STUK-A129 JANUARY 1996
Radioactivity of surface water and freshwater fish in Finland in 1991 - 1994
R. Saxen and U. Koskelainen
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Radioactivity of surface water and freshwater fish in Finland in 1991 - 1994
R. Saxen and U. Koskelainen
FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY P.O. Box 14 00881 Helsinki Tel. +358 0 759 881 ISBN 951-712-091-5 ISSN 0781-1705
Oy Edita Ab Helsinki 1996
Sold by: Finnish Centre for Radiation and Nuclear Safety P.O. Box 14, FIN-00881 Helsinki Tel. +358 0 759 881 FINNISH CENTRE FOR RADIATION STUK-A129 AND NUCLEAR SAFETY
SAXEN R, KOSKELAINEN U. Radioactivity of surface water and freshwater fish in Finland in 1991-1994. Helsinki 1996, 62 p.
ISBN 951-712-091-5 ISSN 0781-1705
Key words: 137Cs, ^Sr, freshwater fish, surface water
ABSTRACT
Changes over time in the activity concentrations of 3H, ^Sr and gamma-emitting radionuclides in lake and river water were studied.
The uneven distribution of Chernobyl deposition is still seen in areal concentra- tions. 137Cs in surface water has decreased significantly: In the drainage area where the activity concentrations were highest after the Chernobyl accident the concentrations in October 1992 were only about 1-4% of the maximum values in May 1986. The decrease in the activity concentrations of MSr was much slighter, and 30-90% of the values for ""Sr in May 1986 still remained in various drainage areas in October 1992. The difference in changes over time in the activity con- centrations of 137Cs and ^Sr refer to the different behaviour of these two radionuc- lides in the aquatic environment.
Amounts of 137Cs and *°Sr transported by the five largest rivers to the Baltic Sea after the Chernobyl accident were estimated to be 38 and 5.5 TBq, respectively, during 1986-1994.
Areal and temporal changes in the activity concentrations of 137Cs in fish were also studied in 1991-1994. In all, about 1800 fish samples from southern and central Finland were analysed gammaspectrometrically during this period. Nineteen different fish species were included in the study. The highest activity con- centrations of 137Cs were detected in small oligotrophic lakes in the area of highest deposition. The average activity concentrations, weighted by catches, in each of the eight statistical fisheries and in the whole country were calculated. The countrywide averages of 137Cs in the three fish groups (predatory, non-predatory and intermediate) were: HNNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY STUK-A129
Year Predatory Nonpredatory Intermediate
1991 660 Bq/kg 170 Bq/kg 410 Bq/kg 1992 550 " 150 " 380 " 1993 520 " 140 " 310 " 1994 380 " 120 " 310 "
In the catch of freshwater fish in the three most important fisheries, 137Cs decreased with a half-life of 3.5-6 years during 1991-1994; the figure for the catch of the whole country was about 5 years. FINNISH CENTRE FOR RADIATION STUK-A129 AND NUCLEAR SAFETY
CONTENTS
ABSTRACT 3
CONTENTS 5
1 INTRODUCTION 6 1.1 Lakes in Finland 6 1.2 Monitoring of surface water 6 1.3 Monitoring of fish 6
2 MATERIAL AND METHODS 8 2.1 Surface water 8 2.1.1 Samples, their treatment and analyses 8 2.1.2 Calculations 9 2.2 Fish 10 2.2.1 Samples, their treatment and analyses 10 2.2.2 Data treatment and calculations 13
3 RESULTS 15 3.1 Surface water 15 3.1.1 Radionuclide contents 15 3.1.2 Transfer of 137Cs from deposition to surface water 16 3.1.3 Amounts of 137Cs and ^Sr transported by rivers 16 3.2 Fish 17 3.2.1 Radionuclide contents 17 3.2.2 137Cs in fish catch, in various areas and countrywide 18 3.2.3 Transfer coefficients 19 3.2.4 Half-life of 137Cs 19
4 DISCUSSSION 20 4.1 Surface water 20 4.2 Fish 21
ACKNOWLEDGEMENTS 23 REFERENCES 24 FIGURES 27 TABLES 43 FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY STUK-A129
1 INTRODUCTION 1.1 Lakes in Finland
In Finland, freshwater lakes and rivers cover an area of 33 600 km2, which is 9.9% of the total area of the country. The number of lakes (surface area >1 ha) is about 56 000. They are most abundant in central and eastern Finland, where about 25% of the total area is occupied by water in some places. Finnish lakes are shal- low, their average depth being about 7 m. The total volume of the lakes is about 230 km3. The following figures give the size distribution of Finnish lakes:
Surface area Number of lakes
> 200 km2 17 > 100 km2 37 > 50 km2 81 > lkm2 2 589 > lha 56 000
In addition to the above, there are almost 132 000 very small lakes or ponds with an average area of 5 a - 1 ha.3-4 The 37 lakes with surface areas of > 100 km2 account for nearly 50% of the total surface area of lakes in Finland and for over 60% of the total volume of the lakes.
1.2 Monitoring of surface water
The purpose of the monitoring was to acquire data on the long-term behaviour of radionuclides deposited in surface water in different drainage basins. The results can also be used for intake estimations via drinking water.
The abundances of radionuclides transported by rivers to the Baltic Sea were estimated. The estimation was based on analyses of water samples from the mouths of the five largest rivers in Finland.
13 Monitoring of fish
Eating freshwater fish after deposition of radionuclides is one of the most important exposure pathways to man in the long term. To be able to estimate radionuclide intakes and radiation doses via fish, we need information on long- FINNISH CENTRE FOR RADIATION STUK-A129 AND NUCLEAR SAFETY
term radionuclide transfer to freshwater fish. The purpose of this study was to acquire a true countrywide picture of the radioactivity situation in freshwater fish, not merely to look for the highest possible activity concentrations. The uneven distribution of deposition and certain environmental factors cause large variations in the activity concentrations of 137Cs in fish; therefore the study was still rather extensive in 1991-1994.
Figures are presented for estimating intakes of 137Cs and radiation doses to man via freshwater fish in different parts of Finland and in the country as a whole. The study also gives data on factors affecting long-term radionuclide transfer from deposition to different types of fish in different types of environment.
Attention was paid to the differences in radioactivity between fish species and fish groups with different feeding habits. The characteristics of the lakes, such as area, water volume, flow rate and limnological type, as well as the characteristics of the catchment area also affect the contamination of fish by radioactive substances. Not all of these points are discussed at any length in this paper, but were still taken into account in sampling. FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY STUK-A129
2 MATERIAL AND METHODS 2.1 Surface water
2.1.1 Samples, their treatment and analyses
The distribution of radioactive substances deposited in the surface waters of various drainage basins was determined in 1991-1992 with the aid of a sampling programme of the National Board of Waters and Environment that involved about 180 sampling stations all over Finland (Fig. I)1-3. The samples were taken in May and October 1991, and in October 1992. The sample volume from each station was 2 litres. Before analyses, the samples were grouped together to represent different drainage basins or their subregions or watercourses (Fig. 2). Thus the volumes of the samples analysed ranged from 6 to 60 1, depending on how many samples were bulked together.
The artificial radioactive substances transported in rivers from Finland to the Baltic Sea were monitored. Samples were taken from the mouths of the five largest rivers, the Kymijoki, Kokemäenjoki, Oulujoki, Kemijoki and Tornionjoki, usually four times a year, in March, May, August and October (Fig. 1). In 1993 and 1994, the samples were taken only three times. Samples from three smaller rivers, the Porvoonjoki, Vantaanjoki and Karjaanjoki, which discharge into the Gulf of Finland, were also taken (Fig. 1). The sample volumes were about 30 1.
Samples from two lakes (Inari and Päijänne) and one river (Kemijoki) were taken monthly for tritium analyses (Fig. 1).
To preserve the surface water samples until further treatment, 2 g of solid citric acid was added to each 2-litre sample in the field. In the laboratory 10 ml of concentrated nitric acid, 50 mg of Sr-Cs and 20 mg of Ba-Ce carriers were added to the samples. The samples were analysed after evaporation to dryness, and then ashed at 450°C.
All samples were analysed gammaspectrometrically.13 The eight germanium detec- tors used for the analyses in our laboratory are either lithium drifted or high purity crystals with relative efficiencies of between 30 and 100%. The measurements were performed in background shields of 12-cm lead, which are lined with copper (2 mm) or cadmium (1 mm) and copper (0.5 mm) to reduce X-rays from the shields. The measuring times were between 6 and 24 hours. The measurements were made in beakers with cylindrical geometry (volume 30 ml). The activity FINNISH CENTRE FOR RADIATION STUK-A129 AND NUCLEAR SAFETY
concentrations of the samples were calculated using the computer program GAMMA-83.20-21
After gammaspectrometric measurement, the bulked surface water samples were analysed for s9Sr and ^r using the method described by Osmond et al.8 or the extraction method of Lapid et al.6, both of which were modified to some extent. After radiochemical separation, 89Sr and '"Sr were measured together as strontium carbonate. After a 2-week ingrowth period, *°Y, the daughter of ^Sr, was precipitated as Y-oxalate and measured. The measurements were made using either a low-background gasflow beta-counter, Berthold LB 770-1, or a low- background liquid scintillation counter, Quantulus 1220 by Wallac.
The samples for tritium analyses were distilled to dryness to remove impurities. The tritium level was then determined by the electrolytic enrichment method presented by Östlund et al.25, with some modifications.
2.1.2 Calculations
The amounts of137 Cs and ^Sr transferred by the five largest rivers to the Gulf of Finland and the Gulf of Bothnia were estimated for each of the rivers as follows:
3 2 T(Bq) = MQ(m /y) x 2 Cwi{Bq/m ) il where T = transferred total amount of a nuclide during a period of n years, Bq MQ = annual mean discharge of a river, m3/y, (ref. 3). 0,; = annual average concentration of 137Cs in the river, Bq/m3, in year i.
For 1986, when activity concentrations of radionuclides, of 137Cs in particular, decreased quickly, a period of one month was used in the calculations instead of one year. Values of 137Cs for 1986-1990 were taken from refs 15,16 and 19.
The amount of 137Cs retained in the drainage basin during n years was calculated as follows:
R(Bq) = A(m2) x D(Bq/m2) x d""1 - T(Bq) FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY STUK-A129
where A = total surface area of the catchment, m2 D = average deposition of 337Cs (Bq/m2) in the catchment d = annual decay correction of 137Cs
The transfer coefficients (CJD) of 137Cs deposited to surface water were calculated in large drainage basins annually. The coefficient is the ratio of the annual average concentration of 137Cs in surface water in a drainage basin to average deposition, corrected annually for radioactive decay, (Bq m'3 / Bq m"2), in the same drainage area. The average depositions of 137Cs in each of the large drainage areas were the same as in ref. 18 and originally derived from ref. 2.
2.2 Fish 2.2.1 Samples, their treatment and analyses
The monitoring programme included fish samples taken from five of Finland's largest lakes (Fig. 3) and from other large lakes of great importance for freshwater fishing. In order to locate the highest concentrations of ™7Cs in fish, samples were also taken from small oligotrophic lakes (surface area a few hectares) mainly in the area of high deposition (fallout categories 4 and 5 in Fig. 5). Sampling was done during the main fishing season, that is, from spring to autumn. The sampling times were to some extent affected by the seasons in which different species are caught.
