The coral atolls of the Pacific are some of the worst places in which to leave radioactive material, say marine biologists in Australia and France. Some of the islands were for decades used for nuclear weapons tests, and several countries would now like to store nuclear waste on others. Ross Jeffree of the Australian Nuclear Science and Technology Organisation in Menai collected zooplankton from atolls throughout French Polynesia.
Polonium is removed from surface waters by the rain of faeces descending from zooplankton.
They eat algae which have absorbed polonium, keep some and excrete the rest. Faecal pellets then take up yet more polonium from the water as they fall. Although Jeffree and his colleagues studied a naturally occurring radioisotope, they are confident that the findings will also apply to isotopes from nuclear waste and bomb tests. Jeffree estimates that radioisotopes accumulate in the marine food chain near coral atolls at five times the rate of those released into temperate oceans. The waters sampled by Jeffree did not include those near the former French nuclear bomb testing sites at Mururoa and Fangataufa.