Research Reveals Link Between Development And Contamination In Urban ...( A U.S. Geological Survey study of urban...)

This link is inferred from analysis of surface sediment samples collected from different watersheds and from sediment cores in reservoirs. The samples were collected as part of the USGS National Water-Quality Assessment (NAWQA) Program.

These findings will be presented as part of the American Chemical Society Meeting, at the Dallas Convention Center on Tuesday, March 31 at 3 p.m., Room A215/217, Level 2.

Rivers transport significant quantities of sediment seasonally, and reservoirs accumulate sediment over time, creating a partial chemical record of historical water quality. These sediment cores are laid down in distinct layers. They are comparable to tree rings in recording historical climate changes. Three reservoirs sampled in suburban areas of Dallas and San Antonio, Texas, and Washington, D.C., showed dramatic increases in PAH'S with urbanization. These increases are occurring in spite of more stringent emissions controls and attempts to control urban runoff.

"During the past 30 years, since passage of the Clean Air and Clean Water Acts in the early 1970s, efforts have been made to reduce auto emissions and control pollutants in urban runoff," said Pete Van Metre, USGS hydrologist based in Austin, Texas and coordinator of the sediment coring project. "These efforts have produced some promising results, for example, large reductions in lead in aquatic ecosystems and urban air. They have not, however, stopped all urban pollution."

PAH'S's are an organic chemical class consisting of numerous individual compounds. They are universal products of combustion of natural fuels, such as wood or grass, and fossil fuels. They are also pre
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Contact: Heidi Koehler
hkoehler@usgs.gov
303.236.5900x302
United States Geological Survey
31-Mar-1998