The total numbers of fish samples analysed and the number of lakes from which fish samples were taken in the various provinces (cf. Fig. 4) in 1991-1994 were as follows:
10 FINNISH CENTRE FOR RADIATION STUK-A129 AND NUCLEAR SAFETY
Province Number offish samples analysed Number of lakes analysed 1991 1992 1993 1994 1991 1992 1993 1994 Häme 244 182 106 107 23 22 15 19 Central 103 92 43 52 11 10 8 10 Finland Kuopio 28 23 10 10 4 3 2 2 Kymi 42 42 14 18 5 4 4 4 Mikkeli 94 82 34 46 10 9 8 8 North 15 17 7 16 1 1 1 2 Karelia Oulu 10 27 17 28 1 2 2 3 Turku 95 90 10 5 7 6 2 2 and Pori Uusimaa 27 0 0 0 3 0 0 0 Vaasa 4 18 9 13 1 2 2 2 Aland 4 0 3 0 1 0 1 0 Total 666 573 253 295 67 59 45 52
The fish species analysed were those most commonly used for human consump- tion: perch, pike, vendace, bream, burbot, roach, whitefish, pike-perch and trout. Some samples of silver bream, smelt, dace, eel, ide, ruff, rudd, bleak and crusian carp were also analysed. Of these species, perch, pike and vendace each account for more than 20% of the total catch of freshwater fish in Finland. The fishes were of the normal size for edible fish and represent typical catches. Samples weighted about 1 kg fresh fish. Thus each sample consisted of one or, more usually, several individuals, depending on their size.
The fish species sampled, with their Latin and Finnish names, are24:
FISH SPECIES LATIN NAME (Finnish name)
BLEAK (salakka) Albumus alburnus L. BREAM (lahna) Abramis brama BURBOT (made) Lota lota CRUSIAN CARP (ruutana) Carasshis carassius L.
11 FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY STUK-A129
DACE (seipi) Leuciscus leuciscus EEL (ankerias) Anguilla anguilla IDE (säyne) Leuciscus idus PERCH (ahven) Perca fluviatilis PIKE (hauki) Esox ludus PIKE-PERCH (kuha) Stizostedion lucioperca ROACH (särki) Rutilus rutilus RUFF (kiiski) Gymnocephalus cernua SILVER BREAM (sulkava) Abramis ballerus SMELT (kuore) Osmerus eperplanus TROUT (taimen) Salmo trutta VENDACE (muikku) Coregonus albula WHITE BREAM (pasuri) Blicka bjoerkna WHITEFISH (siika) Coregonus lavaretus (col) RUDD (sorva) Scardinius erythrophthalmus
Samples were obtained from several sources. Fishery districts, which are under the supervision of the Ministry of Agriculture and Forestry, organized the sampling in each province. The Finnish Game and Fisheries Research Institute also supplied a large number of samples. Samples were received by the Finnish Centre for Radiation and Nuclear Safety and preserved deep-frozen for further treatment.
The fish were cleaned and gutted as normally in the kitchen. Big fish were filletted, and their heads, entrails, scales or skin, fins, backbone and other big bones were removed. Only the heads and entrails were removed from perch, vendace, roach and other small fish. Thus only edible parts were taken for analysis. Some samples, consisting of a large number of fish of different size, were subsampled according to the size of the fish.
The cleaned samples were cut into small pieces and packed into Marinelli beakers with a volume of about 560 ml. If only a small amount of sample was avaUable, a smaller cylindrical geometry (volume 30 ml) was used.
Gammaspectrometric analyses were performed as presented in ref. 13. The activity concentrations of the samples were calculated using the computer program GAMMA-8320-21. The measuring times were usually 2-3 hours. The 137Cs con- centrations in all samples were clearly above the detection limit.
12 FINNISH CENTRE FOR RADIATION STUK-A129 AND NUCLEAR SAFETY
2.2.2 Data treatment and calculations
Classification of fish The fish species studied were divided into three groups by feeding habits: Predators (e.g. pike, pike-perch, burbot) Non-predators or benthic feeders (e.g. vendace, bream, roach and other roach-related fish) Part predators and part non-predators (intermediate group) (e.g. perch, whitefish)
Classification of lakes The lakes were divided into four classes by size:
class surface area number of lakes 1991 1992 1993 1994 1 > 890 km2 3 4 4 5 2 20-890 km2 24 21 19 24 3 1-20 km2 19 15 9 10 4 The first class comprised five of the largest lakes in Finland: Saimaa, Päijänne, Kallavesi, Oulujärvi and Pielinen (Fig. 3). Though the lowest size limit of the second class was 20 km2, the area of most of the lakes in this class (class 2) exceeded 100 km2. The third class comprised lakes with an area of 1 to 20 km2 (class 3). Although of minor importance in terms of fishing, the lakes with a surface area of less than 1 km2 (class 4) consisted mainly of very small (surface area a few hectares), oligotrophic lakes, which is the type of lake with the highest radionuclide contents in freshwater fish. Areal and countrywide averages of 137Cs in fish catches Annual 137Cs values in freshwater fish, weighted by catches, Q, for the whole country for 1991-1994, were calculated using the following formula: 13 FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY STUK-A129 Ajj = activity concentration of 137Cs in fish group j in fishery i (Bqkg-1) niij = catch of fish in fish group j in fishery i, wo-" (kg) M = total annual catch of freshwater fish (kg),7-9'10'" Data on fish catches 7>9-10-11 and average concentrations of 137Cs for each of the three fish groups in each drainage basin were used. In addition, in drainage basins 4 and 5, the average concentrations of 137Cs for the three fish groups were calculated using the estimate that lakes covering more than 20 km2 accounted for 90% and those covering less than 20 km2 accounted for 10% of the total catch of the fishery. The division of the fish into three groups was based on their feeding habits. The catches of each fish group in each statistical fishery were calculated from information on catches of each species in the group. Recreation, subsistence and professional fishing were all taken into account. The catch statistics used were for 1986 (recreational and subsistence fishing) and 1988 (professional fishing). Statistical fisheries 1-7 correspond roughly to drainage basins 1-7, whereas statistical fishery 8 corresponds to drainage basins 8, 9,10 and 11 (cf. Figs 2 and 3). The transfer coefficients of 137Cs from deposition to different types of fish in various fisheries were calculated as the ratio of 137Cs in fish (Bq/kg) to 137Cs deposited (Bq/m2) in the area. The original deposition of 137Cs was corrected annually for radioactive decay. The effective half-lives of 137Cs in fish catches were estimated from the figures, where the calculated annual values of 137Cs for fish, weighted by catches, were plotted as a function of time. 14 FINNISH CENTRE FOR RADIATION STUK-A129 AND NUCLEAR SAFETY 3 RESULTS 3.1 Surface water 3.1.1 Radionuclide contents The dominant gamma-emitting radionuclide, 137Cs, was detected in all the 134 samples. The amounts of the shorter-lived cesium isotope, Cs (Tly2 = 2.1 y), were below the detection limit in several samples from the areas of low deposi- tion. The concentration of 134Cs was about 8% of that of 137Cs in 1992. 12SSb occurred in some samples in 1991-1993 (Tables I-VII). The beta-emitting ra- dionuclide, '"Sr, was detected in all samples analysed. During 1991-1992 the activity concentrations of 137Cs ranged from 4.6 to 120 Bq m"3 in different watercourses or their subregions. Temporal changes were small compared with areal variation. The highest concentrations of 137Cs were still found in subregion a) of the drainage basin of the Kymijoki (100-120 Bq m"3) and in subregion b) of the drainage basin of the Kokemäenjoki (110 Bq m~3) (Tables I- II). Concentrations of 137Cs were lowest in samples from the drainage basins of the Kemijoki and Tornionjoki and from the drainage area of small rivers discharging into the Arctic Ocean (Tables I—II). The effect of uneven areal distribution of Chernobyl deposition is still reflected in 137Cs concentrations in the surface water of the large drainage basins (Fig. 6). Activity concentrations of ^Sr were lower than those of 137Cs in the drainage basins of the Kymijoki and Kokemäenjoki, but almost the same in the drainage basins in eastern and northern Finland. The concentrations were highest in the Kymijoki and Kokemäenjoki drainage basins and in the Sotkamo water course in the Oulujoki drainage basin (Tables I-II). The concentrations remained the same or decreased slightly during 1991-1992 (Fig. 7). The annual averages of 137Cs in the water of five rivers, the Kymijoki, Kokemäenjoki, Oulujoki, Kemijoki and Tornionjoki, decreased by 30-40% during the study period. A decrease of 10-30% in the concentrations of '"Sr was noted during the same period (Tables III—VI) in the same rivers. The mean annual 137Cs and ^Sr concentrations in those rivers are compared in Figs 8 and 9. Clear differences in activity concentrations of 137Cs in the three smaller rivers, the Porvoonjoki, Vantaanjoki and Karjaanjoki were seen (Table VII). Each of them had tower activity concentrations of n7Cs than the Kymijoki, which also flows 15 FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY STUK-A129 into the Gulf of Finland but through a larger and more contaminated drainage area. Low concentrations of 12SSb were detected in a few samples. The detection limit for 12SSb is typically 20 Bq m~3, depending on sample volume and measurement time. The annual mean concentrations of 3H in the river Kemijoki, Lake Päijänne and Lake Inarinjärvi were 2.6 + 0.2, 2.7 + 0.7 and 2.6 + 0.2 kBq m~3, respectively, in 1993, and almost the same in 1994 (Table VIII). The values for the study period were far below the maximum values measured in the 1960's and no increase due to the Chernobyl accident was noticed (Fig. 10). 