Monitoring of oysters and sediments in Acajutla, El Salvador

Oysters (Ostrea irridescens) and fine-grained sediments from Acajutla, El Salvador were analysed for petroleum hydrocarbons, chlorinated organic compounds, pesticides and trace elements. Most oysters contained only background levels of PAHs, with the exception of those collected very close to an industrial discharge canal which were up to 100 times background levels. Only black mud accumulating in the main harbour contained PAHs at levels of environmental concern. Pesticides in oysters and fine-grained sediments were below the detection levels in most samples. PCBs were also low. Trace elements in sediments and oysters varied widely, reflecting differences in loadings and degree of bioavailability. Zinc and copper in oysters were elevated to levels normally considered representative of moderately polluted sites, whereas arsenic, cadmium, chromium, lead and nickel were not elevated at most sites. These results were generally associated with potential sources of contamination identified through a questionnaire on product storage, handling and waste disposal from facilities operating in the area.