BIOACCUMULATION AND EXCRETION OF ARSENIC COMPOUNDS BY A MARINE UNICELLULAR ALGA, POLYPHYSA-PENICULUS

Polyphysa peniculus was grown in artificial sea-water in the presence of arsenate, arsenite, monomethylarsonate and dimethylarsinic acid. Th e separation and identification of some of the arsenic species produce d in the cells as well as in the growth medium were achieved by using hydride generation-gas chromatography-atomic absorption spectrometry m ethodology. Arsenite and dimethylarsinate were detected following incu bation with arsenate. When the alga was treated with arsenite, dimethy larsinate was the major metabolite in the cells and in the growth medi um; trace amounts of monomethylarsonate were also detected in the cell s. With monomethylarsonate as a substrate, the metabolite is dimethyla rsinate. Polyphysa peniculus did not metabolize dimethylarsinic acid w hen it was used as a substrate. Significant amounts of more complex ar senic species, such as arsenosugars, were not observed in the cells or medium on the evidence of flow injection-microwave digestion-hydride generation-atomic absorption spectrometry methodology. Transfer of the exposed cells to fresh medium caused release of most cell-associated arsenicals to the surrounding environment.