batteries a factor of 0.02 for the Jungner type reflects the high recycling rate, i.e. 98% of the Cd consumption per decade will never reach the environment. For the sintered plate type, the recycling rate has been low, 10 to 20%. At present large efforts are made to improve this rate. However, for 1970 to 1990 an emission factor of 0.2 has been used due to the uncer tainty of what will happen to ’’lost” batteries.

20 Obviously, the time period of Cd release from these batteries may exceed 10 years, i.e. the calculated emissions ought to be delayed. Release will be mainly from the waste fraction through incineration and/or via landfills. ¥ or,stabilizers a factor of 0.15 leaves 85% of the Cd consumed in a specific decade for this purpose to remain in various plastic goods within the anthroposphere. The time period of one decade is too short, i.e. the calculated emissions ought to be delayed. Release will be from goods in use, but mainly from the waste fraction through incineration and/or via landfills.

For plating a factor of 0.15 corresponds to a release of 15% of Cd net inflow per decade for this purpose. Cd plating has been used in more demanding corrosive environments, e.g. vehicles. Release will be mainly from corro sion.

For pigments the factor of 0.5 is reasonable for the Cd in artists' paint, but it is far too high for Cd in general as most of these pigments have been used in various plastics. Here, a factor similar to stabilizers is more relevant. The time period of one decade is too short, i.e. the calculated emissions ought to be delayed. Release will be from goods in use, but mainly from the waste fraction through incineration and/or via landfills.

For batteries, stabilizers and pigments the emission factors may be over estimations when used for calculation per decade. The release from these categories will probably take more than 10 years. However, in a longer time perspective these factors may represent the proportion of Cd that will even tually be released.

21 6. Calculations of emissions in Sweden 1940-1990

In order to assess Cd emission from various sources in Sweden, estimations have been made for the most important industrial branches, the use of phos phorus fertilizers and consumer uses for the period 1940 to 1990. This 50 year period clearly reflects the development of anthropogenic emissions in Sweden. The calculations are mainly from Bergback et al. (1994).

The contribution from foreign sources has not been taken into consideration. Instead, a state of equilibrium has been assumed with imports and exports counterbalancing each other. This is obviously an approximation, at least in southern Sweden where the impact from Central Europe is significant.

The importance of the long-range transport of heavy metals has been shown by, for example, Pacyna et al. (1984). In Sweden, both deposition calculated from moss analysis and measured wet deposition exceeded domestic emis sions in the 1980s (Monitor, 1987).

The main principle for calculating production emissions has been to use the earliest available estimations for branches of industry and then let the emis sions follow the development of production and/or cadmium use backwards in time. For consumption emissions specific factors for various goods have been used (c.f. section 5.3).

6.1 Production emissions

The national emissions have been estimated by the Swedish Environmental Protection Agency for various heavy metals and branches of industry since the beginning of the 1970s. These estimates have been used for the calcula tion of emissions from the most important industries backwards in time. Water emissions have been calculated for metal works, iron & steelworks, mining and the manufacture of batteries, phosphoric acid and phosphorus fertilizers. These branches of industry accounted for 98% of emissions at the end of the 1970s (sewage treatment plants excluded). Atmospheric emis sions have mainly originated from metal works (primary and secondary), iron & steelworks and battery manufacturing. The estimations of industrial emissions to water and air are summarized in Figure 2, section 6.3.

22 6.2 Consumption emissions

The consumption emissions have been calculated, with all simplifications, according to Ayres & Ayres (1994). An alternative method, with a differen tiation of lifetimes of goods and with a more realistic emission factor for pigments in plastics, is also presented.

6.2.1 Consumption emissions - the simple method

Consumption emissions from various goods containing cadmium have been calculated from the actual net inflow for different time periods. The diffu sion of cadmium from a specific use has been calculated according to emis sion factors, which give the proportion of the cadmium content in a good which eventually will be mobilized into the environment.

These emissions were accounted for in the same decade as the actual use. For further discussion see section 5. The following factors given by Tarr & Ayres (1990) have been used:

Metallic uses (Alloys) 0.001 Batteries, Jungner (pocket) type 0.02 Batteries, sintered plate 0.20 Stabilizers 0.15 Plating 0.15 Pigments 1 0.50 1 Obviously too high for pigments in plastics, c.f. 5.3

For batteries, Tarr & Ayres give a factor of 0.02 for all types. However, in Sweden the recirculation of the sintered plate type has been limited (10- 30%). Thus, in this study the same factor has been used as for mercury bat teries (0.20).

The total use of cadmium in alloys (250 to 1000 tonnes) or as an impurity in zinc (20 to 200 tonnes) combined with a small emission factor (0.001) has given rise to limited consumption emissions (less than 1.2 tonnes). Further more, for pigments the rather limited use of cadmium in artists' paint and in glass or ceramics has been excluded due to the longevity of these goods. The calculated consumption emissions are shown in Table VII. Table VII. Calculated consumption emissions of cadmium from various uses in Sweden 1940-1990, when using emission factors according to Ayres. Period Pigments Stabili NiCd-batteries Plating Total zers t/lOyr Jungner Sint. plate

1940-50 - - 1,3 - 33 34 1951-60 7,2 4,5 2,3 - 45 59 1961-70 37 24 3,0 - 58 122 1971-80 63 50 4,1 17 45 179 1981-90 13 21 3,5 88 12 138 Total 120,2 99,5 14,2 105 193 532

These consumption emissions are calculated with the simplifications men tioned in section 5.2.

6.2.2 Consumption emissions - an alternative method

In a study by Flyhammar (1995) the corresponding emissions have been calculated for the same time period but with respect to the lifetime of the good and differentiation of emission factors (Table VIII). A division of plastics goods into three major groups according to use and lifetime was made.

Table VIII. Lifetime, emission factor and recycling rate for different Cd applications. After Flyhammar (1995). Use Percent Lifetime Emission factor Recyc included yr ling rate Plating 100 15 0.15 50% Alloy 100 15 0.001 50% Battery, pocket type 100 15 0.02 80% Battery, sint. plate type 100 7 0.2 15% Pigment and stabilizer 25 35 0.5 and 0.2 0% 50 10 0.2 25 <1

This somewhat more sophisticated method of calculation gives a total con sumption emission of 370 tonnes of Cd instead of 530 tonnes. The differ ence is mainly due to a smaller emission factor for pigments in plastics (0.2 instead of 0.5) and more realistic lifetimes for different goods. Further,

24 Flyhammar estimates an accumulation of Cd in landfills at approximately 1 500 tonnes up to 1990.

6.3 Total emissions

The development of different sources of cadmium emissions is shown in Figure 2. Production emissions, both to air and water, reached a peak in the 1970s, and then decreased as a result of legislation and improved technol ogy.

The contribution from consumer uses has been significant since the 1960s. Furthermore, even taking into account the whole period studied (1940 to 1990), consumption emissions constitute 33% of the total calculated emis sions. The total amount of cadmium used in goods was approximately 3400 tonnes for the period 1940 to 1990 (cadmium in alloys excluded).

The emissions from these goods, according to the emission factors chosen in this study, were 530 tonnes (or 370 tonnes according to the alternative method of calculation), that is 15% of the total amount used. Again, these emissions represent what eventually will be released from the use and end- use of various goods according to the calculations presented here. However, a major part of the remaining 85% or 2900 tonnes have accumulated in the anthroposphere as goods in use or as waste, and may constitute a future po tential risk. This conclusion will be the same even if the consumption emis sions are calculated after considering different lifetimes, emission factors and recycling rates.

25 Consumption emissions Fertilizer

Production to air

■x — Production to water

1940 1950 1960 1970 1980 1990

Figure 2. Calculated cadmium emissions (t/yr) from different sources in Sweden 1940-1990.

For the 1990s the trends shown in Figure 2 continue, i.e. there is a further decrease in the production emissions while the calculated consumption emissions remain at a high level.

26 7. Conclusions

• Emissions of Gd from industrial plants and other point sources have been historically important. However, these point source emissions must be seen in relation to the increasingly significant fugitive "consumption emissions ”. In Sweden today, there are strong indications that the pro duction emissions of Cd are exceeded by emissions from the use and end-use of various Cd containing goods.

• The stock of Cd in goods in the Swedish anthroposphere is dominated by NiCd-batteries. However, if one considers the degree of exposure to cor rosion, Cd stabilizers are dominant.

• Strongly elevated Cd concentrations in surface sediments in central Stockholm indicate an ongoing release of Cd from the anthroposphere. These concentrations cannot be explained by known sources within the city. Approximately 40 tonnes of Cd in goods are exposed to corrosion in varying degrees. This stock is dominated by Cd in stabilizers and pig ments, and as impurities in Zn.

• In order to calculate consumption emissions, specific factors may be used. The consumption emission factors are, of course, tentative and should be considered more as indicators of magnitude than absolute val ues. The uncertainty of the factors is high, but still they provide a simple method to assess major flows of Cd in the anthroposphere. Even if the factors are reduced to 10% of the values given in the calculations in sec tion 6, consumption emissions in Sweden today will exceed production emissions.

• For the time period 1940 to 1980 the calculated consumption emissions have been dominated by plating, stabilizers and pigments. After the Cd ban in the early 1980s these emissions have levelled out.

• A continued reduction of the use of NiCd-batteries would in a most sig nificant way increase the rate of phasing out Cd from the Swedish an throposphere (c.f. Table II). This positive trend would, of course, be strongly contradicted by a new use of Cd in stabilizers, pigments or plating which would lead to a rebuilding of a Cd stock with a low poten tial for recycling.

27 8. Glossary

1 Anthroposphere The anthroposphere is the field where hu- 1 man activities take place; it is embedded in 1 the natural environment. The anthro- 1 posphere can also be described as a system 1 of processes and fluxes of goods, mate- 1 rials, energy and information. (Baccini P. & Brunner P., 1991)

1 Consumption emission Emissions from the use and end-use of goo

1 Consumption emission factor The emission factor gives the proportion of heavy metal in a specific good that will ever be released into the environment. The emission is then accounted for a decade as a function of the actual use of the good (as defined by Tarr & Ayres). 1 Enrichment factor Ratio between the actual concentration and expected ’’background concentration ”. Here calculated from [Cd-sediment]/[Sc- sediment] / [Cd-soil]/[Sc-soil] where Sc = Scandium I Good Materials or material mixture with func tions valued by man. (products) 1 Production emission Emission from the industry and energy sector

28 9. References

Ayres R.U. & Ayres L.W., 1994. Consumptive uses and losses of toxic heavy metals in the United States, 1880-1980. In: Ayres R.U. & Simonis U.E. (eds.), 1994. Industrial Metabolism. Restructuring for Sustainable De velopment. United Nations University Press. Tokyo, New York, Paris.

Baccini P. & Brunner P., 1991. Metabolism of the Anthroposphere. Springer-Ver- lag Berlin.

Bergback B., Anderberg S. & Lohm U., 1994. Accumulated environmental impact: the case of cadmium in Sweden. The Science of the Total Environ ment 145: 13-28.

Bergback B. & Johansson K., 1996. Metaller i stad och land. Lagesrapport 1996. Naturvardsverket Rapport 4677. In Swedish.

Blomqvist, S. & Larsson, U., 1996. Metal levels of aquatic bottom sediments in Stockholm. Report to the Swedish Environmental Protection Agency.

Flyhammar P., 1995. Analysis of the Cadmium Flux in Sweden with Special Emphasis on Landfill Leachate. Journal of Environmental Quality 24: 612-621.

Fulkerson, W. & Goeller, H., 1973. Cadmium the dissipated element. Oakridge National Lab. Tenn.

Jonsson, U., Elfstrom, M., Wallin, S., Tamm, E., Hammarberg, I., Backstrom, C.J. och Lundqvist, G., 1991. Klara fakta om avloppsvatten Iran biltvatt. Olika tvattmetoders inverkan Iran en automatisk biltvatt. Rapport Iran Stockholm Vatten och Svenska Shell AB. In Swedish.

Lohm, U., Bergback, B., Hedbrant, J., Jonsson, A., Sorme, L. och Ostlund, C., 1996. Metallmetabolism: analys av ackumulerad miljopaverkan i storstadsomraden. Slutrapport for arbetet 1994/95- 1995/96 till Naturvardsverkets forskningsavdelning. In Swedish.

Monitor, 1987. Tungmetaller - forekomst i mark och vatten Swedish Environmental Protection Agency (in Swedish).

29 Pacyna, 1, Semb, A. & Hanssen, J., 1984. Emission and long-range transport of trace metals in Europe. Tellus, 36B, 163-178.

Persson, D. & Kucera, V., 1996. Metallutslapp orsakade av korrosion och nedbrytning av olika materialytor. En kunskapssammanstallning. Korrosionsinstitutet Rapport 1996:3. In Swedish.

Nriagu,. J.O., 1990. Global metal pollution. Poisoning the biosphere. Environment 32, 7-33.

Swedish Environmental Protection Agency, 1994. Metals in the Urban and Forest Environment - Ecocycles and Critical Loads. Research Programme 1994/95-1998/99. Report 4435.

Tarr J.A. & Ayres R.U., 1990. The Hudson-Raritan Basin. In: Turner II et al. (eds.) The Earth as Transformed by Human Action. Cambridge Univer sity Press, New York, pp 623-639.

30 Part III Cadmium in fertilizers, soil, crops and foods - the Swedish situation

Stefan Hellstrand and Lars Landner, Swedish Environmental Research Group (MFG) Content

Summary 6

Sammanfattning 11

1. Introduction 15 1.1. Purpose of the report 15 1.2. Current cadmium restriction in Swedish agriculture 17 1.2.1. Soil and fertilizers 17 1.2.2. Animal feeds 17 1.2.3. Human food 17

2. The Natural Setting is 2.1. Geological background and soil properties 18 2.2. Variation in cadmium content in top soils of arable land 22 2.3. Precipitation, evaporation and runoff 27 2.4. Conclusions 30

3. Atmospheric deposition 31 3.1. Deposition of cadmium 31 3.2. Acid fallout 35 3.2.1 Sulphur and nitrogen compounds 3 5 3.2.2. Vulnerability of soils to acid fallout 37 3.3. Conclusions 40

4. Agricultural practices 40 4.1. Structural trends in Swedish agriculture 40 4.2. Agricultural production and its impact on cadmium accumulation in soils 43 4.3. Acidification through N-fertilization 44 4.4. Liming 45 4.5. Level and changes in soil pH 48 4.6. Application of phosphorus from manure and phos phorus fertilizers 50 4.6.1. Regional variation in application 50 4.6.2. Temporal trends in P-fertilizer application 51 4.7. Conclusions 52 5. Influx and efflux of cadmium in agricultural soils 53 5.1. Influx of cadmium to soils 53 5.1.1. General aspects 53 5.1.2. Temporal trends 55 5.1.3. Regional variation of some influxes 5 7 5.2. Efflux of cadmium from soils 59 5.3. Balance between influx and efflux 60 5.4. Possible future trends in cadmium content of soils 62 5.5. Conclusions 63

6. Factors influencing cadmium transfer from soils to crops 65 6.1 General aspects 65 6.2. Top soil properties and crops 67 6.2.1. Oat 68 6.2.2. Winter wheat 68 6.2.3. Spring wheat 69 6.2.4. Carrot 69 6.2.5. Potato 70 6.2.6. Comment 70 6.3. What are the most important factors? 70 6.3.1. The relation between soil content and crop content 70 6.3.2. Fertilization and the micro-environment of the roots 71 6.4. Conclusions 74

7. Cadmium Levels in Swedish Crops 75 7.1. Regional variation of Cd in crops 76 7.2. Conclusions 77

8. Cd levels in Swedish food 11 8.1. Content in individual foodstuffs 77 8.2. The major influxes of Cd with food to humans in Sweden 80 8.3. Conclusions 81 9. Scenarios of Long-Term Cadmium Exposure via P- Fertilizers si 9.1. Points of departure 81 9.2. Increase of Cd in soil 82 9.3. The effect on Cd in agricultural products 84 9.4. Conclusions 84

10. Overall Conclusions 86

11. References 88 11.1. Personal communication 94

Appendix 1.

Analysis of the Cd fluxes to and from soils through animal feed and through crops 95

1. Influx of Cd with purchased animal feeds 95 1.1. Regional variation in animal production 96

2. Efflux of Cd with crops 101 2.1. Regional variation in Swedish crop production 101 2.2. Variation in Cd content between crops and varieties 105 2.3. Regional variation in effluxes of Cd with crops 107

Appendix 2.

Cadmium content in food 111 Summary

The aim of this report is to review available information on the fluxes of cadmium (Cd) to agricultural soils and crops in Sweden from phosphorus fertilizers (P-fertilizers) and other sources, and to discuss how the content of Cd in soils, crops and human food may be influenced by the specific envi ronmental conditions in Sweden, as well as by the agricultural practices used in the country.

In earlier work, published in 1985, it was found that the content of Cd in grains of a specific variety of winter wheat had more than doubled in the period 1918-1980, and during the same period, the Cd content of agricul tural top soil increased by 33%. Later investigations of the relationships between Cd in soils and Cd in crops have provided new information allow ing a broader understanding of the relative importance of different factors that may influence the uptake of Cd by agricultural crops. These new find ings are presented and discussed as well as some recent changes in Cd in put to arable land. Both the average situation and the regional variation bet ween the eight main production zones in Sweden are considered.

The natural geological background determines, to a large extent, the con tent of Cd in the soil. Parent materials such as Cambrian bedrock, alum shales and some sandstones are generally rich in Cd. Soils that have develo ped from these formations are naturally rather rich in Cd, while, for example, the marine clays in SW Sweden generally have lower-than- average Cd contents. The national average for total (nitric acid extractable) Cd in agricultural top soil is 0.26 mg Cd/kg, but 5% of the cultivated soils have levels of >0.49 mg Cd/kg.

Especially in SW Sweden, there is a typical surplus of precipitation over evaporation, which causes an efficient wash-out of base cations from the soil and tends to reduce the buffer capacity and, eventually, to depress the pH of the soil solution, thereby enhancing the mobility and bioavailability of Cd to crops. This climatic factor, influencing the behaviour of Cd in the soil, probably is more pronounced in parts of Sweden than in most other European countries.

Furthermore, the predominance of magmatic bedrock in most parts of Swe den has resulted in a low, natural content of base cations in the relatively thin soil layers, formed after the latest glaciation.

6 Therefore, most Swedish soils are more vulnerable to impact of acidifying substances than soils in, e.g. central Europe.

The atmospheric fallout of Cd in Sweden has decreased by a factor of 2-3 over the past 15-20 years. The average influx of Cd to arable land through atmospheric fallout (in 1993-1995) varies between 0.1 (in the north) and about 0.5 g per ha and year (in plain districts in the south).

In spite of the recent reduction in deposition rate of acidifying substances (sulphur and nitrogen) , the actual acid load from the atmosphere, in SW Sweden, exceeds the critical load by more than five times, which is a situa tion similar to the one in large parts of central Europe. The annual deposi tion rate of sulphur and nitrogen is usually lower in Sweden than in central Europe (for each element, 6-18 kg/ha in S. Sweden, and 2-6 kg/ha in N. Sweden), but the generally higher susceptibility of Swedish soils to acid fallout results in a considerable excess of the critical level.

The agricultural practices have undergone a considerable modification over the past decades. One modification of certain importance for the mobility and bioavailability of Cd in the soil is the separation of crop from animal production at individual farms and in whole farming districts, as well as the decreasing use of ley in crop rotations and decreasing use of manure in ce real producing districts. These transformations result in a reduction of the content of organic matter in these soils, which tends to mobilise Cd.

There was a switch from nitrate- to ammoniumbased nitrogen fertilizers in the 1950s, which increased the acidifying load on soils until about 1980, when ammonium sulphate was partly substituted by ammonium nitrate in compound fertilizers. It has been estimated that 18-29% of the total lime requirement for maintaining the buffer capacity of Swedish agricultural soils is needed to counteract the effects of acidifying fertilizers. About the same fraction of lime is needed to counteract the acid fallout from the at mosphere, and twice that fraction would be needed to cope with the wash out of base cations.

The average liming rate on arable land has decreased from 90-120 kg cal cium oxide per ha and year in the period 1976-1983 to about half this level in the beginning of the 1990s, which is well below the recommended rate (70-450 or 150 kg/ha and year, on average). There are, however, great va riations in liming, from 3 kg/ha in the north to 157 kg/ha in some southern counties of Sweden. The southern counties are the most important wheat- producing districts.

7 The average influx of Cd with lime to agricultural soils is estimated at 0.02 g/ha and year, but in sugar beet producing districts, an additional contribu tion of up to 0.13 g/ha and year with sugar mill lime can occur, which, strictly speaking, is not an influx but a recycling of Cd.

A considerable decrease in nation-wide average application rate of mineral P-fertilizers has taken place since the middle of the 1970s, from about 22 kg P/ha and year, to the current average rate of 8 kg P/ha and year. The varia tion between production zones is (on average) from 4.8 to 11.4 kg P/ha and year, but in some areas in southern Sweden, application rates are at 25 kg P/ha and year.

The average concentration of Cd in 78% of the P-fertilizers used in Sweden during the cropping season 1995/96 was 25 mg Cd/kg P, which is a conside rable decrease from the level of 64 mg Cd/kg P, recorded at the end of the 1980s. Consequently, the current average influx of Cd to agricultural soils with P-fertilizers can be estimated at 0.20 g/ha and year. In the parts of some farming districts where the application of phosphorus was made exclusively by mineral fertilizers, at a rate of 25 kg P/ha, the influx of Cd with P-fertilizers can be estimated at >0.60 g Cd/ha and year.

The net influx of Cd to soils with animal feeds (i e manure) is on average 0.05 g/ha and year, with a variation between production zones ranging from 0.03 to 0.08 g Cd/ha and year.

The net efflux of Cd from soils with the crops exported from the farms shows a great variation, from nil in the production zones in the north to 0.34 g Cd/ha and year in the plain districts in the south.

As an average for the whole of Sweden, the total influxes of Cd to arable land (0.66 g/ha and year) exceed the effluxes (0.16 g Cd/ha and year) by an amount of 0.50 g Cd/ha and year. In some southern districts, where the ap plication rates of mineral P-fertilizers are high, the balance might be a sur plus of >0.70 g Cd/ha and year. Thus, in spite of the considerable reductions in the influx of Cd to agricultural soils during the last 5-10 years, there is still a long way to go before a steady-state is achieved between influx and efflux of Cd in soils.

If the current average rate of accumulation of Cd in Swedish soils would continue for another 100 years, the relative increase of the amount of Cd in the top soil would be 6.4 %.

8 A doubling of the average content of Cd in the top soil would take about 1,600 years if the current rate of accumulation will persist. Calculated on the whole drainage zone (100 cm), for which we have a direct estimate of the Cd leaching rate, the doubling time would be about 4,400 years.

The possible future development of the Cd content in Swedish agricultural soils was examined under the assumption that the average Cd concentration in P-fertilizers would be reduced to 5 mg Cd/kg P, or enhanced to a level of 140 mg Cd/kg P, respectively. Even in the case of the low-Cd scenario, the average balance value (influx minus efflux) for the soils would only de-crease from 0.50 to 0.34 g Cd/ha and year. Thus, in spite of the almost total elimination of Cd from P-fertilizers, a steady-state situation with respect to Cd in average Swedish soils would not be achieved, unless the atmospheric deposition of Cd is also significantly reduced.

In the high-Cd scenario, the average balance value would rise to 1.4 g Cd/ha and year. After 100 years, the percent increase of the total amount of Cd in the top soil would be 18%, to be compared with an increase by 6.4%, in 100 years, if the present conditions will persist. Calculated on the whole drain age zone (100 cm), the resulting increases in Cd content would be 7 % after 100 years.

The calculations were repeated, for an application rate of 25 Kg P-fertilizer per ha. This resulted in an increase of Cd in top soil with 49% in 100 years, in the alternative with the high Cd-content in P-fertilizers.

