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PAH volatilization following application of coal-tar-based pavement sealant

Peter C. Van Metre·Michael S. Majewski·Barbara Mahler·William T. Foreman·Christopher L. Braun·Jennifer T. Wilson·Teresa L. Burbank
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Abstract

Coal-tar-based pavement sealants, a major source of PAHs to urban water bodies, have recently been identified as a source of volatile PAHs to the atmosphere. We tracked the volatilization of PAHs for 1 year after application of a coal-tar-based pavement sealant by measuring gas-phase PAH concentrations above the pavement surface and solid-phase PAH concentrations in sealant scraped from the surface. Gas-phase concentrations at two heights (0.03 and 1.28 m) and wind speed were used to estimate volatilization flux. The sum of the concentrations of eight frequently detected PAHs (ΣPAH 8 ) in the 0.03-m sample 1.6 h after application (297,000 ng m -3 ) was about 5000 times greater than that previously reported for the same height above unsealed parking lots (66 ng m -3 ). Flux at 1.6 h after application was estimated at 45,000 μg m -2 h -1 and decreased rapidly during the 45 days after application to 160 μg m -2 h -1 . Loss of PAHs from the adhered sealant also was rapid, with about a 50% decrease in solid-phase ΣPAH 8 concentration over the 45 days after application. There was general agreement, given the uncertainties, in the estimated mass of ΣPAH 8 lost to the atmosphere on the basis of air sampling (2–3 g m -2 ) and adhered sealant sampling (6 g m -2 ) during the first 16 days after application, translating to a loss to the atmosphere of one-quarter to one-half of the PAHs in the sealcoat product. Combining the estimated mass of ΣPAH 8 released to the atmosphere with a national-use estimate of coal-tar-based sealant suggests that PAH emissions from new coal-tar-based sealcoat applications each year (~1000 Mg) are larger than annual vehicle emissions of PAHs for the United States.

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Peter C. Van Metre, Michael S. Majewski, Barbara Mahler, William T. Foreman, Christopher L. Braun, Jennifer T. Wilson, Teresa L. Burbank. 2012. PAH volatilization following application of coal-tar-based pavement sealant. https://doi.org/10.1016/j.atmosenv.2012.01.036

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