Second summary of data on chemical concentrations in sediments from the national status and trends program

The National Oceanic and Atmospheric Administration's (NOAA) National Status and Trends (NS&T) Program has analyzed samples of surface sediment collected at almost 300 coastal and estuarine sites throughout the United States since 1984. When the first NS&T report on sediments (NOAA, 1988) was written, only about 200 sites had been sampled. This second report is based on more data. Even with this larger data set, the original observation holds that most of the highest concentrations for any particular contaminant are found at sites near the urban areas of Boston, New York, San Diego, Los Angeles, and Seattle. The overall concentration distributions for each contaminant are approximately lognormal, allowing a definition of high concentrations as those exceeding the mean plus one standard deviation of the lognormal distribution. The high concentrations in units of micrograms per gram of dry fine-grained sediment for each contaminant are (in parentheses): Ag (1.2), As (24), Cd (1.2), Cr (230), Cu (84), Hg (0.49), Pb (89), Sn (8.5), Zn (270), low molecular weight polycyclic aromatic hydrocarbons (LMWPAH) (1.0), high molecular weight polycyclic aromatic hydrocarbons (HMWPAH) (3.0), total dichloro-diphenyl- trichloro-ethane (tDDT) (0.037), and total polychlorinated biphenyls (tPCB) (0.20).