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Pavement Sealcoat, PAHs, and the Environment: An Introduction Barbara J. Mahler and Peter C. Van Metre U.S. Geological Survey SETAC, 9 November 2010.

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Presentation on theme: "Pavement Sealcoat, PAHs, and the Environment: An Introduction Barbara J. Mahler and Peter C. Van Metre U.S. Geological Survey SETAC, 9 November 2010."— Presentation transcript:

1 Pavement Sealcoat, PAHs, and the Environment: An Introduction Barbara J. Mahler and Peter C. Van Metre U.S. Geological Survey SETAC, 9 November 2010

2 USGS NAWQA Program: PAHs in lake sediment are increasing Van Metre et al., 2000, ES&T; Van Metre and Mahler, 2005, ES&T Increasing concentrations No trend Decreasing concentrations

3 Carcinogenic, teratogenic, mutagenic, and toxic Produced by combustion of organic matter Ubiquitous in the urban environment: Used motor oil Exhaust Industrial emissions Asphalt Tires Coal-tar-based pavement sealant What Are PAHs? (polycyclic aromatic hydrocarbons)

4 The first clue: high PAH in Austin stream-bed sediment Extremely high (>1,500 mg/kg) PAHs in some small drainages Compare to Probable Effect Concentration (PEC) of 23 mg/kg So … whats upstream?

5 What is sealcoat? Asphalt-based product West of the Continental Divide Coal-tar based product contains coal- tar pitch East of the Continental Divide

6 How do urban sources of PAHs stack up? Tire wear particles –175 (mean of 3 studies) Road dust –59 Brake-lining particles –9–9 Air particles, major roadway –104 Fresh asphalt –2–2 Weathered asphalt –9–9 Fresh motor oil –7–7 Used motor oil –726 Diesel engine –304 (mean of 2 studies) Gasoline engine –35 Pavement sealcoat –Asphalt based ~ 50 –Coal-tar-based ~ 92,000 (mean of 4 products) All concentrations in mg/kg

7 Environmental relevance Is use extensive? Is the contaminant mobile? Are concentrations elevated?

8 How extensive is sealcoatuse? How extensive is sealcoat use? 200,000 gallons applied annually in Springfield, MO, area (applicator estimate) 1,400,000 gallons applied annually to New York Harbor watershed (New York Academy of Science estimate) 4,800,000 gallons (20,000 tons) of CT- based sealcoat applied in Texas annually (sealcoat industry estimate) Within watersheds: –4 watersheds in Texas: 1-2% area –1 watershed in Illinois: 4% of area 42% of parking lot area 89% of driveway area

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11 Sealed 570 3,800 3,400 1, Unsealed Coal tar Asphalt 9 U.S. Cities: Pavement Dust PAH (mg/kg) 1, < <8.5 3,200 Van Metre et al., ES&T, 2009

12 23 ground-floor apartments

13 Ancillary Information Gathered Smoking Incense/candles Fireplace use Type of stove/heat Shoe wear in house Indoor/outdoor pets Distance to major roadway Intensity of urbanization including

14 Out-CT = 530 x Out-NCT In-CT = 25 x In-NCT ,760 Median total PAH [ g/g] n=12n=11 Mahler et al., 2010, ES&T

15 Increasing trends in PAHs

16 What are the principal sources of PAHs to urban lakes? Source-Apportionment Modeling Start with source profiles receptor profiles CMB model combines sources to best match the receptor profile Results are the contribution of each source to each sediment sample Example source Example receptor

17 Sources Considered Coal combustion –Power plant emissions –Residential heating –Coke oven Fuel-oil combustion Vehicle related –Diesel vehicle emissions –Gasoline vehicle emissions –Traffic tunnel air –Used motor oil –Tire particles –Asphalt Wood burning –Pine-wood soot particles Coal-tar-sealcoat related –NIST coal tar standard –Sealcoat products –Sealcoat scrapings –Sealcoat dust (average, 6 cities) –Sealcoat dust, Austin

18 PAH Source Apportionment to 40 U.S. Lakes Mass PAH contribution from coal-tar-based sealcoat Van Metre and Mahler, STOTEN, in press

19 PAH Trends in New Urban Lakes

20 All urban is not equal Decker Lake 2,090 people/km PAH 0.76 mg/kg Tanasbrook Pond 844 people/km PAH 1.34 mg/kg Lake Anne 2,095 people/km PAH 17.0 mg/kg Palmer Lake 939 people/km PAH 34.1 mg/kg


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