Research Product

Elemental contamination has been examined in sediments collected from 350 sites along the coast of the United States by NOAA's National Status and Trends (NS&T) Program. To isolate natural from man-made factors, data from 60 sites with fewer than 10,000 people living within 20 km were used to test correlations between concentrations of trace elements and four candidate normalizing factors: iron, aluminum, grain size, and total organic carbon. At least 50% of the concentration variations for the elements As, Cr, Cu, Ni, Pb, Sn, and Zn can be accounted for by covariation with Fe or Al, and either of those major elements can be used for normalization. For Ag, Cd, Hg, Sb, and Se, on the other hand, no candidate normalizers accounted for more than even 30% of the variation. Based on these results, the spatial extent of contamination has been examined, and it was found that severe contamination is mostly limited to small areas near large population centers.