Problems associated with an environmental assessment of organotins: Application to the organic polluted Saladillo Harbor (southern Spain)

Problems associated with assessing the environmental effects of organotin ( OT) include extraction efficiency, whether to filter the water samples, eff ect of grain size of sediments, and mobility characteristics of OT species from sediments. This study considered these effects on the six OT species t ributyltin, dibutyltin, monobutyltin, triphenyltin, diphenyltin, and monoph enyltin in seawater and sediments collected from Saladillo Harbor, a repres entative enclosed area in southern Spain that receives inputs of both OTs a nd organic matter. Yields of organotin extracted from sediments with a high organic content by using dichloromethane were higher than those obtained b y using pentane. Concentrations of butyltins were higher than those of phen yltins. A gradient was observed of decreasing butyltin concentrations in se diments from 280 ng Sn/g in the inner stations to 0.5 ng/g in the outer sta tions of the harbor No dissolved organotin compounds were detected in the o verlying seawater. Because OTs are related to the presence of organic matte r, iron oxyhydroxides, and phylosilicates, they were strongly adsorbed onto particulate matter in both sediment and suspended matter. Low percentages of butyltins, ranging from undetectable to 0.54%, were released by extracti ng in unpolluted seawater at pH 8 and 5. Higher concentrations were found i n finer sediments.