DISTRIBUTION OF CHEMICAL CONCENTRATIONS IN US COASTAL AND ESTUARINE SEDIMENT

A Coastal Sediment Database (COSED) of chemical concentrations in sediment has been compiled from various electronic sources. It contains data for nearly 13 500 US coastal sediment samples and over 80 analytes, including metals, pesticides, polyaromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB), and physical parameters. Data were assessed relative to the NOAA National Status and Trends (NS & T) 'high' concentrations, which correspond to the geometric mean plus one standard deviation of all NS & T Mussel Watch (NS & T/MW) site means. The greatest numbers of sites with concentrations greater than Jive times the 'high' (5 x high) were near densely-populated areas in poorly flushed water bodies. The most common chemicals at these '5 x high' levels were the metals, in decreasing frequency: Hg, Cd, Sn and Ag. Total PAH was the organic compound group most commonly found in the '5 x high' range. Based on data from the Estuarine Component of the EPA Environmental Monitoring and Assessment Programme, about 75% of the US coastal and estuarine area has concentrations below 'high' for all chemicals analyzed,while '5 x high' concentrations are exceeded in less than 2% of the area.