Effect of Potassium on Uptake of 137Cs in Food Crops Grown on Coral Soils: Annual Crops at Bikini Atoll

In 1954 a radioactive plume from the thermonuclear device code named BRAVO contaminated the principal residential islands, Eneu and Bikini, of Bikini Atoll (11o 36 minutes N; 165o 22 minutes E), now part of the Republic of the Marshall Islands. The resulting soil radioactivity diminished greatly over the three decades before the studies discussed below began. By that time the shorter-lived isotopes had all but disappeared, but strontium-90 (90Sr), and cesium-137, (137Cs) were reduced by only one half-life. Minute amounts of the long-lived isotopes, plutonium-239+240 (239+240Pu) and americium-241 (241Am), were present in soil, but were found to be inconsequential in the food chain of humans and land animals. Rather, extensive studies demonstrated that the major concern for human health was 137Cs in the terrestrial food chain (Robison et al., 1983; Robison et al., 1997). The following papers document results from several studies between 1986 and 1997 aimed at minimizing the 137Cs content of annual food crops. The existing literature on radiocesium in soils and plant uptake is largely a consequence of two events: the worldwide fallout of 1952-58, and the fallout from Chernobyl. The resulting studies have, for the most part, dealt either with soils containing some amount of silicate clays and often with appreciable K, or with the short-term development of plants in nutrient cultures