Fate of14C dieldrin in a simulated terrestrial ecosystem

Abstract

The disposition of14C-dieldrin (HEOD) was examined in a Terrestrial Microcosm Chamber (TMC) model ecosystem consisting of a synthetic soil medium, agricultural crops, numerous invertebrates and a microtine rodent. Residues were determined in air, soil, water, plants, invertebrates, and tissues of the vole (Microtus canicaudus) and her offspring. Design considerations for this experiment were (a) whether the test system satisfactorily measured the fate of the material applied, (b) whether the results were comparable to field and laboratory studies of the rates and extent of movement, transformation and biological effects of HEOD, and (c) whether the TMC was comparable to other microcosm test systems. The average accountability was 89% of the14C-dieldrin applied to three TMCs. At termination, the soil contained 55% (± 19%) of the14C, plants 30% (± 18%) and fauna 1.5% (± 0.9%). The vole exhibited an average Ecological Magnification index of 59.5. An average concentration of 17.7 ppm HEOD was noted in the vole brain. Dieldrin adversely affected both vole survival and reproductive performance. The results in the TMC are highly consistent with the behavior of the chemical in the natural environment and in other microcosm systems.