Anthropogenic radionuclides 137Cs and 90Sr in the southern Baltic Sea ecosystem

Abstract

The radioisotopes of caesium (¹³⁷Cs) and strontium (⁹⁰Sr) make the greatestcontribution to the radioactivity level due to artificial radionuclides in the BalticSea, where the level of ¹³⁷Cs contamination is higher than in any otherpart of the world ocean. The main sources of man-made radionuclides are the Chernobylaccident in 1986 and the nuclear weapons tests carried out in the 1950s and 1960s.This study discusses the distribution patterns and trends in activity concentrationsof ¹³⁷Cs and ⁹⁰Sr recorded in various compartments of the marineenvironment of the southern Baltic Sea. It is based on an investigation of radioactivesubstances as part of the Polish National Environmental Monitoring Programme.In 2010 the average concentration of ¹³⁷Cs in the southern Baltic was35 Bq m^-3, while the level of ⁹⁰Sr in these waters has remained at much the same levelin recent years (ca 8 Bq m^-3). The distribution of isotopes in the bottomsediments reflect historical events that can be identified in sedimentprofiles. The activity concentrations of the caesium isotope are the highestin sediments from the Gulf of Gdansk, whereas the least polluted sedimentsare found in the Bornholm Basin, in the western part of the southern Baltic.The highest concentrations of ¹³⁷Cs in benthic plants were measured in the red alga <i>Polysiphonia fucoides</i>: 22.3 Bq kg^-1 d.w. in June and 40.4 Bq kg^-1 in September. These levels were much higher than those found in the bivalve <i>Mytilus trossulus</i> (7.3 Bq kg^-1 d.w.). ¹³⁷Cs concentrations in fish have decreased in time, reflecting the trends recordedin seawater. In 2010 the respective ¹³⁷Cs activities in Clupea harengus, <i>Platichthys flesus</i> and <i>Gadus morhua</i> were 4.7, 4.9 and 6.6 Bq kg^-1 w.w

137Cs and 40K in gray seals Halichoerus grypus in the southern Baltic Sea

“…The calculation of TF values in the case of seals is justified by the fact that the bioaccumulation of heavy metals and radionuclides in larger sea organisms by means of food is a predominant route. The CF values for herring were within the range of 109 to 154 dm 3 kg −1 ww with a mean value of 123 dm 3 kg −1 ww, similar values were determined for the period 2000–2010 (Zalewska and Suplińska 2013 ). The TF values in placentas remained at a low level, between 0.85 and 2.42, and the average value was 1.34, indicating a small degree of biomagnification in the case of seal placentas.…”

“…In the period 2005–2011, the average annual load of 137 Cs from the Vistula River to the Gulf of Gdańsk was 406 GBq and from atmospheric fallout was 18.1 GBq (Saniewski and Zalewska 2016 ). Long-term observations of the changes in concentrations of 137 Cs in Baltic waters show that from 1991, the continuous decrease is observed (Zalewska and Suplińska 2013 ). Although the Vistula water is still sources of 137 Cs to the Gulf of Gdańsk, the input of 137 Cs is compensated by processes such as radioactive decay of 137 Cs, sediment deposition, and in minor extent bioaccumulation in flora and fauna organisms like macrophytobenthic plants and fish.…”

Marine Waste—Sources, Fate, Risks, Challenges and Research Needs

“…Presently, 137 Cs is the main indicator of anthropogenic radioactivity in the Baltic Sea. Compared to Chernobyl, releases from Fukushima Daiichi nuclear power plant were considerably smaller (estimated at 10–15% of the Chernobyl value) [ 56 , 104 , 106 , 107 ]. Literature sources give divergent data on the total activity released during accidents at both power plants.…”

“…The Chernobyl accident is responsible for 82% of 137 Cs input to the Baltic Sea, 14% come from nuclear weapons tests, and 4% from nuclear fuel reprocessing facilities in Sellafield (England) and La Hague (France) [ 56 ]. For 90 Sr, the proportions are reversed—81% come from the atmospheric testing of nuclear weapons and 13% from the Chernobyl release [ 106 ]. In recent years, nuclear reprocessing plants in Western Europe (Sellafield and La Hague) have become a minor source of radionuclides due to significant reductions in discharges [ 104 ].…”

Assessment of the External Exposure Dose to Humans From 137cs and 90sr in the Coastal Waters of the Baltic Sea Near Lithuania

“…137 Cs and 90 Sr are one of the most hazardous anthropogenic radionuclides due to their long physical and biological half-life (about 30 years) (IAEA, 2005). Anthropogenic radionuclides are penetrated in the marine environment mostly as a result of nuclear explosions, accidents at nuclear power plants and due to the operation of nuclear industry (HELCOM, 2009;Zalewska and Suplińska, 2013).…”