The fate of plutonium, 241Am, 90Sr and 137Cs in the Antarctic ecosystem

A radioecological survey around Terra Nova Bay showed that Pu239+240, Pu-238, (241)ALm, Sr-90 and Cs-137 activities were detectable in nearly all the samples. The Pu239+240 and Am-241 concentrations in seawater were slightly lower than those in the northern Pacific Ocean. The activity level of Pu239+240, Am-241 and (CS)-C-137 in Antarctic sediments (Ross Sea) was c. 5-20 times lower than in northern Adriatic sediments (Mediterranean Sea), but the Pu-238 activities were relatively high. The Sr-90 concentrations in all the sediment samples from both the Ross and Adriatic seas tended to be low which might be due to an easier exchange of Sr-90 in seawater. On the other hand, high concentrations were detected in Antarctic mosses, lichens and algae and their activity levels are comparable to those in central Italy. The radionuclide ratio analyses show that the major part of Pu239+240, Am-241, Sr-90 and Cs-137 is the result of nuclear weapon tests. A higher Am-241/Pu239+240 ratio might be due to the fallout of earlier atmospheric nuclear tests. The (Pu239+240Pu)-Pu-238 ratio in the Antarctic matrices is about seven times higher than in the Northern Hemisphere and this could suggest that the major part of Pu-238 originated from the SNAP-9A satellite accident.