Parking Lots Create Sticky Pollution Problem

摘要

Suburbia, beware. Vast stretches of parking lots in the U.S. are coated with toxic coal tar that is slowly crumbling into dust. Coal-tar-based sealants, which give the lots an ebony finish, produce dust containing 100 to 1000 times higher PAH levels than unsealed lots, accordine to new research published in ES&T (DOI 10.1021/es802119h). Many PAHs are carcinogenic and harm aquatic life, and runoff from the lots could be a major source of urban water contamination, the scientists report.rnThe sealants first drew attention in Austin, Texas, when city workers discovered high PAH levels in sediments near Barton Springs, a popular swimming spot and home to an endangered salamander species. Scientists from the U.S. Geological Surveyrn(USGS) first reported in ES&T in 2005 that runoff from Austin parking lots sealed with coal tar contained 65 times more PAHs than runoff from unsealed lots. Since then, Austin and Dane County, Wise, home to the city of Madison, have banned coal-tar sealants. Now the USGS team, led by research hydrologist Peter Van Metre, has compared lots sealed with coal tar and with asphalt in nine U.S. cities.