Chemical characteristics of arsenic in a marine food chain

The various chemical forms of ⁷⁴As accumulated from either water or food by the marine food chain Fucus spiralis (L.) Littorina littoralis (L.)Nucella lapillus] have been separated and characterized. Arsenic components were separated by differential extraction followed by high-voltage paper electrophoresis/paper chromatography of the water-soluble fraction and thin-layer chromatography of the lipid-soluble fraction. The algae assimilates arsenic mainly (60%) as one lipid-soluble compound with R_f=0.18, and 12 water-soluble organo-arsenic compounds as minor components. On the other hand, the snails, whether labelled from water or food, produce predominantly one major water-soluble organo-arsenic compound with R_f=0.66. This water-soluble arsenic compound was produced by the snails and not by intestinal microbes. Time-course studies on the relative proportions of labelled arsenic compounds in algal tissue indicate a transition from arsenate through water-soluble organo-arsenic components to a lipid-soluble arsenic compound. The water-soluble organo-arsenic compounds in the food chain studied were different from those previously found or proposed in marine organisms.