BALWOIS 2004 Ohrid, FY Republic of Macedonia, 25-29 May 2004

Mining Activities And Heavy Metal River Pollution In The Apuseni Mountains,

Mihaela Serban, Dan Balteanu Institute of Geography Bucharest, Romania Mark G. Macklin, Paul A. Brewer, Graham Bird Institute of Geography and Earth Sciences, University of Wales Aberystwyth, Ceredigion, UK

Abstract The mining activities in the Apuseni Mts., Romania date as far back as Roman times. There are several stages in the mining evolution in what regards human impact on the environment with different intensities and developments. The most affected environmental component, both in terms of quantity and quality, by metal mining is the water. In the Apuseni Mts., there are several categories of river basin systems grouped upon mining activities impact: systems with historical mining activity, present, active or inactive; systems where tailings dam accidents took place causing casualties ( catchment); systems where new mining sites are to be opened. The rivers that drain the mining sites in the Apuseni Mts. are the Crisuri/Tisa and Mures/Tisa river basins, and the potential accidents and accidental pollutions have large implications in transboundary river pollution. The paper analyses the heavy metal concentrations (Pb, Zn, Cu, Cd) in surface waters and river and floodplain sediments, their downstream dispersion and transboundary effects. The metal levels in the Apuseni Mts. rivers are assessed to those found in other mining affected river systems in Romania. Key words: metal mining, Apuseni Mountains, tailings dam failures, river pollution

Introduction The Apuseni Mountains are the most extended and highest sector of the Western Carpathians, being limited in south by the Mures transversal corridor and in north by the Barcau and Somes valleys. They feature a great lithological diversity, being the place where all the main rock categories are met: metamorphic rocks (characteristic of large watersheds and deep narrow valleys); volcanic rocks (of Neogene eruptions) and sedimentary rocks. The Apuseni Mountains hold a great variety of ground resources (non-ferrous, gold-silver and mixed ores), some of them having been exploited constantly since antiquity, fact that testifies the ancient and intense humanisation process in this Romanian Carpathian space. Mining is a traditional activity in the Apuseni Mountains, thus its impact on the environment had different intensities over time. There are 4 metalogenetic subprovinces in the Apuseni Mountains, separated upon their genesis and ore type (Popescu, 2003): the northern part of the Apuseni Mountains; the Mezozoic magmatite; the one associated with the Paleogene magmatism and the Neogene subprovince. Neogene is the most important period for ore forming being well extended in the southeastern part of the Apuseni Mountains (the Metaliferi Mountains). Here one might distinguish several districts that shape the “golden quadrilateral”: Brad-Sacaramb, -Stanija, Rosia Montana-Bucium as well as single fields at Baia de Aries and Deva (Fig. 1). The ores’ space distribution was infuenced by the faults system, which imposed the placement of the volcanic units. The Neogene metalogenesis has been explained by the tectonics concept, the Neogene volcanism being directly connected with the subduction processes. Presently, in the Apuseni Mountains, there are 7 active mines, belonging to the Minvest Deva Company, and administrating 73 waste dumps of 243 ha and 48 tailings dams, of which 18 under conservation and 5 held in reserve, covering an area of more than 1 000 ha (Fodor, Baican, 2001). The waste dumps and tailings dam have a direct impact on the river system, groundwaters, soils, vegetation and fauna.

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Figure 1 Distribution of mineral substances in the Apuseni Mountains in relation with the main faults

