BACKGROUND A newly designed electrostatic precipitator (ESP) in tandem with Versatile Aerosol Concentration Enrichment System (VACES) was developed by the University of Southern California to collect ambient aerosols on substrates appropriate for chemical and toxicological analysis. The laboratory evaluation of this sampler is described in a previous paper. The main objective of this study was to evaluate the performance of the new VACES-ESP system in the field by comparing the chemical characteristics of the PM collected in the ESP to those of reference samplers operating in parallel. RESULTS The field campaign was carried out in the period from August, 2007 to March, 2008 in a typical urban environment near downtown Los Angeles. Each sampling set was restricted to 2-3 hours to minimize possible sampling artifacts in the ESP. The results showed that particle penetration increases and ozone concentration decreases with increasing sampling flow rate, with highest particle penetration observed between 100 nm and 300 nm. A reference filter sampler was deployed in parallel to the ESP to collect concentration-enriched aerosols, and a MOUDI sampler was used to collect ambient aerosols. Chemical analysis results showed very good agreement between the ESP and MOUDI samplers in the concentrations of trace elements and inorganic ions. The overall organic compound content of PM collected by the ESP, including polycyclic aromatic hydrocarbons (PAHs), hopanes, steranes, and alkanes, was in good agreement with that of the reference sampler, with an average ESP -to -reference concentration ratio of 1.07 (+/- 0.38). While majority of organic compound ratios were close to 1, some of the semi-volatile organic species had slightly deviated ratios from 1, indicating the possibility of some sampling artifacts in the ESP due to reactions of PM with ozone and radicals generated from corona discharge, although positive and negative sampling artifacts in the reference filter sampler cannot be ruled out. CONCLUSION The very good overall agreement between ESP and reference samplers makes it an attractive alternative to filters and biosamplers for chemical and toxicological evaluation of PM properties, including the possibility of conducting direct in vitro cell exposures. Moreover, the concentration enrichment of ambient aerosols by the VACES allows for short-term exposure studies, which preserve cell viability and enable studies to PM generated from specific sources and-or formation mechanisms in the atmosphere.

中文翻译：

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用于测量颗粒物化学和毒理学特性的新型颗粒浓缩器-静电除尘器系统的现场评估。

背景 南加州大学开发了一种新设计的静电除尘器 (ESP) 与多功能气溶胶浓缩系统 (VACES) 相结合，以收集适合化学和毒理学分析的基质上的环境气溶胶。该采样器的实验室评估在之前的一篇论文中有所描述。本研究的主要目的是通过比较 ESP 中收集的 PM 的化学特性与并行操作的参考采样器的化学特性，评估新 VACES-ESP 系统在现场的性能。结果 实地运动于2007年8月至2008年3月期间在洛杉矶市中心附近的典型城市环境中进行。每个采样组被限制在 2-3 小时内，以最大限度地减少 ESP 中可能出现的采样伪影。结果表明，随着采样流速的增加，颗粒渗透率增加，臭氧浓度降低，在 100 nm 和 300 nm 之间观察到最高的颗粒渗透率。参考过滤器采样器与 ESP 并行部署以收集浓缩气溶胶，并使用 MOUDI 采样器收集环境气溶胶。化学分析结果表明 ESP 和 MOUDI 采样器在痕量元素和无机离子的浓度方面非常一致。ESP 收集到的 PM 的总有机化合物含量，包括多环芳烃 (PAHs)、hopanes、steranes 和烷烃，与参考采样器的有机化合物含量非常一致，平均 ESP 与参考浓度比为 1.07 （+/- 0.38）。虽然大多数有机化合物的比率接近 1，一些半挥发性有机物种的比率略高于 1，表明由于 PM 与臭氧和电晕放电产生的自由基反应，ESP 中可能存在一些采样伪影，尽管参考过滤器采样器中存在正负采样伪影不能排除。结论 ESP 和参考采样器之间非常好的整体一致性使其成为过滤器和生物采样器的有吸引力的替代品，用于 PM 特性的化学和毒理学评估，包括进行直接体外细胞暴露的可能性。此外，VACES 对环境气溶胶的浓度富集允许进行短期暴露研究，从而保持细胞活力并能够研究由特定来源和/或大气中形成机制产生的 PM。