Uptake of I131 by Fresh-water Organisms—An Abstract

Abstract

The Fern Lake Mineral Metabolism Program, which was initiated in 1957, has as its objective the improvement of the productive capacity of the land and water resources of an impoverished watershed in western Washington. Radioactive tracer experiments were conducted during 1960–1961, both in the laboratory and in the lake, to determine which biologically important minerals are deficient in Fern Lake and to study the patterns of uptake of the minerals by organisms living in the lake. The environmental conditions of the laboratory simulated those of the lake. Twelve radionuclides in mc amounts were added to separate tanks containing Fern Lake water, bottom material and important members of the lake community. Later, four radionuclides in c amounts were added to the lake itself. In both series of experiments, samples of organisms, water and bottom material were obtained at designated intervals and were assayed for radioactive content. This report summarizes the results of the I131 analyses in both experiments. In the closed-system experiment of the laboratory, all tissues of the organisms assayed contained I131, with maximum values attained about the fourth day after application of the radioisotope; a notable exception was the thyroid tissue of fish, which reached a maximum value after the fifteenth day. Under the natural conditions of the lake, radioiodine intake via the food chain was greater than from the water, although apparently slower. Concentration factors, however, were greater than those observed in the laboratory experiments.