One of the most important problems related to these dumps is their stability. So far now, 75 accidents related to tailings dam failures have been recorded world-wide, 7 of them in the last 4 years alone, many resulting in casualties and great damage for the environment (Diehl, 2003). In Romania three such accidents occurred, too: a very severe one in 1971, on the Certej River (one of the River Mures tributaries) causing more than 90 deaths. The most recent accidents happenned in 2000 in Maramures County at two tailings dams (Brewer et al., 2002; Macklin et al., 2003; Bird et al., 2003). These accidents and mining affected rivers from Romania were investigated in order to assess their long-term impact (Brewer et al., 2002; Macklin et al., 2003; Bird et al., 2003). This paper is a synthesis of the results obtained in the mining affected areas, in the Apuseni Mountains, carried out by researchers from the University of Wales, UK and the Institute of Geography, Romanian Academy. The aim of the investigation was to assess the magnitude and spatial extent of metal contamination in river systems affected by metal mining activity in the Mures drainage basin (Aries, , Cris and Certej tributaries) and to relate pollution patterns to other Romanian river basins affected by mining. Further more, 3 of the mining exploitation in the Apuseni Mountains are included into major risk category, according to the Directive 96/82/CE Seveso II on the control of major accidents involving hazardous substances. The last two accidents that occurred on the Romanian territory amended the European Directive, including the mining industry activities to accidents involving hazardous substances.

Main river systems and heavy metal pollution The drainage rivers of the Apuseni Mountains and of the mining exploitation space are tributary to the Mureş River (the Aries, Ampoi and Certej rivers) and to Tisa River (the three Cris rivers). The Aries River is the most important right side tributary of the Mures River, being 164 km long and extended over 3 005 sq.km. Hydrologically, it is the most important water resource in the Apuseni Mountains. Its multiannual average discharge is of 19 m3/s at Baia de Aries and 25.5 m3/s at its mouths. Its main tributaries have relatively slow average multiannual discharges: the Abrud River, where Rosia Montană and Bucium-Izbita mines are located, has a 1.5 m3/s multiannual discharge.

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The Aries River Basin holds the richest metal potential stoked in 20 ore sites, the most important being at Rosia Montana and Rosia Poieni (Popescu et al., 1995). Rosia Poieni is the largest copper quarry in Europe having an opening larger than 1 km in its upper part and 800 m to the level where the ore was found. There are 4 important active mines in the Aries River Basin: Rosia Montana, Abrud, Baia de Aries and Iara. During 1997-2002, 28 accidental pollution events happened at those exploitation units, consisting in damages at the waste transport bands towards the tailings dam or towards the mechanical-chemical treatment stations, particular at Valea Sesei tailings dam (EM Abrud) (Batinas, 2003). The Ampoi River, the Mures River right-side tributary, is 60 km long and has a realtively slow discharge (4.22 m3/s at the confluence). A large metallugic plant is located at Zlatna, on the Ampoi River, and a connected chemical unit. The Certej River is one of the small river (18 km long, 78 sq. km river basin surface area) with 2 mining exploitations, Săcărâmb and Sohodol. Presently, the Coranda quarry is active and the waste is deposited at Mialu tailings dam. Close to this, there is a tailing dam under conservation (Valea Miresului) and another one where a major accident happened in 1979 (within the area of locality). The western side of the Apuseni Mountains is drained by the Crisul Repede, Crisul Alb and Crisul Negru rivers. Mining activities are concentrated in the upper river basins (Brad, on Crisul Alb River and on Crisul Baita River, a tributary of the Crisul Negru River). There are 10 ores, economically important, out of which two are active. In the Crisul Negru basin 7 ore deposits are significant, some of them being exploited for the polimetaliic potential. The mining activity induced pollution lasts for a long time in the river basins. Often one sees that the environment problems no longer exist once the mining activity is ceased. But, the abandoned mining sites might release large waste amounts with a high metal content, which could be reintroduced into the river through drainage or rain off. This is the reason for which the abandoned sites are potential sources for large-scale river pollution. Heavy metals are not biodegradable, being deposited in different components aquatic ecosystems (water, river and floodplain sediments, soils and organisms). Under certain conditions (changes in the chemical river composition, in the erosion and accumulation processes, in the river bed shape due to global environmental change), they might be mobilised and reach the rivers again (secondary pollution). This is why, the assessment of heavy metal river pollution is an important factor in water resources analyses and in the rehabilitation and management of long-term affected rivers. The main source of heavy metal river contamination is industrial and municipal wastewaters and the waters that drain the mining sites. It might be considered a secondary pollution, which occur through the reintroduction of old polluted sediments into rivers. In this respect, the river characteristics play a fundamental role, referring particularly to transport capacity, river bed dynamics, sediments shape and size and hydrological regime. When transported, metal associated sediments, which are deposited in floodplain and river ecosystems, are the last metal reservoir of a river basin and could last in these deposits for years, centuries or even millenia, until they are remobilised through physical, chemical or biological processes (Hudson-Edwards et al., 2001). The environmental changes have a strong influence upon the river dynamics, leading to river instability, and thus to changes in the erosion, transport and accumulation processes, in the sediments dynamic, heavy metal transport and geographical distribution throughout the river basin (Macklin, 1996).

