NO9700044 PLUTONIUM IN FISH, ALGAE, AND SEDIMENTS IN THE BARENTS, PETSHORA, AND KARA SEA

T. K. Dcaheimonen, K. Rissanen, *D. G. Matishov and *G. G. Matishov Finnish Centre for Radiation and Nuclear Safety, Finland "Murmansk Marine Biological Institute,

INTRODUCTION

This work contributes to the joint research programme between the Finnish Centre for Radiation and Nuclear Safety (STUK) and the Murmansk Marine Biological Institute (MMBI) in the Arctic. Attention has been focussed to measuring amounts and locating possible sources of artificial radionuclides in the Russian Arctic Sea area. Sediments, algae, bottom fauna and fish samples were collected by experts from STUK and MMBI during several scientific expeditions organized by MMBI in 1993 and 1994W. The first results on plutonium concentrations in fish, algae and sediment samples analysed by STUK are presented in this paper.

MATERIALS AND METHODS

Commercial fish species: arctic cod, haddock, seithe, seacat, plaice, flounder, halibut, redfish, and also ray were collected by trawling on the most common fishing areas of the in 1993 and 1994. 20 plutonium analyses have been so far performed on fish flesh, bone, and liver samples. Flesh and bones were dried and homogenized before analysing. Liver samples were analysed fresh.

Red and brown algae were collected at the shoreline or by diving at nine locations in the Barents, Petshora, and White Sea (Fig. 1). One species of red and five of brown algae, twelve samples altogether, were analysed for plutonium isotopes. Samples were dried (105 °Q and homogenized before analysing.

Figure 1. Sampling sites for alga samples.

Sediment sampling was carried out using a Russian ocean crab, van Veen crab or a box corer. Top layer of sediment was collected from the crab with a spoon. Box corer allowed a more quantitative sampling. The samples were sliced with a large spatula. Surface sediment samples from 21 sites in the Barents Sea, surface and deeper sediment layers from nine sites in the Petshora Sea and seven sites in the Kara Sea were analysed for plutonium (Fig. 2.). Sediment samples were dried at 105 °C and homogenized before analysing.

227 Figure 2. Sampling sites for sediment samples.

and 239'240Pu was analysed with a method used in STUK3. Internal M2Pu tracer was used. After wet ashing and acid leaching (350 °C) of samples, plutonium isotopes were separated by means of anion exchange. Plutonium was electrodeposited onto a stainless steel disc. Alpha activity was measured with a semiconductor detector - multichannel analyser equipment. For quality assurance the analysis series also contained environmental reference samples of IAEA and reagent blancos.

RESULTS AND DISCUSSION

Fish 239-24OPu concentrations in the flesh of commercial fish species, arctic cod (Gadus callaris). haddock (Gadus aeglofinus). seacat (Anarhichas lupus), saithe (Gadus virens). and redfish (Sebastes marinus) were all below detection limits, 0.6 - 2 mBq/kg fresh weight. The flesh of ray (Raja radiatd). not consumed by man, contained slightly more plutonium, 7.9 mBq/kg f.w. This is probably due to the living habits of ray different from other fish species analysed. It lives near the bottom, and feeds mostly on bottom animals and also bottom deposits. All 238Pu concentrations of fish flesh were below detection limits (0.6 - 2 mBq/kg f.w.).

In other organs of fish, small amounts of "'-^u were detected only in three samples: bones of ray (4.9 mBq/kg f.w.), bones of cod head (43 mBq/kg f.w.), and liver of haddock (17 mBq/kg f.w.). Plutonium concentrations in all other bone samples (cod, haddock, seacat, plaice) and liver of cod were below detection limits.

228 All the observed plutonium contents in the fish of the Russian Arctic Sea areas investigated are at the same level as in earlier studies of fish and sea animals in the North Atlantic Ocean and Arctic Sea areas and do not show any exceptional concentrations of plutonium in fish in the Russian arctic area studied4-5-6.

Algae Results for plutonium concentrations in alga samples are presented in Table I. All the concentrations were low, but some differences were found between different species and also between sampling sites of the same species. Red alga (Ptilota plumosd) from the east shore of Ostrov contained 0.28 Bq/kg (d.w.) of 239-24OPu. Also "Co was detected in this sample2. In Fucus vesiculosus 239-240Pu concentrations varied from 0.035 to 0.23 Bq/kg d.w. In other brown alga species concentrations varied from 0.020 to 0.12 Bq/kg d.w. Differences of this order in plutonium concentrations are typical for alga samples taken at separate sites. All ^Pu concentrations were below the detection limit, 0.01 Bg/kg d.w.

In comparison to other studies in the Arctic waters and also to the Baltic Sea area the plutonium concentration in algae were at the same average level and did not show any source of excess plutonium in the area studied5-7-8-'.

Sediments ^'Pu and 239-24°Pu concentrations analysed in the Barents Sea surface sediments are presented in Table II. ""Pu concentrations varied from below detection limit to 0.14, and those of 2M'240Pu from 0.5 to 3.2 Bq/kg d.w. Plutonium concentration ratios (238Pu/23'-2<0Pu) ranged from 0.023 to 0.049, except for one sample (20a), where it was 0.082. Large uncertainty in measurements of ^'Pu near its detection limit can affect the ratio.