3.1.2 Transfer of 137Cs from deposition to surface water Transfer was highest in drainage area 7 and next highest in area 3; it was lowest in drainage area 5 (Fig. 11). The half-life of 137Cs in the Kymijoki was about 9 years before 1986. Since the period of rapid decrease during the couple of years immediately following 1986, the rate of decrease has gradually slowed down and hence the half-life of :37Cs in water has lengthened. The half-life for 137Cs is now about 7 years in the Kymijoki and is thus rather close to the pre-Chernobyl situation. 3.1.3 Amounts of 137Cs and ^Sr transported by rivers The total amounts of 137Cs and WST transferred to the Baltic Sea by the five largest rivers during 1986-1994 were as follows: River 137Cs Kymijoki 22 TBq 1.8 TBq Kokemäenjoki 12 TBq 1.3 TBq Oulujoki 1.5 TBq 0.9 TBq Kemijoki 1.6 TBq 0.9 TBq Tornionjoki 1.0 TBq 0.6 TBq 16 FINNISH CENTRE FOR RADIATION STUK-A129 AND NUCLEAR SAFETY Calculations showed that more than 97% of the 137Cs deposited was retained in the catchment areas - in bottom sediments, biota, sou and vegetation, - until the end of 1994. Only a minor proportion (2-3%) of the total amounts deposited in the catchment areas was removed with the rivers to the Baltic Sea. 3.2 Fish 3.2.1 Radionuclide contents The radioactive substances detected by gammaspectrometric measurements on freshwater fish are the two cesium isotopes, 134Cs and 137Cs. The concentration of mCs was about 4% of that of 137Cs in 1994. Studies on fish from Finnish Lapland are given in other reports14. The average concentrations of 137Cs in fish from individual lakes in classes 1-3, and the average concentrations of 137Cs in individual fish species in class 4 lakes, listed by province, are given in Tables IX-XII for 1991-1994. As would be expected on the basis of the areal distribution of 137Cs deposition from Chernobyl (Fig. 5), concentrations of 137Cs in fishes were highest in the provinces of Häme and Central Finland. In most lakes, 137Cs in different fish species decreased by 30- 80% between 1991 and 1994. In classes 1 and 2 lakes the average concentrations of 137Cs in fish ranged from 4.4 to 4500 Bq kg"1 in 1991-1994 (Tables IX-X). The variation in class 3 lakes was from 6.4 to 3800 Bq kg"1 in 1991 -1994 (Table XI). The oligotrophic lakes in class 4 represent the conditions of maximum accumula- tion of 137Cs in fish. The highest 137Cs value in fish during these four years was found in a pike sample (16 000 Bq kg"1) taken from a small oligotrophic lake in deposition category 4+5 (Fig. 5) in 1992 (Table XII). The concentrations of 137Cs in fish still show an association with the 137Cs deposited in the area: the higher the amount of 137Cs deposited the higher the concentration in fish (Fig. 12). The predators group and intermediate group still had somewhat higher concentrations of 137Cs than the non-predators in 1993- 1994, though differences between the fish types were not as pronounced as earlier. The intermediate group reached its maximum in 1987 and the predators group in 1988, whereas concentrations of 137Cs in non-predators started to decrease in 1986 already19. The variation in activity concentrations of 137Cs in a certain fish 17 FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY STUK-A129 species is still large in each deposition area (Fig. 13). Thus a large number of samples is needed to obtain a representative result. In addition, concentrations of 137Cs in the three fish groups, predators, non- predators and intermediate or in a certain fish species, were highest in the smallest (class 4) lakes, most of which were also oligotrophic, in deposition area 4+5 (Figs. 14 and 15). The smallest lakes do not differ from the others in the areas of slighter contamination (areas 1 and 2+3 in Fig. 5) as much as they do in deposition area 4+5 (Fig. 14). Classes 1, 2 and 3 lakes did not differ from each other and are therefore presented as one group with the smallest lakes (class 4) in Figs. 14 and 15. An example of one lake shows that the temporal variation between different species and the variation between samples of the same species in the concentra- tions of 137Cs has diminished in recent years (Fig. 16). Though differences between fish species have declined, predatory fish still have somewhat higher concentrations of 137Cs than the intermediate group; the non-predatory group has the lowest. 3.2.2 137Cs in fish catches in various areas and countrywide The most important area for freshwater fishing in Finland is drainage basin 3, which accounts for somewhat more than 30% of the total catch. The next most important are drainage basins 4 and 5 which represent about 18% and 15% of the total catch, respectively. Coastal areas 1, 2 and 6 each account for 4-7% of the total freshwater catch. The catch statistics used for calculations were for 1986 (recreational and subsistence fishing) and 1988 (professional fishing)7-9'10'11. The annual average concentrations of 137Cs in all fish and in the three fish groups (predatory, non-predatory and intermediate) countrywide, weighted by catches, in Bq/kg fresh weight, were in 1991-1994 as follows: Year Predatory Nonpredatory Intermediate All 1991 660 170 410 400 1992 550 150 380 350 1993 520 140 310 310 1994 380 120 310 270 The decrease in 137Cs in the Finnish catch of predators, non-predators and intermediate group fish and in fish as a whole after 1986 is given in Fig. 17 16-17-19. 18 FINNISH CENTRE FOR RADIATION STUK-A129 AND NUCLEAR SAFETY 3.2.3 Transfer coefficients The transfer of deposited 137Cs to fish was most effective in 1987 in all drainage basins. The transfer of 137Cs for the three fish groups (predators, non-predators and intermediate) was then most effective in drainage areas 7 and 3, 11-24% (Bq kg"1 / Bq m'2); at the same time the coefficients in the other areas were between 0.9 and 15%19. The same ratio varied between 0.4 and 7% in the seven areas in 1994 (Table XIII). The transfer coefficients for all fish were lower in drainage area 5 than in areas 3 and 4 (Fig. 18). In area 4 they were almost the same as for the whole catch in Finland. 3.2.4 Half-life of mCs The effective environmental half-life of 137Cs in the whole Finnish freshwater catch was estimated to be about 3 years during 1987-1990 and about 5 years after 1990. The variation in the half-lives in the three most important freshwater fisheries in Finland (areas 3, 4 and 5) was from 2 to 3 years during 1987-1990 and from about 3 to about 6 years during 1990-1994. In general, the longer the time since deposition, the longer is the half-iife of 137Cs in freshwater fish. 19 FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY STUK-A129 DISCUSSION 4.1 Surface water Concentrations of 137Cs in surface water varied greatly in different drainage basins in 1992. In October 1992 they were 1-20% of the maximum values in May 1986. 137Cs decreased more in watersheds of the Kokemäenjoki and Kymijoki (96-99%) drainage basins than in those of the Oulujoki drainage basin (80-93%) between May 1986 and October 1992. The high clay content of soD in the catchment of the Kokemäenjoki and to a lesser extent in that of the Kymijoki restrain cesium effectively. The Oulujoki drainage basin is occupied by extensive bogs but has virtually no clay deposits. The organic material and humic substances of the bogs keep cesium longer in the water phase in this basin than in the Kokemäenjoki and Kymijoki drainage basins. 137Cs is also leached much more readily from a catch- ment rich in organic material and humic substances than from a clay area, where leaching is negligible and occurs mostly as suspended particles, which easily sink to the bottom sediment of lakes and rivers. The concentrations of 137Cs in rivers carrying water from catchments to the Baltic Sea also decreased significantly, being in 1994 only 2-9% of the maximum concentrations in May 1986. The concentrations decreased most in the Kokemä- enjoki (98%) and least in the Oulujoki (91%). There are large clay areas in the catchment of the Kokemäenjoki drainage basin and a higher content of suspended solids in the river Kokemäenjoki. Concentrations of MSr in surface water decreased conspicuously less than those of 137Cs. In the Kymijoki drainage area, 30-40%, and in the Oulujoki and Koke- mäenjoki drainage basins, 40-90% of the maximum contents of May 1986 were still in the water. Likewise in river water, concentrations of '"Sr decreased less than those of 137Cs. For example, in the Kymijoki, Kokemäenjoki and Oulujoki, 36%, 23% and 60% of the ^Sr values for May 1986 remained in 1994. The results show that both 137Cs and ^r are removed from the Kokemäenjoki more effectively than from the other rivers studied. The different behaviour of the two long-lived radionuclides is also reflected in the 137Cs /""Sr ratio in water. Before 1986 the ratios in waters from the five river mouths were all below 0.5, ranging from 0.1 in the Kokemäenjoki to 0.4 in the Kemijoki and Tornionjoki.23 This ratio increased by a factor of about 100 in the main deposition area and by about 10 in the area of lowest fallout in 1986.15 In 20 FINNISH CENTRE FOR RADIATION STUK-A129 AND NUCLEAR SAFETY October 1994, the ratio ranged from 0.6 in the Tornionjoki and Kemijoki to 4.4 in the Kymijoki. Thus in the rivers flowing through areas of low deposition, that is, the Kemijoki and Tornionjoki, the values of the ratio are already near pre- Chernobyl values. The values are also gradually approaching those of the steady- state situation in the rivers in areas of higher deposition, that is, the Kymijoki and Kokemäenjoki (Fig. 19). Though in 1986 the "'Cs/^Sr ratio was almost the same in these rivers, it later decreased more rapidly in the Kokemäenjoki. 