Environmental impacts. A historical perspective There are several stages in Romanian mining history, which differ in what regards the extractive techniques and the quantity of extracted ores. A first phase is known in the Daco-Roman antiquity, when mines were exploited in the Apuseni Mountains. The methods of collecting the precious metals from the rivers were quite rudimentary (by pestling or stamping). The Romans brought new technologies of extracting and processing metals straight from the ores through galleries. This practice continued up to 16th-17th centuries. Reservoirs were built in the upper part of the river basins to store the water needed for the exploitation process. Historical documents say that during Roman times 720,000 kg of silver and 1,345,000 kg of gold were extracted from the Apuseni Mountains mines alone (Haiduc, 1940). After the Romans’ withdrawal from Dacia, the mining activity slowed down, yet without ceasing altogether. In the Middle Ages, German miners were brought into and colonized in a few

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gold-rich localities (e.g. Abrud). As from the year 1000, the mines of the Apuseni Mountains, being systematically operated. Apart from gold and silver, complex ores were exploited as well as copper, lead and zinc. Also, the extraction techniques were improved. In the 18th-19th centuries, mines were licenced to some foreign mining companies and operated with modern technologies. The capitalist phase (mid-19th century – mid-20th century) is characterized by a strong development of the mining industry due to the improvement of exploitation and processing techniques (the invention of the steam machine, electric energy), to the emergence of big metallurgical plants and to a favorable legislation (The Mining Law adopted in 1924). Ores were exploited both by private and state companies. The socialist period (mid-20th century – 1989) witnessed an intensive ore exploitation with high extraction and production rates defying rational use. Geological R&D activities gained importance and new pits were opened (Rosia Poieni, the largest copper mine in Europe). The quantitative development implied major losses and negative impact on the environment. The wastes resulted from primary metal extraction was no longer spilled into the rivers, but deposited in dumps and tailings dams, which thus became the main sources of pollution. At present (since 1990), the mining industry has been declining considerably: under the current technical and technological conditions mines were no longer economically viable, many deposits having been exhausted in the previous period. The closed mines are not benefiting from ecological rehabilitation and conservation programmes, continuing to have a direct impact on the environment. In spite of these, some companies are still operational, new pits are going to be opened (Rosia Montana, in the Aries river basin).

Field sampling and laboratory metal analysis In July 2002-July 2003, over 300 surface and groundwater, as well as floodplain and channel sediment samples were collected from the main mining-affected rivers in the Apuseni Mountains. This paper presents the result obtained after July 2002 sampling period. Water samples were filtered through 0.45 µm filter papers and acidified with three drops of 50% nitric acid in the field, before multi-element analysis using an ICP-MS (VG Elemental Plasma Quad II+). River channel and floodplain sediment samples were collected using a stainless steel trowel from bar surfaces and river banks, respectively. Sediment samples were air dried, sieved through a 2 mm plastic mesh, digested in nitric acid and metal levels determined using AAS (Perkin-Elmer 2380). Channel sediment samples (<63 µm fraction) were subjected to a sequential extraction procedure (SEP) based on a method described by Ure et al., 2003. Metal concentrations in surface water were assessed against target and imperative values in the EC directive (75/440/EEC) required of surface water intended to be used for the abstraction of drinking water (Table 1). Metal levels in river and floodplain sediment were compared with the latest (4 February 2000) Dutch target and soil remediation intervention values (Table 2). The Dutch intervention values for soil / sediment remediation are considered to be numeric manifestations of the concentrations above which there can be said to be a case of serious contamination. These values indicate the concentration levels of metals above which the functionality of the soil for human, plant, and / or animal life may be seriously compromised or impaired. Target values indicate the level at which there is a sustainable soil quality and gives an indication of the benchmark for environmental quality in the long term on the assumption of negligible risk to the ecosystem.

