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Volatilization of PAHs from sealcoated pavement

Volatilization of PAHs from sealcoated pavement. Peter C. Van Metre, Barbara J. Mahler, William Foreman, Christopher Braun, Jennifer Wilson, Teresa Burbank, and Rhiannon ReVello. Mean S PAH in six coal-tar based products (dried 3 days indoors) is ~90,000 mg/kg 1

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Volatilization of PAHs from sealcoated pavement

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  1. Volatilization of PAHs from sealcoated pavement Peter C. Van Metre, Barbara J. Mahler, William Foreman, Christopher Braun, Jennifer Wilson, Teresa Burbank, and Rhiannon ReVello

  2. Mean SPAH in six coal-tar based products (dried 3 days indoors) is ~90,000 mg/kg1 Mean SPAH in 12 scraping samples from coal-tar sealed lots is ~20,000 mg/kg1,2 PAHs in fresh and aged sealcoat 1Mahler et al., 2005 2Van Metre et al., 2009

  3. PATHWAYS

  4. Ksa=Csurf/Chat,eq F(T°) “Hat” sampling1 Ambient Air 1.28 m Gradient: source or sink? Surface air layer 0.03 m Impervious surface 1Meijer et al., 2003

  5. In-use parking lots Ten “in use” parking lots in Austin, TX. Seven with sealcoat, three unsealed pavement Summer 4 pm samples at all sites, 4 am samples at five Pavement dust sampled

  6. “Pickle” Test Plot Newly CT sealed “test” plot at UT Pickle Research Campus Sampled for 1 year: 2 hours after sealing, then after 1, 5, 16, 45, 149, 232, 328, 373 d Monitored wind and temperature Collected pavement dust and scraping samples at each time

  7. Analysis PUFs were ASE extracted and PAH analyzed by GC/MS 19 PAH quantified 8 PAH frequently detected: Phe, An, 4,5-MP, 1-MP, Flu, Py, Chy, and B(b)F

  8. The Solid Phase SPAH8 in dust at in-use lots Coal-tar sealed (n=6) 1,200 – 7,100 mg/kg Asphalt sealed (n=1) 29 mg/kg Unsealed (n=3) 0.47 – 6.3 mg/kg • SPAH8 at Pickle • Dust (n=2) 2,500 & 1,400 mg/kg • Scrapings (n=4) 11,000 – 28,000 mg/kg

  9. PAH in Air SPAH8 in unsealed lots HAT = 73 AMB = 26 ng/m3 dC/dzPhe= 17 ng/m SPAH8 in sealcoated lots HAT=1,770 AMB = 190 ng/m3 dC/dzPhe = 466 ng/m

  10. Source/Sink?

  11. Surface source

  12. PAH Pickle test plot SPAH8 2 hours after application HAT = 290,000 AMB = 5,400 ng/m3 dC/dzPhe= 165,000 ng/m SPAH8 149 days after (during winter) HAT=291 AMB = 28 ng/m3 dC/dzPhe = 180 35° C 34° 41° 31° 31° 17° 11°

  13. PAH Pickle test plot R2 = 0.95 t1/2 = 7 days

  14. Fluxes? Q = u* K’T [Ca(zhat) - Ca(zamb)] (1) • Q = flux • [C – C] = air concentration gradient • u* K’T = mass transfer coefficient u* K’T is primarily a function of wind speed (1) Scholtz et al., 2002

  15. Flux = f (gradient)

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