Alion Science and Technology , P.O. Box 12313, Research Triangle Park, North Carolina 27709, United States.
Environ Sci Technol. 2011 Apr 15;45(8):3511-8. doi: 10.1021/es103400h. Epub 2011 Mar 14.
Intensive ambient air sampling was conducted in Tampa, FL, during October and November of 2002. Fine particulate matter (PM(2.5)) was collected at 30 min resolution using the Semicontinuous Elements in Aerosol Sampler II (SEAS-II) and analyzed off-line for up to 45 trace elements by high-resolution ICPMS (HR-ICPMS). Divalent reactive gaseous mercury and particulate bound mercury were also measured semicontinuously (2 h). Application of the United States Environmental Protection Agency's (EPA) Unmix receptor model on the 30 min resolution trace metals data set identified eight possible sources: residual oil combustion, lead recycling, coal combustion, a Cd-rich source, biomass burning, marine aerosol, general industrial, and coarse dust contamination. The source contribution estimates from EPA Unmix were then run in a nonparametric wind regression (NWR) model, which convincingly identified plausible source origins. When the 30 min ambient concentrations of trace elements were time integrated (2 h) and combined with speciated mercury concentrations, the model identified only four sources, some of which appeared to be merged source profiles that were identified as separate sources by using the 30 min resolution data. This work demonstrates that source signatures that can be captured at 30 min resolution may be lost when sampling for longer durations.
于 2002 年 10 月和 11 月在佛罗里达州坦帕市进行了强化环境空气采样。使用气溶胶采样器 II（SEAS-II）以 30 分钟的分辨率收集细颗粒物（PM（2.5）），并通过高分辨率电感耦合等离子体质谱仪（HR-ICPMS）离线分析多达 45 种痕量元素。二价反应性气态汞和颗粒态汞也连续半定量（2 小时）测量。美国环保署（EPA）的 Unmix 受体模型在 30 分钟分辨率痕量金属数据集上的应用确定了八个可能的来源：残余油燃烧、铅回收、煤燃烧、富含镉的来源、生物质燃烧、海洋气溶胶、一般工业和粗尘污染。然后，将 EPA Unmix 的源贡献估计值应用于非参数风回归（NWR）模型，该模型令人信服地确定了合理的源起源。当将痕量元素的 30 分钟环境浓度（2 小时）时间积分并与特征汞浓度结合时，该模型仅识别出四个来源，其中一些来源似乎是合并的源谱，通过使用 30 分钟分辨率数据识别为单独的来源。这项工作表明，在更长时间采样时，可能会丢失在 30 分钟分辨率下捕获的源特征。
