Organic compounds and trace elements sorb onto streambed sediments and can persist in the environment for many years.
Streambed sediments provide habitat for a wide variety of aquatic organisms.
Forty or more organic compounds were detected in streambed-sediment samples from two urban basins. Most sampling sites were in basins of mixed land use, so assessing the source of the compounds was extremely difficult. The median number of organic compounds detected was highest in streambed-sediment samples from urban basins. Although most organochlorine pesticides are no longer used, they persist in streambed sediments and are potentially available for biological uptake. Mirex was detected at 22 percent of sites and chlordane was detected at 26 percent of sites.