The Cd concentration in winter wheat has been reported from two separate studies, each comprising 120-200 samples from the whole country. Average values were 53, and 43 pg Cd/kg dry weight (dw), respectively. Maximum recordings were up to 207 pg Cd/kg dw. Mean concentrations in potatoes in two separate studies were 53 and 80 pg Cd/kg dw, respectively. Mean levels in sugar beets were 167 pg Cd/kg dw and in carrots, 276 pg Cd/kg dw. Stu dies of the regional variation indicated that the highest mean concentrations in winter wheat were found in the southernmost part of the country (73 pg Cd/kg dw), while the highest values in oat grains were found in the north (52 pg Cd/kg dw).

The performed examination of the Swedish situation with regard to Cd in agricultural soils clearly shows that no steady-state in the Cd flux has yet been achieved in any part of the country, and it is indicated that such steadystate will not be reached in the foreseeable future.

9 Nonetheless, any unnecessary input of Cd to agricultural soils should be avoided as far as possible.

In addition to the natural factors reducing the buffer capacity, and hence, increasing the risk of acidification of soils, some of the agricultural prac tices associated with the transformation process towards a modem agricul tural production system have also contributed to increasing the mobility and the bioavailability of Cd in soils.

Therefore, in addition to efforts to keep the future influxes of Cd to arable land as low as possible, it is strongly recommended also to consider mea sures aiming at controlling the mobility and the bioavailability of the Cd already existing in the soils, in order to reduce the risk of future, unaccep table exposure of humans to Cd through agricultural products. Sammanfattning

Rapportens syfte ar att granska tillganglig information om Roden av kadmium (Cd) till akermark och grodor i Sverige fran fosforgodselmedel (P- godselmedel) och andra kallor, och att diskutera hur mangden Cd i aker mark, grodor, och livsmedel kan paverkas av Sveriges sarskilda, naturgivna villkor, liksom av de odlingsmetoder som anvands.

I tidigare arbeten, publicerade 1985, fann man att innehallet av Cd i host- vetekama av en specifik sort hade mer an fordubblats 1918-1980, och att halten i matjordslagret under samma period hade okat med 33 %. Senare undersokningar av relationen mellan Cd i jord och Cd i groda har gett ny information som mojliggor en djupare forstaelse av betydelsen av olika faktorer, som kan paverka jordbruksgrodors upptag av Cd. Dessa nya resultat presenteras och diskuteras, liksom nagra andringar vad galler infid- den till akermark, som nyligen agt rum. Saval den nationella som den regionala nivan ingar i analysen. Den regionala analysen utgar fran de atta produktionsomraden, vilka svenskt jordbruk officiellt delas in i.

Den naturliga geologiska bakgrunden bestammer i hog utstrackning innehal let av Cd i jord. Model-material, sasom kambrisk berggrund, alunskiffer och sandsten har generellt hoga Cd-halter. Marina leror i sydvastra Sverige har i allmanhet lagre Cd-halter an genomsnittet. Genomsnittet for Cd i matjord i Sverige ar 0,26 mg Cd/kg matjord. For 5% av odlade jordar ar Cd-innehallet 0,49 mg Cd/kg matjord eller mer.

Nar nederborden overstiger avdunstningen, lakas baskatjoner ut ur matjorden. Detta tenderar att reducera buffertkapaciteten och sanker efterhand markvatskans pH, vilket okar rorligheten och biotillgangligheten for det Cd som finns i jorden. Overskottet mellan nederbdrd och avdunstning ar sarskilt stort i sydvastra Sverige. Denna klimatfaktor, som paverkar egenskapema for Cd i marken, ar sannolikt mer uttalad i delar av Sverige an i de fiesta andra europeiska lander.

Den basfattiga berggrunden i storre delen av Sverige har medfort att de re- lativt tunna jordlagren, som bildats efter den senaste nedisningen, har ett lagt naturligt innehall av baskatjoner. Darfor ar de fiesta svenska jordar kansligare for tillfbrsel av forsurande amnen an vad jordama i t ex central- europa ar.

11 Den atmosfariska depositionen av Cd i Sverige bar minskat med en faktor 2- 3 over de senaste 15-20 aren. Den regionala variationen var ar 1993-95 fran 0,1 (i norr) till 0,5 g Cd per ha och ar i de sodra slattbygdema.

Trots det pa senare tid minskade nedfallet av forsurande amnen (svavel och kvave), overstiger det sura nedfallet i sydvastra Sverige den kritiska belastningsgransen med mer an fem ganger. Denna situation ar likartad den som galler i stora delar av centrala Europa. Den arliga depositionen av svavel och kvave ar vanligen lagre i Sverige (6-18 kg/ha i sodra Sverige, och 2-6 kg i norra, for bada amnena), an i centrala Europa, men den i allmanhet hogre forsumingskansligheten for svenska jordar, resulterar i att den kritiska belastningsgransen likval kraftigt overskrids.

Odlingsmetodema har genomgatt en avsevard fbrandring de senaste decen- niema. En fbrandring av sarskild betydelse for rorlighet och biotill-ganglig- het for Cd i jord ar separeringen av djurskotsel och vaxtproduktion pa gards- saval som pa regions- och nationsniva, liksom den minskande anvandningen av vail och stallgodsel i vissa produktionsomraden. Dessa forandringar leder till en reduktion av mullhalten pa dessa jordar, vilket tenderar att mobilisera Cd.

Under 1950-talet ersattes nitrat-baserade kvavegodselmedel med ammo- niumbaserade, vilket medfbrde okande forsumingstryck fram till 1980, da ammoniumsulfat delvis ersattes med ammoniumnitrat i sammansatta gbd- selmedel. Det har beraknats att av det totala kalkbehovet for att uppratthalla buffertkapaciteten i svensk akermark, 18-29 % forklaras av de surgorande gbdselmedlen. Ungefar samma kalkmangd behovs for att motverka effektema av forsurande nedfall, medan den dubbla kalkmangden behovs for att motverka effektema av utlakningen av basiska katjoner.

Den genomsnittliga kalkningen pa jordbruksmark har minskat fran 90-120 kg kalciumoxid per ha och ar perioden 1976-1983, till ungefar halva denna niva under borjan av 1990-talet. Detta ar klart under den rekommenderade nivan (70-450 eller 150 kg/ha och ar i medeltal). Variationen ar dock stor, fran 3 kg per ha i norr till 157 kg per ha i nagra av Sveriges sydligare lan. Dessa sydliga lan ar de viktigaste veteodlingsdistrikten. Tillskottet av Cd till jordbruksmark via kalk ar skattad till 0,02 g/ha och ar, men i utpraglade sockerbetsdistrikt kan ytterligare 0,13 g/ha i snitt tillkomma, till foljd av den aterforsel som sker via sockerbrukskalk. Anvandningen av P-gOdselmedel i Sverige har minskat kraftigt, fran ca 22 kg P/ha och ar i mitten pa 1970-talet, till dagens niva pa i genomsnitt ca 8 kg P/ha och ar.

Den regionala medelgivan spanner fran 4,8 till 11,4 kg P/ha och ar i de olika produktionsomradena. I de mest intensiva jordbruksdistrikten ar givor pa 25 kg P/ha och ar via handelsgddsel ej ovanliga.

Innehallet av Cd i snitt i 78 % av totalt anvanda P-godselmedel i Sverige var vaxtodlingsaret 1995/96 25 mg Cd/kg P. Detta ar en avsevard minskning fran de 64 mg Cd/kg P, som rapporterades som medelvarde i slutet pa 1980- talet. Foljaktligen kan nuvarande infldde av Cd till akermark i snitt beraknas till 0,2 g per ha och ar. I de omraden dar tillforseln av P endast sker via handelsgddsel, och givan ar pa 25 kg P per ha, kan tillforseln av Cd via P-gdd- selmedel beraknas till 0,60 g Cd/ha och ar, eller mer.

Nettotillfbrseln av Cd till akermark raknat pa regionsniva via import av foder ar 0,05 g/ha och ar i snitt, med en variation mellan regioner som stracker sig fran 0,03 till 0,08 g Cd/ha och ar.

Nettoutflbdet av Cd pa den regionala nivan via exporterade grddor varierar starkt, fran inget utflbde i de norra produktionsomradena, till 0,34 g Cd/ha och ar i de sddra slattbygdema.

Som medelvarde for Sverige dverstiger den tillforda mangden Cd till aker mark (0,66 g Cd/ha och ar), den bortforda mangden (0,16 g Cd/ha och ar) med 0,50 g/ha och ar. I nagra av de sddra produktionsomradena, dar givan av P-godselmedel ar hog, kan overskottet vara 0,70 g Cd per ha och ar eller mer. Salunda, trots betydande reduktioner i tillford mangd Cd till akermark de senaste 5-10 aren, ar det fortfarande lang vag kvar innan tillford mangd Cd till akem ar lika med eller mindre an den bortforda mangden.

Om nuvarande medeltakt i dkningen av Cd i akermark fortsatter i 100 ar, blir dkningen i matjordsskiktet (0-25 cm djup) 6,4 %. Pa 1 600 ar skulle da halten av Cd i matjorden fordubblas. Raknat pa hela draneringszonen (100 cm), for vilken direkta matvarden finns vad galler lackaget av Cd, blir fdr- dubblingstiden ca 4 400 ar.

Den framtida utvecklingen av Cd-innehallet i svensk akerjord undersoktes under antagandet att medelhalten Cd i P-godselmedel skulle sankas ytterligare, till 5 mg Cd/kg P, respektive hojas till 140 mg Cd/kg P.

13 Avert i fallet med den fortsatt sankta Cd-nivan, skulle balansen i snitt for svensk aker-mark (tillford mangd minus bortford mangd), endast sjunka fran 0,50 till 0,34 g Cd per ha och ar. Salunda, trots en narmast total elimi- nering av Cd fran P-godsel, skulle andock ej den tillforda mangden Cd komma ned till samma niva som den bortfbrda, med mindre an att aven luftnedfallet av Cd reduceras kraftigt.

I scenariot med den hogre halten Cd i P-gosel, skulle den tillforda mangden i snitt for Sverige overstiga den bortfbrda mangden Cd med 1,4 g/ha och ar. Efter 100 ar, skulle okningen av totalmangden Cd i matjorden vara 18 %, att jamfora med 6,4 % bkning pa 100 ar, givet dagens Cd-balans. Raknat pa hela draneringszonen, (0-100 cm), skulle okningen av Cd vara 7 % pa 100 ar.

Berakningama upprepades for en P-godselgiva pa 25 kg per ha och ar. Ok ningen av Cd i matjorden blev da 49 % pa 100 ar, i altemativet med den hoga halten Cd i P-godseln.

Cd-innehallet i hostvete i tva oberoende studier, en for vete odlat i Skane och en for vete odlat i Sverige, med 120-200 prover, skattades till 43 respektive 53 mg Cd/kg torrsubstans (ts) kama. Det hogsta uppmatta vardet var 207 mg Cd/kg ts kama. I tva oberoende studier av potatis, var medelhalten 53 respektive 80 mg Cd/kg ts. Medelhalten for sockerbetor var 167 mg Cd/kg ts, och for morotter 276 mg Cd/kg ts. Studier over den regionala variationen indikerade att de hogsta medelhaltema for hostvete fanns i Gota- lands sodra slattbygder (73 mg Cd/kg ts), medan de hogsta medel- nivaema for havre aterfanns i norr (52 mg Cd/kg ts).

Den utforda genomgangen av den svenska situationen vad galler Cd i jordbruksmark visar klart att inget produktionsomrade annu natt steady-state (tillford mangd=bortford mangd), vad galler Cd. Resultaten indikerar ocksa att steady-state ej kommer att uppnas inom overskadlig tid. Icke desto mindre ar det angelaget att all onodig tillforsel av Cd till jord- bruksmarken undviks sa langt det ar mojligt.

Forutom de naturgivna faktorer som tenderar att reducera markens buffertkapacitet, och darmed oka risken for fbrsuming, har vissa av de odlingsmetoder som inforts som ett led i omvandlingen till ett modemt produktions- system ocksa bidragit till att oka rorligheten och biotillgangligheten av Cd i marken.

14 Darfor, utover anstrangningama att halla ned framtida tillforsel av Cd till akermark sa mycket som mojligt, ar det synnerligen motiverat att overvaga atgarder som syfitar till att kontrollera mobilitet och biotillganglighet for det Cd som redan finns i jorden, i syfte att reducera riskema for framtida, oa- cceptabel exponering av manniskor for Cd via jordbruksprodukter.

1. Introduction

1.1. Purpose of the report

The issue of cadmium (Cd) content in commercial phosphorus fertilizers (P- fertilizers) and its possible connection with increased Cd exposure of hu mans via the food have been the subject of several recent papers. In a back ground document, "Cadmium in Fertilizers", for the OECD Cadmium Workshop, held in Sweden, in October 1995, these questions were discussed in an international context (Landner et al., 1996). The present report will focus on the Swedish situation and will investigate how the fluxes of Cd to soils and crops from P-fertilizers and other sources, and how the levels of Cd in agricultural soils, crops and human food may be influenced by the specific environmental conditions in Sweden as well as by the agricultural practices used in the country. In particular, the time trends in Cd fluxes and Cd accumulation in the past will be analyzed and interpreted, and some fo recasts on future Cd fluxes will be made, based on various assumptions re garding the Cd content in P-fertilizers.

The comprehensive and commendable work on Cd in Swedish agricultural soils and cereals, carried out by Kjellstrom and co-workers (1975) and by Andersson and co-workers (Andersson and Bingefors, 1985; Andersson, 1992) has a central position in the debate, in Sweden, on the potential risks associated with the use of Cd-contaminated P-fertilizers. It was found that the content of Cd in grains of a variety of winter wheat had increased from 25 to 56 pg Cd/kg, in the period 1918-1980, i e more than a doubling in 62 years. It was also noted that there was a simultaneous increase in the Cd content of agricultural top soil, from 0.18 to 0.24 mg Cd/kg soil, in the per iod 1900-1990. Since these observations were made, the researchers at the Swedish University of Agricultural Sciences have continued their inves tigations on various aspects of this problem. Later findings have provided a broader understanding of the relative importance of different factors that may influence the uptake of Cd by agricultural crops.

15 Thus, the present report is based on the most recent Swedish research in this field. It was felt pertinent to make a critical review and evaluation of older data in the light of the more recent information and also to consider recent changes in Cd input to agricultural soils. By combining all relevant scien tific information available by May 1997, the report will try to describe the current situation in Sweden and based on this, the relative importance of different factors for the uptake of Cd in crops will be discussed and evalua ted.

The Swedish average situation, as well as the regional variation between the eight main production zones in Sweden, will be examined with regard to the following aspects that may be of relevance for the understanding of the pre sent and future exposure to Cd of arable land and crops:

The natural environmental conditions, such as geological factors, soil pro perties and climate; atmospheric deposition of cadmium and acidifying substances; past and current agricultural practices influencing the Cd flux to soils and the availability of Cd for uptake into crops; balance between influx and outflux of Cd in agricultural soils and requirements for the achievement of a steady-state situation; long-term evolution of the future Cd exposure of soils and crops in different production zones, based on scenarios specifying the future Cd content in P-fertilizers; the main factors that influence the transfer of Cd from soil to crops. Furthermore, a brief review is made of the current Cd levels in various Swedish crops for human consumption and for animal feeding, as well as in Swedish food in general.

The present report is also intended to serve the purpose of providing a back ground for an examination of the costs and benefits, from the individual farm to the national context, associated with different levels of Cd content allowed in P-fertilizers. This examination is presented in a separate report to the National Chemicals Inspectorate, entitled "The Economics of the Swe dish Cadmium Policy" (Drake and Hellstrand, 1997).

A separate report to the National Chemicals Inspectorate, dealing with the health aspects of Cd exposure, is also being prepared by a group of resear chers from the Karolinska Institute, the University of Umea and the Stock holm County Council, with the title "Health Effects of Cadmium Exposure - A Review of the Literature and a Risk Estimate" (Berglund et al., 1997).

The possible effects of Cd in the Swedish environment are assessed in a third separate report entitled ’’Cadmium in Sweden - environmental risks” (Parkman et al., 1997).

16 1.2. Current cadmium restriction in Swedish agriculture

1.2.1. Soil andfertilizers

In Sweden, there are currently both official, legally binding, and voluntary limits to the Cd content in fertilizers. The official, current restriction on Cd in P-fertilizers in Sweden is 100 mg per kg of phosphorus (?) (Swedish Code of Statutes, SFS 1985:839). An environmental fee is raised for Cd concentrations between 5 and 100 mg Cd/kg P, which amounts at 30 SEK per g (Swedish Code of Statutes, SFS 1984:409).

The Swedish farmers supply and crop marketing organisation ("Lant-man- nen" ) applies a voluntaiy regulation of the Cd content in fertilizers, with the limit set at 50 mg Cd/kg P. This limit applies to the total tonnage of P-ferti lizers sold to farmers by Lantmannen, which corresponds to a market share of 78%, in 1995/96 (Christersson, 1997; personal communication).

The regional Lantmannen associations, have also issued a voluntary limit for Cd in agricultural soil, which is set at 0.30 mg Cd/kg soil (dry weight). Wheat grown on soils meeting this criterion can be sold under the trade mark "Svenskt Sigill" (Swedish Seal), launched by Lantmannen without any further check of the Cd content in the grains.

1.2.2. Animal feeds

The official maximum allowed Cd content is set at 0.5 to 5 mg/kg in com plete feed and feed mixes (88% dry matter content) (Landner et al., 1996).

1.2.3. Human food

Pending the issuance of EU regulations regarding limit values for Cd in hu man food, the Swedish authorities are relying upon the values recommended by the Codex Alimentarius Commission (FAO/WHO, 1993). The Codex Committee on cereals, pulses and legumes has proposed a limit of 0.1 mg Cd/kg for cereals. Maximum acceptable levels of Cd in other types of food range from 0.05 to 2.5 mg Cd/kg. The higher values (1.25 mg/kg and higher) are valid for fish and edible offal. FAO and WHO have recommended that, for Cd, the "Provisional

Tolerable Daily Intake" (PTDI) should be below 1 pg Cd per kg body weight, which implies a maximum level of 60-80 pg Cd per day for an adult human being (Landner et al., 1996).

17 However, recent findings indicate that adverse health effects from Cd exposure may develop at lower levels than previously estimated (Berglund et al., 1997).

The Lantmannen associations also use the limit value of 0.1 mg Cd/kg in wheat and oat grains as a clearance for allowing the cereals to be sold under the trade mark Svenskt Sigill.

Also one of the major associations supplying the food retail stores in Swe den with fruits and vegetables ("ICA Frukt och Gront") is currently applying a quality control programme for the products delivered to the retail stores, in which limit values for Cd are included. For the past three years, this volun tary regulation of the Cd content has focused on carrots, and it is planned to include also potatoes in the future, using successively more strin-gent Cd limits. The main aim of this initiative is to keep the Cd levels in these pro ducts as low as possible in an attempt to link the trade mark with a percep tion of healthy products, good quality and good environment (Hacklou, 1997).

2. The Natural Setting

2.1. Geological background and soil properties

Most of the Swedish territory resides on the 2 billion years old Fenno- Scandian Precambrian Shield. During the run of the geological eras, this shield has - for extended periods of time - been below the sea surface and has therefore been covered by sediments. After the rise of the land above the level of the sea, great parts of these sediments have been eroded by ice and streaming water. However, in some areas in the southern and middle parts of Sweden, small remnants of these younger, sedimentary rocks, such as shales, limestone, sandstone and claystone, have been left on top of the Precambrian shield.

The distribution of surficial bedrocks in Sweden is shown in Figure 1, where special emphasis is given to the content of base cations in the geological material.

The bedrocks, and the overlying soils, which are rich in calcium and other base cations are less vulnerable to acidification than are the base-poor and/or the silica-rich ones (see also section 3.2.2).

18 Soils in Sweden are usually rather thin, compared to the situation in central Europe, because loose sediments were removed by the ice cap during the latest glaciation, and the time period for build-up of a new soil layer has been relatively short.

The main soil types in Sweden are shown in Figure 2. The dominating soil type is moraine, covering large parts of the country, but fine-grained soils, such as clay and silt, occur mainly in the plain districts of southern Sweden. The organic (humus) content in the top soil of the rich brown earth soils in southern Sweden is usually <10-15%, while the podsolic soils in northern Sweden and in hilly districts of southern Sweden may have a humus content in the top layer of up to 80% (Andersson, 1977a).

19 Poor in base cations and rich in quartz Comparably poor in base cations Comparably rich in base cations Rich in calcium and other base cations

Figure 1. The distribution of major types of bedrocks in Sweden, showing differences in the content of base cations and, thus, the different vulner ability to acidification (from SEPA, 1981).

2.2. Variation in cadmium content in top soils of arable land

In a study made during the second half of the 1970s, 361 samples of top soil (usually 0-20 cm depth) were taken from agricultural soils, both cultivated and noncultivated (pasture) soils, all over Sweden. The samples were ana lyzed for total content of several metals including Cd and the content of humus and clay was also determined as well as the pH value (Andersson, 1977a).

The average Cd content in the top soil was 0.22 mg/kg dry weight (dw) and the median level was 0.19 mg Cd/kg dw. The average content of humus was 10% and 6% and the average content of clay was 13% and 16%, in the non cultivated and cultivated soils, respectively. The Cd concentration in the top soil was significantly correlated with both the humus and the clay content, with the highest correlation coefficient (0.29) between Cd and humus. In fact, no other metal, among the eight metals analyzed, showed such strong correlation with humus content as Cd (Andersson, 1977a).

The vertical distribution of Cd the soil surface to about 100 cm depth was investigated in four type soils, three of them had developed on the same parent material, namely the Archean till of central Skane. Among these soils, one was slightly podsolized, one was a dystrophic brown earth and the third one was hydromorphic. The forth soil tested was a eutrophic brown earth developed on glacial clay in northern Uppland. All soils showed a strong gradient in Cd content from the top and downwards. The podzolic and the hydromorphic soils contained about 1.0 mg Cd/kg dw in the top layer, but <0.1 mg Cd/kg dw at the depth of 50 cm, i e the distribution of Cd in the profile was very similar to the distribution of humus content (see Figure 3). Although there was a clear gradient in the Cd content also in the eutrophic brown earth, the concentrations were more uniform throughout the profile in this soil (Andersson, 1977a).

22 Humus

. Soil 1

Depth

Figure 3. Distribution of organic matter (humus) and Cd in four soil pro files. Soil types were the following: 1 - podsolic; 2 = brown earth, dys trophic; 3 — hydromorphic; 4 - brown earth, eutrophic. Soils no. 1-3 from Skane; soil no. 4 from Uppland (from Anderssnn. 1977a).

In a later study, based on 1811 samples of top soil from arable land all over Sweden, the average Cd content was found to be 0.26 mg Cd/kg dw (Eriksson et al., 1995). The geographical variation in Cd content of the top soils is quite obvious.

23 It is expressed in the average Cd content in the different production areas (Table 1). The location of the 8 production areas is shown on the map in Figure 4. For the sake of comparison, average levels of Cd in top soils in some nations in Europe are also included in Table 1.

1. Plain districts, s, Gotaland 2. South east Gotaland 3. Plain districts, n. Gotaland 4. Plain districts, Svealand 5. Forest districts, Gotaland 6. Forest districts, central Sweden 7. Lower parts of Norrland 8. Upper parts of Norrland

Production areas

Figure 4. The location of the eight different production areas in Sweden (from Eriksson, 1990).

