Regulation of Tin and Methyltin Compounds by the Green Alga Enteromorpha under Simulated Estuarine Conditions

Abstract

The cycling of inorganic tin and methyltin compounds was examined in the presence of the green alga Enteromorpha at different salinities. We monitored flasks containing live and dead Enteromorpha under oxic experimental conditions for 17 d and determined inorganic tin and methyltin compounds by chromatography – atomic absorption spectrometry. Addition of acidic inorganic tin to some flasks resulted in plant decay. Processes associated with healthy and decaying plant material included release of inorganic tin and methyltin compounds, their interconversions in solution, and uptake of inorganic tin. Enteromorpha releases inorganic tin as well as mono-, di-, and trimethyltin. Added inorganic tin was mostly removed from solution after its addition, and all three methyltin compounds were produced. The methyltin compounds cycle such that high concentrations of trimethyltin were concomitant with low mono- and dimethyltin concentrations and vice versa. We describe possible biological and chemical processes responsible for interconversions of inorganic tin and methyltin compounds in solution and the environmental significance of seaweed in the biogeochemical cycling of tin.