4.2 Fish In perch, pike and whitefish of the largest lakes, concentrations of 137Cs in 1994 were, on average, about 25% of those detected in 198818, when maximum values were recorded in most lakes and in many fish species. The greatest source of variation in the activity concentrations of radiocesium in fish in different provinces and different drainage basins is the uneven areal distribution of cesium deposition. The variation in the radiocesium contents offish is caused not only by local differences in deposition within each deposition area but also by the different chemical and hydrological characters of the lakes and the quality of their drainage basins. In the samples studied here, the 137Cs concentrations are highest in the smallest lakes (class 4) in a deposition area. Most of the small lakes studied are oligot- rophic, and thus represent conditions of maximum accumulation of radiocaesium in fish 5. The contribution of runoff may also be higher in small than in large lakes. The flow rate and water residence time in a lake also affect the transport of radiocesium to fish, causing differences between lakes even when there is no difference in deposition. In a lake, nutrition affects the radiocesium level in fish. This causes variations in different fish species and different sizes of fish of the same species. In a single lake, the activity concentrations of 137Cs in various fish species may vary by a factor of 13 and in individual samples of the same species by a factor of 10 during one fishing season. Reasons for the variation are differences in the nutrition of different species and in the size of the same species. The reliability of the areal values for 137Cs in fish, notably in the areas most important for freshwater fishing in Finland (fisheries 3, 4, 5), can be considered rather good. The values are based on a fairly large number of samples, especially in areas 4 and 5 (cf. page 11), representing different conditions of accumulation. 21 FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY STUK-A129 One source of uncertainty for the areal and countrywide values, weighted by catches, is that the catch statistics of different areas are not for the same year as the data on radiocesium. The areal transfer coefficients of 137Cs from deposition to fish are most reliable in drainage basins 4 and 5, where the highest numbers of fish samples were taken and analysed. Bulletins containing data on radioactivity of fish were still being issued by the Finnish Centre for Radiation and Nuclear Safety in 1991-1994. To restrict the 137Cs intake of the main consumers of fish, still in spring 1992 people living in the main deposition area (fallout categories 4-5 in Fig. 5) were advised not to eat perch, pike, pike-perch or burbot from lakes with surface areas of less than 1 km2 as their main course more than 2-3 times a week, people were also advised that fish from other parts of Finland and from large lakes in deposition areas 4+5 could be eaten without restrictions. No recommendations related to consumption of freshwater fish have been given since 1992. 22 FINNISH CENTRE FOR RADIATION STUK-A129 AND NUCLEAR SAFETY ACKNOWLEDGEMENTS We thank the National Board of Waters and Environment and the other institu- tions and individuals who helped us to obtain water samples. We are grateful to the personnels of Fishery Districts of Central Finland, Häme, Kuopio, Kymi, Mikkeli, North Karelia, Oulu, Turku and Vaasa, and the Ministry of Agriculture and Forestry for organizing sampling of fish and for all the persons who collected and sent the samples for us. We are especially grateful to Pirkko Saira and Ulla Yli-Arvo, who treated the water samples and performed the radiochemical MSr analyses. We also express our appreciation to the staff of the gamma laboratories of the Surveillance Department who performed the gammaspectrometric analyses of the samples. We are also indebted to Aino Rantavaara, the head of the Foodchain Laboratory for her valuable comments. 23 FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY STUK-A129 REFERENCES 1 Analyysituloksia virtahavaintopaikoilta v. 1970. Helsinki: National Board of waters, Finland, 1973; report 45. (In Finnish) 2 Arvela H, Markkanen M, Lemmelä H. Mobile survey of envi- ronmental gamma radiation and fall-out levels in Finland after the Chernobyl accident. Radiation Protection Dosimetry Vol. 32, No 3,177-184 (1990). 3 Atlas of Finland, Folio 132. Water. Helsinki: National Board of Survey, Geographical Society of Finland, 1986. 4 Atlas of Finland, Folio 232-233. Agriculture-special branches, fisheries. Helsinki: National Board of Survey, Geographical Society of Finland, 1980. 5 Kolehmainen S, Häsänen E and Miettinen JK. 137Cs levels in fish of different limnological types of lakes in Finland during 1963. Health Physics 12,1966, 917-922. 6 Lapid J, Münster M, Farhi S, Eini M, Lalouche L. A rapid method for the determination of radiostrontium in river water. Journal of Radioanalytical and Nuclear Chemistry 86(5) 321-326 (1984). 7 Leinonen K, Lehtonen H, Hilden M. Virkistys- ja hotitarve- kalastus Suomessa vuonna 1986. (Abstract: The profitability of professional fishing in Finland in 1986.) Suomen kalatalous 58 (13-17) 1991. 8 Osmond RG, Owers MJ, Healy C, Mead AP. The determination of radioactivity due to caesium, strontium, barium and cerium in waters and filters. Harwell, 1959; AERE-R 2899. 9 Partanen H, Parmanne R, Tuunainen A-L, Ammattikalastus Suomessa vuonna 1986. (Abstract: Professional fishing in Finland in 1986.) Suomen kalatalous 58 (1-12) 1991. 10 Partanen H, et ai, Ammattikalastus Suomessa vuonna 1987. 11 Partanen H, et ai, Ammattikalastus Suomessa vuonna 1988. 24 FINNISH CENTRE FOR RADIATION STUK-A129 AND NUCLEAR SAFETY 12 Rantavaara A. Radioactive substances of foodstuffs in Finland in 1987 and 1988. Helsinki: Finnish Centre for Radiation and Nuclear Safety, 1991; STUK-A78, Supplement 4 to Annual Report STUK-A74. 13 Rantavaara A, Klemola S, Saxen R, Ikäheimonen TK. and Moring M, 1994. Radionuclide analysis of environmental field trial samples at STUK. Report on Task FIN A 847 of the Finnish Support Programme to IAEA Safeguards. Helsinki: Finnish Centre for Radiation and Nuclear Safety, 1994; Report STUK-YTO-TR 75. 14 Rissanen et ai, Radioactivity of reindeer, game, fish and plants in Finnish Lapland in 1987-1988. Helsinki: Finnish Centre for Radiation and Nuclear Safety, 1991; STUK-A80, supplement 6 to Annual Report STUK-A74.(to be published) 15 Saxen R, Aaltonen H. Radioactivity of surface water in Finland after the Chernobyl accident in 1986. Helsinki: Finnish Centre for Radiation and Nuclear Safety, 1987. Report STUK-A60, Supple- ment 5 to Annual Report STUK-A55. 16 Saxen R, Radioactivity of surface water and freshwater fish in Finland in 1987. Helsinki: Finnish Centre for Radiation and Nuclear Safety, 1990. Report STUK-A77, Supplement 3 to Annual Report STUK-A74. 17 Saxen R and Rantavaara A. Radioactivity of freshwater fish in Finland after the Chernobyl accident in 1986. Helsinki: Finnish Centre for Radiation and Nuclear Safety, 1987. Report STUK- A61, Supplement 6 to Annual Report STUK-A55. 18 Saxen R. Transport of :37Cs in large Finnish drainage basins. In: Nordic Radioecology, the transfer of radionuclides through Nordic ecosystems to man. Studies in Environmental Science 62. Dahlgaard H. (ed.). Amsterdam, 1994. 19 Saxen R and Koskelainen U. Radioactivity of surface water and freshwater fish in Finland in 1988-1990. Helsinki: Finnish Centre for Radiation and Nuclear Safety, 1992. Report STUK-A94. Supplement 6 to Annual Report STUK-A89. 25 FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY STUK-A129 20 Sinkko K. Computer analysis of gamma-ray spectra in sample measurements. Licentiate Thesis. Helsinki: University of Helsinki, Department of Physics, 1981. (In Finnish) 21 Sinkko K, Aaltonen H. Calculation of the true coincidence summing correction for different sample geometries in gamma-ray spectroscopy. Helsinki: Finnish Centre for Radiation and Nuclear Safety, Surveillance Department, 1985; STUK-B-VALO 40. 