18 October 2022

Pavement Sealant Leaches Environmental Contaminants

Coal tar pavement sealant contains 50,000 to 75,000 ppm of carcinogenic polycyclic aromatic hydrocarbons (PAHs). Weathering by sunlight and rain can contaminate natural waterways through oxidation of the PAHs contained in the pavement sealant.           Coal tar pavement sealant contains 50,000 to 75,000 ppm of carcinogenic polycyclic aromatic hydrocarbons (PAHs). Weathering by sunlight and rain can contaminate natural waterways through oxidation of the PAHs contained in the pavement sealant. Taylor Glattke, MagLab

New research shows that high concentrations of polycyclic aromatic hydrocarbons (PAHs) found in coal tar pavement sealants are oxidized into toxic, water-soluble compounds by sunlight and subsequently washed into the environment by rainwater, polluting natural water systems, negatively impacting marine ecosystems and public health. 

What did scientists discover?

Laboratory simulated weathering of coal tar pavement sealant revealed that carcinogenic polycyclic aromatic hydrocarbons (PAHs) are oxidized by sunlight into oxy-PAHs and then transferred into water. Toxicity testing of water that contained oxy-PAHs revealed high toxicity of water fractions collected from coal tar sealant.

THE TOOLS THEY USED

This research was conducted in the 9.4 T, 220 mm Fourier Transform at the MagLab's ICR Facility.

Why is this important?

Little has been known about how pavement sealant is transformed when it is exposed to weathering, such as sunlight and rain. This new research reveals that toxic compounds in coal tar sealant can easily leach into and pollute natural water systems, thus negatively impacting marine ecosystems and public health. These new findings provide critical evidence to support phasing out of these materials in the United States and elsewhere.

Who did the research?

Taylor J. Glattke1,2, Martha L. Chacón-Patiño2, Sarajeen Saima Hoque3, Thomas E. Ennis4, Steven Greason5, Alan G. Marshall1,2, Ryan P. Rodgers1,2

1Ion Cyclotron Resonance Program, National MagLab 2Department of Chemistry and Biochemistry, Florida State University 3Department of Civil & Environmental Engineering, FAMU-FSU College of Engineering 4Watershed Protection Department, City of Austin, TX 5Sitelab Corporation

Why did they need the MagLab?

The MagLab's ultrahigh-resolution FT-ICR (Fourier Transform - Ion Cyclotron Resonance) mass spectrometers allow for identification of tens of thousands of compounds from complex mixtures, such as the weathered coal tar sealant and water samples analyzed in this work.

Details for scientists

Funding

This research was funded by the following grants: G.S. Boebinger (NSF DMR-1644779)


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Details

  • Research Area: Chemistry- Analytical,Chemistry - Environmental, Chemistry - Petroleum, FT-ICR Mass Spectrometry Technique & Inst. Development
  • Research Initiatives: Materials
  • Facility / Program: ICR
  • Year: 2022
Last modified on 18 October 2022