24 Table 1. Average Cd levels in top soils in Swedish production areas and in some European nations. mg Cd/kg top soil References

Sweden and its regions Sweden, total mean value 0.26 1 1. Plain districts, S. Gotaland 0.28 1 2. South east Gotaland 0.31 1 3. Plain districts, N. GOtaland (0.23) 1 4. Plain districts, Svealand 0.28 1 5. Forest districts, Gdtaland 0.23 1 6. Forest districts, central 0.22 1 Sweden 7. Lower parts of Norrland 0.28 1 8. Upper parts of Norrland 0.17 1 Percentiles 75 0.30 1 90 0.40 1 95 0.49 1 European nations Belgium 0.22 or 0.28 2 Denmark 0.22 2 Finland 0.25 or 0.06 2 France 0.22 2 Germany 0.26 or 0.30 2 Italy 0.40 2 Netherlands 0.39 or 0.48 2 Portugal 2 Spain 0.11 2 United Kingdom 0.44 2 Sweden 0.22 2 1. Eriksson et al. (1995). 2. Landner et al. (1996).

Notes. When two values are given, they refer to different studies. The values from Eriksson et al. are mean-values, most from Landner et al. are median values.

The parenthesis for the value for plain districts in N. Gotaland is because this production area is constituted of two plains, one in Ostergotland, and one in Vastergotland. The median-value for Ostergdtland was 0.28 mg Cd per kg top soil dw, while it for V8sterg6tland was 0.16-0.17.

25 The variation within production areas was also fairly large, and the general pattern of variation in the Cd content of the plough layer was relatively strongly related to the properties of the parent material.

For example, it was found that districts associated with Cambrian bedrock, such as Osterlen in Skane, western Ostergotland and Narke and the basin of Lake Storsjon in Jamtland, had enhanced Cd contents in the soils. Alum shales and sandstone are important components of the Cambrian formation, and these materials are generally found to have high Cd contents. The farm land areas around Lake Malaren also had higher than average values. On the other hand, the marine clays in western Sweden and around Lake Vanem, as well as the coarser textured sediments and Archean tills in forest regions throughout the country generally had lower-than-average Cd contents (Eriksson et al., 1995).

In a special study in Skane, where the relationship between the parent mate rial and the soil Cd content was investigated, Soderstrom and Eriksson (1995) demonstrated that districts dominated by Rhaetian-Jurassic shales and sandstones were generally very low in soil Cd. Also in soils developed from Precambrian granites and gneisses the Cd content was low, but the range of data was wider than in the former group. Districts with soils deve loped from Cambrian alum shales and sandstone had the highest levels of Cd in the top soil (Figure 5 a).

Also the influence of the soil type was tested. It was found that north-wes tern and north-eastern tills had about the same soil Cd content, which was lower than in the case of south-western till, clay shale-Archean till and south-eastern till (Figure 5 b). It was also found that samples from glacial and post-glacial clays were very low in Cd (Figure 5 c), while fluvial de posits had the highest values (Soderstrom and Eriksson, 1995).

26 E 120

« 00

l 2 3 < 5 Beikock code Till code

а) Bedrock codes b) Till codes 1) Tertiary - Danian limestone (46) 1) Northeastern till (64) 2) Cretaceous - limestone, sandstone, clay (31) 2) Clay shale - Archean till (29) 3) Rhaetian , Jurassic - shale, sandstone (39) 3) Southeastern till (32) 4) Triassic - sandstone, claystone (19) 4) Southwestern till (54) 5) Silurian - limestone, shale (21) 5) Northwestern till (15) б) Ordovician - shale (5) 7) Cambrian - alum shale, sandstone (8) 8) Precambrian - granite, gneiss (22)

Sub-soil code

c) Sub-soil codes ~T~ Min-Max 1) Postglacial and glacial clay (30) I---- 1 25%-75% d Median value 2) Silt, sand, giavel (11) 5) Glacioliuvial sediments (9) Till (subdivision as above) 61} NE (17) 62) C-AT (23) 63) SE (26) 64) SW (45) 65) NW (10)

Figure 5. Box-and-Whisker plots of ranked soil cadmium data in relation to substratum. Comparisons made using Kruskal-Wallis H-test by ranks, which indicated differences among groups in all three cases (p<0.01). Number of observations are given in brackets (from Soderstrom and Eriksson, 1995).

27 2.3. Precipitation, evaporation and runoff

The distribution of the mean annual precipitation as well as the mean annual runoff in Sweden, for the years 1961-1990, is shown in Figure 6. It is cle arly seen that there is a gradient in precipitation from west to east with al most twice as high values in the western parts of the country as compared with the east coast.

Since the annual temperatures are generally low in Sweden, the evaporation is lower than the precipitation throughout the country. Such a situation pro vokes a wash-out of base cations from the top soils. This wash-out corres ponds to about half the liming need in Sweden (Siman, 1997; personal communication) (see Table 3). The process implies an ongoing decrease in the buffer capacity.

The soils are approaching a threshold, where a small further input of acidi fying substances, which earlier was harmless to the system when there was 4still buffer capacity left, may cause a substantial fall in the pH (Mattsson, 1997, personal communication), if not adequate counter-balancing measures are taken.

28 •200

200-400

400-500

500-600

600-900

600-1200 •1200

Figure 6. Mean annual precipitation and runoff (mm) in Sweden in the pe riod 1961-1990 (from Brandt et al., 1994).

29 The surplus of precipitation over the evaporation can be expressed as the runoff (in mm), also shown in Figure 6. In the agricultural areas in south western Sweden the difference between precipitation and evaporation may be as high as 600 mm per annum, which implies that the soils in this region are subject to a strong acidification pressure, simply due to the elevated wash-out of base cations. In the south-eastern parts of the country and aro und the Great Lakes, the situation is more favourable, with runoff values below 200 mm per annum.

The combination of relatively high precipitation and low temperatures and evaporation in large areas of Sweden tend to make the vulnerability of agri cultural soils, which already through the geological background are poor in base cations, higher than in many other parts of Europe.

2.4. Conclusions

Geological factors to a large extent determine the content of Cd in the soil. Parent materials such as Cambrian bedrock, alum shales and some sandsto nes are generally rich in Cd. Soils that have developed from these forma tions are usually enriched in Cd, and in geographical terms, this has resulted in elevated Cd levels in the top soils of Jamtland, Osterlen in Skane, some parts of Ostergotland and Narke.

On the other hand, the marine clays in SW Sweden and around Lake Va- nem, as well as the coarser textured sediments and Archean tills in forest regions throughout the country, generally have lower-than-average Cd con tents.

The average Cd content in the top soil of the eight agricultural pro-duction districts varies between 0.17 mg Cd/kg (upper Norrland) to 0.31 (SE Gdta- land), the national average being 0.26 mg Cd/kg. Some areas exhibit much higher Cd levels in the top soil, which is indicated by the 90 percentile being 0.40 mg Cd/kg and the 95 percentile 0.49 mg Cd/kg.

Compared to the Cd levels in the top soil in other European countries, the average values in Sweden are well within the general range.

• Due to the geological background (predominantly magmatic bedrock), the relatively thin soils in most parts of Sweden are mainly poor in base cations, and are therefore vulnerable to additions of acidifying sub stances.

30 Among the natural factors influencing the buffer capacity and, eventually, the pH of the soil, the most important one, distinguishing Sweden from most other European countries, seems to be the combi-nation of relatively high precipitation and low temperature, particularly in SW Sweden. This results in a surplus of precipitation over evapo-ration, which causes an efficient wash-out of base cations from the soil and tends to depress the pH of the soil solution.

3. Atmospheric deposition

3.1. Deposition of cadmium

The atmospheric deposition of Cd over the Swedish territory has shown a rapid decrease over the past 20 years. Therefore, any figure on the rate of deposition must be specified in time. The most recent estimates, based on the wet deposition of Cd during the time period 1993-1995, are in the range of 10-50 pg Cd/ m2 and year (IVL, 1995; 1996; SEP A, 1995). Estimates, based on moss analyses, for the different regions of Sweden have given the following deposition rates (Ruhling, 1997, personal communication):

- Norrland: 10-20 pg Cd/ m2 and year - Svealand and Gotaland: 20-30 - " - - Skane and west coast: 30-40 - " -

In 1991, the wet deposition of Cd was estimated to be on average 10 pg Cd/m2 and year in northern Sweden and 50 pg Cd/ m2 and year in southern Sweden, while the corresponding figures for 1990 were 20 and 80 pg Cd/ m2 and year, respectively (Ross, 1991).

The atmospheric deposition of metals in different parts of the country is usually measured in an indirect way by means of sampling and analysis of samples of land mosses. The results obtained in the years 1975, 1980, 1985 and 1995 are shown in Figure 7 (SEPA, 1997). It is clearly seen that the deposition rate has decreased rapidly over the time period surveyed. It is also obvious that the highest deposition at the two last sampling occasions was found in the south-western part of the country, reflecting the long-range transport from sources outside Sweden.

31 The temporal trend in the deposition of Cd is quite clearly shown in Figure 8, which is based on intrapolations from the data obtained in moss investi gations (SEPA, 1997). As an average, the deposition decreased by 48% between 1975 and 1985, and by further 15% between 1985 and 1990 (Notter, 1993). After 1990, the reduction has continued, as indicated above.

Figure 7.a Content of Cd in mosses (jug/g dw) in 1975, 1980 and 1985 (from SEPA, 1997).

1970 1975 1980 1985 1990

Figure 8. Temporal and regional trends in Cd content in mosses in Sweden, 1970-1990 (from SEPA, 1997).

3.2. Acid fallout

3.2.1 Sulphur and nitrogen compounds

The deposition of acidifying substances is determined by both the amount of precipitation and the content in the atmosphere of the substances in ques tion. The substances usually measured are sulphate-sulphur, nitrate-nitrogen and ammonium-nitrogen. In Figure 9, the distribution of the wet fallout of sulphur and nitrogen over the Scandinavian countries during the period 1986-1990 is shown. To obtain the total deposition of acidifying substances, the dry fallout must be added, and - at least on forest land - this is almost of the same magnitude as the wet fallout (Bernes, 1993).

35 In Figure 9 it is clearly seen that the Swedish regions with the highest fal lout of both sulphur and nitrogen compounds are the agricultural regions in the south-western part of the country, where the current fallout of sulphur exceeds 10 kg/ha, and the fallout of nitrogen compounds also exceeds 10 kg/ha. However, the deposition of sulphur even in the southwest of Sweden is well below the deposition rates measured in central Europe. For example, in the eastern parts of Germany, the sulphur deposition reaches levels of about 50 kg/ha (Statistics Sweden, 1995).

Figure 9. Distribution of the annual wet deposition of sulphate-sulphur and of nitrate- and ammonium-nitrogen in the Scandinavian countries, in 1986- 1990 (from Bernes, 1993).

Per hectare, the fallout of sulphur and nitrogen compounds in different regi ons of Sweden, around the year 1990, was the following, in kg/ha and year (SEPA, 1993):

Sulphur Nitrogen - Gotaland 7-18 6-18 - Svealand 5- 9 5- 9 -Norrland 3- 6 2- 6

The atmospheric fallout of nitrogen compounds can be compared with the average rate of N-fertilization, which is about 100 kg/ha and year.

36 3.2.2. Vulnerability of soils to acidfallout

The impact of the acid fallout in terrestrial ecosystems is a function both of the amount of fallout and of the sensitivity of the ecosystem being exposed to the acidifying substances. In Figure 10, the sensitivity to acidification in different parts of Europe is shown. The map is developed on the basis of the properties of the bedrock and the soil type, but also the land use and climatic factors are incorporated in the evaluation of the overall sensitivity of the ecosystems (Bernes, 1993).

Generally speaking, the Fennoscandian Precambrian Shield and its asso ciated soils, together with the prevalent land use and climate, constitute a particularly vulnerable area to acid fallout. This is in contrast to most other parts of Europe. Also the calcareous soils in southwest Skane, which is one of the most important agricultural districts in Sweden, have a low sensitivity to acid fallout.

37 Susceptibility T77 low high

Figure 10. The general susceptibility of terrestrial ecosystems in Europe to acidifying loading through atmospheric fallout of sulphur and nitrogen compounds (from Chadwick & Kulylenstierna, 1990).

38 In order to assess the risk of environmental damage related to the current level of acid fallout, the assimilative capacity of terrestrial ecosystems with regard to loading of acidifying substances has been determined. Thus, the highest permissible loading, which is not causing any detrimental effects on the soil microbial activity or on the terrestrial flora and fauna, has been established, mainly with regard to forest land. This level is usually called "the critical acid load", and is, of course, dependent on various soil parameters, such as buffering capacity etc.

Based on the determination of critical acid loads for different regions, it has also been possible to produce maps showing the extent to which the current acid load exceeds or is below the critical load in different parts in Europe. Such a map is shown in Figure 11 (SEPA, 1993b). It should be noted that SW Sweden (maybe with the exception of the SW part of Skane) actually belongs to the areas in Europe, where the critical acid load from the atmos phere is exceeded by the greatest number of times. It should, however, be held in mind that the critical load is defined on the basis of the sensitivity to acidification of forest land. It is therefore not fully relevant for agricultural soils. However, it might be concluded that the regions where the actual acid load is very much in excess of the critical one are subject to a considerable pressure towards acidification, also in the case of agricultural soils.

Figure 11. Map of Europe showing where the actual acid load exceeds the critical load and the extent to which the critical load is exceeded. Data from 1990 (from SEPA, 1993b). 39 3.3. Conclusions

The atmospheric fallout of Cd in Sweden has decreased by a factor of 2-3 over the last 15-20 years. The average influx of Cd to arable land through atmospheric fallout (in 1993-95) varies between 0.1 (upper Norrland) and about 0.5 g per ha and year (plain districts, S Gotaland).

Also the deposition of acidifying substances (sulphur and nitrogen) from the atmosphere has decreased during the last decade and, based on data from 1990, it was estimated that the annual fallout of sulphur and that of nitrogen compounds over Sweden were of about the same magnitude. For each element, the annual deposition rate was 6-18 kg/ha in S Sweden and 2-6 kg/ha in N Sweden.

The susceptibility of Swedish soils, with the exception of those in SW Skane, to acid fallout is generally higher than the susceptibility of soils in most other parts in Europe. In parts of SW Sweden, the actual acid load from the atmosphere exceeds the critical load by more than five times, which is a situation similar to the one in large parts of central Europe.

4. Agricultural practices

4.1. Structural trends in Swedish agriculture

Kjellstrom et al. (1975) investigated long term time trends concerning Cd level in one variety of winter wheat, grown on the same experimental farm, close to Uppsala, in the plain districts in Svealand. They found increasing levels over time. Andersson and Bingefors (1985) repeated the analysis (see section 1.1). They point out that the “more than a doubling of the Cd content in grain during the period 1918-1980, may be partly due to increased solu bility and availability to plants of the soil Cd, and partly due to increasing soil levels. Alterations in solubility may have been brought about by changes in fertilization and soil management practice during the period, and increasing soil levels are most likely caused by the continuos supply of Cd in phosphorus fertilizers and from the atmospheric deposition." .

40 Further:

“During the period covered by the samples the fertilization practice has been fundamentally changed, from one dominated by organic manure in the beginning of the period to the present one dominated by commercial fertil izers. The organic matter has a tendency to retain heavy metals like Cd, whereas the commercial fertilizers are often acidic and based on soluble salts that may release soil Cd by acidification and ion exchange, leading to higher availability and uptake in places where commercial fertilizers are used (Andersson, 1983). Another factor that may contribute to the trend is that the deposition of both Cd and acidic components from the atmosphere was probably lower in the beginning of the period and has then been in creasing since World War II. Phosphorus fertilization shows a similar trend (Gunnarsson, 1980).

Thus the uptake of Cd has been influenced both by factors tending to increase the soil Cd levels and by factors tending to increase the solubility and availability of the soil Cd, resulting in the time trend found. “

The quotations have been made extensive, because they are crucial to this report: Both the aspect of the influx (and efflux) of Cd to soil and the availability aspect are associated with changes in management practices.

Thus an understanding of the changes in the animal and crop production systems is vital to understand to what extent the agricultural practices contribute to observed increases in Cd content in some agriculture products, through the changes of the level of the Cd in the soil, and its availability.

Since the last world war, there has been a separation of crop-production from animal production in the Swedish agriculture. As a result of both the exploitation of regional comparative advantages, and a food policy with social and regional objectives, different forms of crop production and different forms of animal production have been separated between regions and between farms. This trend is seen in the statistics, as an increasing number of farms with no domestic animals. Currently 23 % of the total number of farms (with more than 400 hours of labour requirement per year), are specialised in crop production (Statistics Sweden, 1996a), where the animal production plays a small or insignificant role.

The general trends in Swedish agriculture since 1945 are in animal production:

41 • increasing production per dairy cow,

• a corresponding decrease in the number of dairy cows,

• decreasing share of forages fed the dairy cows, and increasing share of grains and protein feeds fed the dairy cows,

• decreasing supply of meat from the dairy stock to consumers, as a consequence of fewer steer calves bom from this stock,

• increasing dependency on pig production for fulfilment of the demand for meat, and

• substitution of horse-power in horses, by horse-powers in tractors.

The domestic animals are the main consumers of the crop production in Sweden. Thus, these trends within the animal production imply an increa sing demand for grain to feed the increasing number of pigs, and, in relative terms, an increasing dependency of grains and protein feeds in the dairy production. Simultaneously, the trends described imply an overall decrease in the demand of forages, through decreasing number of cattle and horses. Thus, the result is an increase of grain production, and a decrease in forage production. The importance of ley in the crop rotation has decreased. These trends are common knowledge within the agricultural sector, and to most parts common all around the industrialised world.

Parallel to these trends, the dependency on commercial fertilizers for the nutrition of plants has increased, while the dependency of manure and ley has decreased. Nilsson and Mattsson (1993) found that within production systems, the organic content in top soil increases with fertilization, where the compared production systems are production with ley and cattle, and without, respectively. They also found that the organic content in the system with cattle and ley was higher, compared to the system without ley and cattle, after 25 years of farming. The effect of production system on the content of organic matter was higher than the effect of increasing fertili zation on clay. On soils without clay, the effect of increasing fertilization was greater than the effect of production system. The level of organic matter was around 1.5 % C on clay, and around 2.0-2.2 % C on soils without clay. The average content of organic matter in Swedish soils, found by Mattsson (1995), was around 3.0 % C.

42 The effect on the content of organic matter in the soil, when moving from a system with ley and cattle, to a system without ley and cattle, was not shown by Nilsson and Mattsson (1993). Mattsson (1997; personal communication), suggested that this change could be expected to decrease the organic matter in the soil with 1-2 %-units, during the time period 1918- 1980, for the specific fields, where the wheat grain analysed by Andersson and Bingefors (1985), was grown.

4.2. Agricultural production and its impact on cadmium accumulation in soils

In Table 2 the total arable land used for production of different crops in Sweden is listed. The main crops are ley (39 % of total arable land), barley and oat (30 %), rye and wheat (11 %), fallow (10 % ; strictly speaking not a crop), oils seeds (4 %), sugar beets 2 %, and potatoes 1 %.

Andersson (1992) calculated the fluxes of Cd to and from typical farms representing the different production areas in Sweden. The farm and the region with the highest rate of increase of Cd in the soil is the one in which all the ley and crops produced are fed the animals on the farm. The alterna tives where some or all crops are sold, have a slower accumulation of Cd in g per year and ha, despite the same (one case) or higher (two cases) application rates through fertilizers.

Table 2. Surface of arable land usedfor production of main crops in Sweden 1995 (from Statistics Sweden, 1996a)

Crop Ha

Rye and wheat 301 073 Barley and oat 803 398 Oil seeds 104 643 Ley 1 066 758 Potatoes 35 001 Sugar beets 57518 Others 59 802 Fallow 278 633 Not used 59 816 Sum 2 706 626

43 Andersson ’s results indicate that the analysis in this study cannot only deal with average values for Swedish agriculture. Significant redistribution of Cd between farms and production areas with different specialisation may occur. This can influence, on one hand, the levels in the food now produced, and, on the other, the options available for the production on the individual farm in the future, within possible Cd-restrictions posed for health reasons by authorities and by commercial actors.

The trends described, and the difference in the Cd balance for crop produc ing farms and farms with animal production, imply that when analysing the Cd-fluxes, Sweden cannot be seen as one unit, nor can different regions be seen as one unit. Instead, in the ideal case, sustainable use of P-fertilizers with respect to Cd, should be analysed at the farm level. However, such a resolution in the analysis is not possible to perform in this context. The level of resolution applied in this study is the result of a compromise between the wanted and the possible. Thus the analysis of fluxes of Cd to and from agri culture is performed on the regional level; in order to catch (i) the balances within the different production areas in Sweden, with their specific mix of crop and animal production, (ii) and information about the impact of these regional variations on the factors affecting the availability of Cd to the plants, in the different production areas.

4.3. Acidification through N-fertilization

Since 1955, there has been a shift in the type of N-fertilizers used. N in the form of nitrate has been substituted by N in the form of ammonium. This has increased the acidifying pressure in the soils. In Figure 12, the need of liming as a function of the acidifying effect of fertilizers from 1950 to 1980 is shown.

44 Ton CaO xIO 3

+60 -

Figure 12. The total need of liming as a function of the acidifying pressure through used commercial fertilizers in Sweden from 1950 to 1980 (from SEPA, 1981).

Since 1980, the acidifying pressure due to acidifying fertilizers has slightly decreased. This is an effect of the fact that ammonium sulphate has partly been substituted by ammonium nitrate in compound fertilizers (Siman, 1997).

4.4. Liming

In Table 3, the maintenance liming requirement, measured as kg CaO per ha arable land in Sweden is shown, and the size and range of different factors contributing to this need.

45 Table 3. Current need of annual liming on average per ha arable land in Sweden, and the magnitude and range of different factors contributing to the overall need (the absolute values from Simon, 1997; personal communi cation, the relative ones calculatedfrom the same source)

Kg CaO per ha and year %

Requirement liming 70-450, 100 average 150

Precipitation exceeding 30-300 43-67 transpiration Acidifying deposition: Sulphur 10-35 8-14 Nitrogen 10-35 8-14

Acidifying fertilizers 20-80 18-29

As can be seen from the table, the main reason for the need of maintenance liming, is the surplus in precipitation minus evaporation. The application rate of acidifying fertilizers contributes to about the same extent to the liming requirement as the sum of the effects from acid fallout from the atmosphere.

The liming rate has changed over time (Table 4).

From the second world war to 1963 the liming rate decreased smoothly. From 1963 to 1976 the liming increased again. From that time and ten years further, the application rate was relatively high, though varying. In the beginning of the 1990s, the rate declined, but has now started to increase again. The variation in the application rate can, among other things, be a function of shifting economic conditions between years (Statistics Sweden, 1996a). Erik Stjemdahl, adviser in plant production to individual farms in Skane at the Agricultural Society, concluded that liming, just like P-fertilization and investments in machinery on crop farms, is a function of the business cycles in crop production (1997).

46 Table 4. The liming rate over time in Sweden

Year Kg CaO per ha and year 1947 75 1963 20 1976 115 1980 90 1983 120 1990 66 1991 56 1992 49 1993 56 1994 67 Notes. The values from 1947 to 1976 are from SEPA (1981), the rest from Statistics Sweden (1996).

According to Andersson (1992), the average content of Cd in lime is 0.15 mg per kg CaCOS. This corresponds to a level of 0.27 mg per kg CaO. Thus the average inflow of Cd per ha from lime in 1994 was 0.018 g.

According to information from Danisco Sugar AB (Landkvist, 1997; personal communication), two thirds of the Cd in sugar beet, is returned to the fields in the form of sugar mill lime. This corresponds to 65 kg Cd in the total amount of sugar mill lime. If the total amount of regular lime produced in Sweden in 1994 (171 900 tonnes; Statistics Sweden, 1996a), is multiplied with the average content of Cd reported by Andersson, the total inflow of Cd through lime to Swedish agricultural soils is estimated to around 45 kg. However, the inflow only to the sugar beet producing farms through sugar mill lime is around 65 kg Cd per year (Landkvist, 1997; personal com munication). Strictly speaking, this is not an influx, but a recycling of Cd. In the calculations in later sections concerning inflows of Cd to arable land in different regions of Sweden, it is assumed that the average inflow is 0.02 g per ha and year. However, in regions where sugar beets are produced, the net increase of Cd added to soils through the decrease of the effluxes through sugar beets, due to the recycling via sugar mill lime not considered in Andersson (1992), is added to this figure.