22 Suomela M, Blomqvist L, Rahola T, Rantavaara A. Studies on environmental radioactivity in Finland in 1987. Helsinki: Finnish Centre for Radiation and nuclear Safety, 1991. Annual Report STUK-A74. 23 Studies on environmental radioactivity in Finland 1984-1985. Helsinki: Finnish Centre for Radiation and Nuclear Safety, 1987. Annual Report STUK-A54. 24 Varjo M. Kalannimiluettelo (List of Finnish fish names). Luonnon Tutkija 85 (supplementary number): 1-60, Suomen Biologian Seura Vanamo r.y., 1981. 25 Östlund HG, Werner E. The electrolytic enrichment of tritium and deuterium for natural tritium measurements. In: Tritium in the physical and biological sciences. Vienna: International Atomic Energy Agency, 1962; 95-104. 26 FINNISH CENTRE FOR RADIATION STUK-A129 AND NUCLEAR SAFETY 30° Fig. 1. Sampling points of lake and river systems (•), and at the mouths of the five largest rivers discharging into the Baltic Sea: I Kymijoki HI Oulujoki V Tornionjoki II Kokemäenjoki IV Kemijoki, and at three rivers discharging into the Gulf of Finland: 1 Porvoonjoki 2 Vantaanjoki 3 Karjaanjoki and sampling stations for tritium determinations: A Lake Päijänne (Kalkkinen), B Kemijoki, C Lake Inari (Nellimö). 27 Fig. 2. Drainage basins with their subregions or watercourses: 1. Small rivers discharging into the Gulf of Finland 2. Small rivers discharging into the Archipelago Sea 3. Vuoksi drainage basin a Pielisjärvi subregion b Kallavesi subregion c Saimaa 4. Kymijoki drainage basin a Keitele - Päijänne b Päijänne c Päijänne - Gulf of Finland 5. Kokemäenjoki drainage basin a Längelmävesi, Hauho and Vanaja watercourses b Ähtäri and Keuruu watercourses, Palovesi- Pyhäjärvi c Pyhäjärvi - Rautavesi, Ikaalinen watercourse Kokemäenjoki and Loimijoki basins 6. Rivers discharging into the Gulf of Bothnia 7. Oulujoki drainage basin a Hyrynsalmi watercourse b Sotkamo watercourse ••• c Oulujärvi - Gulf of Bothnia 8. Kiiminginjoki, Iijoki and Simojoki rivers 9. Kemijoki drainage basin 10. Tornionjoki drainage basin u u 11. Rivers discharging into the Arctic Ocean ffip Shaded area inside the dotted lines indicates the oo ž main fallout area. FINNISH CENTRE FOR RADIATION STUK-A129 AND NUCLEAR SAFETY Fig. 3. The statistical fisheries (numbers 1-8 in circles) in Finland y/ith the large lakes: 1 = Saimaa 2 = Päijänne 3 = Kallavesi 4 = Pielinen 5 = Oulujärvi 22*26* A 3 LAPLAND ( r\ OULU / ^v f-I | KUOPION rVAASAV >NORTH\ \CENT 1_ / KARELIA' 62* XTFINJ RAL- >^/ ^MIKKELI Fig. 4. The provinces in Finland. JANOr \\ y P0RTURKII T 1ÄME ' / ALAND ( KYMI J "DrJsT- , Ka JJAA-^"^ 0 50 WO 22* 30* 29 FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY STUK-A129 to STUX «k Cs-137 deposition 1.10.1987 Deposition sj kBq/m2 area 0- 6 1 6-11 2 11-23 23-45 45-78 Fig. 5. The distribution of137Cs in Finland after the Chernobyl accident. The municipalities are divided into five categories according to their average 137Cs deposition.2 30 FINNISH CENTRE FOR RADIATION STUK-A129 AND NUCLEAR SAFETY Bq/l Bq/l 10.00 10.00 1.00 1.00! 0.10 0.10 0.01 0.01 \iiiiiiiuii|iiiiiiinii| Miiii| ii|niminn|iiui"i'"|»miiiiii( 1986 1987 1988 1989 1990 1991 1992 1993 1986 1987 1988 1989 1990 1991 1992 1993 M43 BBS4 »»«5 »9<7 MAI BBB2 «««6 Fig. 6. Activity concentrations of137 Cs in surface water (Bq/l) in various large drainage basins in Finland in 1986-1992. Location of the basins is given in Fig. 2. Bq/l Bq/l 10.00. 10.00 1.00 1.00 0.10 0.10: 1986 1987 1988 1989 1990 1991 1992 1993 1986 1987 1988 1989 1990 1991 1992 1993 &64J BBB4 OOO5 »«7 4441 8BB2 «««6 Fig. 7. Activity concentrations of ^Sr in surface water (Bq/l) in various large drainage basins in Finland in 1986-1992. Location of the basins is given in Fig. 2. 31 FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY STUK-A129 Bq/l 10.000 — KYMIJOKI 1.000 — KOKEMÄENJOKI 0.100 0.010 0.001 J-.— 1965 1970 1975 1980 1985 1990 1995 Bq/l 10.000 T 137CS — OULUJOKI 1.000 •- KEMUOKI — TORNIONJOKI 0.100 0.010 0.001 J-r 1965 1970 1975 1980 1985 1990 1995 Fig. 8. Annual mean concentrations of137Cs (Bq/l) in water of the rivers Kymijoki, Kokemäenjoki, Oulujoki, Kemijoki and Tornionjoki in 1965-1994. 32 FINNISH CENTRE FOR RADIATION STUK-A129 AND NUCLEAR SAFETY Bq/l 10.000 KYMIJOKI 1.000^ KOKEMÄENJOKI 0.100 0.010 0.001 1965 1970 1975 1980 1985 1990 1995 Bq/l 10.000 — OULUJOKI 1.000 • -- KEMUOKI — TORNIONJOKI 0.100 0.010 0.001 1965 1970 1975 1980 1985 1990 1995 Fig. 9. Annual mean concentrations of^Sr (Bq/l) in water of the rivers Kymijoki, Kokemäenjoki, Oulujoki, Kemijoki and Tornionjoki in 1965-1994. 33 FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY STUK-A129 0 'li'""""'!'"""""!1 """""I """'"" I""1"""!""""1 "I""1"""!"""1 ""I" "'"""I 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Fig. 10. 3H in the water of Lake Päijänne (Bq/l) in 1986-1994. 34 FINNISH CENTRE FOR RADIATION STUK-A129 AND NUCLEAR SAFETY Csl37 Csl37 Cw/D Cw/D 0.100 0.100 _\_ 0.010 0.010 1 1 0.001 ! r i i i ' i ' p .• • ii •• ii 0.00M.VUI-1 | i i i p 1986 1987 1988 1989 1990 1991 1992 1986 1987 1988 1989 1990 1991 1992 JUkJL I ^^^^^ J ^^^A C VUV7 m t r^^ A t^^k £ ^^SQ J CDC3 4 Fig. 11. Annual transfer coefficients of131 Csfrom deposition to surface water (Bq m~3/Bq m'2) in various large drainage basins in Finland in 1986-1992. 35 FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY STUK-A129 PREDATORS I991 KON-PR£DAT0flS 1991 INTERMEDIATE 1991 4000 4000 2000 3000 uu u 000 •• 2000' 2000 000 H 1000 1000 OWMJ. 1 2+3 4+5 I 2+3 4+5 1 2 + 3 11-5 DEPOSITION CATECORY DEPOSITION CATECORY DEPOSITION CATEGORY 3I'ooSi PREDATORS 1992 NON-PREDATORS 1992 MURHEOWE1992 400O 4000' 3000 3000 000- 2000 2000 000' H 1000 1000 i—mJL o 1 2+3 4+5 1 2+3 «+5 1 2+3 4+5 DEPOSITION CATECORY DEPOSITION CATECORY OEPOSITION CATECORY PREDATORS 1993 NON-PREDATORS1993 INTERMEDIATE 1993 4000 4000 4000 3000 3000 3000 2000 200O 2000 1000 1000' 1000' 1 2+3 4+5 1 2+3 4+5 1 2+3 4+5 DEPOSITION CATECORY DEPOSITION CATECORY DEPOSITION CATEGORY Btfko8, PREDATORS 199* NON-PREDATORS 1994 INTERMEDIATE 1994 4000- 4000 4000 3000' 3000' 3000' 2000 2000 2000 1000 1000' 1000 1 2+3 4+5 I 2+3 4+5 1 2+3 4+5 DEPOSITION CATECORY DEPOSITION CATECORY DEPOSITION CATECORY Fig. 12. Average annual concentrations of 137Cs (Bq kg'1 fresh weight) in three fish groups (predators, non-predators and intermediate) in deposition areas 1, 2+3 and 4+5 (cf. Fig. 5) in 1991-1994. 36 FINNISH CENTRE FOR RADIATION STUK-A129 AND NUCLEAR SAFETY Bq/kg 4O0OO: PERCH 3OOOO 281 221 174 1E30 2OOOO 84 1OOOO: 1S6 T T 65 8! C3 M O H O \ 8 1986 1987 1988 1989 199O 1991 1992 1993 1994 Bq/kg 4OOOO 3OOOCH 20OOO 1OOOO 1986 1987 1988 1989 199O 1991 1992 1993 1994 Bq/kg 4OOOO VENDACE 3OOOO 20000^ 1OOOO- 36 56 1 6 27 19 20 s 3 8 0 I I I I I I • I 1986 1987 1988 1989 199O 1991 1992 1993 1994 Fig. 13. Variation in 137Cs (total range, median and quartiles) in perch, pike and vendace in deposition area 4+5 in 1986-1994. Numbers of samples are also given. All the lakes studied are included. 37 FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY STUK-A129 I 2+3 4+5 I 2+3 4+5 1 2+3 4+5 DEPOSITION AREA DEPOSITION AREA DEPOSITION AREA Fig. 14. Average annual activity concentrations ofwCs (Bq kg'1) in the three fish groups in > 1-km2 ( I I) and < 1-km2 lakes ( Ü J in deposition areas 1, 2+3 and 4+5 (cf. Fig. 5) in 1991-1994. 38 FINNISH CENTRE FOR RADIATION STUK-A129 AND NUCLEAR SAFETY Bq/kg 12000 LAKE AREA > 1 km2 10000 -*- PERCH -a- piKE -*- VENDACE 8000 LAKE AREA < 1 km2 "••-.. A --A-- PERCH -a- PIKE 6000 a •••-.. a. 4000 •"•••A ""• 2000 -y D- I I ' " I " " I l i T 1986 1987 1988 1989 1990 1991 1992 1993 1994 Fig. 15. Average annual activity concentrations of 137Cs (Bq kg'1 fresh weight) in perch, pike and vendace in > 1-km2 lakes and in perch and pike in < 1-km2 lakes, in deposition areas 4+5 (cf. Fig. 5), in 1991-1994. The lakes in both groups were almost the same in all years, 39 FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY STUK-A129 Bq/kg 5000 -A- PERCH 4000 -e- PIKE -*- BURBOT -*- VENDACE 3000 PIKE 2000 1000 x VENDACE 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Bq/kg A PIKE-PERCH 4000 a BREAM X WHITE BREAM * ROACH o IDE 3000 SILVER BREAM A A 2000 1000 A n- 'S ^>Bg j-JD DSH «SD a G 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 Fig. 16. Temporal variation in 137Cs in different fish species in Kyrösjärvi, a lake with a surface area of about 100 km2, in deposition area 4+5 (cf. Fig. 5) in 1986-1994. 40 FINNISH CENTRE FOR RADIATION STUK-A129 AND NUCLEAR SAFETY Cs137 Bq/kg 1400 1200 -&- PREDATORS • -*- NON-PREDATORS 1000 •*- INTERMEDIATE -B- ALL FISH 800 600 400 200 i : i 1 1 1 1 1 r 1986 1987 1988 1989 1990 1991 1992 1993 1994 Fig.17. Countrywide annual averages of 137Cs in predatory, nonpredatory and intermediate fish and in all fish (Bq/kg fresh weight) in the catch of freshwater fish in Finland in 1986-1994. 0.01 H i—•—i—•—i—'—i—•—i—'—i—i—i—i—i—>—r 1986 1987 1988 1989 1990 1991 1992 1993 1994 " " 4 3 B-B-B 4 ooo 5 Fig. 18. Annual transfer coefficients of137Cs from deposition to freshwater fish in three large drainage basins (cf. Fig. 2) in 1986-1994. 