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Near-Road Mulltipollutant Profiles: Association between Volatile Organic Compounds and a Tracer Gas Surrogate Near a Busy Highway
Citation:
BARZYK, T. M., A. CIESIELSKI, R. C. SHORES, E. D. THOMA, R. L. SEILA, V. ISAKOV, AND R. W. BALDAUF. Near-Road Mulltipollutant Profiles: Association between Volatile Organic Compounds and a Tracer Gas Surrogate Near a Busy Highway. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION. Air & Waste Management Association, Pittsburgh, PA, 62(5):594-603, (2012).
Impact/Purpose:
The National Exposure Research Laboratory′s (NERL) Human Exposure and Atmospheric Sciences Division (HEASD) conducts research in support of EPA′s mission to protect human health and the environment. HEASD′s research program supports Goal 1 (Clean Air) and Goal 4 (Healthy People) of EPA′s strategic plan. More specifically, our division conducts research to characterize the movement of pollutants from the source to contact with humans. Our multidisciplinary research program produces Methods, Measurements, and Models to identify relationships between and characterize processes that link source emissions, environmental concentrations, human exposures, and target-tissue dose. The impact of these tools is improved regulatory programs and policies for EPA.
Description:
This research characterizes associations between multiple pollutants in the near-road environment attributed to a roadway line source. It also examines the use of a tracer gas as a surrogate of mobile source pollutants. Air samples were collected in summa canisters along a 300 m transect normal to a highway in Raleigh, North Carolina for five sampling periods spanning four days. Samples were subsequently measured for volatile organic compounds (VOCs) using an electron capture gas chromatograph. Sulfur hexafluoride (SF6) was released from a finite line source adjacent to the roadway for two of the sampling periods, collected in the canisters and measured with the VOCs. Associations between each VOC, and between VOCs and the tracer, were quantified with Pearson correlation coefficients to assess the consistency of the multi-pollutant dispersion profiles, and assess the tracer as a potential surrogate for mobile source pollutants. As expected, benzene, toluene, ethylbenzene, and m,p- and o-xylenes (collectively, BTEX) show strong correlations between each other; further, BTEX shows a strong correlation to SF6. Between 26 VOCs, correlation coefficients were greater than 0.8, and 14 VOCs had coefficients greater than 0.6 with the tracer gas. Even under non-downwind conditions, chemical concentrations had significant correlations with distance. Results indicate that certain VOCs are representative of a larger multi-pollutant mixture, and many VOCs are well-correlated with the tracer gas.
URLs/Downloads:
Journal of the Air and Waste Management Association
Near-Road Mulltipollutant Profiles: Association between Volatile Organic Compounds and a Tracer Gas Surrogate Near a Busy Highway (PDF, NA pp, 112 KB, about PDF)