W11 AM Environmental Chemical Forensics
Wednesday, 16 November 2005: 8:00 AM - 11:40 AM in 343-344

(VAN-1117-822607) Parking lot sealcoat: an unrecognized source of urban PAHs.

Van Metre, P¹, Mahler, B¹, ¹ U.S. Geological Survey, Austin, Texas, USA

ABSTRACT- Polycyclic aromatic hydrocarbons (PAHs) are a ubiquitous contaminant in urban environments and are increasing in concentration in a majority of urban lakes sampled by the USGS National Water-Quality Assessment Program. Although numerous sources of PAHs to urban runoff have been identified, their relative importance remains uncertain. We show that a previously unidentified source of PAHs in urban environments, parking lot sealcoat, might dominate loading of PAHs to urban water bodies in the United States. Particles in runoff from six parking lots with coal-tar emulsion sealcoat had a mean concentration of PAHs of 3,500 mg/kg, 65 times higher than the mean concentration from four unsealed asphalt and cement lots. Contaminant yields projected to the watershed scale for four urban watersheds indicate that runoff from sealed parking lots could account for the major part of PAH loads in streams. Diagnostic ratios of individual PAHs indicate similar sources for particles from coal-tar emulsion sealed lots and suspended sediment from the four urban streams. PAH ratios in sediment cores from lakes undergoing rapid urbanization and coincident increases in PAH concentrations also indicate sealcoat as an important source of PAHs.

Key words: PAHs, parking lots, sealcoat, coal-tar