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Kirk O’Reilly, Ph.D., J.D. Jaana Pietari, Ph.D. Paul Boehm, Ph.D.

Use of Alkyl Polycyclic Aromatic Hydrocarbon Data in Evaluating the Contribution of Pavement Sealers to Urban Sediments

Project funded by the Pavement Coatings Technology Council

2

Questions Are refined tar sealers (RT-sealers) a significant source

of PAHs in urban sediments?– Using pre-ban data, focus on two cities where bans have

been enacted

Can the use of extended PAH profiles assist in differentiating sources of pyrogenic PAHs?– Integrate use of available extended PAH profiles together

with more commonly available data

3

Key References Mahler, et al. 2005. ES&T 39:5560

O’Reilly, et al. 2011. ES&T. 45:3185

O’Reilly, et al. 2012. Env. Forensics. 13:185

Van Metre, et al. 2009. ES&T. 43:20.

Van Metre, et al. 2010. Sci. Total Env. 409:334

Watts, et al. 2010. ES&T. 44:8849

4

Are RT-sealers a significant source of PAHs in urban sediments?

Apparent similarities in PAH profiles does not demonstrate causation

5

Are RT-sealers a significant source of PAHs in urban sediments? (continued)

A number of potential sources are similar to sediments (O’Reilly, et al. 2012)

6

A Mixing Model Suggests RT-Sealers may be a Source (Van Metre and Mahler 2010), but… Model assumptions of including all potential sources

and their stabilities were not met (O’Reilly, et al. 2012)

Model results are not consistent with forensic assessments (O’Reilly, et al. 2011a)

Results are not consistent with site-specific analyses (O’Reilly, et al. 2011b)

7Site-Specific Principal Component Analysis (PCA) Indicates Differences Between RT-Sealer and Sediment PAH Profiles (O’Reilly, et al. 2011b)

Lake Ballinger

Newbridge Pond

Town Lake

Lake of the Hills

Sediment

RT-Sealer

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Approach Focus on two urban systems with alkylated PAH data

available— Austin, Texas, and Washington, DC

Combine alkylated and standard PAH results to expand dataset

Use PCA to assess similarities and differences between sealer and sediment samples

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Additional Data Sources De Mott, et al. 2010. Env. Forensics 11:372

Mahler, et al. 2004 (revised 2007). USGS Open-File Report 2004–1208

NOAA Anacostia River Database at http://response.restoration.noaa.gov/watersheddownloads

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PAH34 Histograms

RT-Sealer Chip

NH Study

Austin Sediment

LightNon-alkylated

HeavyNon-alkylated Alkylated

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Alkylated PAH Data from Sediments Collected in 2005 and 2008 (De Mott, et al. 2010)

Town LakeTown LakeTown Lake

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Using 34 PAHs, PCA Indicates a Difference between RT-Sealer and Austin Sediment Samples

RT-SealerSediment

13

Reducing the PAH Dataset to 18 Allows Inclusion of the USGS Data, but Still Indicates a Difference between RT-Sealers and Austin Sediments

RT-Sealer

Sediment

14

There is Even Less Overlap When Focusing on the 11 Most Stable PAHs

RT-Sealer

Sediment

15

The Results Suggest Sealers are Not a Significant Source of PAHs in Creeks, but What about the Larger Town Lake?

16

PCA was able to Separate Sealers and Town Lake Sediments

Town Lake

17

The Results Suggest There is Not a Single Source of PAHs in Town Lake

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Washington, DC Banned RT-Sealers in 2009 because of Perceived Threats to the Anacostia River

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Pre-ban Alkylated PAH Data Available from NOAA’s Database

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Using 34 PAHs, PCA Indicates a Difference between Sealer and Anacostia River Sediments

RT-Sealer

Sediment

21

RT-Sealer

Sediment

Reducing the PAHs to 16 Allows Inclusion of the USGS Data, but Still Indicates a Difference between Sealers and Anacostia River Sediments

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Independent Watershed Studies Indicate Sealers Are a Minor PAHSource

Control of Toxic Chemicals in Puget Sound: Assessment of Selected Toxic Chemicals in the Puget Sound Basin, 2007–2011. Washington State Department of Ecology. 2007

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Independent Watershed Studies Indicate Sealers Are a Minor PAH Source (continued)

Data from:Pollution Prevention and Management Strategies for Polycyclic Aromatic Hydrocarbons in the New York/New Jersey Harbor. New York Academy of Science.2007

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Conclusions PCA-based forensic analyses do not support hypothesis

that RT-sealers are the primary source of PAHs in either Austin, Texas, or Washington, DC– Enacted bans are unlikely to have an effect on PAH

concentrations

The addition of alkylated PAH data did not improve the ability to characterize the source of pyrogenic PAHs– Alkylated PAH analysis is still critical when evaluating

petrogenic sources

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Questions?

Town Lake, Austin, Texas