The example of the sugar mill lime shows that in the perspective of the individual farm, the Cd from lime can be important. This implies that, in this perspective, there is a need to look closer at the real Cd levels in lime with different origin.

47 The regional variation in lime application rates is great, with the lowest levels in some counties in the north of Sweden (3 kg/ha in the county of Jamtland, and 4 kg/ha in the county of Vastemorrland). The highest application rates in 1994 were found in the counties of Blekinge (157 kg/ha) and Halland (144 kg/ha). In the two counties of Skane, 118 kg/ha (Kristianstad), and 98 kg/ha (Malmohus), respectively, were applied (Statistics Sweden, 1996a). The counties in southern Sweden with the highest lime application rates correspond to the areas with intense wheat production.

4.5. Level and changes in soil pH

Preliminary results (Eriksson et al, 1997) show that 50 % of the arable land has a pH of 6.3 or lower, 30 % has pH 6.0 or lower, and 5-10 % has a pH of 5.5 or lower.

In Figure 13, the percentage of different pH-values by county is shown. It is not uncommon with low pH-values, though the situation in the major production districts is quite good.

Figure 13. Percentage of different pH-values by county. From left to right pH<5.5, pH 5.5-6.0 and pH > 6.0 (from Mattsson, 1993, based on analyses performed 1975-1993).

48 Available information from the period 1940-1978 indicates that the pH of soils has decreased over time, see Table 5.

Table 5. Share of soil samples from arable land with low pH-values in % (from SEPA, 1981)

PH 1940-54 1959-60 1965-69 1970-78 The west coas <6.0 55 60 70 70 Sk&ne <6.5 30 40 50 55 The east coast <6.0 30 50 65 70 The middle of Sweden <6.0 - 30 35 50 Norrland <6.0 60 80 75 85

In all areas, the pH-value in soils, according to SEPA (1981), has decreased over time.

A more recent investigation shows a different picture. Among 24 counties, a decrease in average pH in soil from the period 1966-74, to the period 1975- 1993, was noted for only six counties, and for 5 of them, it was a decrease of about 0.1 pH-unit or less (Mattsson, 1993). For most of the counties, including most of the major production areas, the average pH-value increa sed. The averages are based upon information from field experiments in plant production, spread all over the country, with 1251 observations for the period 1975-93. The number of observations for the period 1966-1974 was not noted.

It should be noted that in the most recent and thorough review of field experiments concerning factors influencing the Cd content in crops, the average pH-value in soil in five of six studies was between 6.1 and 6.8, i.e. in the optimal range (Eriksson et al., 1996). These results, too, are in con flict with the picture given by Table 5. They indicate that the liming is suf ficient. An alternative explanation is that there is an insufficient liming, which decreases the buffer-capacity of the soil. The pH-values in the soil cannot reflect this trend, as long as the buffer-capacity is not exceeded. However, when this threshold is finally passed, the effect on the pH-value can be significant (Mattsson, 1997; personal communication).

49 4.6. Application of phosphorus from manure and phosphorus fertilizers

4.6.1 Regional variation in application

In Table 6, the application rate of P from P-fertilizer and manure in the different production areas is shown. The amount of manure used is measured as kg P applied per ha.

Table 6. Regional variation in application of P from manure and commercial fertilizers to arable land in Sweden during the crop season 1994/1995 (from Statistics Sweden, 1996a) Application of P Fraction of Total application P- Manure Production area total crop tonne kg/ha fertilizer kg/ha area kg/ha 1. Plain districts, 0.13 5 620 18.0 9.2 8.8 - S. Gotaland 2. South east 0.12 5 430 18.3 6.1 12.2 - Gotaland 3. Plain districts, 0.16 7 070 18.6 11. 7.2 - N. Gotaland 4 4. Plain districts, 0.21 7210 14.4 9.1 5.3 - Svealand 5. Forest districts, 0.20 9 320 19.8 5.5 14.3 - Gotaland 6. Forest districts, 0.07 2 420 14.4 7.3 7.1 - central Sweden 7. Lower parts of 0.06 2 020 13.6 4.8 8.8 - Norrland 8. Upper parts of 0.04 1 950 18.4 7.5 10.9 - Norrland Total (ha) 2 384 000 17.2 7.9 9.3

Notes. The area given in the table is excl. fallow, and the categories "others", and "not used" in Table 2.

The values in the table reflect the regional variation in crop and animal production. In some sub-districts in southern Sweden, where only P-fertilizers were used (30-40 % of the surface), the application rates were as high as 25 kg P/ha, year (Statistics Sweden, 1996b).

50 4.6.2. Temporal trends in P-fertilizer application

In Figure 14, the temporal trend in application of P from commercial fertili zers in Sweden is shown.

Kg P/ha

Mineral fertilizers on

Figure 14. Temporal trend in application ofP from commercial fertilizers in Sweden (from Bertilsson, 1996)

The figure shows how Sweden has moved from a phase of enrichment ferti lization, to replacement fertilization. In most industrialised countries the use of phosphorus has started to decline, and there is a transition from an enrich ment phase to a replacement phase. In Sweden this development started earlier and is more evident than in most other countries (Bertilsson, 1996). Some reasons for this are:

• Swedish farmers and advisers are especially sensitive to production eco nomics and marginal economic return. The sharp rise in phosphorus prices in 1974 provoked a rethinking about phosphorus application (ibid.).

• The environmental discussion started earlier in Sweden. In combination with the higher prices, this initiated rethinking. The taxes on phosphorus imposed in 1988 made excessive application very costly (ibid.).

• Much of the previous "overdose" was caused by the neglect of manure as a phosphorus supplier. Manure was often seen as a "premium" in addi tion to normal fertilizer supply. The structure of animal production made development of correct manure use easier than in surrounding countries (density not too high). Consequently, more fertilizer phosphorus could be replaced by manure (ibid.).

51 To these factors, we add the revision of the Swedish food policy around 1990, implying decreasing prices on products as an effect of a change in subsidy-strategy, with a transition from subsidies on products, to subsidies stimulating curbing of over-production (Department of Agricul-ture, 1989). With lower prices on products, the balance-point between marginal costs and benefits will occur at a lower rate of application of P-fertilizer.

4.7. Conclusions

• The agricultural practices as well as the changes in these practices over the past decades have been found to have a significant impact both on the content of Cd in the soils and on the availability of the soil Cd for uptake by crops. In order to be able to interpret the relative importance of different factors for the observed increase in Cd content in certain crops, it is therefore pertinent to acquire a certain understanding of the relevant structural trends in Swedish agriculture.

• Among the most important modifications in agricultural practice, that may influence the bioavailability of Cd, is the increasing separation between crop and animal production at individual farms and in whole farming districts, as well as the decreasing use of ley in crop rotations in cereal producing districts. These transformations, notably the decreasing use of manure in fertilization of the fields on farms and in districts specialised in cereal production for human consumption, negatively affect the content of organic matter in these soils, which tends to mobilise Cd and enhance its availability to plants.

• The switch from nitrate- to ammoniumbased nitrogen fertilizers in the 1950 ’s resulted in an overall acidification from nitrogen fertilizer’s from the mid 1960 ’s. The relative importance of this factor for the resulting pH reaction of the soil can be expressed in terms of how large a fraction of the liming requirement that is related to the use of acidifying fertilizers.

• It has been estimated that now 18-29% of the total lime requirement (150 kg CaO per ha and year, on average) are needed to counteract the acidifying fertilizers. As a comparison, this is about the same fraction of lime that is needed to counteract the total acid fallout from the atmos phere, and about half the fraction needed to cope with the wash-out of base cations due to the precipitation surplus over the evaporation.

52 • It is, however, also obvious that the total amount of lime (including Thomas phosphate) applied to Swedish arable land is far from sufficient to counteract the combined input of acidifying substances and the wash out of base cations. The average amount of lime applied to arable land in the period 1990-1994 varied between 49 and 67 kg/ha and year, which is far below the calculated need (150 kg/ha) for maintaining optimal soil properties. However, there is a great variation between different counties in Sweden, from application of 3 kg/ha in Jamtland to 157 kg/ha in Blekinge.

• The average influx of Cd with lime to agricultural soils has been esti mated at 0.02 g per ha and year, but in sugar beet producing districts, an additional contribution of up to 0.13 g Cd per ha and year with the sugar mill lime can be noticed.

• The application of phosphorus nutrients to the total crop area, during the cropping season 1994/95, was on average 17.2 kg P per ha, with 46% originating from commercial fertilizers and the rest from manure. The average use of P-fertilizers varied between the different production areas between 4.8 and 11.4 kg P per ha and year. However, on farmland in southern Sweden fertilized exclusively by commercial fertilizers (30— 40% of the area), the application rates may be as high as 25 kg P/ha and year. A considerable decrease in the application rate of P-fertilizers has occurred since the middle of the 1970s, partly due to economic reasons.

5. Influx and efflux of cadmium in agricultural soils

5.1. Influx of cadmium to soils

5.1.1. General aspects

The average Cd levels in Swedish top soils are shown in Table 1. In Table 7 the influxes of Cd to agricultural land in Sweden are shown.

53 Table 7. Load of Cd to arable land in Sweden Source g Cd per ha and year Year and reference Atmospheric deposition o o in Sweden Calculated from wet deposition 1993, 1994 and 1995; SEPA 1995; IVL 1995 and 1996 Norrland 0.15-0.30 1993 to 1995; Riihling, 1997; personal communication Svealand and Gotaland 0.30 - 0.45 Sk&ne and some western parts 0.45 - 0.60 Fertilizer 0.2 The crop season 1995/96; Christersson, 1997; personal communication

Sewage sludge 0.03 Calculated from Eksvard, 1997; personal communication Net contribution from feeds 0.3 Calculated from Andersson, 1992 Lime 0.02 SOU 1992:14

Total 0.70-1.15

Notes. The contribution from fertilizer is calculated from the average content in P- fertilizers sold by the Lantmannen organisations. They have a market-share of 78 % (Christersson, 1997, personal communication). The atmospheric deposition is calculated from the wet deposition (the range given for Sweden as a whole), and from analyses of the content of Cd in mosses (the values for the different regions). By multiplying the content of Cd in mouses in pg/g dw (see figure 7.b), the deposition in g/ha and year is obtained (Riihling, 1997, personal communication).

In the table the regional variation in atmospheric deposition is shown. By considering the regional variation in application rates of commercial ferti lizers (Table 6), the regional variation in Cd influx from P-fertilizers can be calculated. It ranges from 0.28 g per ha for the plain districts in N. Gotaland to 0.12 g per ha in the lower parts of Norrland.

According to Table 7, the contributions from atmospheric deposition, commercial fertilizers, and from feeds are now of similar size.

54 The uncertainty in the value for net contribution from feeds is high. It is based on a study, almost 20 years old (Andersson, 1977b). The animal production, the feeding strategies, and the individual feedstuffs used can have changed significantly since then. As an example, Zn is used in increasing amounts in Swedish pig production the latest years as an alternative to antibiotics. How this has influenced the influx of Cd is unclear.

5.1.2. Temporal trends

The temporal trends can be expressed by a comparison between Table 7 and the values given by Andersson (1992), see Table 8. In rough terms, Andersson's data describe the situation 5-10 years before the situation described in Table 7.

Table 8 . The temporal trends in Cd-influxes to agricultural land, g Cd per ha and year Around 1995 as Around 1988/89 as described by Table 7 described by Andersson (1992) Atmospheric deposition Norrland 0.15-0.30 0.4 Svealand and Gota- 0.30 - 0.45 0.65 to 0.78 land 0.45 - 0.60 1.1 Skane and some western parts Fertilizer 0.2 0.65 to 0.85 (Norrland 0.39) Sewage sludge 0.03 not included Net contribution from 0.05 0.3 feeds Lime 0.02 0.02 Total 0.45 - 0.90 1.11 to 2.27

Notes. A significant part of the study has been an analysis of the regional fluxes, motivated by the substantial difference in the Cd balance on farms specialised in crop production and animal production respectively, found by Andersson (1992). In this regional analysis, an important part has been to consider new information concerning the amount of purchased feeds used in different regions, and their content of Cd. According to this information, the current net inflow of Cd though purchased feeds on average per ha arable land is 0.05 g (see Table 9). Cont.

55 Cont. This value is used in Table 8, however, according to the other influxes, the values in Table 7 are used. The net influx through feeds for around 1988/89, is calculated from Andersson (1992).

The influxes have decreased with a factor of two, when it comes to atmospheric deposition, and with a factor of three to four, when it comes to commercial fertilizers, during a period of five to ten years. The reason why the application of Cd through fertilizers has decreased is mainly that the content of Cd per kg P has decreased from 64 mg/kg P (Andersson, 1992), to 25 mg currently (Christersson, 1997; personal communication). The rest of the difference is explained by a higher fertilizer application rate used by Andersson. The total influx has decreased by a factor of three.

Figure 15 gives the temporal trend in the influx of Cd through commercial P-fertilizer in Sweden during the period 1900-1990.

g Cd/ha/year

11.2 U.O 1931- 190fr* 1911-1916" 1921-1926- 1931- 1936-1961- 19<*- 1951- 1956-1961-1966-4971* 1976- 19&1- 1966- 1903 1910 1915 *1920 1925 1930 1935 I960 1965 1950 1955 I960 1965 1970 1975 1960 1965 1990

Figure 15. The influx of Cd to arable land in Sweden in g per ha and year 1901-1990 as 5-year averages, cumulative fluxes per 5 years and the total cumulative flux. Figures are from Hydro Supra AB (source Notter, 1993).

In the beginning of the century, the annual influx of Cd with P-fertilizers was around 0.5 g/ha arable land. It reached its peak in the beginning of the 1970s (about 3 g/ha and year), while in 1986-1990, it was down to less than 1 g /ha and year (Figure 15). In 1995, the influx of Cd to arable land in Sweden was on average 0.2 g/ha (Table 8), that is, about half the level of the influx in the beginning of this century.

56 5.1.3. Regional variation of some influxes

Currently, the main influxes of Cd to arable land in Sweden, according to Table 7, are via atmospheric deposition, commercial fertilizers, and animal feeds (excl. the ones produced on the farm; this fraction of Cd participates in an internal recycling on the farm). In the following, the regional variation in the influx of Cd through these three pathways will be examined. Sewage sludge is not included. While acknowledging its importance for the Cd fluxes on the fields where it is used, its average contribution is so low that it is not considered in the following analysis.

The contribution of Cd through P-fertilizer per ha in the different regions can easily be calculated from the average application rate of P-fertilizer (Table 6), and the average content of Cd per kg P-fertilizer of 25 mg per kg (Christersson, 1997; personal communication).

The influxes of Cd to arable land through animal feeds in different pro duction areas in Sweden have been analysed in some detail in Appendix 1. The results of this analysis together with other influxes of Cd to soils in the different regions are summarised in Table 9.

It should be noted that the figure for Cd influx with lime includes the amount supplied with sugar mill lime, which, strictly speaking, is not an input but a recycling of Cd. Table 9. Regional variation in main influxes of Cd to arable land in Sweden 1995, g per ha and year Production area Atm. Comm. Feeds Lime Total deposition fertilizer 1. Plain districts, 0.52 0.23 0.05 0.02 0.95 - Gbtaland +0.13

2. South! east 0.37 0.15 0.08 0.02 0.68 - Gotaland +0.06

3. Plain districts, 0.37 0.28 0.04 0.02 0.71 - N. Gotaland

4. Plain districts, 0.37 0.23 0.03 0.02 0.65 - Svealand

5. Forest districts, 0.37 0.14 0.07 0.02 0.60 - Gtitaland

6. Forest districts, 0.30 0.18 0.04 0.02 0.54 - central Sweden

7. Lower parts of 0.30 0.12 0.05 0.02 0.49 - Norrland

8. Upper parts of 0.15 0.19 0.06 0.02 0.42 - Norrland Average, Sweden 0.39 0.20 0.05 0.02 0.66

Notes. The total crop of sugar beets in Sweden take up 100 kg Cd from the field. Two thirds are returned to the field in the form of sugar mill lime, and one third is found in fractions used for dairy feeds (Landkvist, 1997; personal communication). Related to the area of farms with sugar beet production, assuming that the sugar beet is produced one year in a crop rotation of a total of four years, the return of this lime implies an addition of 0.29 g per ha and year.

This recycling is not considered in Andersson (1992). In order to com pensate for the overestimation of the net efflux of Cd through sugar beets in Andersson, the return of Cd through sugar mill lime is added to the average inflow through lime assumed to be 0.02 g per ha and year. It should, however, be kept in mind that in addition to the variation between production areas, there is also a considerable variation within each of the areas, particularly with regard to the Cd influx with P-fertilizers.

58 For example, in the plain districts in S. Gotaland, 30% of the arable surface are fertilized exclusively with P-fertilizers, and the application rate on these fields is, on average, 25 kg P per ha.

The corresponding figure for the plain districts in N. Gotaland is 39% with the same P application rate (Statistics Sweden, 1996b). Using the same as sumptions on Cd content of the P-fertilizer, the farmland in question receives about 0.62 g Cd/ha and year, respectively, in stead of 0.23 and 0.28 g Cd/ha and year. The calculated total influx to these fractions of the farmland (without addition by feeds, and other conditions unchanged) would be 1.29 and 1.01 g Cd/ha and year.

The total influxes of Cd to arable land in Gotaland are close to twice the ones in the forest districts in central Sweden and in Norrland. The main cause for this difference is the atmospheric deposition.

5.2. Efflux of cadmium from soils

The main effluxes are through leaching and crops exported from the farms. The most recent and thorough study of factors influencing the Cd content in crops under Swedish field conditions, was made by Eriksson et al. (1996). These authors calculated the Cd balance in soils for the whole drainage zone (approx. 1 m). We will also follow this new approach, in addition to the traditional top soil approach. Thus, we will discuss the effluxes, balances and relative changes of Cd in the soil both for the top soil, as well as for the whole drainage zone.

The drainage zone approach is a new approach, most studies in the field concern only the top soil. The reasons for our choice are that:

• available, reliable data concerning leaching under Swedish conditions are from the drainage zone, not from the top soil (see Eriksson et al., 1996),

• new findings indicate that a significant part of the Cd in crops is taken up from the subsoil (Obom et al., 1997, found that as much as 20-60 % of the Cd content in the grain of spring wheat could be taken up from the subsoil), and

• it agrees with the approach used by the group of scientists from the Department of Soil Sciences, at the Swedish University of Agricultural Sciences, who are specialised in this question.

59 However, as mentioned above, parallel to this, we will also apply the more common approach, where the fluxes of Cd are related to the content of Cd in the top soil. Thus, in the scenarios presented later, the effect on Cd in crops of Cd in fertilizer will be estimated by regression coefficients which relate Cd in the top soil to Cd in crops.

Thus, our results can still be compared with other studies, which take their departure in the more common approach.

It should be noted that the regional variation in leaching rates presumably is substantial, due to climatic and soil factors. In the following, the same leaching rate of Cd in g per ha is assumed in all production areas, while we acknowledge the need of accurate regional measurements, in order to provide a better agreement between the regional balances calculated, and reality.

To calculate the regional effluxes from arable land through crops, it is necessary to know:

• the regional distribution of crops,

• the variation in average yields for different crops between regions, and

• the average content of Cd in crops.

To be able to calculate the net effluxes through crops, it is also necessary to know to what degree the crops produced are consumed by domestic animals in the region.

The effluxes of Cd from arable land through crops are elaborated in Appendix 1.

5.3. Balance between influx and efflux

By combining the data in Table 9 with the data obtained in Appendix 1, the balance between in- and outflows of Cd to arable land can be calculated as regional averages, see Table 10. In this calculation the measure of the leaching used by Andersson (1992) of 0.06 g Cd per ha is used.

60 Table 10. Balance between in- and outflows o/Cd (as g Cd/ha and year) in arable land in Sweden for different production areas in 1995 Inflows Outflows Atm. P- Leach Bal Production area deposit fertil. Feeds Lime ing Crops ance

1. Plain districts, 0.52 0.23 0.05 0.15 0.06 0.34 0.55 - S. GOtaland 2. South east 0.37 0.15 0.08 0.08 0.06 0.16 0.46 - Gotaland 3. Plain districts, 0.37 0.28 0.04 0.02 0.06 0.10 0.55 - N. Gotaland 4. Plain districts, 0.37 0.23 0.03 0.02 0.06 0.07 0.52 - Svealand 5. Forest districts, 0.37 0.14 0.07 0.02 0.06 0.01 0.53 - Gotaland 6. Forest districts, 0.30 0.18 0.04 0.02 0.06 0.02 0.46 - central Sweden 7. Lower parts of 0.30 0.12 0.05 0.02 0.06 0.00 0.43 - Norrland 8. Upper parts of 0.15 0.19 0.06 0.02 0.06 0.00 0.36 - Norrland Average Sweden 0.39 0.20 0.05 0.02 0.06 0.10 0.50

The results in Table 10 indicate that the regional balances are rather similar, independent of the great variation in farming systems. This implies that the great regional variation in the total influxes is compensated by a corresponding regional variation in the Cd effluxes. Thus the total outflows of Cd per ha in the plain districts in S. Gotaland, are 5 - 7 times the ones in the forest districts, from Gotaland to Norrland. The balances range between an average increase of 0.36 to 0.55 g Cd per ha and year in the different production areas.

Compared with Andersson (1992), the level of the balances is about 40 % of the ones he found. The average contribution from atmospheric deposition and through P-fertilizer was 1.39 g per ha (ibid.). In Table 10, it is 0.59. However, if the assumed “worst possible case“ is considered, i.e. the 30% of the surface in production area 1 and the 39% in production area 3, which are fertilized with 25 kg P/ha and year (section 5.1.3), the balance for these fractions of arable land would be 0.89 and 0.85 g Cd per ha and year, respectively.

5.4. Possible future trends in cadmium content of soils

In Table 11, the increase of Cd content in the top soil is shown, if the current influxes of Cd per ha in the different production areas (Table 10), are sustained for 50 and 100 years, respectively.

Table 11. Calculated regional increase of Cd in the top soil, in g/ha and in percent, if current influxes are sustainedfor 50 and 100 years, respectively. Increase of Cd In 50 years In 100 years Production areas Amount of Ing In % Ing In % Cd in soil, g Sweden 780 25 3.2 50 6.4

1. Plain districts, 840 27 3.2 55 6.5 - S. Gotaland 2. South east 930 23 2.5 46 4.9 - Gotaland 3. Plain districts, a) N. GOtaland - VastergOtland 600 27 4.5 55 9.2 - OstergOtland 1020 27 2.6 55 5.4 4. Plain districts, 840 26 3.1 52 6.2 - Svealand 5. Forest districts, 690 26 3.8 53 7.7 - Gotaland 6. Forest districts, 660 23 3.5 46 7.0 - central Sweden 7. Lower parts of 840 21 2.5 43 5.1 - Norrland 8. Upper parts of 510 18 3.5 36 7.1 - Norrland

Notes. The content of Cd in top soil is calculated from Eriksson et al. (1995) from the assumptions that the weight of one cubic meter soil is 1 200 kg and that top soil has an average depth of 25 cm. The values for Vastergotland and Ostergotland are based on an assumption made here, based on values from Eriksson et al. (1995).

62 According to Table 11, the highest increase of Cd in soil in relative terms is in Vastergotland. In 100 years, the amount of Cd in the top soil will increase by 9.2%, if the balance in Table 10, is sustained. The situation is not in accordance with the sustainability criterion of steady-state.

On average for Sweden, the results presented in Table 11 imply that a doubling of the Cd level in the top soil, assuming that the leaching from top soil is 0.06 g/ha and year, will take 1 600 years. If the balance is related to the content in the drainage zonel, the doubling time will be around 4 400 years. For the areas in the plain districts in S. Gotaland, where 25 kg P- fertilizers are used per ha, the doubling time with regard to the top soil is 900 years, and with regard to the drainage zone it is 2 600 years.

