HELCOM MORS-PRORadioactivity in the Baltic Sea

Erkki Ilus

STUK - Radiation and Nuclear Safety Authority, Finland

Sources of artificial radioactivity in the Baltic Sea

Total injections of Cs-137 and Sr-90 into the Baltic Sea from different sources

Source Cs‑137TBq

Percent of total amount

Sr‑90TBq

Percent of total amount

Chernobyl accident, incl. river discharges

4700300

82 80 13

Nuclear weapons tests 800 14 500 81

Discharges from nuclear reprocessing plants in Western Europe

250 4 40 6

Discharges into the Baltic Sea from local NPPs, cumulative amount up to 2006

1.5 0.03 0.73 0.1

Special features of the Baltic Seaincreasing its radioecological interest

• Location close to one of the test areas (Novaya Zemlya) of the nuclear weapons tests carried out in the 1950s - 1960s

• Small volume of water• Slow exchange of water• Climatic conditions• Large proportion of river waters• Low salinity of water• Scarce biota• Sensitivity of the biota to changes in environmental

circumstances

History of Radioecological studies / Monitoring of radioactive substances in the Baltic Sea

1959-1981 National studies in different countries (in Finland since 1959) - bilateral and multilateral international cooperation

1981-1984 Research programme on radioactive materials in the Baltic Sea coordinated by the IAEA (International Atomic Energy Agency)

1986-1995 HELCOM MORS Expert Group (Monitoring of Radioactive Substances) - first meeting in Helsinki 8-11 April 1986 - participated by 7 countries

1996- HELCOM MORS-PRO - 3-5 years projects - participated by 9 countries

HELCOM MORS-PRO

• All the Baltic Sea countries have ratified the Helsinki Convention• Helsinki Commission (HELCOM) coordinates the international co-

operation focusing on the implementation of the Convention• Recommendation 26/3 of HELCOM defines the programme for

Monitoring of Radioactive Substances (MORS) in the Baltic Sea• All the Baltic Sea countries contribute to the monitoring with their

own national programmes• The results are reported annually to the HELCOM data base• The results are published every five years in Periodical Assessment

Reports of HELCOM • Discharge data from all nuclear facilities operating in the Baltic Sea

area are reported annually to the Discharge Register of MORS

• STUK is responsible for the Finnish part of the programme (~120 annual samples from sea water, bottom sediments and biota)

• STUK is responsible for maintaining the Discharge Register

”Radiologically, the sea most affected by the Chernobyl accident was the Baltic, since the first radioactive clouds from Chernobyl travelled to north and caused high deposition in the area” (Povinec et al., IAEA Bulletin 1/1996)

The average caesium-137 activity of the surface seawater (Bq m-2) esti-mated for the reference year 1990 (Povinec et al., IAEA Bulletin 1/1996).

(The average values for the sub-regions in the Baltic Sea (in brackets) are based on Finnish data from 1990).

Terrestrial deposition of 137Csin the Baltic Sea drainage area (kBq m-2); compiled by STUK.

Date 15.8.1985 28.4.1986 (18:00) 21.5.1986 14.8.1986 9.7.1987 40K 650 590 690 690 750 54Mn 68 18 37 57 140 58Co 25 0a 0 14 8 60Co 100 70 110 94 84 65Zn 21 3.3 23 26 12 95Zr 0 690 110 4.2 0 95Nb 0 920 220 7.6 0 95mNb 0 10 0 0 0 103Ru 0 570 1900 52 0 106Ru 0 110 590 61 0 110mAg 9.5 2.2 170 62 23 125Sb 0 0 24 4.0 0 129mTe 0 22 2800 0 0 131I 0 410 29000 6.8 0 132Te 0 500 300 0 0 134Cs 0 8.3 710 140 86 136Cs 0 3.4 150 0 0 137Cs 7.0 25 1300 280 220 140Ba 0 1000 4700 0 0 140La 0 810 3700 17 0 141Ce 0 690 94 1.7 0 144Ce 0 360 130 7.1 0 144Pr 0 320 65 0 0 147Nd 0 230 0 0 0 237U 0 38 0 0 0 239Np 0 3500 0 0 0 a below the detection limit b not analysed

