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

Michał Saniewski,Lucyna Falkowska,Maria Suplińska,Iwona Pawliczka,Tamara Zalewska,Marta Staniszewska,Iga Nehring,Dominika Saniewska,Agnieszka Grajewska

doi:10.1007/s11356-019-05145-7

Abstract

This study presents levels of 137Cs and 40K concentrations in the placentas of seals gathered in the period 2007–2015. The mean activity of 137Cs and 40K was 5.49 Bq kg−1w.w. and 136.6 Bq kg−1 ww respectively. Statistically significant correlation was observed between the 137Cs activities in placenta and in herring—the staple food for seals. The concentrations of 137Cs and 40K were also determined in other tissues (muscle, liver, lung, and brain) of wild seals. The concentrations of 137Cs were from 2.59 Bq−1 ww (lungs) to 24.3 Bq kg−1 ww (muscles). The transfer factor values for 137Cs (seal tissue/fish) ranged from 0.89 to 2.42 in the case of the placentas and from 1.35 to 8.17 in the case of the muscle. For adults seal, the effective dose from 137Cs was 2.98 nGy h−1. The mean external radiation dose to pup was 0.77 nGy h−1 from 137Cs and 6.69 nGy h−1 from 40K.

Highlights

The Baltic Sea, being a largely enclosed area in terms of its connection with ocean waters, is much more sensitive to pollution than other seas
There was a decrease in the concentrations of 137Cs in herring caught in the Polish Baltic region, with mean values ranging from 5.4 Bq kg−1 ww in 2007 to 3.0 Bq kg−1 ww in 2015, which was statistically significant (r = − 0.88, p < 0.001) (Fig. 2a)
In spite of the absence of correlation between 137Cs concentrations in the placentas and the concentrations observed in seawater (p = 0.078), it was proven that there was a statistically significant correlation between the levels of 137Cs in the placenta and those observed in fish that were the staple seal feed (r = 0.59, p = 0.002)

Summary

Introduction

The Baltic Sea, being a largely enclosed area in terms of its connection with ocean waters, is much more sensitive to pollution than other seas. Sea were the Chernobyl Nuclear Power Plant accident in 1986 and the atmospheric tests of nuclear weapons carried out during the late 1950s and early 1960s. The total deposition was assessed to amount to 800 TBq after the nuclear weapons tests and 4700 TBq following the Chernobyl accident. In the period 2005–2011, the average annual load of 137Cs from the Vistula River to the Gulf of Gdańsk was 406 GBq and from atmospheric fallout was 18.1 GBq (Saniewski and Zalewska 2016). The Vistula water is still sources of 137Cs to the Gulf of Gdańsk, the input of 137Cs is compensated by processes such as radioactive decay of 137Cs, sediment deposition, and in minor extent bioaccumulation in flora and fauna organisms like macrophytobenthic plants and fish. In the period 2005–2011, the shares of these processes in decrease of 137Cs activity in the Gulf of Gdańsk were 355 GBq year−1

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