Pavement Sealcoat, PAHs, and the Environment: An Introduction

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 Increasing concentrations No trend Decreasing concentrations Van Metre et al., 2000, ES&T; Van Metre and Mahler, 2005, ES&T

3. What Are PAHs? (polycyclic aromatic hydrocarbons) • 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

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 … what’s upstream?

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

6. Tire wear particles 175(mean of 3 studies) Road dust 59 Brake-lining particles 9 Air particles, major roadway 104 Fresh asphalt 2 Weathered asphalt 9 Fresh motor oil 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) How do urban sources of PAHs stack up? All concentrations in mg/kg

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

8. 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 How extensive is sealcoatuse?

11. 9 U.S. Cities: Pavement Dust PAH (mg/kg) Coal tar Asphalt Sealed 5.2 570 <13 3,400 1,300 3,800 2.1 3,200 Unsealed 8.5 1,200 24 <8.5 47 30 21 0.8 54 Van Metre et al., ES&T, 2009

12. 23 ground-floor apartments

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

14. Median total PAH [mg/g] n=12 n=11 5.1 129 9.0 4,760 In-CT = 25 x In-NCT Out-CT = 530 x Out-NCT 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 Palmer Lake 939 people/km SPAH 34.1 mg/kg Tanasbrook Pond 844 people/km SPAH 1.34 mg/kg Lake Anne 2,095 people/km SPAH 17.0 mg/kg Decker Lake 2,090 people/km SPAH 0.76 mg/kg