Scientific reports and information by the Contracting Parties and IAEA

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1 HELSINKI COMMISSION HELCOM MORS EG 1/211 Expert Group on Monitoring of Radioactive Substances in the Baltic Sea First Meeting Roskilde, Denmark, May 211 Agenda Item 4 Scientific reports and information by the Contracting Parties and IAEA Document code: 4/1 Date: Submitted by: Russia RADIOACTIVITY OF THE BALTIC SEA, 21 This document contains the report by V.G. Khlopin Radium Institute (St. Petersburg, Russia) on results of the Gulf of Finland and Baltic Sea Monitoring in 21 (seawater, sediments, fish). The Meeting is invited to take note of the information. Page 1 of 13

2 RADIOACTIVITY OF THE BALTIC SEA, 21 V.Tishkov, A. Stepanov, A. Osokina, A. Maksimova, I. Saveljeva, L. Sedova, A. Sadykin V.G. Khlopin Radium Institute, St. Petersburg, Russia Abstract In 21 the monitoring of radioactive contamination of the Baltic region has been continued. The Baltic Sea radioactivity data allow making a conclusion about the laws of radioactive nuclide behaviour in the environment. The research work on investigation the laws of Strontium-9 and Caesium-137 behaviour in bottom sediments has been continued because the bottom sediments play a tremendous role in monitoring of the environment and radioactivity of the Baltic Sea. THE RADIOACTIVE NUCLIDES IN THE RIVERS AND LADOGA LAKE WATERS Regular monitoring of Strontium-9 and Caesium-137 in waters of the Russian Baltic rivers (Neva, Luga and Narva) is carried out since 197. The analysis of river water allows making control of the large drainage territory including the basin of the Ladoga Lake. Sampling of water from the rivers is carried out usually in May, August and September. For determination of Caesium-137 and Strontium-9 in river water samples the volume of 5-6 liters is used. Results of Strontium-9 and Caesium-137 in the water samples taken from rivers, lakes and Ladoga Lake in 21 are given in Tables 1,2. Table 1 Strontium-9 and Caesium-137 in water of the rivers and lakes in 21 River Sampling Place Sampling Date 137 Cs Bq/m 3 9 Sr Bq/m 3 Neva Narva Luga 59 о 57,12 N 3 о 23,966 E 59 о 22,673 N 28 о 12,573 E 59 о 24,63 N 28 о 34,774 E ±4 7,5± 1, ,9±1, ,± 1, ,4±1, ±3 8,9± 1, ,±,8 Shepelevskoe lake ±3 7,3±1,5 Kalischenskoe lake ±5 9,3±2, Kopanskoe lake ±2 7,7±1,5 Voronka river <3 3,9±,8 Kovash river <2 1,9±,4 Sista river <2 2,9±,6 The analysis of results submitted in Table 1 shows that Strontium-9 in river and lake water from spring to autumn of 21 was within the limits from 1,9 to 9,3 Bq/m 3. Caesium-137 activity in river and lake waters was within the limits from background values up to 3 Bq/m 3, moreover the Caesium-137 activity in lake waters was higher than in river water. Probably it can be explained if we would consider the lake as closed ecosystem which has been contaminated as a result of Chernobyl accident. If compare Caesium-137 in water of these lakes to the same values of 29 we can state that they are at a former level (in Page 2 of 13

