Arsenic Circulation in Marine Ecosystems

Microbial conversion behavior was investigated with several standard arsenicals. As typical origin of marine micro-organisms, sediments, macro-algae, mollusk intestine and suspended substances were used. The degradation of arsenobetaine was observed with every origin, suggesting the ubiquitous occurrence of arsenobetaine-decomposing microorganisms in marine environment. Especially, the microorganisms occurring in the sediments and the suspended substances completely degraded it to inorganic arsenic. From these results, it was hypothesized that there is an arsenic cycle that begins with the complete degradation of arsenobetaine to inorganic arsenic.