Table 1: EC target and imperative values for the abstraction of surface water for drinking (75/440/EEC). Target Value Imperative value (µg/L) (µg/L) Pb ― 50 Zn 500 3,000 Cu 20 50 Cd 1 5

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Table 2: Target values and soil remediation intervention values for selected metals from the Dutch Ministry of Housing, Spatial Planning and Environment (VROM, 2001). Values have been expressed as the concentration in a standard soil (10% organic matter, 25% clay). Target Value Intervention value (mg/kg) (mg/kg) Pb 85 530 Zn 140 720 Cu 36 190 Cd 0.8 12

Tailings dam failure and heavy metal pollution The Certej catchment, a tributary of the River Mures, lies within the Metalliferous Mountains (southern part of the Apuseni Mpuntains) and contain open-cast base and precious metal mines and tailings ponds. Today, ore processing waste is stored in the Mialu tailings pond which is impounded by a 64 m tailings dam (Fig. 2). The tailings are enriched in As (370 mg/kg), Pb (3400 mg/kg) and Zn (2200 mg/kg). In 1971, a pond which was located on the hillside above the town of Certeju de Sus failed and resulted in death of more than 90 people. An investigation is presently being undertaken which is examining the long-term effects of 1971 dam failure, particularly on downstream floodplain sediment quality in the Certej valley. Initial data suggest that highest metal concentration (550 mg/kg Pb and 1000 mg/kg Zn) in surface floodplain soils (0-15 m) are found within 20 metres of the river channel.

Figure 2 Certej river basin: sample site locations and main pollution sources

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In July 2002, Cd concentrations in both surface water and river channel sediment significantly increase immediately downstream of the Coranda mine. However, Cd concentrations in water and sediments exhibit very different downstream patterns. Whilst Cd concentrations in surface water reduce with distance downstream in the Certej river from a peak concentration at 3400 µg/l at 5.2 km, concentrations of Cd in river sediment increase, peaking at 22 km downstream (Fig. 3 and Fig. 4). This suggests that there may be an exchange of metals between the solute and sediment-bound phases, which is probably related to downstream changes in the physico-chemical environment.

Figure 3 Certej River: Cd concentration in surface water

Figure 4 Certej River: Cd concentration in river sediments

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Present-day mining activity and heavy metal pollution Aries catchment has the highest metal potential from the Apuseni Mountains. There are about 20 ore deposits, the most important ones being in exploitation at Rosia Montana and Rosia Poieni (Fig. 5).

Figure 5 Aries river basin: sample site locations and main pollution sources

Downstream variations in surface water and river channel sediment Cu and Zn concentrations in the River Aries are plotted against distance downstream in Fig. 6 and Fig. 7. Despite the presence of long- established mining activity in the Aries system, particularly at Baia de Aries and Rosia Poieni, solute metal concentrations are relatively low compared to the River Sasar, and with the exception of three sites downstream of the Sartas Valley confluence, do not exceed target values at any of the sample sites.

Figure 6 Aries River: Cu concentration in surface water

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Figure 7 Aries River: Cu concentration in channel sediments

