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

This study presents levels of Cs-137 and K-40 concentrations in the placentas of seals gathered in the period 2007-2015. The mean activity of Cs-137 and K-40 was 5.49Bqkg(-1)w.w. and 136.6Bqkg(-1) ww respectively. Statistically significant correlation was observed between the Cs-137 activities in placenta and in herringthe staple food for seals. The concentrations of Cs-137 and K-40 were also determined in other tissues (muscle, liver, lung, and brain) of wild seals. The concentrations of Cs-137 were from 2.59Bq(-1) ww (lungs) to 24.3Bqkg(-1) ww (muscles). The transfer factor values for Cs-137 (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 Cs-137 was 2.98nGyh(-1). The mean external radiation dose to pup was 0.77nGyh(-1) from Cs-137 and 6.69nGyh(-1) from K-40.