In the Petshora Sea area the "'-^Pu concentrations in the uppermost sediment layers varied from 0.27 to 4.3 Bq/kg d.w. (Table III). Among these, the highest amounts of plutonium were found at the sampling sites (7 and 8) south of . The ""Pu/239-24^ activity ratio varied from 0.028 to 0.066.

At some locations in the Kara Sea the sediment was softer and it was possible to sample also deeper layers, which allowed determination of vertical distribution and total amounts of plutonium in these cores. Plutonium concentrations varied from site to site and in one core also from depth to depth (Table IV). Highest concentrations of 239-240Pu and that of ^Pu, were found at a coastal sampling site (1) near the Ostrov . There also the greatest total amounts of 23'-240Pu and ^Pu were observed. The ^'Pu/^'-^Pu activity ratios varied from 0.027 to 0.046.

Sediment samples collected at the outlet of the Ob river (6) and the Yenisey river (13) did not show any exceptional plutonium concentrations.

In all the sea areas studied, ^Pu/23'-24^ isotopic ratios suggested a global fallout origin. Generally these plutonium results are in good agreement with other monitoring results in the same areas4-'-10. Although plutonium concentrations were slightly higher in the area near the Kara gate, it is not possible to draw any conclusion from these results of possible plutonium sources in the researched area. In the Barents Sea area, the variation was also of the same order of magnitude. In the Baltic Sea area this kind of variation was found both before and after the Chernobyl accident11-12. It is well known that many factors affect the radionuclide concentrations, e.g. topography of the bottom in the entire sea area and especially in the vicinity of the sampling site, type of sediment (soft or hard bottom), sedimentation rate, effects of river transport, mixing and transport of the paniculate matter by wave action and bottom currents. The type of bottom only, can affect the radioactivity concentration of sediment with a factor of 10 - 201J. Therefore more information is needed of the local variability of these factors.

The sampling locations of this study represent only the open sea areas with a free access; prohibited military areas of the North-west Russia with potential pollution sources are not included.

REFERENCES

1. Matishov D.G., Matishov G.G., Rissanen K. Peculiarities of radionuclide accumulation in benthonic organism and fish of Barents and Kara Sea. International conference on environmental radioactivity in the Arctic, Oslo, 1995.

229 2. Rissanen K. Matishov D.G. Matishov G.G. Radioactivity level in Barents, Petshora, Kara, Laptev and White Sea. International conference on environmental radioactivity in the Arctic, Oslo, 1995. 3. Taipale TK. et al. Radiochemical determination of plutonium and americium from seawater, sediment and biota samples, STUK-B-Valo 26,1985. 4. Strand P. et al, Survey af artificial radionuclides in the Barents Sea and the Kara Sea, J. Environ. Ra- dioactivity 25, 1994. p. 99-112 5. Aarkrog A. et al, Futher studies of plutonium and americium at Thule, Greenland, Health Physics 46, 1984. p. 29-44 6. Bowen V. et al, Distributions of transuranium nuclides in sediment and biota of the North Atlantic Ocean, Transuranium nuclides in the environment, IAEA, 1976. p. 107-120 7. Carlson L. et al, Radioactivity in Fucus vesiculosus from Baltic Sea following the Chernobyl accident, J. Environ. Radioactivity 15, 1992. p. 231-248. 8. Ilus E. et al, Radioactivity of Fucus vesiculosus along the Finnish coast in 1987, STUK-A83,1988. 9. Radioactive contamination at dumping sites for nuclear waste in the Kara Sea, Joint Russian-Norwegian Expert Group for Investigation of Radioactive Contamination in the Northern Areas, 1993 10. Hamilton T. et al, Radiometric Investigations of Kara Sea sediments and preliminary radiological assessment related to dumping of radioactive wastes in the Arctic Seas, J.Environ. Radioactivity 25, 1994. p. 113-134 11. Ilus E. et al, Monitoring of radionuclides in the Baltic Sea in 1989-1990, STUK-A103, 1993 12. Studies on environmental radioactivity in Finland 1984-1985, STUK-A54, 1987 13. Dcaheimonen TK. et al, Monitoring of radionuclides in the vicinity of Finnish nuclear power plants 1991-1992, STUK-A121,1995

Table I. 23tPu and 239-24OPu concentrations in red and brown algae in the Barents, Petshora and White Sea (for sampling sites see Fig 1).

