South Dakota Water Science Center
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Nonpoint Sources of Volatile Organic Compounds in Urban Areas--Relative Importance of Urban Land Surfaces and AirThomas J. Lopes and David A. Bender
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
Many of the same volatile organic compounds (VOCs) were commonly detected in both stormwater and shallow groundwater from urban areas across the United States. Commonly detected VOCs included gasoline-related compounds (e.g. toluene, xylene) and chlorinated compounds (e.g. chloroform, PCE, TCE). Urban land surfaces and air are two nonpoint sources that are common to both stormwater and groundwater and could explain why the same VOCs were detected. This paper presents an analysis of stormwater data that examines the relative importance of these nonpoint sources. In stormwater, VOCs frequently occurred together and concentrations were significantly (a=0.05) correlated and different among residential, commercial, and industrial areas. Also, most VOC concentrations in stormwater were higher than those estimated from 75th-percentile concentrations of VOCs in urban air, and trends in concentrations suggest that low concentrations (0.2 ug/L) likely evolved by volatilization. These observations suggest that urban land surfaces are the primary nonpoint source of most VOCs. Urban air is a secondary source, but could be an important source of the gasoline oxygenate methyl tert-butyl ether (MTBE). Flushing of spills and VOCs sorbed to organic particulates and impervious surfaces could be important processes.
in review by Environmental Pollution