41 FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY STUK-A129 Cs137/Sr90 100.00 — KYMIJOKI 10.00 •- KOKEMÄENJOKI 1.00 0.01 1965 1970 1975 1980 1985 1990 1995 Cs137/Sr90 100.00 - OULUJOKI 10.00 - KEMIJOKI -- TORNIONJOKI 1.00 0.10 0.01 1965 1970 1975 1980 1985 1990 1995 Fig. 19. '^Csl^Sr in water of the rivers Kymijoki, Kokemäenjoki, Oulujoki, Kemijoki and Tornionjoki in 1965-1994. 42 FINNISH CENTRE FOR RADIATION STUK-A129 AND NUCLEAR SAFETY Table I. ^Sr and gamma-emitting radionuclides in the surface water of some drainage basins and their subregions and in groups of rivers discharaging into different sea areas in May and October 1991 (Bq/m3). The results are decay corrected to the sampling date. The figures in parentheses refer to the number of the drainage basin, and (a), (b) or (c) refer to the subregions (cf. Fig.2). May October "Sr 134Cs 137Cs "Sr 1MCs "7Cs RIVERS DISCHARGING INTO 10 3.1 22 11 21 26 THE GULF OF FINLAND (1) RIVERS DISCHARGING INTO 12 1.7 21 15 3.9 39 THE ARCHIPELAGO SEA (2) VUOKSI (3) Pielisjärvi subregion (a) 10 1.2 15 9.0 1.1 13 Kallavesi subregion (b) 12 4.4 39 12 4.2 42 Saimaa (c) 11 2.2 24 11 5.7 27 KYMIJOKI (4) Keitele-Päijänne (a) 18 13 110 18 13 122 Päijänne (b) 18 7.1 70 16 7.6 65 Päijänne-Gulf of Finland (c) 18 11 94 16 10 100 KOKEMÄENJOKI (S) Längelmävesi, Hauho and 20 4.0 41 19 4.7 43 Vanaja watercourses (a) Ähtäri and Keuruu water- 16 12 110 16 13 100 courses, Palovesi-Pyhäjärvi (b) Pyhäjärvi-Rautavesi, Ikaalinen 17 7.3 63 15 10 98 watercourse Kokemäenjoki and Loimijoki basins (c) RIVERS DISCHARGING INTO 11 4.2 38 12 4.8 47 THE GULF OF BOTHNIA (6) OULUJOKI (7) Hyrynsalmi watercourse (a) 7.4 1.6 11 7.2 0" 7.8 Sotkamo watercourse (b) 15 6.3 63 14 5.6 60 Oulujärvi-Pohjanlahti (c) 12 4.8 26 10 0 17 KIIMINKIJOKI, nJOKI AND 7.3 0 8.S 6.6 0 8.9 SIMOJOKI (8) KEMIJOKI (9) 5.9 0 8.0 4.9 0 4.9 TORNIONJOKI (10) 5.4 0 9.1 4.9 0 7.3 RIVERS DISCHARGING INTO 4.5 0 6.4 3.8 0 4.8 THE ARCTIC OCEAN (11) a) below the detection limit 43 FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY STUK-A129 Table II. ^Sr and gamma-emitting radionuclides in the surface water of some drainage basins and their subregions and in groups of rivers discharging into different sea areas in October 1992 (Bq/m3). The results are decay corrected to the sampling date. The figures in paventheses refer to the number of drainage basin, and (a), (b) or (c) to the subregion (cf. Fig. 2). "Sr 1MCs 137 Cs RIVERS DISCHARGING INTO THE GULF OF FINLAND 11 ZO 20 (1) RIVERS DISCHARGING INTO THE ARCHIPELAGO SEA 13 0" 18 (2) VUOKSI (3) Pielisjärvi subregion (a) 8.8 0 13 Kallavesi subregion (b) 11 2.6 33 Saimaa (c) 12 2.4 21 KYMIJOKI (4) Keitele-Päijänne (a) 16 7.6 100 Päijänne (b) 16 4.6 61 Päijänne-Gulf of Finland (c) 15 7.0 89 KOKEMÄENJOKI (5) Längelmävesi, Hauho and Vanaja watercourses (a) 18 2.6 31 Ähtäri and Keuruu watercourses, ')_ <0_ Palovesi-Pyhäjärvi (b) *)_ Pyhäjärvi-Rautavesi, Ikaalinen watercourse 13 5.0 61 Kokemäenjoki and Loimijoki basins (c) RIVERS DISCHARGING INTO THE GULF OF BOTHNIA 11 2.7 36 (6) OULUJOKI (7) Hyrynsalmi watercourse (a) 5.5 0 9.5 Sotkamo watercourse (b) 11 3.5 47 Oulujärvi-Pohjanlahti (c) 9.1 0 16 KIIMINKIJOKI, njOKI AND SIMOJOKI (8) 7.1 0 7.7 KEMIJOKI (9) 5.7 0 4.6 TORNIONJOKI (10) 5.0 0 5.8 RIVERS DISCHARGING INTO THE ARCTIC OCEAN (11) 3.8 0 4.9 s) below the detection limit b) not analysed 44 FINNISH CENTRE FOR RADIATION STUK-A129 AND NUCLEAR SAFETY Table III. *°Sr and gamma-emitting radionuclides in surface water (in Bq m'3) from the mouths of Finland's five largest rivers discharging into the Baltic Sea in 1991. Sampling "Sr 125Sb 134Cs 137Cs month/river March Kokemäenjoki 19 4.9 11 75 Oulujoki 13 0a 2.0 14 Kemijoki 6.4 0 0 8.2 Tornionjoki 5.9 0 0 5.3 May Kymijoki 19 3.0 14 112 Kokemäenjoki 17 3.6 6.6 57 Oulujoki 11 0 1.9 19 Kemijoki 5.0 0 0.7 7.6 Tornionjoki 4.9 0 0 9.9 August Kymijoki 20 4.6 17 140 Kokemäenjoki 18 4.9 9.4 78 Oulujoki 10 0 1.6 15 Kemijoki 6.0 0 0 8.4 Tornionjoki 5.4 0 0.6 7.0 October Kymijoki 19 3.5 12 110 Kokemäenjoki 17 2.6 10 97 Oulujoki 10 0 1.2 9.8 Kemijoki 4.9 0 0 4.9 Tornionjoki 4.2 0 0.7 6.6 a) below the detection limit 45 FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY STUK-A129 Table IV. ^Sr and gamma-emitting radionuclides in surface water (in Bq m~3) from the mouths of Finland's five largest rivers discharging into the Baltic Sea in 1992. Sampling "Sr 125Sb 134Cs 137Cs month/river March Kymijoki 17 Oa) 5.2 53 Kokemäenjoki 17 1.9 5.7 56 Oulujoki 10 0 0 8.6 Kemijoki 5.3 0 1.0 7.8 Tornionjoki 5.5 0 0 7.4 May Kymijoki 17 0 7.9 90 Kokemäenjoki 14 0 4.4 53 Oulujoki 7.9 0 0 10 Kemijoki 4.1 0 0.8 11 Tornionjoki 4.1 0 0 6.7 August Kymijoki 19 3.0 8.5 110 Kokemäenjoki 17 0 3.9 48 Oulujoki 8.4 0 0.7 12 Kemijoki 6.4 0 0 7.1 Tornionjoki 5.0 0 0 4.5 October Kymijoki 17 2.3 7.8 96 Kokemäenjoki 16 0 5.4 64 Oulujoki 8.4 0 0.8 12 Kemijoki 6.2 0 0 4.3 Tornionjoki 5.4 0 0 4.5 a) below the detection limit 46 FINNISH CENTRE FOR RADIATION STUK-A129 AND NUCLEAR SAFETY Table V. ^Sr and gamma-emitting radionuclides in surface water (in Bq m~3) from the mouths of Finland's five largest rivers discharging into the Baltic Sea in 1993. Sampling ^Sr 134Cs 137Cs month/river March Kymijoki 15 5.4 72 Kokemäenjoki 16 3.0 38 Oulujoki 8.6 0.9 7.7 Kemijoki 5.3 oa> 3.9 Tornionjoki 5.4 0 5.5 May Kymijoki 16 4.6 78 Kokemäenjoki 13 3.2 34 Oulujoki 8.3 0 10 Kemijoki 4.0 0 5.1 Tornionjoki 4.0 0 4.7 August Kymijoki 18 5.3 84 Kokemäenjoki 16 3.1 49 Oulujoki 8.6 0 8.6 Kemijoki 5.1 0 5.4 Tornionjoki 5.1 0 3.9 a) below the detection limit 47 FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY STUK-A129 Table VI. *%• and gamma-emitting radionuclides in surface water (in Bq m~3) from the mouths of Finland's five largest rivers discharging into the Baltic Sea in 1994. Sampling wSr 134Cs 137Cs month/river May Kokemäenjoki 13 2.1 38 Oulujoki 7.0 0» 7.1 Kemijoki 4.2 0 3.9 Tornionjoki 4.2 0 4.6 August Kymijoki 16 4.0 98 Kokemäenjoki 14 0 57 Oulujoki 7.6 0 12 October Kymijoki 15 3.3 65 Kokemäenjoki 13 1.7 43 Oulujoki 7.3 0 6.9 a) below the detection limit 48 FINNISH CENTRE FOR RADIATION STUK-A129 AND NUCLEAR SAFETY Table VII. ^Sr and gamma-emitting radionuclides in surface water (in Bq m'3) in three rivers discharging into the Gulf of Finland in 1991 and 1992. River Sampling "Sr 134Cs 137Cs date Porvoonjoki 22.3.91 5.4 1.0 5.8 Vantaanjoki 18.3.91 8.4 1.1 8.2 Karjaanjoki 18.3.91 8.8 oa 5.8 Porvoonjoki 17.5.91 10.0 1.1 13.5 Vantaanjoki 17.5.91 9.0 0.7 7.5 Karjaanjoki 20.5.91 9.9 0a 6.5 Porvoonjoki 16.8.91 10.2 3.7 34 Vantaanjoki 16.8.91 6.8 1.8 18 Karjaanjoki 19.8.91 8.5 0.8 6.8 Porvoonjoki 23.10.91 12.6 6.5 61 Vantaanjoki 23.10.91 11.7 2.8 21 Karjaanjoki 24.10.91 8.8 0.6 6.3 Porvoonjoki 17.3.92 8.5 2.9 21 Vantaanjoki 17.3.92 7.8 0.8 11 Karjaanjoki 16.3.92 8.1 0a 3.6 Porvoonjoki 22.5.92 8.4 1.3 15 Vantaanjoki 22.5.92 7.5 0.7 9.1 Karjaanjoki 18.5.92 7.9 0 6.0 Porvoonjoki 24.8.92 12 0 6.3 Vantaanjoki 24.8.92 6.2 0.6 5.3 Karjaanjoki 24.8.92 8.7 0 4.3 Porvoonjoki 19.10.92 10 3.8 50 Vantaanjoki 19.10.92 10 1.2 21 Karjaanjoki 16.10.92 8.6 0 4.4 below the detection limit 49 0\ CA Table VIIL Activity concentrations of3!! in surface water in 1990-1994 (kBq/m3). For sampling stations see Fig 1. Jan Fcb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual mean River Kemijoki 1990 3.0 5.0 4.2 3.7 3.1 3.1 2.7 3.5 4.0 4.1 3.5 3.5 3.6 ± 0.6 1991 4.3 4.4 4.8 4.1 2.9 3.7 2.8 3.5 3.8 - - - 3.8 ± 0.7 1992 3.1 - - - 3.0 - 1.5 - - 1.4 - 2.3 ± 0.9 1993 - 2.9 - - 2.5 - - 2.5 - - 2.6 - 2.6 ± 0.2 1994 — 2.0 — — 2.2 — — 2.9 — 3.1 - — 2.6 ± 0.5 Lake Päijänne 1990 3.6 3.7 4.0 3.1 2.6 4.0 5.0 4.0 3.7 - - 2.8 3.7 ± 0.7 1991 2.6 4.0 2.9 3.5 2.8 3.6 2.4 4.3 3.5 - - - 3.3 ± 0.6 § 1992 - 2.9 - _ - 4.0 - 2.3 _ _ 2.3 - 2.9 ± 0.8 1993 2.7 _ _ 3.5 _ _ 2.7 _ _ 1.8 - 2.7 ± 0.7 1 1994 — 3.3 - — 2.2 — - 2.0 - 2.3 - - 2.5 ± 0.6 Lake Inari 1990 3.1 3.7 4.2 3.5 4.0 4.0 3.4 3.6 3.5 4.2 3.6 2.7 3.6 ± 0.4 1991 3.5 3.8 4.2 3.1 3.0 3.5 3.4 4.7 3.1 _ _ _ 3.6 ± 0.6 1992 - 2.9 - - - 3.1 - 2.8 - - 3.4 - 3.1 ± 0.3 1993 - 2.4 _ - 2.8 - - 2.5 - _ 2.5 - 2.6 ± 0.2 1994 ** 1.9 2.3 — 3.7 — 2.2 — 2.5 ± 0.8 '' not analysed O IT) FINNISH CENTRE FOR RADIATION STUK-A129 AND NUCLEAR SAFETY 134 Table IX. Tbc average activity concentrations (H) and the variation in 'ct and Cs (Bq/kg fresh veight) in various fish species in the largest lakes (surface area > 890 km . class 1) in Finland in 1991 - 1994. The number of samples is also given (n). PROVINCE FISH Cs 137Cs LAKE SPECIES n X mln max X min max HXME PXIJXHNE BREAM 1 55 55 55 630 630 630 BURBOT 2 120 68 170 1200 800 1500 PERCH 8 73 30 190 750 470 1600 PIKE 4 84 36 ISO 880 490 1300 ROACH S 26 12 41 290 250 340 TROUT 1 1.1 1.1 1.1 10 10 10 WHITEFISH 5 19 6 38 200 130 290 CENTRAL FINLAND PXIJXNNE BREAM 11 33 3.2 62 370 69 620 BURBOT 7 48 10 100 600 230 830 IDE 1 14 14 14 110 110 110 PERCH 22 48 17 140 540 240 1200 PIKE 8 80 31 140 870 480 1400 PIKE-PERCH 1 240 240 240 2200 2200 2200 ROACH 10 20 4.2 47 220 95 400 TROUT 1 21 21 21 270 270 270 VENDACE 1 6.8 6.8 6.8 87 87 87 WHITEFISH 8 8.9 3.3 14 110 74 140 KALLAVESI BREAM 1 1.2 1.2 1.2 38 38 38 BURBOT 6 11 1.7 24 130 50 220 PERCH 6 6.6 1.7 13 75 43 130 PIKE 5 8.5 2.6 16 110 65 160 PIKE-PERCH 4 8.6 3.2 16 92 13 