This phenomenon can be due to three factors: first, there may not be a direct hydrological coupling between mine sites and river channels in the Aries catchment; second, the large number of unmined tributary catchments in the Aries basin may deliver uncontaminated water to the river, diluting contaminants resulted from active mine sites; third, the natural buffering capacity of the local, limestone rich, geoology, which creates high pH in the River Aries system (7.3 - 8.7), will promote dissolution of solute metals, thus giving rise to low solute metal levels in the River Aries. Channel sediments are relatively more contaminated than surface waters in the Aries river, particularly for Cu and Zn wich exceed intervention values at 61 and 16 percent of sample sites. Cu and Zn concentrations increase downstream of mining-affected tributaries, suggesting their importnace as a source of metals to channel sediments in the Aries river. The presence of large-scale Cu mining at Rosia Poieni may in part account for the number of sites where Cu concentrations exceed the Dutch intervention value. Under periods of flood discharge on the River Aries, the contaminated channel sediments could be remobilised and deposited on local floodplains, ultimately being incorporated into agricultural soils and thus available for uptake by both crops and livestock. The onset of large-scale ore extraction from the Rosia Montana gold deposit could pose potentially serious problems with respect to metal contamination in the Aries-Mures system. Data collected from the River Aries has indicated that the decoupling of mining activity from river systems, in addition to a well-buffered natural environment, can help to keep solute metal levels relatively low, despite the presence of large-scale mining activity and polluted tributary streams. However, it is also apparent that channel sediments in the River Aries are often highly polluted, and highlights the fact that even now attention needs to be paid to the potentially deleterious effects of existing metal mining on local river systems. If large scale mining operations are initiated at Rosia Montana, there is still an opportunity to adopt more stringent environmental quality controls to ensure the Aries and Mures river systems are not degraded to the same extent as many of the mining affected rivers in Maramures County.

Transboundary impact of mining activities in the Apuseni Mountains In July 2001, surface water and sediment samples were collected from 16 sites along the Tisa River on the Hungarian territory, as well as from the principal tributaries coming from Romania, affected by industrial, mining and municipal metal pollution (Somes, Mures, Cris) for assessing the transboundary impact of 2000 tailings dam accidents and of mining activities. The Tisa was the only river sampled in July 2001 where no surface water metal concentrations exceeded intervention values for Pb, Zn, Cu or Cd. River sediments metal concentrations in the Tisa inside Hungary downstream of its confluence with the River Somes, are below intervention thresholds at all of the 16 sample sites. In general, Cd, Cu, Zn and Pb concentrations in the Tisa fall between Dutch target and imperative guidelines.

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In July 2002, surface water and sediment samples were collected from 14 sites along the Mures river on the Romanian territory until the Hungarian border, up- and downstream of the main mining affected tributaries from the Apuseni Mountains (Aries, Ampoi and Certej) (Fig. 8). Despite heavily polluted tributaries and urban areas, surface waters of the River Mures are not contaminated with Cd, Cu, Pb or Zn (Fig. 9). The only element exceeding target values at 2 sites was As. It is likely that urban and industrial pollution is a major source of As concentration in Mures river. River channel sediments exceed target values at 92% of sites for all metals, especially downstream of mined tributaries (Fig. 10). As concentrations in channel sediments fall below target values at all sites, despite higher concentrations in tributaries. Metal and As concentrations in waters and and sediments in the River Mures do not exceed imperative/intervention valued and do not pose a major risk to environment and human health.

Figure 8 Mures river basin: sample sites, main mining affected tributaries

100 Certej

Ampoii )

-1 Aries

g l 10 µ n ( o i at r ent 1 Conc

0.1 100 200 300 400 500 600

Channel distance (km) Figure 9 River Mures – Cu concentrations in surface waters

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1000 Certej

) Ampoii -1 g 100 g k Aries on (m i rat

ent 10 Conc

1 100 200 300 400 500 600

Channel distance (km) Figure 10 River Mures – Pb concentrations in river sediments

Conclusions One of the main findings of this study is that nearly all of the major pollution hotspots in the Apuseni Mountains relate to inputs of mine waste from currently active mines whose minewater treatment plants are not functioning properly. Contamination from mine waste, particularly in river and groundwater, has been shown to extend no more than 5 km from the point of effluent discharge and affects a corridor approximately 1 km width central on the present river channel. Between these relatively localised pollution hotspots, river and growndwater generally comply with EU guidelines, although metal concentrations in river sediment and floodplain soils can be elevated as a result of historical contamination. Data collected from the Aries River has indicated that the degree of pollution is dependent upon the nature of mine waste, the hydrological link between mines and local rivers, and the local physico- chemical environment. In this respect, the identification of the control factors over metal mobilisation and dispersal is critical fro the development of environmentally-sustainable mining operations. Certej catchment, affected by 1971 tailings dam failure, seems to have recovered in terms of surface water quality. Channel sediments are still contaminated with mine tailings, having a long-term effect on the river system. Identifying contaminant sources, the location of temporary contaminant stores (e.g. floodplains) and characterising the phyisical and chemical controls on the mobilisation and dispersal of contaminant metals is critical to the sustainable development of future mining activity in Romania. In these areas research is urgently required on controlling mine-waste generation and preventing its release into rivers that should include: event-based sampling and use of isotope fingerprinting techniques to identify contaminant sources and monitoring the efficiency of mine-waste treatment plants associated with both tailings dams and ore processing plants, facilitating steps towards compliance with the EU Water Framework Directive.

