FATE OF A VOLATILE CHLORINATED SOLVENT IN INDOOR AQUATIC MICROCOSMS -SUBLETHAL AND STATIC EXPOSURE TO [C-14] DICHLOROMETHANE

The goal of this work was to study the fate of dichloromethane in indo or aquatic microcosms after a sublethal and static exposure to simulat e the accidental contamination of a lenitic ecosystem such as littoral lake zone or a pond. This kind of ecosystem is characterized by high productive capacity and rich biocoenose, and are usually first affecte d by acute or chronic pollution. Microcosms containing immersed bryoph ytes (Fontinalis antipyretica), macrophytes (Lemna minor, Groenlendia densa, Elodea canadensis), molluscs (Physa fontinalis), crustaceans (D aphnia magna), and unicellular green algae (Scenedesmus subspicatus) w ere contaminated with sublethal concentrations of dichloromethane or [ C-14]dichloromethane. The initial mean concentration was 9.9 +/- 3.7 m u M. The mean concentration exposure for organisms was 4.5 +/- 1.5 mu M. The fate of C-14 radioactivity was monitored by measuring the radio activity of the sediment, water, macro- and microorganism, and atmosph eric compartments. Radioactivity in the water disappeared quickly from the microcosms, most likely as [C-14]dichloromethane (t(1/2) = 5.31 /- 0.41 days). At the end of the experiments, radioactivity was mainly located in the atmosphere, with traces remaining in the biomass. Unde r static conditions, the bioaccumulation of C-14 radioactivity from th e radiolabeled dichloromethane was negligible. (C) 1994 Academic Press , Inc.