5.5. Conclusions

• Since the average concentration of Cd in 78% of the P-fertilizers used in Sweden during the cropping season 1995/96 was 25 mg Cd per kg P, the estimated influx of Cd with the P-fertilizers was, on average, 0.20 g per ha and year. The variation between the 8 production districts was, on average, 0.12-0.28 g Cd per ha and year. However, in some production areas, the fraction of arable land that was P-fertilized exclusively with commercial fertilizers, amounted at 30-40%, and particularly in S Sweden, the application rate in these cases was as high as 25 kg P/ha and year. The influx of Cd with P-fertilizers in these "worst cases" can be estimated at >0.60 g Cd/ha and year.

• The transfer of Cd between production districts via the import/ export of animal feeds has been analysed in some detail. It turns out that the Cd influx to soils through animal feeds (manure) varies between 0.03 and 0.08 g Cd per ha and year for the various production districts. Recent analyses of purchased feed mixes indicate that a substantial decrease in the Cd content of animal feed, has taken place.

• The net effluxes of Cd from soils with crops exported from the farms show a great variation, from nil in the production districts in Norrland to 0.34 g Cd per ha and year in the plain districts in S Gotaland.

1 Assuming that the content of Cd in the drainage zone per kg soil is 60 % of the one in the top soil (Eriksson, 1997; personal communication). 63 • It has been shown that a considerable fraction (20-60%) of the amount of Cd taken up by cereals from the soil originates from the subsoil (i.e. the layer below the upper 25 cm of the soil, generally referred to as "top soil"). Therefore, it appears reasonable to consider also the soil-Cd dyna mics in the whole drainage zone, i.e. down to a soil depth of about 100 cm. Since the only available accurate estimate of the leaching rate for Cd from the soil (0.06 g Cd per ha and year) was obtained from measure ments at the bottom of the drainage zone, there is an additional reason for defining the borders of the system in this way.

• As an average for the whole of Sweden, the total influxes of Cd to arable land (0.66 g/ha, year) exceed the effluxes (0.16 g/ha, year) by an amount of 0.50 g Cd per ha and year. The balance figures obtained for the diffe rent production districts show, on average, relatively little variation: from 0.36 in upper Norrland to 0.55 in plain districts, N Gdtaland. How ever, if the high P-fertilizer application rates in parts of the southern production areas (which are important wheat production districts) are taken into account, it is noted that this farmland may receive >0.70 g Cd per ha and year more than what is exported through crops and leaching.

• The data on influx and efflux of Cd, on which the balance calculations are based, are mostly well substantiated and reliable. However, there are some weak data; notably the variation in the Cd content of lime used in different parts of the country is not well known. As indicated above, there is also a need to obtain more data on the rate of Cd leaching from different types of soils and from different districts in the country.

• On the basis of available data and balance calculations, it can be con cluded that the sustainability criterion, i.e. a steady-state of Cd in agricultural soil, is not fulfilled, neither on average nor for any of the 8 production districts. Especially the farmland under high P-fertilizer ap plication (3 0—40% of the surface in some areas), is currently accumu lating Cd at a relatively rapid rate. The Cd influx with P-fertilizers accounts for 0.20 g per ha or 30% of the total influx, on average for the country. In parts of the plain districts in N Gdtaland, the Cd influx with P-fertilizers amounts at 61% of the total.

• If the current Cd influx to arable land would continue for an additional 50 years, the average amount of Cd in the top soil would increase with 25 g per ha or 3.2%. After 100 years, the increase will consequently be 50 g per ha or 6.4%.

64 Related to the amount of Cd in the upper 100 cm of the soil (2,180 g/ha), the relative increase will be 1.1% in 50 years, and 2.3% in 100 years. However, since the Cd is not uniformly distributed in the whole soil col umn, the relative increase in the top soil will be greater.

6. Factors influencing cadmium transfer from soils to crops

6.1. General aspects

Many investigations, both experimental studies and field monitoring, con ducted in different parts of the world, have aimed at determining the different factors - natural as well as anthropogenic ones - influencing the transfer of Cd from agricultural soils to crops. Furthermore, in various stu dies, attempts have been made to sort out the relative importance of these factors. The most relevant among these studies were reviewed in the back ground paper to the OECD Cadmium Workshop (Landner et al., 1996).

A summary of this review, describing the general situation with regard to the most important parameters affecting the transfer of Cd to crops, is given below as a background for the following, more specific discussion of the condition in Swedish soils.

Today, it is generally accepted that the magnitude of uptake of Cd into plants, as well as that of Cd leaching from soils, is related to the Cd concen tration in the soil solution, not directly to the total concentration of Cd in the soil. Unfortunately, the concentration of Cd in the soil solution is usually not measured in large monitoring programmes of the level of Cd contami nation of soils. Therefore, the actual risk of Cd contamination of various crops on a specific field can only be indirectly inferred - with great uncer tainty — from data on the total Cd level in the soil, unless knowledge is available on the different influencing soil parameters. In addition to the soil parameters, which primarily determine the Cd concentration in the soil solution, a certain number of other factors are also affecting the uptake of Cd by crops.

Among the most important soil parameters, affecting the concentration of Cd in the liquid phase of the soil, the following should be noted:

• The total concentration of Cd in the soil.

65 • The pH of the liquid: a high pH tends to reduce the concentration of dissolved Cd, whereas a low pH enhances it.

• The salt concentration in the liquid.

• The concentration of dissolved organic ligands in the liquid, forming complexes with Cd.

• The concentration of zinc in the liquid phase: high concentration of zinc tends to increase the concentration of Cd in the liquid.

• The content of organic matter and clay in the solid phase of the soil, as well as the soil texture.

• The occurrence of adsorbents such as iron and manganese oxides in the solid phase of the soil.

• The temperature.

Furthermore, there is another important factor, not related to the soil, affecting the concentration of Cd in the liquid phase, at least in the short term:

• The pathway of entry of Cd to the soil, and thereby the immediate soil mobility of the entering Cd, e.g. via atmospheric fallout, via biosolids or via phosphate fertilizers and lime. This factor, however, is only impor tant during the time period immediately after the occasion when the Cd entered the soil, and, most probably, it decreases with time.

In addition to the Cd concentration in the soil solution, there are several other factors that - directly or indirectly - influence the uptake of Cd into crops:

• The concentration of zinc in the liquid: high concentration of zinc decreases the uptake of Cd into crops, independently of the Cd concentration.

• The concentration of bioavailable calcium and magnesium: high concentrations of these elements tend to decrease the uptake of Cd.

• The concentration of various micro-nutrients, such as iron, selenium and copper.

66 # The type of crop.

• The crop variety: great variations in Cd uptake have been recorded as a function of the genetic set-up of a specific crop.

The above listing of different factors that have been shown to affect the rate and the magnitude of Cd uptake into crops points to a very complex situa tion. In a specific case, there is almost never sufficient information to predict the outcome, i.e. the resulting long-term development of the Cd content in a crop, of a certain combination of these factors. The best that can be done is to try to establish the relative average importance of the different factors in a restricted number of typical cases, where the major crops and varieties are grown under normal conditions.

The situation in Sweden with respect to the relative importance of the dif ferent factors affecting the uptake of Cd into crops has been thoroughly assessed in a recent review of the results of 20 years of field investigations (Eriksson et al., 1996). This assessment provides an excellent basis for con clusions on the major tendencies regarding which variables are more important than others in determining the Cd content of some of the major crops. It is, however, self-evident that there may be many exceptions from the general rules emerging from these studies.

6.2. Top soil properties and crops

Eriksson et al. (1996) reviewed results from 20 years of Swedish field investigations focused on evaluating the influence of soil Cd content on Cd levels in agricultural products.

The data were evaluated by means of stepwise multiple regression analysis. The parameter which explains most of the variation in the dependent vari able is entered first. For the following parameters entered into the model, the Revalue expresses how much more of the variation that is explained, by the new factor. Thus, in the following the Revalues given concern the R% added to the model by the new parameter.

By this method, the Cd content in the crop was related to different, possibly influencing soil variables, such as the Cd content, the pH, and the content of organic matter, clay or zinc. In the following, the results for the different crops that were analysed are presented. It should be kept in mind that, in spite of the large data base used in the analysis, there are great uncertainties associated with this kind of analysis.

67 6.2.1. Oat

In the case of oat, the pH of the soil explained 24 % of the variation in Cd content of the grain (n=182; the original article is Eriksson, 1990a). The soil pH was the main soil parameter determining the uptake of Cd in this crop. The content of HNOg-extractable Cd in the soil explained 5 % of the variation. An increase by 1 mg of Cd/kg soil, increased the Cd content in the grain by 52 pg/kg dw. Also the soil content of organic matter (R2=0.03), clay (R2=0.01), and zinc (R2=0.01) significantly contributed to explain the variation in Cd in grain. Increasing content of zinc in the soil increased the Cd level in grain of oat. The R adjusted for all these factors together was 0.35 (Eriksson et al., 1996).

6.2.2. Winter wheat

Two studies were reviewed by Eriksson et al. (1996), one dealing with Cd uptake in winter wheat on average in the whole of Sweden (see Eriksson, 1990a), and another specifically focusing on Cd in winter wheat grown in Skane (Eriksson and Soderstrom, 1996).

For Sweden as a whole, the Cd-content in soil, measured as HN03-extractable Cd, explained 19 % of the variation of Cd in grain (n=l 19); one mg increase in the content of Cd per kg soil, would raise the Cd-level in grain by 185 mg per kg dw. The second most important factor was the content of zinc in soil extractable in HN03. It explained 8 % of the variation. The clay content was the third most important factor, explaining 6 % of the variation. The R2adjusted for all factors included in the model was 0.32.

The antagonistic effect of zinc on the uptake of Cd in plants has been established in many field studies (Eriksson, 1990a; McKenna et al., 1993). In a recent field study from Australia (Oliver et al., 1994), it was shown that the Cd concentration in wheat grain can be decreased by up to 50 % by addition of 2.5 to 5.0 kg zinc per ha to soils that are marginally or severely zinc deficient. It was also found that the effectiveness of soil-applied zinc fertilizers to decrease the Cd concentration in grains decreased over time.

68 When the results from the study in Skane (Eriksson and Soderstrom, 1996) are compared to the national survey, some differences must be noted. The content of Cd in soil explains less of the variation of Cd in grain (R.2 =0.12; n=192), with a regression coefficient which is almost half the one obtained in the national study: one mg Cd more per kg soil corresponded to 100 mg Cd more per kg dw grain. The pH-value in the later study explained 10 % of the variation in the Cd-content of the grain, while it only contributed with an explanation of 2 % of the variation in the national study. The R2adjusted was here 0.26.

Two things must be remembered in the comparison of the two winter wheat studies. First, one is a national study, the other one is a regional study, i.e. it is a subsample from the national study, which possibly differs in statistical terms from the national population of winter wheat and soils where winter wheat are produced.

Second, the samples were from different years, where the precipitation was much lower the sampling year in the Skane-study. Thus, in the national study, the average Cd-content in grain for the samples taken in Skane was 73 mg per kg dw (Eriksson, 1990a), while in the Skane-study it was 43 mg per kg dw (Eriksson and Soderstrom, 1996). It seems reasonable that the lower value of the regression coefficient in the Skane-study, between soil content of Cd and grain content, is a function of a generally lower content of Cd in grain, due to the climatic factor.

6.2.3. Spring wheat

For spring wheat the two factors that were important in the model were organic matter and Cd in soil. The first one explained 18 % of the variation in Cd content in grain (n=43), the latter one 14 %. The regression coefficient for Cd in soil implies that one mg more Cd per kg soil would increase the Cd content in grain by 168 pg per kg dw. The R adjusted for the model was 0.29. No other factors were entered into the model.

6.2.4. Carrot

In this case, organic matter and pH were the only factors entered into the model. The former explained 38 % of the variation (n=36), and the latter 28 %. The R adjusted was 0.64. It should be noted that the content of Cd in soil was not entered into the model, which indicates that, at least in this study, the Cd content of soil explains only to a minor extent the Cd-content in carrots.

69 6.2.5. Potato

For potatoes, the most important factors explaining the level of Cd in the potato were pH (R2=0.12), organic matter (R2=0.09), and Cd content in soil (R2= 0.03). An increase of the Cd level in soil by one mg, increased the Cd content in the potatoes with 39 pg per kg dw. The R adjusted was 0.20 (n=69).

6.2.6. Comment

The fact that the pH of the soil explained a relatively great portion of the variation in Cd content of the crop in the cases of oat, carrot and potato, but only a minor portion of the variation of Cd in wheat may be due to the fact that wheat is more sensitive to low pH-values. Thus, the optimal pH-level is higher for wheat, compared to the other crops mentioned (see Eriksson et al., 1996).

6.3. What are the most important factors?

The now classical study by Andersson and Bingefors (1985), in which the analysis of the long term temporal trend concerning Cd in one variety of winter wheat, first described by Kjellstrom et al. (1975), was repeated, showed an increasing level of Cd in grain over time, with more than a doubling of the level from 1918 to 1980 (an increase from 25 to 56 pg per kg). In this paragraph, an effort will be made to understand the causes of this and their relative importance.

6.3.1. The relation between soil content and crop content

The review of Eriksson et al. (1996), indicates that the soil Cd content is one of the main factors affecting crop Cd-levels.

However, the analysis also indicates that a substantial fraction of the variation in the level of Cd in various crops, is associated to other factors, than the content of Cd in soil. That is, both the level and the change of the level of Cd in the soil, as well as the availability and the change of the availability of the Cd in the soil are important for the Cd level in the crops. This conclusion agrees well with the conclusions drawn and/or measures proposed by, e.g., Andersson and Bingefors (1985), Eriksson (1990a), Eriksson et al. (1996), and Obom et al. (1997). The importance of the availability factors might be greater than earlier perceived.

70 However, at this stage of the knowledge, this can only be viewed as a hypothesis, to further probe. The important conclusion is that, in case the human exposure to Cd via food needs to be restricted, actions addressing both availability factors, as well as the influx of Cd to the soil, are needed.

6.3.2. Fertilization and the micro-environment of the roots

With regard to the question of Cd in commercial P-fertilizers, the impact on Cd in crops can be due both to the influx of Cd to the soil, and the effects of the fertilizers on the availability of the Cd added by the P-fertilizer, and on the effect on the Cd already present in the soil. The availability effects concern the very close environment to the fertilizer granulae. At this site the acidifying effect is pronounced.

This creates a soil micro-environment in the immediate vicinity of the fertilizer granulae, where the pH level is substantially lower than in the surrounding soil. The finer roots of the crops seek the zones with enhanced nutrient concentrations, i.e. the acid micro-environment close to the fertil izer granulae, where also the bioavailability of Cd (and several other trace metals) is at its maximum.

Earlier, the importance of the regional variation in application rates of P- fertilizer was discussed. But the importance of nitrogen fertilizers (N- fertilizers) must also be considered. If the application rate of N-fertilizer varies between regions, the acidifying effect in the micro-environment may differ between regions, and also the availability of Cd to plants due to this cause.

In Table 12, the application rate of N-fertilizer in different regions in Sweden is shown.

Andersson and Siman (1991) found increasing levels of Cd in the crop with increasing fertilization. However, the application of N, P, and K increased simultaneously, so the specific effect of N-fertilization, separated from the effect of Cd-addition with the P-fertilizer, was not shown.

Essentially Cd-free single-nutrient N-fertilizers can increase Cd-uptake by plants (Andersson, 1976b; Williams and David, 1976, referred by Eriksson, 1990b).

71 Williams and David (1976, referred by Eriksson, 1990b) found that appli cation of ammonium nitrate increased the uptake of native soil Cd and Cd residues in superphosphate by wheat. Andersson (1976b), in a field experi ment, found that the Cd-uptake inducing effects of nitrate of lime were similar to those of Cd containing combined NPK and PK-fertilizers. The uptake of Cd by plants increased more than would have been expected based on the Cd content of the fertilizers (referred by Eriksson, 1990b).

Table 12. Regional distribution of application rates of N-fertilizer in 1995 (Statistics Sweden, 1996a). Production areas kg N from commercial fertilizers applied per ha Sweden 100 1. Plain districts, S. Gotaland 125 2. South east Gotaland 105 3. Plain districts, N. Gotaland 115 4. Plain districts, Svealand 95 5. Forest districts, Gotaland 90 6. Forest districts, central Sweden 85 7. Lower parts of Norrland 70 8. Upper parts of Norrland 80

Different mechanisms can explain the enhancement of the uptake:

1. The elevated salt content around the fertilizer granulae leads to increased competition for the exchange sites in the soil. Cd ions in soil are replaced by the added base cations, and are becoming more plant available.

2. The added base cations, besides displacing exchangeable Cd, also lower the pH of the soil solution by displacing H+ ions in the soil, which instead go into the soil solution. According to Andersson (1976b), both reactions cause decreases in the adsorption of Cd to the soil, thereby increasing the plant availability of the native soil Cd.

3. Upon suspension in water, many fertilizers cause a decrease in pH as a result of hydrolysis. For fertilizers containing soluble P, the acidity can be as low as pH 2 in the soil around the granulae (Finck, 1982, referred by Eriksson, 1990b). This does not affect the general pH of the soil, but it may be of importance in the immediate surroundings of the fertilizer granulae.

72 4. NH4"1" has a more general acidifying effect, which can be due to nitrification or exchange with H+ during the plant uptake of fertilizer N (Eriksson, 1990b).

Eriksson (ibid.) performed pot experiments in order to examine the effect of nitrogen applied as NH4+ and as N03-, respectively, at two application rates, on the solubility of Cd in soil and the uptake of Cd by plants. Applica tion of N in the three different forms nitrate of lime (Ca(N03)2), nitro-chalk (NH4N03), and ammonium sulphate (NH4)2S04, at two rates was studied.

Nitrate of lime had a small decreasing effect on pH, with increasing effect at increasing application rate. Also nitro-chalk decreased the pH in a similar way. Ammonium sulphate had the strongest, decreasing effect on soil-pH. The acidifying effect of nitrate of lime was small, as the pH-decreasing effect of cation exchange was counteracted by the pH-increase resulting from the crop uptake of the added nitrate. For nitro-chalk and ammonium sulphate, the pH-decreasing effect of ion exchange was accentuated by nitrification and by plant uptake of NH4+.

Soil Cd soluble in NH4AcO was significantly affected by all the main treatments. The amount of available Cd in soil, measured this way, was highest for ammonium sulphate treatment, and lowest for treatment with nitrate of lime. In most treatments, increasing N-dose increased the solubility of Cd in the soil solution.

Cd concentrations in plants were highest after treatment with ammonium sulphate, and lowest after application of nitrate of lime. Higher application rates significantly increased the plant level of Cd for nitro-chalk and am monium sulphate, but not for nitrate of lime. This was analogous to the effect on soil pH (the above referred from Eriksson, 1990b).

The studies referred above support the conclusion that the application strategy for nutrients such as N and P may affect the plant available Cd in soil, even when no Cd is added by the fertilizers. The importance of these effects, together with other possible causes such as the low use of ley in the crop rotation, and the return of Cd to the fields through sugar mill lime, which may imply a high Cd influx to individual fields, must be further studied.

73 To complete the picture, two additional trends towards man-made reduction of the pH of soils may be mentioned. One is the replacement of Thomas phosphate, which has a liming effect, by other P-fertilizers. The other trend is the insufficient liming (Table 4 and 5).

6.4. Conclusions

• In a series of important studies carried out, since 1985, by researchers at the Department of Soil Sciences of the Swedish University of Agricul tural Sciences, some fundamental observations were reported: (i) The average content of Cd in agricultural top soil in Sweden has increased from 0.18 to 0.24 mg Cd per kg soil during the time period 1900 to 1990; and (ii) During almost the same period of time (1918-1980), the average content of Cd in grains of winter wheat has increased from 25 to 56 pg Cd per kg, i.e. it more than doubled in 62 years.

• Based on a detailed evaluation of these and several other studies, where the relative importance of various factors (such as the total Cd concen tration in soil, pH of the soil solution, content of organic matter, clay and zinc in the soil, type of crop and crop variety) for the rate of transfer of Cd from the soil to the crop was investigated, the possible causal rela tionship between the two above mentioned time trends was assessed.

• The results of this assessment indicate that the strong increase in Cd content of the grains of winter wheat can only partly be explained by the simultaneous increase in the total Cd content of the soil. This conclusion is based on the results obtained when applying the regression coefficients observed for the relation between soil and grain content of Cd. Accord ing to this analysis, a relatively small fraction (13-25%) of the increase over time in Cd in grain could be explained by the simultaneous increase of Cd in soil.

• Also important as explanations of the observed increase in Cd content of the grains during the period 1918-1980 appears to be an increased avail ability to the crop of the Cd in the soil as well as of the Cd added with fertilizers. The increased mobility and availability of the Cd in the soil is a function of the continuous wash-out of base cations from soils and of the acid fallout. In addition, the changes in the agricultural practice (e.g. measures causing a decrease of the organic content of soils and the in creasing use of acidifying nitrogen fertilizers) most probably have contributed to increasing the availability of the soil-Cd to the wheat plants, and have therefore also contributed to the overall outcome.

74 7. Cadmium Levels in Swedish Crops

Data on the Cd content of various Swedish crops, both those used as animal feed and those used for human consumption are given in Appendix I. A summary of the Cd content in some of the major agricultural products is presented in Table 13.

Table 13. Content of Cd in agricultural products in Sweden in fig per kg dry weight Crop/product Mean Min-max n Reference Winter wheat 53 12-127 121 (1) 43 8-207 197 (2) Rye 16 10 (3) 42 (4) Spring wheat 69 14-163 43 (5) Winter barley 24 (6) Spring barley 24 (7 ) Oat, mineral soils 36 8-108 182 (1) Oat, organic soils 49 9-115 17 (1) Mixed coarse grain 30 (8) Rye-wheat 46 (9) Oils-seeds 82 (7 ) Ley 60 (7 ) Pasture 60 (10) Potato 53 7-194 69 (5) 80 (7 ) Sugar beets 167 (7 ) Carrot 276 62-873 36 (5)

Sources: (1) Eriksson (1990a). (2) Eriksson and Soderstrom (1996). (3) Ostreus (1993), referred by Obom (1995). (4) Calculated as 68 % of the content of w. wheat. The motive is that in Jorhem and Sundstrom (1993), and also in Jorhem et al. (1984), the content of Cd in rye flour is 68 % of the one in wheat flour. (5) Obom et al. (1995). (6) Assumed to be equal to spring barley. (7) Andersson (1992). (8) Average of oat and spring barley. (9) Assumed to be equal to the average of rye and winter wheat.

75 (10) Assumed to be equal to ley for cutting.

The averages given with bold letters are the ones used in the subsequent analysis of the Cd-balance in the different Swedish production regions.

7.1. Regional variation of Cd in crops

Eriksson (1990a) analysed the regional variation in Cd in grain of oat and winter wheat (Table 14). Basically the same samples were used in the regional analysis, as in the analysis on the national level.

Table 14. Regional variation in Sweden in mean Cd content of grain (jug per kg) and in mean soil Cd extractable in 2M boiling HNO3 (mgper kg soil) (from Eriksson, 1990a)- Oat Winter wheat Production area n Cd-grain Cd-soil n Cd-grain Cd-soil

1. Plain districts, 17 21.8 0.30 27 72.8 0.30 - S. Gotaland 2. South east 19 27.0 0.26 17 58.2 0.29 - Gtitaland 3. Plain districts, 24 22.6 0.22 33 40.6 0.26 - N. Gotaland 4. Plain districts, 40 32.9 0.26 20 58.1 0.30 - Svealand 5. Forest districts, 41 36.2 0.23 10 37.1 0.25 - Gotaland 6. Forest districts, 20 32.0 0.23 4 54.4 0.21 - central Sweden 7. Lower parts of 7 45.5 0.25 " - - Norrland 8. Upper parts of 7 52.2 0.15 - - - Norrland Total 175 31.7 0.24 Ill 54.5 0.28

Oat shows an interesting pattern. The level of Cd in grain increases to the north, while the level of Cd in soil decreases. Thus, from this table, it seems that there is a negative correlation between Cd in soil and Cd in oat grains. Of course there is no such causal relationship. As earlier discussed, the pH in soil has a dominating effect on the content of Cd in oat grain. Eriksson (1990a), also showed that the increasing level of Cd in grain to the north, probably not was caused by genetic differences, but mostly caused by environmental effects.

