Thoma Eben D, Brantley Halley L, Oliver Karen D, Whitaker Donald A, Mukerjee Shaibal, Mitchell Bill, Wu Tai, Squier Bill, Escobar Elsy, Cousett Tamira A, Gross-Davis Carol Ann, Schmidt Howard, Sosna Dennis, Weiss Hallie
a U.S. EPA, Office of Research and Development , National Risk Managment Research Laboratory , Durham , NC , USA.
b Oak Ridge Institute for Science and Engineering Fellow , Durham , NC , USA.
J Air Waste Manag Assoc. 2016 Oct;66(10):959-70. doi: 10.1080/10962247.2016.1184724.
From June 2013 to March 2015, in total 41 passive sampler deployments of 2 wk duration each were conducted at 17 sites in South Philadelphia, PA, 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, R(2) = 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 2-wk 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 detected a benzene signal from the west on one day in particular, with the highest 5-min path-averaged benzene concentration measured at 24 ppbv.
Using a variation of EPA's passive sampler refinery fenceline monitoring method, coupled with time-resolved measurements, a multiyear study in South Philadelphia informed benzene concentrations near facilities and in communities. The combination of measurement strategies can assist facilities in identification and mitigation of emissions from fugitive sources and improve information on air quality complex air sheds.
2013年6月至2015年3月期间，在宾夕法尼亚州南费城的17个地点共进行了41次被动采样器部署，每次持续2周，此处讨论苯的测量结果。还使用成本较低的原型围栏线传感器和开放路径紫外差分光学吸收光谱仪进行了补充的时间分辨测量。每个采样周期的被动采样器苯最低浓度范围为0.08 ppbv至0.65 ppbv，平均为0.25 ppbv，且与环境温度呈负相关（-0.01 ppbv/°C，R² = 0.68）。共同部署的重复被动采样器对（N = 609）显示出良好的精度，平均差异百分比和最大差异百分比分别为1.5%和34%。一组位于炼油厂围栏线50米范围内的被动采样器的苯研究平均浓度为1.22 ppbv，而一组位于距离设施超过1公里的社区中的采样器的平均浓度为0.29 ppbv。在95%置信水平下，这些组平均值的差异具有统计学意义（p < 0.001）。观察到远离设施的苯浓度呈下降梯度，且不同时间段之间存在显著变化。围栏线组记录到的最高2周平均苯浓度为3.11 ppbv。在此期间，原型传感器和开放路径光谱仪的时间分辨数据在某一天特别检测到来自西部的苯信号，测量到的最高5分钟路径平均苯浓度为24 ppbv。
采用美国环境保护局（EPA）被动采样器炼油厂围栏线监测方法的变体，并结合时间分辨测量，在南费城进行的一项多年研究提供了设施附近和社区内的苯浓度信息。测量策略的组合可以帮助设施识别和减少来自逸散源的排放，并改善关于复杂空气质量区域的信息。