160 ROACH 3 2.6 1.8 4 30 26 38 WHITEFISH 4 2.1 0.73 4.6 29 19 48 KYMI SAIMAA BREAM 3 12 5.8 23 88 35 140 BURBOT 2 46 14 77 510 310 710 PERCH 7 28 7 .4 85 360 95 770 PIKE 6 28 9 58 340 210 520 ROACH 2 7 .1 5.8 8.4 95 81 110 SMELT 1 4.5 4.5 4.5 67 67 67 VENDACE 1 4.5 4 .5 4.5 57 57 57 WHITEFISH 5 5.6 3 9 .9 77 41 94 51 FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY STUK-A129 Table IX continued 134 137 PROVINCE FISH cs cE LAKE SPECIES n X mln max X mln max MIKKELI SAIMAA BREAM 6 2.5 1.3 4.5 28 11 47 EEL 1 oa 0 0 27 27 27 PERCH 14 3.6 1.2 16 46 14 190 PIKE 6 3.8 l.S 6.8 46 30 71 ROACH 6 1.3 0.84 1.8 17 14 20 RUDD 4 0.89 0.31 l.S 11 7.6 14 OULUJÄRVI BREAM 3 1.8 1.5 2.2 37 30 48 BURBOT 1 8.6 8.6 8.6 230 230 230 DACE 3 2.5 1.3 4.9 50 36 74 IDE 1 0 0 0 16 16 16 PERCH S 5 3 6.8 110 94 140 PIKE 3 7.7 4.1 14 140 110 200 PIKE-PERCH 2 4.4 3 5.7 100 88 120 ROACH 4 6.1 1.3V 18 35 29 41 SMELT 4 2.3 1.4 3.5 40 34 45 TROUT 4 2.4 0.46 6.1 46 9.9 100 VENDACE 2 2.2 2 2.3 39 34 44 WHITEFISH S 1.6 1.3 2.1 28 21 31 NORTH KARELIA PIELINEN BREAM 1 0.37 0.37 0.37 22 22 22 PERCH 3 1.3 0.85 1.5 44 27 55 PIKE 1 1.7 1.7 1.7 59 59 59 PIKE-PERCH 1 1.5 l.S 1.5 63 63 63 ROACH 1 0.58 0.58 0.58 22 22 22 VENDACE 1 0.54 0.S4 0.54 14 14 14 WHITEFISH 1 0 0 0 9.S 9.5 9.5 below the detection limit 52 FINNISH CENTRE FOR RADIATION STUK-A129 AND NUCLEAR SAFETY Table X. The average activity concentrations (S) and the variation in CE and Cs (Bq/kg fresh weight) In various fish species in lakes with a surface area of more than 20 km (CIBEE 2) In 1991 - 1994. The area of most of the lakes in this clasE exceeds 100 km . The number of samples is also given (n). 13 137 FISH HXME KUOHIJXRVI PIKE 1 370 370 370 4100 4100 4100 KYRÖSJXRVI BREAK 12 7.4 2.1 13 89 36 120 BURBOT 21 28 11 60 330 160 530 PERCH 44 31 8.4 95 310 79 760 PIKE 62 35 14 110 360 130 870 PIKE-PERCH 2 20 16 24 270 230 310 ROACH 1 6.8 6.8 6.8 69 69 69 SILVER BREAM 4 14 8.9 26 140 110 190 VENDACE 12 12 2.6 55 93 64 110 LXNCELMXVESI BREAK 6 10 4.7 IB 120 96 150 BURBOT 3 35 12 67 390 250 600 EEL 2 63 44 82 930 590 1300 IDE 3 B 5.3 9.7 130 78 190 PERCH 13 38 11 110 420 170 920 PIKE 8 31 12 49 400 260 580 PIKE-PERCH 7 48 16 120 510 340 1100 ROACH 6 9.9 3.4 17 110 68 150 RUDD 3 7.3 3 12 120 72 150 SHELT 1 4 4 4 88 88 88 VENDACE 3 9.1 6 13 110 95 140 WHITEFISH 7 12 3.4 18 140 80 210 NÄSIJÄRVI BREAK 2 IS 13 16 280 270 290 BURBOT 2 59 26 91 1000 580 1500 PERCH 2 48 28 68 1100 600 1500 PIKE 1 69 69 69 1100 1100 1100 PIKE-PERCH 2 76 75 76 1400 1200 1600 ROACH 1 13 13 13 230 230 230 SMELT 1 9 9 9 190 190 190 TROUT 1 23 23 23 380 380 380 WHITEFISH 2 17 15 19 320 310 340 PYHXJXRVI BREAK 6 4.1 2.5 5.6 49 39 60 BURBOT 6 19 5.5 40 210 110 370 EEL 4 12 9.1 13 81 72 89 PERCH 12 16 4.6 40 190 100 320 PIKE 6 16 5.3 24 200 110 380 PIKE-PERCH 6 19 12 36 240 180 320 ROACH 1 3.1 3.1 3.1 57 57 57 SILVER Br.CAM 3 7.7 6.5 8.8 87 73 100 SMELT 2.5 2.5 2.5 51 51 51 WHITEFISH 5.1 2.7 8 85 66 110 PÄLKÄNEVESI BREAM 5.6 2.9 9.4 67 58 77 PERCH 7.7 7.7 7.7 160 160 160 PIKE 28 5.8 46 300 130 420 VENDACE 1.5 1.5 1.5 37 37 37 VANAJAVESI EEL 20 18 21 160 150 170 VEHKAJXRVI PERCH 450 110 1000 4500 2500 8600 PIKE 430 420 430 4300 3600 5000 ROACH 190 71 310 2100 1600 2600 VENDACE 150 47 v 310 1700 1100 2500 53 FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY STUK-A129 Table X continued 134 PROVINCE FISH C,s Cc LAKE SPECIES n X mln max X mln max VESIJÄRVI BREAM 5 21 1.9 65 99 56 127 (KANGASALA) BURBOT 2 65 37 93 600 430 770 PERCH 11 33 7 77 400 140 630 PIKE 6 26 12 45 300 220 410 PIKE-PERCH 6 35 16 65 390 210 570 ROACH 1 3.3 3.3 3.3 82 82 82 VENDACE 1 3.1 3.1 3.1 71 71 71 WHITEFISK 3 7.1 5.5 8.3 97 86 110 VESIJÄRVI EEL 1 17 17 17 160 160 160 (LAHTI) BLEAK 1 2.9 2.9 2.9 66 66 66 BREAM 1 2.5 2.5 2.5 48 48 48 PERCH 2 3.7 3.4 3.9 80 71 89 ROACH 1 2.9 2.9 2.9 56 56 56 CENTRAL FINLAND KEITELE BREAM 4 29 10 62 330 190 520 BURBOT 7 92 30 230 1000 420 2000 PERCH 19 56 19 130 600 330 1400 PIKE 8 64 1 120 740 180 1100 ROACH 10 33 13 69 360 180 590 VENDACE 1 13 13 13 160 160 160 WHITEFISH 3 31 19 40 310 200 430 XEURUSSELKÄ BREAM 1 8..6 8..6 8.,6 210 210 210 BURBOT 3 67 IS 96 700 340 920 IDE 1 40 40 40 330 330 330 PERCH 5 31 25 35 440 370 S30 PIKE 5 52 33 92 670 600 750 PIKE-PERCH 1 26 26 26 540 540 540 VENDACE 2 19 17 20 190 190 200 WHITEFISH 3 29 7,.9 49 370 170 660 KIVIJÄRVI BURBOT S 120 39 210 1500 900 2000 PERCH 7 120 45 330 1200 390 2900 PIKE 7 160 65 310 1800 1200 2600 PIKE-PERCH 2 180 110 240 1800 1500 2200 ROACH 4 52 29 94 550 410 860 VENDACE 1 28 28 28 270 270 270 WHITEFISH 6 41 15 79 460 330 680 KOLIMA PERCH 1 16 16 16 130 130 130 RUFF 1 14 14 14 110 110 110 KONNEVESI PERCH 2 33 32 33 700 690 710 PIKE 1 54 54 54 1200 1200 1200 ROACH 1 11 11 11 250 250 250 VENDACE 1 7 .1 7 .1 7.1 160 160 160 WHITEFISH 1 6.1 6.1 6.1 130 130 130 MUURUEJARVI PIKE 1 24 24 24 550 550 550 54 FINNISH CENTRE FOR RADIATION STUK-A129 AND NUCLEAR SAFETY Table X continued 134. FISH 137c SPECIES min SUOHTEE BREAM 5 9.3 4.3 15 110 74 130 BURBOT 4 49 21 110 600 340 960 CRUSIAK CARP 1 17 17 17 400 400 400 IDE 1 6.3 6.3 6.3 75 75 75 PERCH 9 70 29 200 860 410 1900 PIKE 4 46 19 70 610 450 700 ROACH 4 16 12 21 240 190 270 RUDD 1 14 14 14 160 160 160 SMELT 2 24 16 32 270 220 320 VEHDACE 3 11 7.7 14 190 180 210 WHITEFISH 3 14 7.1 27 190 140 250 VUOSJXRVI PERCH 2 38 37 39 600 570 630 PIKE 1 52 52 52 1000 1000 1000 NILAKKA BREAM 2 21 20 21 240 190 290 BURBOT 2 67 66 68 680 610 760 PERCH 3 30 21 40 310 280 390 PIKE 2 59 37 81 580 480 670 ROACH 2 16 15 21 180 170 180 WHITEFISH 2 14 12 16 140 140 150 SORSAVESI BREAM 2 82 29 140 910 650 1200 PERCH 12 120 39 230 1400 820 2500 PIKE 6 160 100 260 2000 1300 2400 ROACH 4 26 3 50 380 370 400 VENDACE 1 53 53 53 480 480 480 KYMI SIMPELEJÄRVI PERCH 3 1.2 0.99 1.6 14 7.5 22 PIKE 1 1.7 1.7 1.7 13 13 13 ROACH 2 0. 89 0 .89 0.89 4.4 3.9 4.9 VENDACE 1 0.92 0 .92 0.92 4.7 4.7 4.7 VUOHIJÄRVI BURBOT 4 61 32 120 600 4 00 990 PERCH 8 41 13 73 4 80 320 710 PIKE 6 60 14 85 740 380 1100 ROACH 6 15 S.4 25 190 130 250 VENDACE 3 16 11 23 170 130 210 VHITEFISH 6 20 3.7 68 120 94 170 BREAM 5 4.7 2.3 9.4 63 34 91 BURBOT 6 27 5.8 57 300 140 540 IDE 1 4.2 4.2 4.2 49 49 49 PERCH 7 17 4 39 220 97 330 PIKE 6 23 7.6 36 270 190 370 PIKE-PERCH 2 12 9.1 IS 200 190 220 WHITEFISH 1 5.8 5.8 5.8 56 56 56 55 FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY STUK-A129 Table X continued 34 PROVINCE FISH I ,C.c CG LAKE SPECIES n X mln max X mln max KORPIJXRVI BURBOT 3 60 44 71 610 S40 710 PERCH 14 40 9.1 160 460 210 1400 PIXE 3 43 37 53 560 490 660 RUFF 1 5.5 .'». 5 5.5 110 110 110 VENDACE 2 11 10 12 120 120 130 UHITEFISH 2 6.4 3.2 9.6 100 79 130 PURUVESI BREAM 2 28 25 30 270 260 280 BURBOT 3 36 25 52 410 350 510 PERCH 7 48 19 69 570 460 690 PIKE 4 64 19 140 720 430 1200 ROACH 5 17 8.7 28 200 120 260 VENDACE 3 10 5.5 14 140 120 160 UHITEFISH 5 9..5 4.1 IB 100 78 140 PUULA BLEAK 1 12 12 12 110 110 110 BREAM 1 23 23 23 250 250 250 BURBOT 3 23 11 39 320 240 440 PERCH 10 33 15 67 390 220 600 PIKE 4 3S 12 58 390 300 510 ROACH 3 15 10 23 ISO 120 190 RUFF 1 25 25 25 300 300 300 SMELT 2 13 9.6 17 120 98 140 TROUT 1 24 24 24 260 260 260 VENDACE 4 6,.9 4.1 13 91 38 130 UHITEFISH 2 6 .5 5.2 7..8 100 77 130 SUONTEE PIKE 1 34 34 34 310 310 310 OULU ONTOJXRVI BURBOT 1 30 30 30 700 700 700 PERCH 2 16 13 18 430 370 500 PIKE 1 13 13 13 340 340 340 ROACH 1 3 .1 3.1 3 .1 85 B5 85 TROUT 1 6 .3 S.3 6 .3 170 170 170 VENDACE 1 3 .1 3.1 3 .1 70 70 70 UHITEFISH 1 3.1 3.1 3 .1 72 72 72 NORTH KARELIA ORIVESI BREAM 5 1 .5 0.6 3.6 24 17 39 BURBOT 5 2.8 1.2 7 .4 53 36 94 PERCH 12 2.9 1.1 6.6 53 35 86 PIKE 5 8 .9 1.1 32 58 41 75 PIKE-PESCH 6 3.8 1 8.9 120 47 390 ROACH 6 0.77 0 1.4 13 1.6 20 SMELT 1 0 .55 0.5S 0 .55 18 IB 18 VENDACE 2 0 .67 0.55 0 .8 IS 12 17 UHITEFISK 4 2.5 0.51 5.9 31 13 75 56 FINNISH CENTRE FOR RADIATION STUK-A129 AND NUCLEAR SAFETY Table X continued 134 l37 PROVINCE FISH Cs C£ LAKE SPECIES n X min max X Din max TURKU AND PORI KYRÖSJARV1 BREAM 12 7.4 2.1 13 89 36 120 BURBOT 21 28 11 60 330 160 530 PERCH 44 31 8.4 95 310 79 760 PIKE 62 3S 14 110 360 130 870 PIKE-PERCH 2 20 16 24 270 230 310 ROACH 1 6.8 6.8 6.8 69 69 69 SILVER BREAK 4 14 8.9 26 140 110 190 VENDACE 12 12 2.6 55 93 64 110 PYHXJXRVI BREAM 1 4.7 4.7 4.7 59 59 59 PERCH 3 21 11 33 230 190 290 PIKE 3 11 4.8 21 120 75 180 ROACH 2 3.8 2.4 5.2 54 47 60 VENDACE 1 1.4 1.4 1.4 25 25 25 WHITEFISH 3 S 2.2 8.9 64 35 110 UUSIMAA a LOHJANJXRVI EEL 5 o 0 0 10 4.5 17 VAASA LESTIJXRVI BURBOT 3 38 26 50 580 520 630 PERCH a 28 15 40 450 320 620 PIKE 4 29 16 47 420 340 SOO ROACH 4 14 7.2 21 200 160 2S0 VENDACE • 4 25 8.4 68 150 120 200 UHITEFISH 4 14 9.2 20 210 180 270 below the detection limit 57 FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY STUK-A129 Table XI. Jhe average activity concentrations (x) and the variation in "CC E and CE (Bq/kg fresh weight) in various fish species in lakes with a surface area smaller than 20 km but larger than 1 km (class 3) in 1991 - 1994. The number of samples is also given (n). 134 137 PROVINCE FISH CE Cs LAKE SPECIES n X min max X min max HXME EKOJSRVI PIKE 1 190 190 190 1600 1600 1600 KERNAALANJXRVI EEL 5 48 7. 