Refrence Batinas, R.H (2003), Fenomenul de poluare accidentala a apei in bazinul hidrografic al raului Aries, Riscuri si catastrofe, II, Casa Cartii de Stiinta, Cluj-Napoca, II, p. 196-204 Bird, G., Brewer, P., Macklin, M., Balteanu, D., Serban, M., Zaharia, S. (2003), The impact and significance of metal mining activities on the environmental quality of Romanian River Systems, Proceedings of the First International Conference on Environmental Research and Assessment, Bucharest, March 23-27, 316-332

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Bird, G., Brewer, P., Macklin, M., Balteanu, D., Serban, M., Zaharia, S. (2003), The solid state portioning of contaminant metals and As in river channel sediments of the mining affected Tisa drainage basin, northwestern Romania and eastern Hungary, Applied Geochemistry 18, 1583-1595 Brewer, P., Macklin, M., Balteanu, D., Coulthard, T., Driga, B., Howard, A., Bird, G., Zaharia S., Serban, M. (2003), The January and March tailings dam failures in Maramureş county, Romania and their transboundary impacts on the river systems, Proceedings of Advanced Research Workshop „Approaches to handling environmental problems in the mining and metallurgical regions of NIS counties”, Mariupol, September 5-7, Kluwer Academic Publishers, 73-83 Diehl, P. World Information Service on Energy (WISE) Uranium project [online], 2003. Available from: http://www.antenna.nl/wise/uranium/ [Accessed December 2003]. Fodor, D., Baican, G. (2001). Impactul industriei miniere asupra mediului, Edit. Informin, Deva Haiduc, I. (1940), Industria aurului in Romania, Imprimeriile „Adevarul”, Bucuresti Hudson-Edwards, Macklin, M., Miller, J., Lechler, P. (2001), Sources, distribution and storage of heavy metals in the Rio Pilcomayo, Bolivia, Journal of Geochemical Exploration, Elsevier, 72, 229- 250. Macklin, M. (1996), Fluxes and storage of sediment-associated heavy metals in floodplain system: assessment and river basin management issues at a time of rapid environmental chenge, In: Anderson, M.G., Walling, D. E. and Bates P. D., Floodplain Processes, John Wiley and Sons, Chichester, 441-460. Macklin, M., Brewer, P., Balteanu, D., Coulthard, T., Driga, B., Howard, A., Zaharia, S., (2003), The long term fate and environmental significance of contaminant metals released by the January and March 2000 mining tailings dam failures in Maramures County, upper Tisa Basin, Romania, Applied Geochemistry 18, 241-257 Popescu, Gh. C., Marinescu, M., Predeteanu, D. (1995), Potentialul metalogenetic al Muntilor Apuseni – actual si viitor potential poluant?, Muntii Apuseni. Studiu geoecologic (G. Popescu, eds.), Societatea de Mineralogie si Petrografie a Mediului „L. Mrazec” Popescu, Gh. C. (2003), De la mineral la provincie metalogenetica, Edit. Focus, Petrosani Radulescu, D.P., Sandulescu, M. (1973), The plate tectonics concept and the geological structure of the Carpathians, Tectonophysics, 16, 155-161 Ure, A.M., Quevauviller, P., Muntau, H. and Griepink, B. (1993), Speciation of heavy metals in soils and sediments, An account of the improvement and harmonization of extraction techniques undertaken under the auspices of the BCR of the Commission of the European Communities. International Journal of Analytical Chemistry 51, 135-151

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