-16- Discussion The retention or rejection of a given radioactive element by the organisms in the contaminated area of the ocean is determined by several factors, many of which also function in the distribution of naturally occurring elements of the sea. The effects of some of these factors are known; others are not. A better understanding of the unknown effects may “be attained by observations on the accumulation of individual radioactive elements from fallout within the trophic levels of the contaminated biosphere. By observing which radioele- ments are concentrated in the phytoplankton, the zooplankton, and the nekton and relating these observations to (a) the known characteristics of the fallout elements before and after entry into the sea; (b) the half lives of the radioisotopes, the amounts produced at detonation, and their distribution with respect to fallout particle size; and (c) the known biological factors involved in the uptake and retention of different elements, the eventual fate of the major fallout radioisotopes in the sea may be determined. DOE ARCHIVES In the waters of the open Pacific Ocean the naturally occurring trace elements, cesium, zinc, cobalt, ruthenium, manganese, strontium, and possibly zirconium and cerium, water are present mainly in solution. in the The small amount of naturally occurring iron occurs in the colloidal and particulate form. All of the above named elements, however, except vil