7 96 340 19 780 KERTEJXRVI BREAK 3 53 50 56 530 470 590 BURBOT 3 290 220 340 2900 2200 3700 PERCH 6 80 47 190 790 500 1900 PIKE 3 200 170 250 2000 1400 2900 ROACH 3 38 28 54 350 300 410 VENDACE 1 26 26 26 240 240 240 UHITEFISH 3 35 26 49 330 300 400 HIESTAMX VENDACE 2 47 22 71 570 540 610 MYLLYJXRVI PERCH 12 170 53 360 2300 1300 4300 PIKE 5 270 120 450 3800 2700 4700 ORMAJXRVI EEL 1 40 40 40 310 310 310 VAHOJXRVI PERCH 3 35 18 61 600 290 1100 PIKE 2 45 40 49 830 750 920 ROACH 2 13 11 14 240 220 260 CENTRAL FINLAND ANGESSELKK BREAM 1 4.8 4. 8 4.8 79 79 79 BURBOT 1 36 36 36 430 430 430 KOLKKU PIKE 2 56 52 59 570 520 620 PETXjXVESI BREAM 6 10 3.2 19 120 74 160 PERCH 13 33 6.3 74 360 98 1000 PIKE 6 38 IS 57 440 250 600 ROACH 6 14 3.5 38 160 65 350 VALKEAJXRVI BREAM 1 24 24 24 570 570 570 PERCH 15 150 45 320 1700 980 2900 PIKE 6 280 98 510 3100 2200 4300 ROACH 4 50 26 72 710 570 810 KUOPIO ISO-II PERCH 2 2.5 2. 3 2.7 24 22 26 PIKE 1 2. 6 2. 6 2.6 27 27 27 PIKE-PERCH 1 5 S 5 51 51 51 MIKKELI PIEKSXNJXRVI BLEAK 1 36 36 36 5S0 550 550 BREAM 3 33 17 44 490 410 540 BURBOT 2 370 370 380 3200 3100 3400 PERCH 12 180 56 550 2100 900 5400 PIKE 7 160 59 370 2000 1400 2900 ROACH 4 69 27 150 790 550 1300 VENDACE 3 82 64 95 740 720 760 58 FINNISH CENTRE FOR RADIATION STUK-A129 AND NUCLEAR SAFETY Table XI continued 134,, 137 PROVIHCE FISH CG Cs LAKE SPECIES n X nin taax X nin max PYHSJXRVI BREAM 3 53 35 64 710 280 1000 BURBOT 3 280 110 570 3400 2500 4800 IDE 1 21 21 21 420 420 4 20 PERCH 12 140 58 270 1800 1200 2500 PIKE 6 290 87 680 3200 1800 6300 ROACH 5 110 35 200 1200 790 1600 VENDACE 2 72 45 98 730 590 870 VANAJAJKRVI PERCH 10 210 92 430 2300 1800 3600 PIKE 3 260 150 340 2600 1900 3300 ROACH 3 89 71 120 880 660 1100 WHITEFISH 3 63 53 69 830 610 1200 OULU HYRYNJÄRVI BURBOT 5 9.9 1.4 35 72 45 96 PERCH 12 4.3 1.2 10 82 24 150 PIKE 6 3.7 1.6 5.8 65 52 79 ROACH 4 1.8 1.4 2.4 28 20 35 VENDACE S 0.97 oa 1.6 20 15 24 WHITEFISH 5 1.4 0 2.4 24 20 31 TURKU AND PORI JÄMIJÄRVI BREAM 4 4.9 3.1 7. 5 41 21 61 PERCH 1 22 22 22 190 190 190 PIKE 4 15 3.9 31 150 75 260 PIKE-PERCH 4 15 6.2 24 170 130 230 KÖYLIÖNJARVI BLEAK 1 1.7 1.7 1.7 19 19 19 BREAM 1 1.3 1.3 1.3 14 14 14 PERCH 3 2.9 1.3 4. 8 37 19 55 PIKE 1 3.5 3.5 3.5 41 41 41 ROACH 1 1.5 1.5 1.5 15 15 15 RUFF 1 0.79 0.79 0.79 7.9 7.9 7.9 UHITE BREAM 1 0.96 0.96 0.96 9.5 9.5 9.5 RUOJSRVI PERCH S 68 49 94 650 510 820 PIKE 3 100 99 100 940 B30 1000 ROACH 2 54 51 56 490 490 500 VAHOJRRVI BURBOT 2 93 74 110 960 940 980 PERCH 6 78 48 130 870 610 1300 PIKE 3 130 62 200 1400 850 1700 ROACH 3 22 18 26 280 240 300 RUI'F 1 16 16 16 210 210 210 below the detection limit 59 FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY STUK-A129 Table XI continued 137_ PROVINCE FISH 134Cc Cs LAKE SPECIES n X min max X oin max UUSIHAA KYTXJXRVI BREAM 1 0.83 0.83 0.83 8.4 8.4 8.4 PERCH 7 1.6 1.1 2.1 13 9.3 20 PIKE 1 1.7 1.7 1.7 16 16 16 PIKE-PERCH 2 2.1 1.9 2.2 21 20 22 ROACH 2 0.39 o" 0.77 6.4 5.9 6.9 VAASA ULLAVANJXRVI BREAM 4 16 2.9 35 200 120 320 BURBOT 1 SO 50 50 1000 1000 1000 PERCH 7 35 11 61 420 220 750 PIKE 4 S3 14 100 640 320 890 ROACH 1 4.6 4.6 4.6 120 120 120 below the detection limit 60 FINNISH CENTRE FOR RADIATION STUK-A129 AND NUCLEAR SAFETY Table XII. The.average activity concentration!: (x) and the variation by province in Cs and Cs (Bq/kg fresh weight) in various fish species in lakes with surface area of less than 1 km" (class 4) in 1991 - 1994. The number of samples is also given (n). 134 137 FISH Cs Cs SPECIES n min max X min max HUME BLEAK 3 42 33 48 390 330 420 BREAM 10 SS 16 120 640 390 1S00 BURBOT 1 96 96 96 900 900 900 EEL 27 110 6.1 410 1300 56 4100 PERCH 203 260 27 840 3000 120 7500 PIKE 42 780 59 1500 8000 1300 16000 ROACH 17 71 22 250 770 2S0 2100 RUFF 1 92 92 92 910 910 910 «HITEFISH 21 140 30 270 1300 310 2200 CENTRAL FINLAND PERCH 2 10 8.S 12 ISO 140 170 PIKE 1 69 69 69 560 S 60 560 ROACH 2 21 17 2S 190 140 240 BREAM 5 9.,1 4. 2 14 110 91 130 IDE 1 32 32 32 400 400 400 PERCH 17 63 20 180 780 120 1500 PIKE 9 86 13 230 970 310 2100 ROACH 10 43 1.9 100 450 41 990 WH1TEFISH 6 34 10 56 390 220 530 MIKKELI BURBOT 1 35 3S 35 800 800 800 PERCH 7 39 IS 9B 520 3S0 880 PIKE 5 74 30 150 930 700 1400 ROACH 5 24 12 45 320 250 430 RUFF 3 20 5.,3 41 260 130 410 TURKU AND PORI PERCH 9 25 7..6 52 330 ISO 470 PIKE 7 41 15 71 440 290 610 ROACH 6 7.5 2,.5 12 100 60 130 UUSIMAA PERCH 4 5.8 4.7 6.9 59 49 74 PIKE 1 12 12 12 120 120 120 ROACH 1 3.5 3.5 3.5 36 36 36 TROUT 1 3.7 3.7 3.7 33 33 33 ALAND PERCH 32 7.1 78 410 170 910 PIKE 41 41 470 470 470 61 FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY STUK-A129 Table XIII. Transfer coefficients from deposition to three fish groups: (A) predators, (B) non-predators and (C) intermediate (Bq kg ~*/Bq m~2), in statistical fisheries 1-7 and in the whole country in 1991-1994. Fishery Fish 1991 1992 1993 1994 group 1 A 0.013 0.035 0.027 0.027 B 0.005 0.009 0.008 0.006 C 0.003 0.031 0.029 0.030 2 A 0.041 0.041 0.026 0.033 B 0.009 0.011 0.010 0.006 C 0.047 0.025 0.022 0.035 3 A 0.073 0.057 0.062 0.049 B 0.023 0.016 0.012 0.018 C 0.060 0.068 0.045 0.031 4 A 0.049 0.039 0.041 0.031 B 0.013 0.016 0.014 0.012 C 0.026 0.025 0.021 0.025 5 A 0.030 0.032 0.023 0.015 B 0.005 0.004 0.007 0.004 C 0.018 0.017 0.017 0.019 6 A 0.061 0.036 0.056 0.031 B 0.022 0.012 0.014 0.011 C 0.032 0.031 0.028 0.023 7 A 0.022 0.029 0.026 0.067 B 0.008 0.011 0.010 0.014 C 0.024 0.019 0.011 0.043 Whole A 0.063 0.056 0.054 0.040 country B 0.015 0.015 0.015 0.013 C 0.037 0.039 0.032 0.033 All fish 0.037 0.036 0.032 0.029 62 FINNISH CENTRE FOR RADIATION STUK-A129 AND NUCLEAR SAFETY STUK-A reports STUK-A -sarjan julkaisuja STUK-A128 Savolainen S, Kairemo STUK-A121 Ikäheimonen TK, K, Liewendahl K, Rannikko S. Klemola S, Uus E, Sjöblom K-L. Radioimmunoterapia. Hoidon radio- Monitoring of radionuclides in the nuklidit ja annoslaskenta. vicinities of Finnish nuclear power plants in 1991-1992. Helsinki 1995. STUK-A127 Arvela H. Asuntojen radonkorjauksen menetelmät. STUK-A120 Puranen L, Jokela K, Hietanen M. Altistumismittaukset STUK-A126 Pöllänen R, Toivonen suurtaajuuskuumentimien hajasätei- H, Lahtinen J. OTUS-reactor lykentässä. Helsinki 1995. inventory management system based on ORIGEN 2. STUK-A119 Voutilainen A, Mäkeläinen I. Huoneilman radon- STUK-A125 Pöllänen R, Toivonen mittaukset Itä-Uudenmaan alueella: H, Lahtinen J, Ilander T. Transport Tilannekatsaus ja radonennuste. of large particles released in a Askola, Lapinjärvi, Liljendal, nuclear accident. Loviisa, Myrskylä, Mäntsälä, Pernaja, Pornainen, Porvoo, STUK-A124 Arvela H. Residential Porvoon mlk, Pukkila, Ruotsin- radon in Finland: Sources, variation, pyhtää ja Sipoo. Helsinki 1995. modelling and dose comparisons. Helsinki 1995. STUK-A118 Reiman L. Expert judgment in analysis of human and STUK-A123 Mustonen R, Aaltonen organizational behaviour in nuclear H, Laaksonen J, Lahtinen J, Ranta- power plants. Helsinki 1994. vaara A, Reponen H, Rytömaa T, Suomela M, Toivonen H, Varjoranta STUK-A117 Auvinen A, Castren T. Ydinuhkat ja varautuminen. O, Hyvönen H, Komppa T, Helsinki 1995. Mustonen R, Paile W, Rytömaa T, Salomaa S, Servomaa A, Servomaa STUK-A122 Rantavaara A, Saxen K, Suomela M. Säteilyn lähteet ja R, Puhakainen M, Hatva T, Ahosilta vaikutukset. Helsinki 1994. P, Tenhunen J. Radioaktiivisen laskeuman vaikutukset vesihuoltoon. STUK-A116 Säteilyturvakeskuksen Helsinki 1995. tutkimushankkeet 1994-1995. Mustonen R, Koponen H (toim.). Helsinki 1994. 1 FINNISH CENTRE FOR RADIATION AND NUCLEAR SAFETY STUK-A129 STUK-A115 Leszczynski K. STUK-A107 Karppinen J, Assessment and comparison of Parviainen T. Säteilyaltistus sydän- methods for solar ultraviolet radi- angiografiatutkimuksissa ja kine- ation measurements. Helsinki 1995. angiografialaitteiden toimintakunto. Helsinki 1993. STUK-A114 Arvela H, Castren O. Asuntojen radonkorjauksen kustan- STUK-A106 Servomaa A, Komppa nukset Suomessa. Helsinki 1994. T, Servomaa K. Syöpäriski säteilyhaittana. Helsinki 1992. STUK-A113 Lahtinen J, Toivonen H, Pöllänen R, Nordlund G. A STUK-A105 Mustonen R. Building hypothetical severe reactor accident materials as sources of indoor ex- in Sosnovyy Bor, Russia: Short-term posure to ionizing radiation. Helsinki radiological consequences in south- 1992. ern Finland. Helsinki 1993. STUK-A112 Uus E, Puhakainen M, Saxen R. Gamma-emitting radionuclides in the bottom sedi- ments of some Finnish lakes. The full list of publications is Helsinki 1993. available from STUK-A111 Huurto L, Jokela K, Täydellisen listan STUK-A - Servomaa A. Magneettikuvaus- sarjan julkaisuista saa laitteet, niiden käyttö ja turvallisuus Suomessa. Helsinki 1993. Säteilyturvakeskus STUK-A110 Jokela K. Broadband Julkaisutoimikunta/Sihteeri electric and magnetic fields emitted PL 14 00881 Helsinki by pulsed microwave sources. Puh. +358 0 759 881 Helsinki 1994. STUK-A109 Saxen R, Aaltonen H, Ikäheimonen TK. Airborne and deposited radionuclides in Finland in 1988-1990. Supplement 11 to Annual Report 1989. Helsinki 1994. STUK-A108 Arvela H, Mäkeläinen I, Castren O. Otantatutkimus asuntojen radonista Suomessa. Hel- sinki 1993. SÄTEILYTURVAKESKUS Strolsäkerhetscentralen Finnish Centre for Radiation and Nuclear Safety ISBN 951-712-091-5 „ mmmmmmmimm