Trace organic contamination in the Americas: An overview of the US National Status & Trends and the International ‘Mussel Watch’ programmes

Abstract

The National Status & Trends (NS&T, 1986–1993) and the International Mussel Watch (IMW, 1991–1992) programmes provide a good coverage of a broad range of environmental conditions along the North, Central and South American coasts. Total concentrations of DDTs, chlordane-related compounds, PCBs and PAHs present fairly homogeneous distributions along the northern Gulf of Mexico coast, with very few sites showing extremely high or low concentrations. In contrast, a larger variability in the geographical distribution of some of these organic contaminants was observed for IMW sites. For example, high concentrations of DDT and its metabolites, DDD and DDE, were generally found in tropical and subtropical areas as compared to more temperate zones of South America. ‘Industrial’ contaminants, such as PCBs and PAHs, have similar distributions with the highest concentrations encountered generally along the southern South Atlantic coast. An overall comparison of the concentrations of these organic contaminants measured at NS&T and IMW sites indicates that contamination is significantly higher along the northern coast of the Gulf of Mexico.