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

Abstract

A radioecological survey around Terra Nova Bay showed that 239 + 240Pu, 238Pu, 241Am, 90Sr and 137Cs activities were detectable in nearly all the samples. The 239 + 240Pu and 241Am concentrations in seawater were slightly lower than those in the northern Pacific Ocean. The activity level of 239 + 240Pu, 241Am and 137Cs in Antarctic sediments (Ross Sea) was c. 5–20 times lower than in northern Adriatic sediments (Mediterranean Sea), but the 238Pu activities were relatively high. The 90Sr 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 90Sr 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 239 + 240Pu, 241Am, 90Sr and 137Cs is the result of nuclear weapon tests. A higher 241Am/239 + 240Pu ratio might be due to the fallout of earlier atmospheric nuclear tests. The 238Pu239 + 240Pu ratio in the Antarctic matrices is about seven times higher than in the Northern Hemisphere and this could suggest that the major part of 238Pu originated from the SNAP-9A satellite accident.