Winter wheat in the plain districts of southern Gotaland shows a higher value of Cd in grain, than in other regions, though the level of Cd in soil is about the same as in other winter wheat producing areas.

7.2. Conclusions

• The Cd concentration in winter wheat has been reported from two separate investigations, comprising 121 (Sweden) and 197 (Skane) samples. The mean concentrations of these samples were 53 and 43 jag Cd/kg dw, respectively. Maximum recordings were up to 207 jag Cd/kg dw. Mean concentrations for potatoes were 53 and 80 jag Cd/kg dw, respectively, for sugar beets, 167 jag Cd/kg dw, and for carrots 276 jag Cd/kg dw.

• In a regional study of Cd in winter wheat, a relatively large geographical variation was noted. Higher mean values were recorded in the southern most part of the country (73 jag Cd/kg), while the lowest average (37 jag Cd/kg) was found in the forest districts of Gotaland.

• In a similar regional study of Cd in oat grains, there was an increasing trend in Cd content from south (22 jag Cd/kg) to north (52 jag Cd/kg). No positive correlation was found between the Cd concentration in grains and the simultaneously analyzed Cd content in the soil.

8. Cd levels in Swedish food

8.1. Content in individual foodstuffs

The most recent study of Cd in foodstuffs in Sweden was carried out by Jorhem and Sundstrom (1993). All values are given in Appendix 2. A summary is presented in Table 15. Table 15. Cadmium content in various types of foodstuffs in mg per weight (from Jorhem and Sundstrom, 1993) Product Mean Std. dev. Min Max n

Beef 0.001 0.001 <0.001 0.003 34 Cattle liver 0.070 0.051 0.001 0.20 33 Cattle kidney 0.35 0.58 0.023 6.4 187 Pork 0.001 0.004 <0.001 0.049 426 Pig liver 0.019 0.010 0.001 0.094 426 Pig kidney 0.11 0.069 0.004 0.88 893 Cloudberries 0.064 0.056 0.072 2 Mushroom Agaricus hortensis 0.012 0.010 0.013 2 Cabbage Chinese 0.017 0.012 0.026 2 Carrots 0.022 0.017 0.004 0.048 6 Potatoes 0.017 0.014 0.008 0.046 8 Alfalfa seeds 0.036 0.007 0.065 2 Soya beans 0.063 0.058 0.067 2 Linseeds 0.42 1 Poppy seeds blue 0.84 0.70 0.98 2 Poppy seeds white 0.038 0.032 0.044 2 Sunflower seeds peeled 0.38 0.10 0.24 0.56 8 Buckwheat 0.046 0.046 0.047 2 Rye flour 0.017 0.006 0.008 0.036 48 Wheat bran 0.13 0.052 0.076 0.25 16 Wheat flour extracted 0.025 0.009 0.014 0.047 55 Dark chocolate 0.15 1

Note, n, number of samples.

Ideally, values that are high in relation to recommendations should be pointed out. However, there are no official limit values concerning Cd in food given by the Swedish authorities. For comments on critical foodstuffs and on possible health risks associated with the intake of Cd in Swedish food, we refer to a parallel health study performed on behalf of the National Chemicals Inspectorate (Berglund et al., 1997).

Jorhem et al. (1984) found an average value for Cd in carrots of 0.041 mg per kg (n=47) and Jansson (1995) found an average of 0.034 mg per kg freshweight in carrots (n=72).

78 The analyses presented by Jorhem et al. (1984) complement the ones of Jorhem and Sundstrom (1993). Some values are presented in Table 16. In Appendix 2 a more extended table is given.

Table 16. Cadmium content in mg/kgfresh weight for some foodstuffs on the Swedish market (Jorhem et al., 1984) Product Mean Min Max n Lamb kidney 0.94 0.10 2.3 4 Moose kidney 2.3 0.18 13 69 Moose calf kidney 0.45 0.18 0.81 16 Moose liver 0.41 0.067 2.4 79 Moose calf liver 0.15 0.067 0.23 18 Moose meat, round 0.003 0.001 0.011 9 Reindeer liver 0.28 0.14 0.51 13 Roedeer kidney 6.9 4.8 9.0 2 Roedeer liver 0.37 0.14 0.87 6 Chicken breast 0.002 0.001 0.004 10 Hen liver 0.13 0.085 0.19 4 Crab, white meat 0.081 0.012 0.26 15 Crab, liver 15 1.5 32 16 Crab, remaining edible parts 2.6 0.32 5.8 16 Crab meat, canned 0.051 0.016 0.098 6 Mussels 0.016 0.069 0.26 37 Mussels in water, canned 0.14 0.10 0.23 8 Prawns/shrimps, white meat 0.079 0.039 0.11 8 Prawns/shrimps, liver 4.0 1.9 5.7 6 Barley flour 0.017 0.008 0.026 2 Barley, pearled 0.016 0.012 0.019 2 Oats, rolled 0.031 0.004 0.050 6

Kumpulainen and Tahvonen (1989) analysed the content of Cd in some foodstuffs in some European nations. Sweden, Austria and Switzerland had significantly lower Cd content in wheat flour than Germany and Fin land. For potatoes, Finland had a significantly lower content of Cd than a group consisting of Norway, Sweden and Scotland. This group in turn had significantly lower Cd-values than Denmark and the Netherlands. The con tent in pork and milk was the same in all nations, and, at least, a factor 10 to 30 times lower than the content in the crop products.

79 Their results indicate that the level of Cd in staple food in Sweden are either the same as in other nations in Europe, or lower.

8.2. The major influxes of Cd with food to humans in Sweden

In Table 17, the main influxes of Cd to humans in Sweden are shown. As a comparison, the influx of Cd to humans is 7 % of the influx of Cd to dome stic animals through crops produced in Sweden. It corresponds to 4 % of the Cd leaving the fields in Sweden, and going into the food system, either as food stuffs or feed stuffs.

Table 17. The main influxes of Cd to humans in Sweden, kg per year Consumptio Content of Product n, Cd, Kg Cd per Share of million kg mg/kg year total

Wheat flour, a 433 0.025 10.8 0.43 Potatoes, b 615 0.017 10.5 0.41 Rye flour, a 85 0.017 1.4 0.06 Carrots, a 51 0.022 1.1 0.04 Milk, b,c 3 243 <0.002 0.6 0.02 Cattle meat, b 157 0.002 0.3 0.01 Pork meat, b 298 0.002 0.6 0.02 Chicken meat, b 62 0.002 0.1 <0.01 Egg, b 92 ? ? Total 25.4

Notes: a. Consumption from Jorhem and Sundstrom (1993). b. Consumption from Statistics Sweden (1996a) c. Content of Cd per kg fatffee dry matter (Kumpulainen and Tahvonen, 1989), which is around 10 % of the fresh weight (see Spomdly, 1989). Content of Cd is per kg fresh weight for wheat flour, rye flour, potatoes, carrots, and chicken meat. For cattle meat and pork meat it is per kg dry matter. The content of Cd is from Tables 15 and 16, except for cattle and pork meat, for which the reference is Jorhem et al (1984). It is not clear to what degree the values for the content of Cd in meat are average values, which includes Cd in offal, such as kidney and liver. If they are not included, in rough terms about the same amount of Cd may pass this way to human intake, as the amount shown in the table through consumption of meat.

80 8.3. Conclusions

The main food items responsible for about 94% of the total intake of Cd are wheat flour, potatoes, rye flour and carrots. By far, the highest concentration of Cd in major agricultural products was, on average, recorded in carrots, where the mean Cd level on a dry weight basis (12% dry matter) was around 180,280 and 340 mg Cd/kg, respectively.

9. Scenarios of Long-Term Cadmium Exposure via P- Fertilizers

In this chapter, a preliminary assessment is made of the possible future development of the Cd content in agricultural soils. The analysis is per formed on the national level, because the difference between regions in the balance of Cd was small (Table 10). The effect of four levels of Cd in P- fertilizer, and of two application rates of commercial P-fertilizers is con sidered. The expected net increase of Cd in the top soil and in the drainage zone in 100 years are calculated. The scenarios are based on the balance of Cd in soil given in Table 10, where all fluxes are held constant, except the flux of Cd to soil through P-fertilizers, and the content of Cd in top soil in Table 11. The content of Cd in the drainage zone is the one calculated in connection to Table 11.

It was furthermore assumed that the combined effect of all other natural or man-related factors on Cd in soil and in products was nil throughout the considered time period. In reality, this is not the case, but the latter assump tion is needed in the first step in an evaluation of the importance of the Cd level in P-fertilizers for the future content of Cd in soils and crops.

9.1. Points of departure

The considered levels of Cd in P-fertilizer examined are:

• 5 mg per kg P (a long term objective expressed in an declaration by the Swedish government),

• 25 mg per kg P (the current level),

• 50 mg per kg P, and

• 140 mg per kg P.

81 The latter level is close to the one examined by the consultant engaged by the European Commission (60 mg per kg P205, which is equal to 138 mg per kg P).

The two application rates of P-fertilizer considered are: e The average application rate in Swedish agriculture (7.9 kg per ha and year, Table 6), and

• the average application rate on fields only fertilized by commercial fertilizers in the plain districts in S. and N. Gotaland (25 kg/ha and year, Statistics Sweden, 1996b). These areas concern 30 and 39 % of the total fertilized areas in these districts, respectively.

The reason why higher average levels of P-application are not assumed is that Sweden has shifted from a period where the strategy in the P-fertilization was to increase the P content in the soil, to a phase where the stra tegy is to replace the amount of P removed through crops. According to Bertilsson (1996), this shift is occurring in other industrialised nations as well, however, Sweden experienced it earlier than most other nations.

A second argument not to assume an increasing application rate is that a revision of the agricultural policy in Europe can be assumed to result in a shift from subsidies laid on the product, which stimulates increasing pro duction even when the market it saturated. To move away from systems for subsidies which stimulate overproduction, will imply decreasing economic incentives for fertilization. This possible trend towards decreasing appli cation rates due to changing economic incentives, will be further strength ened if economic measures for environmental protection will be applied generally in the society.

Thus, it is assumed that the incentives in the future will change in such a way, that the economic optimal level of application of P-fertilizer in the agriculture in the European Union, will decrease compared to the practice of today

9.2. Increase of Cd in soil

The increase of Cd in soil, for the different combinations, is presented in Table 18.

82 Table 18. Expected increase of Cd in agricultural soils in Sweden in 100 years for two application rates of P-fertilizer, and four levels of Cd content in P-fertilizer Expected effects after 100 years Soil Balance, g Cd per ha Increase in % content mg/kg 1 year 100 years Top soil Drainage Top soil zone 7.9kg P applied per ha

5 mg Cd per kg P 0.34 34 4 2 0.271

25 mg Cd per kg P 0.50 50 6 2 0.277

50 mg Cd per kg P 0.70 70 9 3 0.283

140 mg Cd per kg P 1.43 143 18 7 0.308

25 kg P applied per ha 5 mg Cd per kg P 0.43 43 6 2 0.274

25 mg Cd per kg P 0.93 93 12 4 0.291

50 mg Cd per kg P 1.53 153 20 7 0.311

140 mg Cd per kg P 3.83 383 49 18 0.388

Notes. In the calculations the same leaching is assumed from the top soil, as from the drainage zone. Thus the balance for 1 and 100 years, respectively, can be applied on the top soil, as well as on the drainage zone. The top soil is assumed to contain 780 g Cd per ha in year 0, the corre sponding value for the drainage zone is 2 184 g. The content of Cd per kg soil in year 0 is 0.26 mg (Eriksson et al., 1995).

The content of Cd in P-fertilizer is more important than the application rate of P (Table 18) for the temporal trends of Cd content in soil.

The doubling time for the Cd content in top soil varies from around 200 to 2 300 years for the different alternatives. The doubling time for the average Cd level in the drainage zone is 2.8 times longer.

83 9.3. The effecton Cd in agricultural products

In spite of the commendable work carried out by the research group at the Swedish University of Agricultural Sciences with the aim f establishing a quantitative relationship between Cd in crops and various soil factors (Eriksson et al., 1996), it has been considered unwise to make an extrapo lation from the obtained regression coefficients and try to predict - in quantative terms - the future development of Cd levels in crops from the calculated future Cd levels in soil. The uncertainties in making such an extrapolation simply appear to be too great, and therefore, it was not consi dered meaningful to present a figure on the possible Cd content in, for instance, wheat grains after 50 or 100 years from now.

Based on the available data base, it can only be stated that it is quite pos sible that the predicted future increase in Cd content of soils very well may result in future increases of the Cd content also in crops, iccluding wheat grains.

However, the extent of this enhancement of the Cd levels in crops is very difficult to predict, because of the many confounding factors involved. In particular, it has not been possible to predict how the relative impact of these confounding factors will change over time, thereby modifying the manifestation of the increasing Cd levels in soil in terms of increasing Cd content in crops in an unpredictable manner. It can only be assumed that the various soil factors and the agricultural practices influencing the mobility and bioavailability of Cd in soil most probably will change considerably in the next 50 to 100 years.

9.4. Conclusions

The results of the scenario calculations can be summarised as follows:

• If the Cd content of the P-fertilizers should be reduced from the present level of 25 mg Cd/kg P to 5 mg Cd/kg P, the average balance value (influx minus efflux) would decrease from 0.50 to 0.34 g Cd per ha and year, in case the application rate is 7.9 kg P per ha. With a fertilizer application rate of 25 kg P/ha, the balance value would decrease from 0.93 to 0.43 g Cd per ha and year. Thus, with the presumptions used, even an almost total elimination of Cd from the P-fertilizer would not result in a steady-state situation with respect to Cd in the average Swedish agricultural soils.

84 • In order to reach a steady-state situation, the present influx of Cd through atmospheric deposition has to be substantially reduced, to a level of about half the present deposition rate in upper Norrland, in addition to the reduction of the Cd content in P-fertilizers to 5 mg Cd/kg P. However, the assumption that the effluxes will remain the same under these circumstances is quite uncertain. Furthermore, the assumption that the estimate for the leaching of Cd from soils (0.06 g Cd/ha and year) is representative for all soils is not well substantiated, neither at present nor in the future.

• If the Cd content of the P-fertilizers rises to the level 140 mg Cd/kg P, the average balance value will rise to 1.4 g Cd per ha and year at the lower fertilizer application rate, and to 3.8 g Cd per ha and year at the higher applications rate. In 100 years, this would result in an accumula tion of 140 and 380 g Cd per ha, respectively. These amounts corre spond to a relative increase in the Cd content of the top soil by 18% and 49%, respectively. Calculated on the whole drainage zone of the soil (0- 100 cm), the relative increase would be 7% and 18%, after 100 years. These relative increases could be compared with the corresponding in creases if we continue to use P-fertilizers with the actual content of Cd (25 mg Cd/kg P), i.e. 6% and 12% when calculated on the top soil, and 2% and 4%, respectively, when calculated on the drainage zone.

• The consequences of the future accumulation of Cd in agricultural soils, according to the four scenarios, for the Cd content in crops cannot be predicted in quantitative terms. However, the increasing content of Cd in soils present an increasing risk for further enhancement of the Cd levels in crops, compared to the present situation. However, since the future development of the impact of the various soil-related factors as well as that of agricultural practices influencing the rate of uptake of Cd in crops is extremely difficult to predict, the content of Cd in the crops may in crease faster or slower than the increase of Cd in soils. The dynamics of Cd in soils have probably not yet reached a new equilibrium, correspond ing to the new status of soil conditions created by the fundamental changes in agricultural practice over the past few decades. Thus, if there will be a continued increasing bioavailability of Cd in soils, and/or if the Cd added to soils in the future will be in a more bioavailable form than hitherto, the increase in the average Cd content of crops may very well be faster than before.

85 10. Overall Conclusions

The above performed examination and assessment of the Swedish situation with regard to Cd in P-fertilizers, soils and crops has come to the following overall conclusions:

• Previous studies have demonstrated that there has been an increase of the average Cd content in Swedish agricultural top soils, over the period 1900-1990, from 0.18 to 0.24 mg Cd/kg soil, i e a rise by 33%. This accumulation of Cd in soils might be explained by the earlier quite high influx of Cd through atmospheric deposition and through P-fertilizers containing high Cd levels. Both these influxes have decreased by factors of two to four during the past 5-10 years. In spite of these reductions, the average balance between influx and efflux of Cd is 0.50 g Cd/ha and year, meaning that a steady-state situation is far from being achieved. If the current surplus of influx over efflux would continue unchanged, the Cd content in the top soil would increase by 6% in 100 years and be doubled in about 1,600 years. Calculated on the whole drainage zone (100 cm), the doubling time would be about 4,400 years. If the Cd content of P-fertilizers rises to 140 mg Cd/kg P, the Cd level in the top soil would, on average, increase by 18% in 100 years, if all other factors remain constant.

• Studies performed in the middle of the 1980s demonstrated that the average Cd content in grains of a special variety of winter wheat has increased from 25 to 56 pg Cd/kg, in the period 1918-1980, i e the mean concentration more than doubled in 62 years. It was assumed that this result could be explained both by the increasing content of Cd in the soil and by an enhancement of the bioavailability of both the added and the existing Cd in the soil.

• Based on an evaluation of available data, including data from more recent studies, it was found that the addition of Cd to soils per se might not be the dominant determining factor causing the observed increases in the Cd concentrations of crops. Also changes in the mobility and the bioavailability of Cd are important in this context, as well as the content of bioavailable zinc in the soil. However, if such additions are made simultaneously with measures that increase the bioavailability of Cd, the enhanced levels of Cd in the soil constitute an increased risk or, at least, a greater potential for formation of bioavailable Cd, which may - under certain circumstances - be readily taken up by the crops.

86 • It is also strongly indicated that a continued addition of Cd to soils, which have been modified in such a way that they have a weaker capacity to bind and stabilise Cd, may constitute an increased risk of unacceptable exposure of crops and humans to Cd.

• Since especially the agricultural districts in SW Sweden, with soils hav ing a low buffer capacity, are exposed to several phenomena which are out of control by the Swedish society, namely the acidifying effect of a large surplus of precipitation over evaporation and higher-than-average atmospheric deposition of acidifying substances (sulphur and nitrogen compounds) as well as of airborne Cd, the soils in these districts are par ticularly vulnerable to enhanced input of Cd. Therefore, any unnecessary input of Cd, especially in these areas, should be avoided as far as possi ble.

• In addition to the natural factors reducing the buffer capacity, and hence, increasing the risk of acidification of soils, it is important to note that some of the agricultural practices associated with the transformation process towards a modem agricultural production system have contrib uted to increasing the mobility and the bioavailability of Cd in soils. Among these changes may be mentioned the reduced use of manure and ley in crop rotations in cereal producing districts, which tend to reduce the content of organic matter in soils, the increasing use of acidifying nitrogen fertilizers, and the decreasing application rates of lime to counteract the acidification of soils. All this probably contributed to make the added Cd, as well as the Cd already existing in the soil, more bioavailable for uptake by the crops.

• Therefore, in addition to efforts to keep the future influxes of Cd to arable land as low as possible, it is strongly recommended also to consider measures aiming at controlling the mobility and the bioavail ability of the Cd already existing in the soils, in order to reduce the risk of future, unacceptable exposure of humans to Cd through agricultural products.

87 11. References

Andersson, A. 1976b. Swedish Journal of Agricultural Research. 6, 27.

Andersson, A. 1977a. Heavy metals in Swedish soils: On their retention, distribution and amounts. Swedish J. agric. Res., 7:7-20.

Andersson, A. 1977b. In translation: Heavy metals in commercial fertilizers, manure and lime (Tungmetaller i handelsgodsel, stallgodsel och kalk. Kadmiumbudget lor akermarken, Lantbrukshogskolans meddelanden A Nr 283) Uppsala.

Andersson, A. 1983. Composted municipal refuse as fertilizer and soil conditioner. Effects on the contents of heavy metals in soil and plants, as compared to sewgae sludge, manure and commercial fertilizers. In Utilization of sewage sludge on land: Rates of application and long-term effects of metals, (ed. S. Berglund, R.D. Davis & P. L’Hermite). pp.146- 156. Proceedings of a Seminar held at Uppsala, June 7-9,1983, Commission of the European Communities, D. Reidel Publ. Comp., Dordrecht.

Andersson, A. 1992. Trace elements in agricultural soils - fluxes, balances and background values. Swedish Environmental Protection Agency, report 4077 (Naturvardsverket, rapport 4077).

Andersson, A. and S. Bingefors. 1985. Trends and annual variations in Cd concentrations in grain of winter wheat. Acra Agriculturae Scandinavica 35:339-344.

Andersson, A. and G. Siman. 1991. Levels of Cd and some other trace elements in soils and crops as influenced by lime and fertilizer level. Acta Agriculturae Scandinavica 41:3-11.

Anomymous. 1988. In translation: Heavy metals in feeds (Tungmetaller i foder), AB Analy Cen, Box 905, 531 19, S-Lidkoping, Sweden.

Berglund, M, Blinder, C.G., Jarup, L., Nordberg, G. and M.Vahter. 1997. Health effects of cadmium exposure - A review of the literature and a risk estimate. Manuscript.

Bernes, C. 1993. Nordens miljo - tillstand, utveckling och hot. Monitor 13. Naturvardsverket informerar.

88 Bertilsson, G. 1996. Current developments in the use of fertilizer phosphorus and the consequences concerning cadmium. In Fertilizer as a source of cadmium. Proceedings from the OECD Cadmium Workshop, Saltsjobaden, Sweden, on 16-20 October 1995.

Brandt, M., Jutman, T. and Alexandersson, H. 1994. Sveriges vattenbalans. SMHI Hydrologi, Nr 49, 1994.

Chadwick, M. J. and J.C. Kulylenstiema. 1990. The Relative Sensitivity of Eccosystems in Europe to Acidic Depositions. A Preliminary Assessment of the Sensitivity of Aquatic and Terrestrial Ecosystems. 65 p. + map. ISBN:91-881 16-43-3

Drake, L. and S. Hellstrand. 1997. The economics of the Swedish cadmium policy (an ongoing study Department of Agriculture. 1989. In translation: A new food policy (En ny livsmedelspolitik, Ds 1989:63. Allmanna Forlaget, Stockholm.

Eriksson. J.E. 1990a. Factors influencing Cd levels in soils and grains of oats and winter wheat. A field study on Swedish arable soils. In factors influencing adsorption and plant uptake of cadmium from agricultural soils. Dissertation, Department of Soil Sciences, Swedish University of Agricultural Sciences, reports and dissertations, no. 4.

Eriksson, J. 1990b. Effects of nitrogen-containing fertilizers on solubility and plant uptake of cadmium. Water, Air and Soil Pollution 49: 355-368.

Eriksson, and M. Sbderstrbm 1996. Cadmium in soil and winter wheat grain in southern Sweden. I. Factors influencing Cd levels in soils and grains. Acta Agriculturae Scandinavica, section B, Soil and Plant Science, 46: 240- 248.

Eriksson, J., Soderstrbm, M. and A. Andersson. 1995. Cadmium contents in the plough layer of Swedish agricultural soils. Swedish Environmental Protection Agency, report no. 4450. (Kadmiumhalter i matjorden i svensk akermark, Naturvardsverket, rapport 4450). Stockholm.

Eriksson, J., Obom, I., Jansson, G. and A. Andersson. 1996. Factors influencing Cd-content in crops. Results from Swedish field investigations. Swedish Journal of Agricultural Research, 26: 125-133.

