Arsenic in the aquatic environment

Arbab-Zavar, Mohammad Hossein (1982) Arsenic in the aquatic environment. University of Southampton, Doctoral Thesis.

Abstract

Arsenic species in the aquatic environment have been investigated following the development of appropriate techniques. The silver diethyldithiocarbamate (SDDC) colorimetric method and an automated procedure using hydride generation atomic absorption spectrophotometry were applied to the assessment of "total" arsenic levels, these techniques having detection limits of 0.1 pg/ml and 0.9 ng/ml respectively. "Inorganic" arsenic(III) and arsenic(V), "methylarsenic" and "dimethylarsenic" were determined by selective volatilisation of arsines into a heated quartz atomiser atomic absorption spectrophotometer (detection limit 0.25 ng). Interferences were investigated and overcome by suitable pretreatment procedures. Extraction and ashing procedures were studied for the determination of both "total" arsenic and specific arsenic species. "Inorganic" arsenic(III) and arsenic(V), "methyiarsenic" and "dimethylarsenic" were detected in water samples from the estuaries of the rivers Beaulieu and Test. "Inorganic" arsenic(III), "methylarsenic" and "dimethylarsenic" levels were found to apparently depend on water temperature. Dissolved "inorganic" arsenic behaves non-conservatively in the Beaulieu Estuary; laboratory mixing experiments indicating arsenic removal from the water at salinities below 200 .Arsenic in macroalgae and molluscs was found to be present as organoarsenic species which degrade to "dimethylarsenic" species on extraction and analysis. Water-soluble arsenic compounds extracted from molluscs (NueeZZa Zapillua and Littorina Zittorea) were identified as dimethylarsinate, arsenite and arsenate. Lipidsoluble arsenic in the molluscs was polar and behaved chromatographically and enzymatically as phosphatidylethanolamine.

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