Radionuclides in marine mammals off the Portuguese coast

137Cs, 40K and 210Po in marine mammals from the southern Baltic Sea

“…Similar low average concentrations of 137 Cs in muscle were reported in Pacific walruses (Odobenus rosmarus divergens) (0.07 Bq kg − 1 w.w) and bearded seal (Erignathus barbatus) (0.17 Bq kg − 1 w.w.) from St. Lawrence Island, Alaska (Hamilton et al, 2008). In a recent study, average concentrations 137 Cs in common dolphin's muscle (Delphinus delphis) stranded on the Portuguese west coast, were 0.29 ± 0.28 Bq kg − 1 w.w. (Malta & Carvalho, 2011). In contrast, relatively high average (±SD) 137 Cs muscle concentrations of 16.9 ± 5.69 and 9.06 ± 5.72 Bq kg − 1 w.w were reported in Baikal seals, collected in 1992 and 2005, respectively (Udaka et al, 2009).…”

“…In the present study, the average calculated α radiation doses from 210 Po for harbor porpoises were 257 nGy h −1 (range: 23.5-1000) and 336 nGy h − 1 (range: 36.9-1420) for liver and kidneys respectively. In comparison, the average absorbed radiation dose in the human muscle from internally accumulated 210 Po is 0.62 nGy h − 1 (Malta & Carvalho, 2011). The dose rates for 210 Po results in average internal radiation dose equivalents of 45.0 mSv year −1 (range: 4.12-175) and 58.8 mSv year −1 (range: 6.47-249) for liver and kidney tissue respectively.…”

“…Thus, data are available from other regions, including the Arctic, Asian and European coastal waters, Lake Baikal and the Caspian and Black Seas. These studies reported average levels of 137 Cs that varied between 0.2 and 17 Bq kg −1 wet weight (w.w.) (Cooper et al, 2000;Yoshitome et al, 2003;Gwynn et al, 2005;Andersen et al, 2006;Malta & Carvalho, 2011). Cesium-137 levels in tissues of marine mammals have been suggested as chemical marker for radioactive pollution in the marine environment, and correlations between tissue levels and seawater levels have been reported (Yoshitome et al, 2003).…”

“…210 Po has a much higher bioaccumulation potential in marine organisms as compared to 210 Pb (Stepnowski & Skwarzec, 2000;Carvalho, 2011). Thus, 210 Po contributes to a large extent to the natural radiation dose from α-emitting radionuclides in marine biota (Cherry & Shannon, 1974) including marine mammals (Malta & Carvalho, 2011). Due to the relatively short penetration range of α radiation, the accumulating tissues such as liver and kidney (Table 2) are the most susceptible for radiation damage.…”

Too much fear for radioactive contamination of seawater

“…the average radiation dose in man (Malta and Carvalho, 2011). In dolphins 97% of their radiation dose came from polonium against only 3 % from 40 K and 14 C.…”