89 Eriksson, J., Andersson, A. and R. Andersson. 1997. In translation: Current status of Swedish arable soils. Swedish Environmental Protection Agency, report 4778. (Tillstandet i svensk akermark, Naturvardsverkets rapport nr 4778). Stockholm, 59.

FAO/WHO. 1993. Report of the 8th session of the Codex Committee on Cereals, Pulses and Legumes held in Washington D C., 26-30 October 1992. Joint FAO/WHO Food Standards Programme, Codex Alimentarius Commission, 20th Session, Geneva 28 June - 7 July 1993, 3.

Finck, A. 1982. Fertilizers and fertilization. Verlag Chernies, Weinheim, West-Germany, p. 54, 125.

Gunnarsson, O. 1980. Cadmium in the soil-plant environment. Royal Swedish Academy of Agriculture and Forestry, Stockholm. Report No. 4, 4-47.

Hellstrand, S. 1996. The environmental impact of milk production: - From the field to the entrance of the dairy. Department of Systems Ecology, Stockholm University, technical report no. 22, 1996.

Hellstrand, S. 1997. An Approach to Measure the Biophysical Productivity of Conventional and Ecological Animal Production. Manuscript.

IVL. 1995. (Luft- och nederbordskemiska stationsnatet inom PMK. Overvakning av svavel- och kvaveforeningar, baskatjoner, tungmetaller och kvicksilver. B 1206. Gotebog.)

IVL. 1996. Communication with MFG Environmental Research Group.

Jansson, G. 1995. In translation: Cadmium in soil and carrots- results from analyses 1994 and 1994 (Kadmium i mark och morotter - resultat ffan provtagningar 1993 och 1994. Rapport till Statens Livsmedelsverk. Inst, for markvetenskap, Avd. for marklara och ekokemi, Sveriges lantbruksuniversitet).

Jensen, A. and J. Markussen. 1993. Consumption of and pollution with cadmium. FORCE Institutes. MiljoprojektNo. 213, Miljostyrelsen, Copenhagen, Denmark.

90 Jorhem, L., Mattson, P, and S. Slorach. 1984. Lead, cadmium, zinc and certain other metals in foods on the Swedish market. Var Foda, vol. 36, suppl. 3, 1984.

Jorhem, L. and B. Sundstrom. 1993. Levels of lead, cadmium, zinc, copper, nickel, chromium, manganese, and cobalt in foods on the Swedish market, 1983-1990. Journal of Food Composition and Analysis, 6, 223-241.

Kjellstrom, T., Lind, B., Linnman, L. and C.G. Blinder. 1975. Variation of cadmium concentration in Swedish wheat and barley. An indicator of changes in daily cadmium intake during the 20th century. Arch. Environ. Health, 30, 321-328.

Kumpulainen, J. and R. Tahvonen. Report of the activities of the sub network on trace elements status in food. Consultation of the FAO European Research Network on Trace Elements, Lausanne, Switserland, September 5- 8, 1989.

Landner, L., Folke, J., Oberg, M.O., Mikaelsson, H. and M. Aringberg- Laanatza. 1996. Cadmium in Fertilizers - Consultants report prepared for the OECD Cadmium Workshop, Saltsjobaden, Sweden, 16-20 Oct. 1995.

Mattsson, L.1995. In translation: Soil fertility and soil type in Swedish soils, Swedish Environmental Protection Agency, report No. 4533 (Markbordighet och jordart i svensk akermark. Naturvardsverket, rapport 4533). Stockholm.

McKenna, I.M., Chaney, R.L. and Williams, F.M. 1993. The effect of cadmium and zinc interactions on the accumulation and tissue distribution of zinc and cadmium in lettuce and spinach. Environ. Pollut., 79:113-120.

Makela-Kurtto, R. 1995. Cadmium in Finnish Cultivated Soils. Institute of Soils and Environment. Agricultural Research Centre of Finland, Jokioinen, Finland.

Nilsson, L.G. and L. Mattsson. 1993. (Godsling och odling - hur paverkas akermarkens bordighet? Fakta Mark/vaxter nr 14, SLU Info, Sveriges Lantbruksuniversitet, Uppsala).

Notter, M. (ed) 1993. The metals and the environment (Metallerna och miljon). Swedish Environmental Protection Agency, Report 4135.

91 Oliver, D.P., Hannam, R, Tiller, K.G., Wilhelm, N.S., Merry, RH. %Cozens, G.D. 1994. Heavy metals in the environment. The effects of zinc fertilization on cadmium concentration in wheat grain. J. Environ. Qual., 23:705-711.

Ostreus, I. (1993). In translation: Content of cadmium in mill products - Swedish and foreign. In: Cadmium in cereales. Seminar at SLR, April 1993. Report from SLR no. 155 A. (Innehall av kadmium i kvamprodukter - svenska och utlandska. I: Kadmium i spannmal. Seminarium pa SLR april 1993. Rapport Iran SLR nr 155 A).

Parkman, H., Borg, H., Iverfeldt, A. and G. Lithner. 1997. Cadmium in Sweden - Environmental Risks. National Chemicals Inspectorate, Solna, Sweden (vol 1, present report).

Pettersson, O. 1977. Swedish Journal of Agricultural Research 7, 21. Ross, H. 1991. Overvakning av tungmetaller i nederbdrden (Monitoring of heavy metals in precipitation). Rapport Iran verksamheten 1990. Swedish Environmental Protection Agency, Report 3943.

Ruhling, A., Steinnes, E. and T. Berg. 1996. Atmospheric Heavy Metal Deposition in Northern Europe 1995. Nord 1996:37. Nordic Council of Ministers, Copenhagen, 46.

SEPA. 1981. In translation: The acidification of land and water (Forsuming av mark och vatten, Naturvardsverket. Monitor, 1981).

SEPA. 1993a. In translation: A sustainable Society. Report No. 4234 (Ett miljoanpassat samhalle:- Naturvardsverkets aktionsprogram Miljo ’93. Rapport 4234. Naturvardsverkets forlag). Solna.

SEPA. 1993b. Acidification. An everlasting problen, or is there hope?. The Swedish Environmental Protection Agency, report 4242.

SEPA 1995. Report 4403.(Naturvardsverket. Luft- och nederbordskemiska stationsnatet inom PMK, rapport 4403).

SEPA. 1997. Ed. B. Hedlund. In translation: Cadmium, state and trends, in preparation (Kadmium, tillstand och trender, under arbete).

92 SOU 1992:14. In translation: Less cadmium in commercial fertilizers, Department of Agriculture (Mindre kadmium i handelsgodsel, Jordbruksdepartementet).

Spomdly, R. 1989. (ed.) In translation: Tables of feed composition and nutritive value for ruminants (Fodertabeller for idisslare 1989. Speciella skrifter 39, Sveriges Lantbruksuniversitet). Uppsala.

Statistics Sweden. 1996a. Yearbook of Agricultural Statistics.

Statistics Sweden. 1996b. Use of Fertilizers and animal waste in agriculture in 1994/95, order No. Na 30 SM 9602 (Godselmedel i jordbruket 1994/95, bestallningsnummer Na 30 SM 9602).

Statistics Sweden. 1995. In translation: The environment in Europe (Miljon i Europa).

Swedish Code of Statutes, SFS 1984:409. Act concerning charges on fertilizers (Lag om avgift pa godselmedel).

Swedish Code of Statutes, SFS 1985:839. The Cadmium Ordinance.

Soderstrom, M. and J.E. Eriksson. 1995. Cadmium in soil and winter wheat in southern Sweden. II. Geographical distribution and its relation to substratum. In Soderstrom, 1995. Geoinformation in agricultural planning and advisory work, Dissertation, Department of Physical Geography, Gdteborg University.

The Swedish Board of Agriculture. 1996. The journal of agricultural economics, no. 6-7.

Williams, C.H. and D.J David. 1976. Soil Science 141, 86.

Obom, I. 1995. In translation: Cadmium in crops - Increasing levels? In Report 10/95, Chemical Inspectorate (Kadmium i grodan - okande halter? Kemikalieinspektionen, rapport 10/95).

Obom, I., Jansson, G., and L. Johnsson. 1995. A field study on the influence of soil pH on trace element levels in spring wheat (Triticum aestivum), potatoes (Solarium tuberosum) and carrots (Daucus carota). Water, Air and Soil pollution 85: 835-840.

93 Obom, I., Johnsson, L., Jansson, G., Eriksson, J. and A. Andersson. 1997. In translation: Trace elements in wheat, potatoes and carrots. What are the impact of pH and liming? in Health Risks of Acidification, Swedish Environmental Protection Agency, Report No. 4734 (in press) (Sparelement i vete, potatis och morotter. Vilken inverkan har pH och kalkning? i Halsorisker vidForsuming,, Naturvardsverket, rapport 47 34, under tryckning). Stockholm.

11.1. Personal communication

Christersson, Per. Federation of Swedish Farmers (LRF). 1997-02-21.

Eksvard, Jan. Federation of Swedish Farmers (LRF). 1997-02-20.

Eriksson, J. Agr. D., Department of Soil Sciences, the Swedish University of Agricultural Sciences. February, 1997.

Hacklou, Bjorn. Quality Director. ICA Frukt och Grant. 1997-02-20.

Landkvist, Birgit. Agronomist, Danisco Sugar AB. 1997-03-05.

Larsson, Kjell. Director of the feed analysis laboratory, Swedish Farmers’ Selling and Purchasing Association. 1997-03-24.

Mattsson, Lennart. Agr. D., Research leader, Department of Soil Sciences, Swedish University of Agricultural Sciences, Uppsala. 1997-05.

Ruhling, Ake. 1997-10-16. Department of Ecology, Lund University, Lund, Sweden.

Siman, Gyula. 1997. Professor in plant nutrition, Department of Soil Sciences, the Swedish University of Agricultural Sciences. 1997-02-21.

Stjemdal, Erik. 1997-05. Adviser in plant production in Skane, at the Agricultural Society.

94 Appendix 1.

Analysis of the Cd fluxes to and from soils through animal feed and through crops

1. Influx of Cd with purchased animal feeds

The main part of the Cd occurring in purchased animal feeds will end up in the manure produced by the animals. Thus, in order to obtain a reasonably correct picture of the regional variation in the total influx of Cd to soils, it is necessary to analyse the regional variation in Swedish animal production as well as the Cd content of various types of fodder and animal feed mixes.

According to Andersson (1992), the net inflow of Cd to a farm through purchased feeds is substantial. The farm-type with the highest increase of Cd in soil, was a farm with animal production, where as much as 31 % of the gross inflow to the farm was through purchased feeds. However, the data concerning this inflow of Cd was insecure. Changes from farming systems with animals and ley, to systems without animals and ley, affect the availa bility to plants of Cd in soil. In most studies concerning the Cd-question, the existence of animals at the farms is only expressed in terms of manure. Its significance for the crop production, and thus for the fluxes of Cd to and from the farm, and the availability factors, are often not analysed. For these reasons, it is important to understand the regional variation in crop and animal production systems, and how it affects the influxes and effluxes of Cd to the farms, as well as the availability factors.

Thus, in the following section, the regional variation in the animal production is thoroughly analysed. In later sections, dealing with the effluxes of Cd from farms, the crop production is analysed in a corresponding way.

The results from analyses of Cd in purchased feeds produced by the Lantmannen-organisations - one of the farmers co-operatives - became available in March 1997 (Kjell Larsson, 1997; personal communication). Lantmannen has a market share of 75 to 80 % for purchased feed mixes (ibid.). In Table 1 the results are presented.

95 Table 1. The content ofCd in animal feeds in Sweden, source Larsson (799%

Purchased feed Average content of Cd, mg per kg

Laying mash (inch protein feeds, grain, 30 and minerals)

Chicken feed (inch protein feeds, grain, 60 and minerals)

Dairy concentrate (incl. protein feeds, 110 sugar and minerals, excl. grain)

Pig concentrate (inch protein feeds, 70 minerals, excl grain)

When the content of Cd in purchased feeds (Table 1) is combined with the amount of purchased feeds (including grain in feed mixes) used by the different kinds of domestic animals (Statistics Sweden, 1996a), it can be calculated that the total amount of Cd imported to dairy farms is around 100 kg, to pig farms ca 30 kg, and to farms with poultry production ca 25 kg per year. Thus, on the national level, a total of ca 155 kg Cd is imported to the farms with animal production.

The regional variation in the net contribution from animal feeds is more complicated to catch. A prerequisite for this is information about the regional variation in animal production, the feeding to different categories of animals, and the Cd content of different feeds.

1.1. Regional variation in animal production

The regional variation in animal production is of importance for the under standing of the Cd levels found in crops also because it provides knowledge about flows of organic matter in the Swedish food production system. Areas with much crop production and little animal production export organic matter through feeds to areas with relatively little crop production and much animal production.

96 This implies a flow of Cd from the crop production areas to the animal production areas. It also implies farming systems in the animal extensive areas, which tend to decrease the organic matter in the soil to an equilibrium at a low level of organic matter. Simultaneously, in the animal intensive areas, the crop rotation together with the import of feeds tend to move the equilibrium to a higher level of organic matter in soil.

Thus, the information about the regional variation in animal and crop production gives information of flows of Cd within the agricultural system in Sweden. But it also gives information about possible changes in the content of organic matter in soil, which may in a substantial way affect the availability to plants of the Cd in soil. Thereby, we can evaluate the causes behind the regional variation in content of Cd in agricultural products.

In this section the regional variation in the animal production is presented. The regional variation in crop production is shown in the section where the Cd effluxes from soils are treated.

In Table 2, the regional variation in Swedish animal production is shown.

97 Table 2. Regional variation in Swedish animal production (from Statistics Sweden, 1996a) Fraction of total number of animals on the 8 of June 1995 Fatte- Fatte- Production area Dairy cows Sows ning Laying ning pigs hens chicken 1. Plain districts, - S. Gotaland 0.06 0.27 0.30 0.18 0.14 2. South east - Gotaland 0.15 0.19 0.20 0.17 0.42 3. Plain districts, - N. Gotaland 0.12 0.18 0.19 0.22 0.13 4. Plain districts, - Svealand 0.14 0.14 0.12 0.12 0.10 5. Forest districts, - Gotaland 0.32 0.17 0.13 0.21 0.21 6. Forest districts - central , Sweden 0.07 0.02 0.01 0.05 0.00 7. Lower parts of - Norrland 0.08 0.02 0.02 0.02 0.00 8. Upper parts of - Norrland 0.06 0.02 0.02 0.02 0.00 Total, in thousands 482 237 1 300 6 100 4 813

In relation to the area of arable land, dairy cows are most concentrated in the forest areas in Gotaland (29 cows per 100 ha). The area with the second highest concentration of dairy cows is upper Norrland (23 cows per 100 ha) (Statistics Sweden, 1996a).

In Table 3, the amount of feeding stuffs in purchased feeding mixes for different kind of animals produced in Sweden 1994 is presented.

98 Table 3. The amount of feeding stuffs in purchased feed mixes for different kind of animals produced in Sweden 1994 in thousands of tonnes (from Statistics Sweden, 1996a). Cows Pigs Poultry

Oat and barley 109.3 139.3 95.3

Rye and wheat 107.4 111.9 188.3

Other grains 48.8 61.4 33.6

Protein feeds, mineral feeds and other feeds 841.1 334 200.7 Total 1106.6 646.6 517.9

From the total amount of purchased feed mixes produced (Table 3), the regional distribution of animals (Table 2), the content of Cd in purchased feed mixes produced (Table 1), and the total areas used for crop production in the individual production areas (see Table 6 in the main report), the influx of Cd per ha in the different production areas from purchased feeds can be calculated. The results are presented in Table 4. In the table, the contribution from grains in the produced feed mixes is excluded.

It should be noted that the data does not perfectly match each other in time. The amount of feeding stuffs are given for 1994, the content of Cd is from the production of feeding stuffs in the winter 1996/97, while the rest of the data concerns the conditions in 1995.

The weak point in the calculations providing the results in Table 4 is the uncertainty about to what degree mineral feeds are included in the values of Cd in feeds (Table 2). The average contribution from feeds bought by the farm in Table 4 is only about 15 % of the value used by Andersson (1992). The latter value is calculated as the difference between amount of Cd in crops, and the amount of Cd in manure (from Andersson, 1977b).

In Anonymous (1988) the Cd content in feed mixes for pigs and cattle was analysed. The levels were 3.7 and 3.5 times higher respectively, than the ones found by Larsson (1997) for the same type of feed mixes. This indicates that the levels of Cd in purchased feeds might have decreased by a factor of 3 to 4 from 1988 to 1997.

99 The time trends for the fluxes of Cd to land from commercial fertilizers and atmospheric deposition is strongly decreasing. If the same trend is relevant for Cd in total feeds, the results in Table 4 are reasonable. The flux to Finnish soils through manure is 0.13 g Cd per ha and year (Makela-Kurtto, 1995). The average influx to Danish soils from manure and sewage sludge is about 0.1 g per ha and year (from Jensen & Markussen, 1993, referred by Landner et al., 1996). This indicates that the net contribution from feeds found in Table 4 is not unrealistic.

Table 4. Regional, annual influxes of Cd to arable land through purchased feed mixes in Sweden Influx of Cd through purchasedfeeds, excl. grains, kg per year Fatte Laying Production area Dairy Sows ning hens and Total, cows pigs chickens g/ha 1. Plain districts, - S. Gotaland 5.7 2.4 4.3 1.4 0.05 2. South east - Gotaland 14.3 1.7 2.9 4.0 0.08 3. Plain districts, - N. Gotaland 10.9 1.7 2.7 1.4 0.04 4. Plain districts, - Svealand 12.8 1.3 1.8 1.1 0.03 5. Forest districts, - Gotaland 29.4 1.6 1.8 2.1 0.07 6. Forest districts, - central Sweden 6.6 0.2 0.2 0.1 0.04 7. Lower parts of - Norrland 7.2 0.2 0.2 0.02 0.05 8. Upper parts of - Norrland 5.7 0.2 0.3 0.05 0.06 Total 92.5 9.1 14.3 10.0 0.05

Note. It is assumed that laying hens and fattening chickens consume the same amount of purchased feeds.

100 2. Efflux of Cd with crops

2.1. Regional variation in Swedish crop production

In Table 5, the regional distribution of the main kinds of crops is shown.

Table 5. Regional distribution of main kinds of crops in Sweden 1995 (from Statistics Sweden, 1996a) Fraction of total production in Sweden Co- Olei- Grass Pota- Sugar Production area Bread grain arse ferous & pa- toes beets grain plants store 1. Plain districts, - S. Gotaland 0.29 0.17 0.38 0.04 0.30 0.70 2. South east - Gotaland 0.11 0.12 0.19 0.11 0.45 0.29 3. Plain districts, - N. Gotaland 0.34 0.18 0.20 0.09 0.15 0.01 4. Plain districts, - Svealand 0.21 0.29 0.17 0.15 0.00 0.00 5. Forest districts, - Gotaland 0.04 0.14 0.04 0.31 0.00 0.00 6. Forest districts, - central Sweden 0.01 0.06 0.02 0.10 0.03 0.00 7. Lower parts of - Norrland 0.00 0.03 0.00 0.11 0.04 0.00 8. Upper parts of 0.00 - Norrland 0.00 0.02 0.00 0.09 0.03 Total in million kg 1 784 3 086 197 5 650 1 022 2 508

101 The following main observations can be made:

The plain districts in the south of Gotaland accommodate 13 % of the total arable land used for crop production. The share of dairy cows is only 6 % of the total, while the region has as much as 27 % of the sows, and 30 % of the fattening pigs. The crop production is heavily focused on cash crops, such as bread grain, oleiferous plants, potatoes and sugar beets. The share of grass and pasture is about three times less in relation to the total area of arable land, compared with the average of Sweden. This implies that this region produces crops which export Cd from the soils in the region. It also implies that a farming system dominates, which decreases the organic matter in the soil to relatively low levels.

The plain districts in the north of Gotaland and in Svealand are directed to grain production, while the grass production in relative terms is smaller, compared, with the average of Sweden. The animal production such as dairy cows, sows, and fattening pigs, is in relative terms small in the plain distr icts in Svealand. In the plain districts in the north of Gotaland, the relative size of the animal production agrees comparably well with the relative size of the crop area in the region.

The forest districts in Gotaland are specialised in dairy and grass produc tion. The share of the total Swedish production of bread grain and oleiferous plants is small.

The remaining areas, the forest areas in central Sweden and the rest of Norrland, are specialised in dairy and grass production. The production of coarse grains is in relative terms of low and decreasing importance the farther to the north in Sweden the farms are located.

In Table 6, the results from a calculation of the amount of coarse grains produced in the different regions, which are used in the animal production in the production region in question, are given.

In Table 6, forest areas in Gotaland, and the upper parts of Norrland, have values higher than one. This indicates that these areas import grains; the consumption is greater than the production. Lower parts of Norrland is also close to one. Surprising is that the forest districts of central Sweden seems to be the district which in relative terms export most of the grain produced. One explanation for this result is that its share of sows and fattening pigs in relative terms is very small.

102 These categories of animals are huge consumers of grain, thus the results indicate that the exportation of coarse grain from these districts to the pig producing areas in relative terms is an important part of the agriculture in the forest districts of central Sweden.

Table 6. Regional variation in the part of grains producedfor feeding 1995, used within the region Production area Part of produced grains for feeding consumed within the area 1. Plain districts, S. Gotaland 0.67

2. South east Gotaland 0.94

3. Plain districts, N. Gotaland 0.54

4. Plain districts, Svealand 0.29

5. Forest districts, Gotaland 1.07

6. Forest districts, central Sweden 0.46

7. Lower parts of Norrland 0.98

8. Upper parts of Norrland 1.32

Sweden 0.63

Notes. It is assumed that: One dairy cow producing 7 020 kg milk delivered to the dairy, with the average fat and protein content of Swedish cows, including recruitment heifer, consumes 1596 kg grain per year (Hellstrand, 1996).

One sow, including 21 piglets is assumed to consume 1 663 kg grain annually (from Hellstrand, 1997, based on the production branch calculi from the Swedish University of Agricultural Sciences).

One fattening pig (from 25 kg weight to slaughter), is assumed to consume 198 kg grain (ibid.).

103 The amount of grain consumed by laying hens and broilers, is assumed to equal the amount of grain in purchased feeds to poultry 1994 (Statistics Sweden, 1996a).

The amount of bread grains, actually used in purchased feed mixes 1994 (ibid.), is included in grains for feeding. According to the table, only 63 % of the grains produced for feeding in Sweden is actually consumed. The exports of coarse grain harvested 1995 was 361 million kg (the Swedish Board of Agriculture, 1996).

The feeds needed by the meat-race cows, and by the steers from the dairy cows, is not considered in the amount of grain to animals in the table. Correcting for the number of cattle actually slaughtered 1995 (542 271), and their average carcass weight (279.5 kg, and 109.2 kg respectively for older cattle, and greater calves) (Statistics Sweden, 1996a), assuming an average amount of metabolizable energy per kg carcass growth of 150 MJ, and using the energy content of a fifty-fifty mix of oat and barley, increases the amount of grain consumed with 319 million kg. Thus, 82 % of the grains produced for animal feeds, is tracked. As the information about their regional distributions is unclear, they were not considered in the calcu lations. In rough terms, also about 200 000 horses consume grains. By the same reason, their regional distribution was not considered.

