South Dakota Water Science Center
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Semivolatile organic compounds (SVOCs) in streambed sediments, United States, 1992-95Thomas J. Lopes, and E.T. Furlong
U.S. Geological Survey, 1608 Mountain View Rd., Rapid City, SD 57702
Phone (605) 355-4560 ext. 240, Telecopier (605) 355-4523, email@example.com
As part of the National Water-Quality Assesment (NAWQA) program, 65 semivolatile organic compounds (SVOCs) were measured in bed sediment samples collected from streams across the United States between 1992-95. Two objectives of NAWQA are to determine the occurrence and distribution of contaminants and factors related to their occurrence. The SVOCs includes polycyclic aromatic hydrocarbons (PAHs), azaarenes, phthalates, phenols, and chlorinated compounds. At each site, 5 to 10 samples were collected from depositional zones in a 100-m reach of a stream, composited, and then sieved to less than 2 mm using a stainless steel sieve. Only the surficial 2 to 3 cm of bed sediment were sampled to characterize recently deposited sediments. Forty-one SVOCs, were detected in more than 5 percent of samples, and 10 of these were detected in more than 50 percent of samples. PAHs, phthalates, azaarenes, and phenols were the most frequently detected SVOCs. Chlorinated, nitro, and nitroso compounds were detected in less than 5 percent of samples. Concentrations of PAHs, azaarenes, and phthalates were highest in the northeastern United States, and their concentrations were about 10 times greater in urban drainage basins compared to agricultural, reference, and integrator basins. SVOCs had significant (α =0.05) nonparametric correlations with physical/chemical properties, toxic releases to air, population density, and percentage of urban land use surrounding sample sites. Combustion of fossil fuels and materials commonly used and manufactured in urban and industrial regions are likely sources for PAHs, azaarenes, and phthalates. In contrast, concentrations of phenols were not different among land uses and were poorly correlated with site characteristics, suggesting either widespead use, natural sources, or both.
Society of Environmental Toxicology and Chemistry 20th Annual Meeting, Philadelphia, Pa.,
November 14-18, 1999.