3 Shepelevskoe lake - 3,8 Bq/m 3, in Kalischenskoe lake - 3, Bq/m 3, in Kopanskoe lake - 29,7 Bq/m 3 ). As to dependence of Strontium-9 and Caesium-137 activity in the water of Neva, Narva and Luga rivers from the season of sampling we can make the conclusion that the highest concentrations are observed in May. Strontium-9 and Caesium-137 in water of the Ladoga Lake in 21 Sample Index Sampling Date Depth, m N Coordinates E 137 Cs Bq/m 3 Table 2 9 Sr Bq/m 3 L-1 surface ,887 L-1 bottom , ,887 L-2 surface ,9 L-2 bottom , ,9 3 23,7 7,5±1,5 3 23,7 6,2±1,2 3 24,694 3±1 7,1±1,4 3 24,694 4±2 6,5±1,3 L-3 surface о 18,1 L-3 bottom ,5 61 о 18,1 L-4 surface о 51,7 L-4 bottom ,5 6 о 51,7 L-5 surface о 59,9 L-5 bottom ,5 59 о 59,9 3 о 42,3 3 о 42,3 3 о 4,5 3 о 4,5 31 о 9,1 31 о 9,1 3±1 4,9±1, 7±2 6,1±1,2 7,8±1,6 8±3 6,7±1,3 <3 5,8±1,1 <4 5,5±1,1 Comparison of 9 Sr and 137 Cs in the water samples taken from the Ladoga Lake in 21 (mean concentration value of Sr 9 is 6,4 Bq/m 3, mean concentration value of Cs 137 is 5,5 Bq/m 3 ) with the results of previous years confirms that the radiation situation in the Ladoga Lake has not changed. RADIOACTIVE NUCLIDES IN THE BALTIC SEA WATER The results of Strontium-9 and Caesium-137 activity in the water samples taken from the Baltic Sea in 21 are submitted in Table 3. Table 3 Strontium-9 and Caesium-137 in the water samples taken from the Baltic sea in 21 Sample Index Coordinates N E Sampling Date Cs-137 Bq/m 3 Sr-9 Bq/m 3 Gulf of Finland F ±2 6,9±1,4 F-5 bottom ±2 7,1±1,4 F ±2 4,7±,9 F-1 bottom ,4± 1,9 F ,1±1,4 Page 3 of 13

4 F ±2 5,6± 1,1 F-12 bottom ,2± 1,6 F ±2 4,9±1, F-13 bottom ,7±1,1 F ±2 6,7±1,3 F-19 bottom ±4 6,±1,2 F ±2 6,9±1,4 F ±2 7,8±1,6 F ±2 8,2±1,6 F-27 bottom ±4 7,±1,4 F ±2 7,±1,4 F-28 bottom ±4 7,4±1,5 F ,8±2, F-32 bottom ±6 9,5±1,9 Baltic Sea B ,8±1,4 B ,±1,4 ВY ±4 7,3±1,5 BY ,8±1,4 Tritium in waters of the Ladoga Lake, Baltic rivers and Gulf of Finland The sources of tritium in the Baltic Sea are the atmospheric fallout, direct exchange of air moisture with water surface and surface water runoff of soil. In the Tables 4, 5, 6 the results of determination of tritium activity in waters of the Ladoga Lake, Neva, Luga, Narva rivers, Gulf of Finland and Baltic Sea are given. Table 4 Tritium in the Ladoga Lake water Sample index and N Coordinates E Depth, m Sampling date H 3, KBq/m 3 L , ,7 L ,9 3 о 23,7 L ,1 3 о 42,3 L ,7 3 4,5 2,4±1, ,5 2,±1,1 4,2±1, ,5 2,7±1,1 2,8±1, ,5 1,4±1,1 3,5±1, ,5 2,4±1,1 Page 4 of 13

5 L-5 59 о 59,9 31 о 9,1 2,6±1, ,5 2,9±1,2 Tritium content in the Ladoga Lake water lies between 1,4 and 4,2 KBq/m 3 and the mean value in surface samples is 3,1 KBq/m 3, and in bottom water 2,2 KBq/m 3. If we want to compare this values with previous year, the tritium content in the Ladoga Lake water in 29 was from 1,7 to 2,1 KBq/m 3. Sampling place Tritium in waters of the Neva, Luga, Narva rivers Sampling Date H 3, KBq/m 3 Table 5 Neva river ,8±1,2 Luga river ,5±1,2 Narva river ,2±1,1 Neva river ,8±1,3 Luga river ,4±1,2 Narva river ,4±1,2 Analysing the results of Table 5 we see that there is the negligible seasonal raise of tritium activity in the water of rivers: the highest values in September (from 3,4 to 4,8 KBq/m 3 ), and the lowest (from 1,2 to 1,8 KBq/m 3 ) - in May. Tritium in the water of Gulf of Finland and Baltic Sea in 21 Table 6 Sample index Depth, m Sampling date H 3, KBq/m 3 Gulf of Finland F-5 F-1 1,5±1, bottom <1 1,2±1, ,3±1,1 F ,7±1,2 F-12 F-13 F-19 2,6±1, ,7±1,2 1,6±1, <1 < bottom 1,4±1,1 F ,3±1,1 Page 5 of 13