Considering the size of the amount of grain for feeding not included in the table in comparison with the total production of grain for feeding, and the consumption of grain for feeding considered in the table, the calculations are judged to agree well with the real consumption of grain by different kinds of domestic animals. 2.2. Variation in Cd content between crops and varieties

Table 7. Content of Cd in agricultural products in Sweden in mg per kg dry weight Crop/product Mean Min-max n Reference Winter wheat 53 14-149 121 (1) 43 8-207 197 (2) Rye 16 10 (3) 42 (4) Spring wheat 69 14-163 43 (5) Winter barley 24 (6) Spring barley 24 (7) Oat, mineral soils 36 8-108 182 (1) Oat, organic soils 49 9-115 17 (1) Mixed coarse grain 30 (8) Rye-wheat 46 (9) Oils-seeds 82 (7 ) Ley 60 (7 ) Pasture 60 (10) Potato 53 7-194 69 (5) 80 (7) Sugar beets 167 (7 ) Carrot 276 62-873 36 (5)

Sources: (1) Eriksson (1990a). (2) Eriksson & Soderstrom (1996). (3) Ostreus (1993), referred by Obom (1995). (4) Calculated as 68 % of the content of w. wheat. The motive is that in Jorhem & Sundstrom (1993), and also in Jorhem et al. (1984), the content of Cd in rye flour is 68 % of the one in wheat flour. (5) Obom et al. (1995). (6) Assumed to be equal to spring barley. (7) Andersson (1992). (8) Average of oat and spring barley. (9) Assumed to be equal to the average of rye and winter wheat. (10) Assumed to be equal to ley for cutting. The averages given with bold letters are the ones used in the subsequent analysis of the Cd-balance in the different Swedish production regions.

105 It should be noted when reading Table 7, that the primary objective of the studies providing the results, was not always to get the best possible estimate of the mean content of Cd in agricultural products produced in Sweden 2-

Thus, the results must be interpreted with common sense. When different values have been available, the ones used by Andersson (1992) have often been chosen. One reason for this is that the values here are used to estimate influxes and effluxes of Cd to and from arable land in the different produc tion areas in Sweden. Andersson has already performed such an analysis. By using the same values as far as reasonable, comparisons are facilitated.

• Carrots had the by far highest content of Cd per kg (276), measured on a dry matter basis, followed by sugar beets. Potatoes, winter wheat and spring wheat had the highest mean content after carrots. Oat grown on organic soils came next. The value for rye from Ostreus (1993), referred by Obom (1995), seems too low to be a good estimate of the mean for all rye produced in Sweden, as it is lower than the average for rye flour found by Jorhem & Sundstrom (1993). Thus a value is calculated from the level of Cd in winter wheat grain, and the relation between the levels in flour of wheat and rye. This value is used in the subsequent calcu lations of flows of Cd.

There are not only differences between crops. Eriksson (1990a) analysed the content of Cd in grain for different varieties of oat and winter wheat grown on the same places. The mean value for the oat variety Sang (51 mg per kg dw) was twice the one of Svea (25), and a little more than twice the one of Vital (22).

2The sampling strategies were different in the different studies. For winter wheat, the frequency of samples for different sub-areas was proportional to the share of the total area of winter wheat grown in Sweden (or Sk&ne) of the sub-area in question. The frequency of the samples of oat for different sub-areas was proportional to the share of the total area of arable land in Sweden, of the sub-area in question. In the carrot study, the strategy was to cover the most important production areas. How the samples were distributed within these production areas is unclear. Spring wheat and potatoes were sampled in order to cover a wide range of soil types with respect to pH, texture as well as contents of organic matter and trace elements within some regions (Eriksson et al., 1996).

106 The mean values from the countrywide sampling of Pol and Veli, two varieties used in the northern parts of Sweden, were between 45 and 50 mg per kg dw, while the mean for the more southern-grown varieties were between 25 and 35.

However, when the samples were analysed where the varieties were grown on the same places, it was shown that the higher values for Veli and Pol, probably were not genetically caused but caused by environmental differences between the areas where the different varieties were used. Pol and Veli had about the same average, where they were grown on the same places, and Veli and Svea had the same content, where they were grown together.

The results from a corresponding study of varieties of winter wheat, gave very similar levels of Cd in grain for the varieties Folke, Holme and Kosack (ibid.). Solid, which was mainly used in the very south of Sweden, seemed to have a genetically caused higher content. Pettersson (1977), referred by Eriksson (1996a), showed that the grain Cd content in Starke was 50 % higher than in Holme.

2.3. Regional variation in effluxes of Cd with crops

From the area used in crop production, the mean content of Cd in crops (Table 7), and the production of the different crops in the different production areas (Table 5), the regional variation in gross effluxes can be estimated. The regional effluxes of Cd are explicitly calculated for the following crops:

• Winter wheat, • Spring wheat, • Rye, • Winter barley, • Spring barley, • Oat, • Rye-wheat, • Mixed grains, • Winter rape, • Spring rape, • Winter turnip rape, • Spring turnip rape, • Grass for hey and silage, • Pasture,

107 • Potatoes, and • Sugar beets.

The effluxes with leguminous plants were not considered, as the production area was only ca 12 000 ha in 1995 (Statistics Sweden, 1996a). When calcu lating the effluxes of Cd per ha, the amount of Cd in total crops is divided with the total area for the production of the crops mentioned above. Thus, e.g., the area for fallow fields, and for leguminous plants is not included in the division.

In Table 8, the gross effluxes from the fields through crops in different production areas are shown. "Gross" implies that all Cd leaving the field, is included, also the fraction in ley and pasture. The removal of Cd through pasture only results in an elevation by one meter, before the main part of the Cd in pasture, after the passage through the cow’s digestive system, is relea sed to the field again. In Table 8, Cd in pasture, ley and grains fed on the farm and/or in the region is considered, the difference between them is that they participate in recycling loops on different system levels; pasture: field — cow— field; ley: field — silage silos — cowshed — field; bread grain: field — consumer — field. Another difference is that the degree of closure differs between the loops.

Table 8. Gross effluxes of Cd from the field in different production areas in Sweden in 1995, including all Cd in pasture, ley, and grain fed on the farm and/or in the region Effluxes of Cdfrom arable land Production area Kg g/ha 1. Plain districts, S. Gotaland 131 0.43 2. South east Gotaland 90 0.31 3. Plain districts, N. Gotaland 79 0.21 4. Plain districts, Svealand 87 0.18 5. Forest districts, Gotaland 102 0.21 6. Forest districts, central 34 0.20 Sweden 7. Lower parts of Norrland 35 0.23 8. Upper parts of Norrland 26 0.24 Sweden 584 0.25

Note. Basic source is Statistics Sweden, 1996a).

108 The effluxes per ha are highest in the plain districts in southern Gotaland. The calculations underpinning the results shown in the tables, have a higher degree of resolution, than the results given. These calculations show that with the mean contents of Cd assumed, most Cd is removed from the fields in grass for hey and silage (about 230 kg per year). In order after grass come sugar beets (100 kg), winter wheat (70 kg), pasture (60 kg), and spring barley and oat, with about 30 kg each.

In Table 9, the net effluxes of Cd from arable land via crops in the produc tion areas are shown, after, first, omitting the fraction from grass and pas ture, and second, the fraction from grain fed to domestic animals within the production area.

Table 9. Net effluxes of Cd from arable land through crops in different regions in 1995 Net effluxes of Cd from arable land, g/ha Production area Excluding grass Excluding grass, & pasture pasture and grain fed in region fed in region 1. Plain districts, S. Gotaland 0.39 0.34 2. South east Gotaland 0.20 0.16 3. Plain districts, N. Gotaland 0.14 0.10 4. Plain districts, Svealand 0.09 0.07 5. Forest districts, Gotaland 0.03 0.01 6. Forest districts, central 0.04 0.02 Sweden 7. Lower parts of Norrland 0.02 0.00 8. Upper parts of Norrland 0.02 0.00 Sweden 0.13 0.10

Notes. Net effluxes imply the gross efflux of Cd from fields in Table 8, subtracted with the amount of Cd participating in loops within the agricultural system in the region in the form of Cd in pasture and ley fed the domestic animals, and in the form of Cd in grains, fed the domestic animals in the region. Grain in purchased feed mixes used is included in the amount of grain fed domestic animals, when the net effluxes is calculated, where grain used as feed is omitted. The main difference between the gross effluxes and the net effluxes, is the impact of grass and pasture, and thus of milk production on the results. In the regions, where dairy production in relative terms is intensive, the net effluxes are about 0.2 g per ha less, than the gross effluxes through crops. In south east Gotaland, the difference is a little smaller, which is explained by the fact that in this area the production of crops exported from the farms also is important.

110 Appendix 2.

1. Cadmium content in food

The most recent study of Cd in foodstuffs in Sweden was carried out by Jorhem and Sundstrom (1993) In Table 1, some of their results are shown.

Ill Table 1. Cadmium content in various types of foodstuffs in milligrams per kilogram fresh-weight (from Jorhem and Sundstrom, 1993) Product Mean Std. dev. Min Max n Beef 0.001 0.001 <0.001 0.003 34 Cattle liver 0.070 0.051 0.001 0.20 33 Cattle kidney 0.35 0.58 0.023 6.4 187 Pork 0.001 0.004 <0.001 0.049 426 Pig liver 0.019 0.010 0.001 0.094 426 Pig kidney 0.11 0.069 0.004 0.88 893 Arctic char 0.002 0.002 0.001 0.005 3 Baltic herring 0.008 0.011 0.002 0.030 6 Cod <0.001 0.001 <0.001 0.002 5 Hake Chilean <0.001 1 Kingklip red 0.008 1 Mackerel Atlantic 0.002 1 Perch 0.002 0.001 <0.001 0.004 8 Pike 0.002 0.002 <0.001 0.012 47 Pike-perch 0.002 0.003 <0.001 0.006 3 Trout <0.001 0.001 <0.001 0.003 13 White fish 0.004 0.005 <0.001 0.013 6 Apples <0.001 0.000 <0.001 0.001 6 Bananas <0.001 <0.001 <0.001 3 Blueberries 0.002 0.002 <0.001 0.006 13 Black currants 0.001 0.001 <0.001 0.002 13 Cloudberries 0.064 0.056 0.072 2 Lingonberries 0.002 0.002 <0.001 0.006 13 Pears 0.006 0.002 0.004 0.008 3 Raspberries 0.007 0.007 <0.001 0.018 6 Strawberries 0.008 0.009 <0.001 0.030 10 Mushroom Agaricus hort. 0.012 0.010 0.013 2 Cabbage Chinese 0.017 0.012 0.026 2 Carrots 0.022 0.017 0.004 0.048 6 Green beans 0.002 0.001 0.003 2 Lettuce 0.008 0.004 0.002 0.018 8 Green beas 0.003 0.002 0.001 0.004 3 Potatoes 0.017 0.014 0.008 0.046 8 Tomatoes 0.002 0.001 0.004 2 Alfalfa seeds 0.036 0.007 0.065 2 Brown beans 0.006 0.005 0.007 2 Soya beans 0.063 0.058 0.067 2 Green lentils 0.002 1 Linseeds 0.42 1 Chick peas 0.002 0.001 0.002 2 Yellow peas dried 0.012 0.011 0.012 2 Poppy seeds blue 0.84 0.70 0.98 2 Poppy seeds white 0.038 0.032 0.044 2 Sunflower seeds peeled 0.38 0.10 0.24 0.56 8 Buckwheat 0.046 0.046 0.047 2 Rye flour 0.017 0.006 0.008 0.036 48 Wheat bran 0.13 0.052 0.076 0.25 16 Wheat flour extracted 0.025 0.009 0.014 0.047 55 Milk chocolate 0.003 1 Dark chocolate 0.15 1 Icecream vanilla <0.001 <0.001 <0.001 5 Sugar white 0.001 0.001 <0.001 0.002 5 Note, n, number of samples.

112 In Table 2 some values from the study of Jorhem et al. (1984) for foodstuffs not considered by Jorhem and Sundstrom (1993) are shown.

Table 2. Cadmium content in mg/kg fresh weight for some foodstuffs on the Swedish market (Jorhem et al, 1984) Product Mean Min Max n Hare kidney 0.34 i Hare meat 0.001 i Lamb kidney 0.94 0.10 2.3 4 Moose kidney 2.3 0.18 13 69 Moose calf kidney 0.45 0.18 0.81 16 Moose liver 0.41 0.067 2.4 79 Moose calf liver 0.15 0.067 0.23 18 Moose meat, round 0.003 0.001 0.011 9 Reindeer liver 0.28 0.14 0.51 13 Roedeer kidney 6.9 4.8 9.0 2 Roedeer liver 0.37 0.14 0.87 6 Venison 0.002 0.001 0.002 2 Chicken breast 0.002 0.001 0.004 10 Chicken liver 0.018 0.006 0.050 8 Hen breast 0.003 0.002 0.006 6 Hen liver 0.13 0.085 0.19 4 Crab, white meat 0.081 0.012 0.26 15 Crab, liver 15 1.5 32 16 Crab, remaining edible parts 2.6 0.32 5.8 16 Crab meat, canned 0.051 0.016 0.098 6 Crayfish, freshwater, white meat 0.060 0.004 0.16 5 Crayfish, freshwater, liver 0.32 0.17 0.47 4 Crayfish, freshwater, roe 0.15 1 Eel 0.027 0.014 0.042 3 Lobster, white meat 0.16 0.10 0.23 3 Lobster, liver 3.6 2.6 4.4 3 Lobster, meat, canned 0.042 1 Mussels 0.016 0.069 0.26 37 Mussels in water, canned 0.14 0.10 0.23 8 Oysters 0.77 0.50 1.0 6 Oysters in water, canned 0.32 1 Prawns/shrimps, white meat 0.079 0.039 0.11 8 Prawns/shrimps, liver 4.0 1.9 5.7 6 Prawns/shrimps, roe 0.067 0.034 Oil 6 Prawns/shrimps, canned 0.028 0.007 0.064 5 Sardines in oil, canned 0.011 0.005 0.018 6 Sardines in tomato sauce, canned 0.013 0.006 0.022 28 Tuna in oil, canned 0.014 0.006 0.037 15 Tuna in water, canned 0.015 0.011 0.026 7 Barley flour 0.017 0.008 0.026 2 Barley, pearled 0.016 0.012 0.019 2 Oats, rolled 0.031 0.004 0.050 6

113 KEMI REPORT SERIES

5/88 Flotation chemicals from ore 1987 dressing plants (in Swedish)

1/87 Supervision project - part I 6/88 Environmental effects of orga- Monitoring of chemical product notin in antifouling paints information from 86 companies (in Swedish) (English summary) 7/88 1-4 -dichlorobenzene 2187 Formaldehyde - a hazard anal (in Swedish) ysis (English summary) 8/88 The use of OSAR for chemicals 3/87 Classification and labelling of screening (in English) preparations containing carcinogenic substances 9/88 Initial assessment of the envir Reportf rom a Nordic working group onmental hazard of chemical (in Swedish) substances An evaluation of the "ESTHER 4/87 Analysis of tris (1,3 -dichloro- manual" (English summary) propyQphosphate in products and human blood 10/88 Effect catalysis (in Swedish) A concept for assessment of the environmental risk of chemicals 5/87 A strategy for ranking chemi (in Swedish) cals for biological testing (in English) 11/88 Introduction into genetic toxi cology 6/87 Applied toxicology A background document for Some basic views (in Swedish) assessment of the genotoxicity of chemicals (in Swedish) 7/87 Environmental effects of ma rine antifouling paints Survey by the laboratory section 1989 for aquatic toxicology withinthe 1/89 Trimellitic anhydride (TMA) National Environmental Protec A hazard analysis tion Board (in Swedish) (in English) 1988 2/89 Benzene and total hydrocar bon exposure during petrol 1/88 Methyl-tert-butylether filling of private automobiles A bibliography (in Swedish) (in Swedish) 2/88 Biological control of pest and pb 3/89 The algal microtest battery seases on agriculture and A manual for routine tests of horticultural crops in Sweden (English summary) growth inhibition (in English) 4/89 Systems for testing and haz 3/88 Formaldehyde emission from ard evaluation of chemicals furniture in the aquatic environment A critical review (in Swedish) A manual for an initial assess ment - ESTHER (in English) 4/88 Fluxing agents (in Swedish) 5/89 Methods to quantify the toxi 6/90 Cadmium city and hazard of insecti An Analysis of Swedish cides to honeybees Regulatory Experience (Apis mellifera L.) (in Egnlish) (English summary) 7/90 Detergents and cleaners for 6/89 Risk assessment of air pollut domestic use (in Swedish) ants The Swedish Toxicological 8/90 Approval of pesticides Council (in Swedish) Assessments, restrictions and information (in Swedish) 7/89 Carcinogenic substances Review of the substances on 9/90 The use of chemicals in the Keml list (in Swedish) Sweden Flows, functions (applications) 8/89 Organotin in the Swedish and effects (in Swedish) aquatic environment (in English) 10/90 Environmental risk reduction A Government Commission 9/89 Comparison of different Report models for environmental (in Swedish) hazard classification of Appendix chemicals Report on risk reduction of Chemicals 10/89 Environmental hazardous (in Swedish) substances List of examples and scientific 11/90 Non-genotoxic carcinogens documentation Report from a seminar. The Swe dish Toxicological Council 11/89 Evaluations of carcinogenic (in Swedish) substances I 12/90 Environmentally suited 1990 degreasing of motor vehicles (in Swedish) 1/90 Car cleaning products A pilot study (in Swedish) 13/90 Pattern of lead emissions in Sweden 1880 -1980 2/90 Effects on reproduction of sty (in English) rene, toluene and xylene Nordic Council of Ministers 1991 (in English) 1/91 Risk reduction of chemicals 3/90 Effects on reproduction of tri- A Government Commission and tetrach loroethylene Report Nordic Council of Ministers (in English) (in English) 2/91 Overview of allergenic sub 4/90 Use of mortality and morbi stances included in chemical dity registers for detecting products and goods chemical health hazards (in Swedish) A Seminar Report (in Swedish) 3/91 Hazard evaluations of aller 5/90 Characterization of industrial genic properties of 20 sub oils (in Swedish) stances (English summary) 4/91 Supervision project on curing 3/92 Car care products - a super resins (epoxy, isocyanates vision project and acrylates in products) Promotion of safer products (English summary) (English summary) 5/91 Brominated flame retardants 4/92 Principles for identifying (in Swedish) unacceptable pesticides (in English) 6/91 Environmental hazards of mi crobiocides in cooling water 5/92 Carcinogenic substances II (English summary) (in Swedish) 7/91 Data for assessment of health 6/92 The health risks of gasoline and environmental hazards of chemical substances (in Swedish) 7/92 Effects on reproduction of chloroform and 1,2-dibromo- 8/91 Flow analysis of metals 3-chloropropane Nordic Council of Ministers (in Swedish) (in English) 9/91 The burden of proof in toxicology 8/92 Lubricants (in English) (English summary) 10/91 Effects on reproduction on di- chloromethane, n-hexane 9/92 Cleaning stations against and 1,1,1-trichloroethane growth on pleasure boats (in English) (in Swedish) 11/91 Plasticizers 1993 A survey of plasticizers in Sweden (In Swedish) 1/93 A pilot procedure to select 12/91 The substitution principle candidate substances for under section 5 of the act on general restrictions on use chemical products (In English) (in Swedish) 2/93 Antifouling products 13/91 Limit values Pleasure boats, commercial (in Swedish) vessels, nets, fish cages and other underwater equipment 14/91 Cleaning products and skin (in English) effects (in Swedish) 3/93 Sensitizing substances 15/91 Flame retardants (in English) (in English) 4/93 The occurrence and use of chemicals in Society (English summary) 1/92 HF-90, substitution of hydrofluoric acid, - a super 5/93 Mutagenic substances vision project (English (in Swedish) summary) 6/93 Boat care products - 2/92 Printing inks a supervision project Composition, occurrance (English summary) and development (English summary) 7/93 Nickel allergy 9/94 Risk assessment of poly- Seminar Report, the Swedish brominated diphenyl ethers Toxicological Council (in English) (English summary) 10/94 Chemical substances lists 8/93 Databases containing A Guide to the lists used in ecotoxicological facts the Swedish Sunset project (in Swedish) Supplement to report 13/94 (in English) 9/93 Gallium, germanium and indium - a toxicological 11/94 Mono and di-substituted survey organotins used as plastic (English summary) additives Vol. 1 Environmental hazard assess 1994 ment Vol. 2 Health hazard identification (in English) 1/94 Photochemicals - are they hazardous? 12/94 Phtalatic acid esters used as A supervision project plastic additives (English summary) Vol. 1 Ecotoxicological risk assess ment 2/94 Mapping of the chemical and Vol. 2 Comparisions of toxicological toxicological knowledge of effects producers and importers of (in English) chemcial products (English summary) 13/94 Selecting multiproblem chemicals for risk reduction 3/94 Some uses of lead and their A presentation of the Swedish possible substitutes Sunset Project (in English) (in English) 4/94 Supervision of suppliers of 14/94 Seminar on international chemicals aspects on risk assessment (In Swedish) Seminar report the Swedish Toxicological 5/94 Detergent and cleaning Council products (in English) A report of the work of a Governmental Commission 15/94 Chlorine and chlorinated (English summary) compounds A report of the work of a 6/94 New ruts governmental commission - A product study of tyres (English summary) (English summary) 16/94 Chlorine and chlorinated 7/94 Use reduction of compounds in Sweden trichloroethylene for (in Swedish) industrial degreasing (In Swedish) 17/94 Chlorine and chlorinated Mona Olsson Oberg substances in Sweden (English summary) 8/94 Phasing out lead and mercury (in English) 1995 11/95 Risk assessment and risk management in chemicals control 1/95 Chlorine and chlorine compounds 12/95 Hazard assessments Report on a Governmental -Chemical substances assignment selected in the Swedish (in English), Swedish version Sunset project - 15/94 Supplement to Keml report 13/94

2/95 A priority setting scheme 13/95 Natural environment and for scoring hazardous health properties -how to improve exposure Supplement to report 13/94 analysis? (in English) Toxicological Council (in Swedish) 3/95 Chlorine compounds in chemical products 14/95 Chromium and nickel in -description and selection for Sweden furtherinvestigation Viveka Palm, Bo Bergback (in English) and Per Ostlund (in English 4/95 Tumour promotion 15/95 Plastics additives - studies with pesticides -final report from the Plastic (in English) additives project (summary in English) 5/95 Chlorine and chlorinated compounds in Sweden 16/95 The flame retardants project (in English), Swedish version Final report 16/94 (in Swedish), English version 5/96 6/95 An Introduction to Health Risk Assessment of 1996 Chemicals Marie Haag Gronlund 1/96 Endocrine effects of (in English) chemicals Toxicological Council 7/95 Car wash products (in Swedish) - a supervesion project. Promotion of environmental 2/96 One shade greener information (in Swedish) (summary in English) 3/96 Overview of the chemical 8/95 Car care products and toxicological knowledge - development and incidence and competence of (summary in English) manufacturers and import ers of chemical 9/95 Risk assessment of products in 1995 slimicides (summary in English) Ulf Eriksson, Anders Johnson, Monica Tomlund

10/95 Cadmium and its health risks Toxicological Council (in Swedish) 4/96 Alternatives to persistent 5/97 Chemicals in textiles organic pollutants Report of a Government The Swedish input to the IFCS Commission expert meeting on persistent (in English, Swedish version organic pollutants in Manila, 2/97) the Philippines, 17-19 June 1996 6/97 The Phase-Out Project (in English) Report of a government commission 5/96 The flame retardants project (in Swedish) Final report (in English), Swedish 16/95 7/97 Nickel in hand-tools Study to assess the risk of 6/96 Additives in PVC allergy Labelling of PVC (in Swedish) A report of the work of a Governmental Commission 8/97 Hollow Product Information (English summary) on Tooth Filling - an inspection project 7/96 Fargleverantdrer bekanner farg (in Swedish) Tillsynsprojekt farger Johan Hakans 9/97 POPs Karin Rumar - persistent organic pollutants in the environment, 8/96 Behavioural toxicology - to measure effects of Toxicological Council environmental toxins (in Swedish) Toxicological Council (in Swedish) 10/97 Mercury in products - a source of transboundary 1997 pollutant transport 1/97 Hormonal effect from (in English) chemicals - summing upp the state-of- the-art (in Swedish)

2/97 Chemicals in textiles Report of a Government Commission (in Swedish, English version 5/97) 3/97 Acute poisonings with pesticides - a comparative study at the Swedish Poisons Information (in Swedish)

4/97 Additives in PVC Marking of PVC Report of a Government Commission (in English, Swedish version 6/96)