Gamma-emitting radionuclides in Fucus vesiculosus (Bq/kg-1 dry weight) at sampling station Olkiluoto A in 1985-1987

Estimated average con-centrations of 137Cs and 90Sr (Bq m-3) in the Both-nian Bay, Bothnian Seaand Gulf of Finland in1960-1982. (IAEA-TECDOC-362)

Activity concentrations of 137Cs in surface seawater at four stations in the Baltic Sea in 1974-2005. The activity concentrations of 40K in seawater: 1000 - 3000 Bq m-3.

Baltic Proper (BY 15,except 1989:BY 2) Bothnian Bay (C VI) Bothnian Sea (EB 1) Gulf of Finland (LL 3a)

Bq/m3

0

100

200

300

400

500

600

700

Year

1974

1976

1978

1980

1982

1984

1986

1988

1990

1992

1994

1996

1998

2000

2002

2004

2006

Activity concentrations of137Cs (Bq kg-1 dry weight)in Fucus vesiculosus along the Finnish coast in 1987and the Chernobyl falloutin the drainage areas of the rivers Kokemäenjoki (A), Kymijoki (B) and Vuoksi (C).

Activity concentrations of 137Cs(Bq kg-1 dry weight) in Fucus vesiculosus along the coasts of the Nordic countries in 1991.

The activity concentrations of 40Kin Fucus: 500 - 1000 Bq kg-1 d.w.

Vertical distribution (Bq kg-1 d.w.)of 137Cs in sediment profiles at a coastal station of the Gulf of Finland in 1986-2002.

0 1000 2000 3000 4000 5000 6000 7000

0

5

10

15depth [cm]

[Bq kg-1 d.w.]

1986

0 1000 2000 3000 4000 5000 6000 7000

0

5

10

15depth [cm]

1988

0 1000 2000 3000 4000 5000 6000 7000

0

5

10

15depth [cm]

1990

0 1000 2000 3000 4000 5000 6000 7000

0

5

10

15depth [cm] 1995

0 1000 2000 3000 4000 5000 6000 7000

0

5

10

15depth [cm]

2002

Total amounts of 137Cs (Bq m-2)in bottom sediments of the Baltic Sea in 1998.

Activity concentrations of 137Cs in Baltic herring and pike in four areas along the Finnish coast during 1975-2005.

Herring HailuotoHerring SeiliHerring TvarminneHerring VaasaPike HailuotoPike SeiliPike TvarminnePike Vaasa

Bq/kg f.w.

0

100

200

300

Year1970 1975 1980 1985 1990 1995 2000 2005

Ringed seal

(Phoca hispida)

Grey seal

(Halichoerus grypus)

Gulf of Finland

May 1986 - November 1988

SW coast of Finland

1987 - 1988

98 + 5 (71 - 120) 176 + 63 (117 - 280)

Activity concentrations of 137Cs (Bq kg-1 fresh weight) in seal fleshon the Finnish coast after the Chernobyl accident.

Radiation doses• The exposure of the population to radiation caused by ingesting

Baltic Sea fish and other marine products and living by the sea after the Chernobyl accident was evaluated in the EC/ Marina Balt Project in 1996-1998

• The dose for the Critical Groups living on the coasts of the Bothnian Sea and the Gulf of Finland peaked at 0.2 mSv in 1986

• This can be considered a very low value, as on an average,

a Finn receives an annual 3.7 mSv dose from other sources (2 mSv year-1 from indoor radon)

• Since 1986, the impact of the Chernobyl fallout has significantly decreased in the Baltic Sea

• At the same time, individuals in the critical groups had a dose rate of 0.7 mSv year-1 from polonium-210 occurring naturally in the sea.

• The average internal radiation dose from Baltic Sea fish to Finnish

people was 0.01 mSv in 1986 and 0.002 mSv in 2006.