6 F <1 F-27 F-28 F-32 1,7±1,2 13,5 <1 1,2±1,1 23 1,2±1,1 3,1±1,6 12 2,3±1,2 Baltic Sea BY ,5±1,3 BY ,5±1,1 B <1 B <1 The analysis of obtained results shows that the tritium content in 21 in the Gulf of Finland and Baltic Sea was within the limits of 1,2-3,1 KBq/m 3 that is typical for seas with the low water exchange between surface and bottom water and doesn t not differ from the values determined in Radioactive nuclides in the bottom sediments of the Gulf of Finland and Baltic Sea During the 21 no essential increase in the levels of contamination of the Baltic Sea bottom sediments by artificial radioactive nuclides was observed. The sources of radioactivity contamination of bottom sediments are still the fallouts as a result of the Chernobyl NPP accident in 1986 and global fallouts of 5-6th. The results of radioactive nuclide determination in bottom sediments of the Baltic Sea in 21 are presented in Table 7. The map of bottom sediment sampling is given at Fig 1 and Fig 2. Fig.1. Sampling map of the Koporskaya Bay and the central part of the Gulf of Finland in 21 Page 6 of 13

7 Fig. 2. The sampling map of the eastern part of the Gulf of Finland Table 7 Radioactive nuclides in the bottom sediments taken from the Gulf of Finland and the Baltic Sea in 21 Sample index, layer in cm 137 Cs Activity, Bq/kg (dry weight) 4 K 226 Ra 228 Ra F-1 (6 5N 29 2E) ± ±178 52±14 14± ± ±176 56±9 138± ± ±16 45±4 87± ±18 157±18 53±4 65± ± ±11 69±1 138± ±4 148±141 57±9 176± ± ±122 54±5 144± ±12 142±98 5±4 96± ±2 1174±16 43±3 69± ,2±1,3 1438±11 48±3 112± ,5±1,2 1248±1 4±3 9± ,5 <,6 1376±11 44±3 73±22 F-12 (6 5N 29 3E) -2 3± ±199 68±9 178± ± ±224 75±13 16± ± ±271 82±15 283± ± ±174 8±6 1± ± ±182 83±9 325± ± ±129 69±4 16± ± ±11 64±3 98± ± ±12 63±4 137±18 F-13 (6 2N 28 45E) -5 24±2 123±98 134±8 88± <,2 184±129 65±3 18±13 Page 7 of 13

8 F-14 (6 11N 28 44E) ±25 186±278 63±9 11± ± ±18 57±13 79± ±54 122±18 79±7 98± ±57 116±157 73±8 1± ±6 956±142 67±6 91± ±11 899±86 57±3 69± ±2 11±1 45±4 55± ±2 155±99 38±3 73± ±1,1 871±84 31±2 5±5 F-23 (59 49'N 25 3E) ±22 123±267 47±6 58± ± ±17 41±7 73± ±6 165±126 67±7 75± <6, 145±152 51±8 83± <2,4 123±143 52±5 85± <3,3 1326±114 6±4 77±9 F-25 (59 4'N; 24 'E) ± ± ± 9 52 ± ± ± ± 8 53 ± ± 51 9 ± 24 4 ± 7 64 ± ± ± ± 7 53 ± ± ± ± 6 56 ± ± 4 89 ± ± 7 63 ± ± 1 34 ± ± 6 56 ± <2 76 ± ± 5 62 ± 11 F-88 (6 16N 28 24E) -5 28±2 145±11 9±5 89±12 5-1(8) <,1 1825±128 74±4 111±2 F-12 (6 5N 29 3E) ±9 945±14 35±3 31± ±9 123±14 31±3 48± ±8 139±126 3±5 94± ±9 1324±128 38±6 49± ±1 75±91 31±2 53± ± ±96 42±4 59± ± ±99 35±2 64± ± ±14 35±4 9± ± ±12 39±6 117± ±4 168±91 39±3 91± ±2 <79 16±2 65± ±6 864±98 37±3 68± ±3 827±8 4±3 119± ,5 16±3 911±9 41±3 9±14 F-13 (6 5N 29 4E) -2 97±8 1563±188 67±15 134± ±7 1534±138 4±12 88± ±8 1512±136 45±7 157± ±1 1418±142 62±9 73± ±1 1479±118 43±4 77± ± ±89 39±2 76± ± ±97 41±3 84± ±1 1361±96 38±2 8±19 Page 8 of 13