Sample Sea area Date Bq kg"1 dry weight (± 16%) Sampling site ^Pu mwopy Ptilota plumosa Barents Sea (5) 18.7.1994 <0.01 0.28 (6) Kolguyev Laminaria saccharina Barents Sea (2) 12.7.1993 <0.01 0.057 (11) Seven Islands Laminaria saccharina Barents Sea (4) 21.7.1994 <0.01 0.029 (17) Kanin peninsula

Laminaria saccharina White sea (8) 23.7.1994 <0.01 0.039 (25) Chupa

Fucus vesiculosus Barents Sea (1) 11.7.1993 <0.01 0.076 (11) Dalnye Zelentsy Fucus vesiculosus Barents Sea (2) 12.7.1993 <0.01 0.11 (11) Seven Islands Fucus vesiculosus White Sea (9) 26.7.1994 <0.01 0.035 (25) Solovetsk Fucus vesiculosus Barents Sea (3) 1.8.1994 <0.01 0.23 (10) Ostrov Nokuyav

Fucus sp. Petshora Sea (7) 20.7.1993 <0.01 0.041 (25) Vaygach

Fucus sp. Petshora Sea (6) 23.7.1993 <0.01 0.12(12) Novaya Zemlya Laminaria sp. Petshora Sea (6) 23.7.1993 <0.01 0.042 (20) Novaya Zemlya

Chorda filum Barents Sea (3) 1.8.1994 < 0.01 0.020 (25) Ostrov Nokuyav

230 Table II. ^Pu and "'•wpu concentrations in sediments of the Barents Sea in 1993 (for sampling sites see Fig. 2). Sampling site Sample depth Date Bq kg"1 dry weight (+ 16%) cm ™Pu 1. -0-2 10.6. 0.037 (16) 0.63 (4) 2. -0-2 11.6. 0.062 (16) 1.7 (4) 3. -0-2 11.6. 0.074 (11) 2.0 (3) 4. -0-2 12.6. 0.050 (13) 1.2 (3) 5. -0-2 12.6. 0.073 (14) 1.9 (3) 6. -0-2 12.6. 0.021 (31) 0.87 (5) 7. -0-2 13.6. 0.053 (17) 1.6 (4) 8. -0-2 13.6. 0.025 (30) 1.1(6) 9. -0-2 14.6. 0.059 (13) 1.6 (3) 10. -0-2 15.6. 0.033 (23) 0.88(5) 11. -0-2 15.6. 0.095 (17) 1.9(5) 12. -0-2 16.6. 0.14 (14) 3.2 (4) 13. -0-2 16.6. 0.11 (11) 2.4 (3) 14. -0-2 17.6. 0.076 (9) 1.6 (3) 15. -0-2 18.6. <0.02 0-59(5) 17. -0-2 20.6. 0.047 (16) 1.0 (4) 18. -0-2 23.6. 0.049 (25) 0.94 (6) 19. -0-2 24.6. 0.052 (17) 1.1 (4) 20a. -0-2 24.6. 0.078 (23) 0.95 (6) 21. -0-2 26.6. <0.03 0.50 (9) 22. -0-2 26.6. <0.02 0.55 (9)

Table III. 23iPu and m240Pu concentrations in sediments of the Petshora Sea in 1993 (for sampling sites see Fig. 2). Sampling site Sample depth Date Bq kg"1 d.w. (+ 16%) an

1. 0-2 14.7. <0.03 0.40 (10) 2. 0-2 15.7. 0.049 (25) 1.1(5) 7. 0-2 16.7. 0.13 (15) 4.3(5) 2-4 0.13 (10) 3-7 (4) 8. 0-2 16.7. 0.17 (10) 2.6 (5) 2-4 0.062 (15) 1.5 (3) 15. 0-2 18.7. 0.037 (20) 13(5) 2-4 0.057 (12) 1.3 (3) 17. 0-3 19.7. <0.02 0.65 (5) 20. 0-2 19.7. <0.04 0.36 (8) 32. 0-3 25.7. < 0.02 0.27 (10) 33. 0-2 25.7. 0.053 (24) 1.0 (6)

231 Z39 2 Table TV. ^'Pu and - *°pu concentrations in the sediments of the Kara Sea in 1993 (for sampling sites see Fig. 2).

Sampling site Sample depth Date Bq kg"1 d.w. (± 16%) cm

1. 0-3 12.9. 0.10 (10) 2.2 (4) 3-5 0.10(12) 2.4 (4) 5-10 0.11 (12) 3.3 (4) 2 0-10 total BqnT 3.7 100

6. 0-2 15.9. 0.020 (20) 0.51 (5) 2-4 <0.02 0.46 (7) 4-6 <0.02 0.66 (5) 6-8 0.028 (35) 0.88 (6) 0-8 total Bqm~: - 24 7. 0-2 15.9. <0.02 0.55(7) 2-4 <0.02 0.46 (7) 9. 0-2 16.9. 0.034 (20) 1.1 (5) 2-4 0.030 (26) 1.1 (5) 4-6 0.047 (18) 1.2 (4) 6-8 0.048 (18) 1.2 (4) 0-8 total Bqm~z 1.3 37 10. 0-2 16.9. <0.02 0.18 (8) 11. 0-2 17.9. <0.02 0.30 (7) 13. 0-2 18.9. 0.026 (20) 0.74 (8) 2-5 0.029 (20) 0.65 (7) 5-8 0.042 (18) 1.1 (5) 8-11 0.040 (18) 1.1 (5) 11 - 14 0.041 (20) 1.2(5) 14-17 0.032 (20) 0.72 (6)

0-17 total BqnT2 2.5 67 asloteUkj

232