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South Philadelphia Passive Sampler and Sensor Study
Thoma, E., H. Brantley, K. Oliver, D. Whitaker, S. Mukerjee, Bill Mitchell, T. Wu, B. Squier, E. Escobar, T. Cousett, C. Gross-Davis, H. Schmidt, D. Sosna, AND H. Weiss. South Philadelphia Passive Sampler and Sensor Study. JOURNAL OF AIR AND WASTE MANAGEMENT. Air & Waste Management Association, Pittsburgh, PA, 66(10):959-970, (2016).
This peer reviewed journal article submission discusses the multiyear Philadelphia Passive Sampler and Sensor study. It builds on the interim report from the 2015 AWAM conference and begins to include time-resolved sensor and optical remote sensing data. This study overview paper help set up for other papers to follow.
From June 2013 to March 2015, a total of 41 two-week duration passive sampler deployments were conducted at 17 sites in South Philadelphia, with results for benzene discussed here. Complementary time-resolved measurements with lower cost prototype fenceline sensors and an open-path ultraviolet differential optical absorption spectrometer were also conducted. Minimum passive sampler benzene concentrations for each sampling period ranged from 0.08 ppbv to 0.65 ppbv, with a mean of 0.25 ppbv, and were negatively correlated with ambient temperature (-0.01 ppbv/C, R2 = 0.68). Co-deployed duplicate passive sampler pairs (N = 609) demonstrated good precision with an average and maximum percent difference of 1.5% and 34%, respectively. A group of passive samplers located within 50 m of a refinery fenceline had a study mean benzene concentration of 1.22 ppbv, whereas a group of samplers located in communities > 1 km distant from facilities had a mean of 0.29 ppbv. The difference in the means of these groups was statistically significant at the 95% confidence level (p < 0.001). A decreasing gradient in benzene concentrations moving away from the facilities was observed, as was a significant period-to-period variation. The highest recorded two-week average benzene concentration for the fenceline group was 3.11 ppbv. During this period, time-resolved data from the prototype sensors and the open-path spectrometer indicated a significant fenceline plume and benzene signal on one day in particular with the highest five-minute path-averaged benzene concentration measured at 24 ppbv.
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