9 B-6 (58 'N 2 45'E) ±25 115±279 <19 < ±2 982±273 28±8 74± ±1 785±179 24±6 59± ±24 774±289 <2 < ± ±215 32±8 88± ±5 112±119 34±1 45± ,5±3,1 119±16 23±6 53± <3,3 172±136 34±4 87± <3,7 1±119 39±4 58±11 B-5 (55 3'N; 18 53'E) -2 1,9±,7 1396±98 44±4 65± ,2±,4 997±8 41±2 42±1 BY-15 (57 2'N 2 3'E) -2 32±3 137±17 98±5 83± ±3 1353± ±7 13± ±2 151± ±7 96± ,8±1,7 1552± ±6 11± ,4±1,6 1321± ±7 93± <,9 1523± ±6 83± <,7 1463± ±9 92±23 In 21 the radioactive study of bottom sediments taken from the Gulf of Finland and Baltic Sea has shown that Caesium-137 activity is being on the same level that in previous year. The interesting fact is that the highest values (98 Bq/kg dry weight, 928 Bq/kg dry weight, 679 Bq/kg dry weight) of Caesium-137 activity in the bottom sediments were observed in the layers of 1-2 cm while the Caesium-137 content in surface layers was 1-3 Bq/kg dry weight. The data of Caesium-137 inventory in bottom sediments are given in Table 8. Caesium-137 inventory in bottom sediments Table 8 Layer, cm 137 Cs, Bq/m 2 F , ,5 261 Total F Page 9 of 13

10 Total 2972 F ,5 8 Total F F <1 Total 1183 F Total F Total 142 F ,71 Page 1 of 13

11 , , , , ,6 Total 2614 B , , , , , , , , ,49 Total 4178 BY , , , , , , ,42 Total 367 F , , , , , , , ,11 Total 6439 B , ,53 Total 183 On the base of the results of Table 7 the vertical distribution of Caesium-137 in bottom sediments is presented at Fig.3 (points F-1, F-12, F13 and F-12). The figure shows that for chosen samples the dependence of Caesium-137 activity from the depth has different character. Dependence of Caesium-137 activity decrease with the depth is typical for samples F-13, F-88, B-6, B-5. Page 11 of 13

12 Fig. 3. Vertical distribution of 137 Cs in the bottom sediments of the Gulf of Finland (F-1, F-12, F-12,F-13) Radioactive nuclides in fish taken from rivers and the Gulf of Finland The results of gamma-emitting radionuclide activity in fish samples are presented in Table 9. Fish samples due to small size of fish wasn t divided into parts and analyzed in whole. Caesium-137 content varies from 1,4 to 6,5 Bq/kg wet weight. Sample index Sampling place Radionuclide content in fish Activity, Bq/kg wet weight 137 Cs 4 K 226 Ra Table Ra SB-28 perch Gulf of Finland 6,5 ±,5 159 ± 13 1, ±,3 < 1, SB-28 roach SB-29 perch and roach SB-3 perch and roach SB-31 perch and roach Gulf of Finland 2, ±,2 152 ± 11 1,3 ±,3 4,6 ± 1, Kovash river 2,6 ±,2 171 ± 12 1,5 ±,2 3,8 ±,4 Voronka river 1,4 ±,4 135 ± 14 1,9 ±,3 4,7 ± 1,3 Sista river 4,8 ±,4 239 ± 22 2,4 ±,4 5,3 ± 1,7 Page 12 of 13

13 Strontium-9 in bottom sediments of the Gulf of Finland In samples of bottom sediments taken from the Gulf of Finland the activity of Strontium-9 was also determined. The results of these analyses are given in Table 1. Table 1 Strontium-9 in bottom sediments taken in 21 Sample index Layer, cm Sr 9 Bq/kg, dry weight F-12 F ,8±, ,8±, ,8±,8-5,7±,1 5-11,4±,8 The obtained results indicate the global level of Strontium-9 in bottom sediments. Comparison of Strontium-9 activity in bottom sediments taken in 21 from the Gulf of Finland with data of previous year shows that Strontium-9 content approximately remains on the same level. Conclusion In 21 the radioactive situation in the Baltic region again was determined by Caesium-137 from atmospheric fallout and as result of Chernobyl accident. In the decreasing of contamination in the Baltic Sea by Caesium-137 the great role belongs to the rivers. The activities of Caesium-137 in waters of the rivers and especially of the Ladoga Lake are negligible that provides the decrease of contamination of the Baltic Sea waters including the eastern part of the Gulf of Finland. The Strontium-9 and tritium activity in all observed regions doesn t exceed the levels of previous years. The gamma-spectrometer analysis data has again confirmed the various character of the Baltic Sea bottom sediments contamination. The analysis of the obtained results allow to draw a conclusion that radiation situation in the Baltic region remains on the same level. Page 13 of 13