Diurnal variations of individual organic compound constituents of ultrafine and accumulation mode particulate matter in the Los Angeles basin
Diurnal variations of individual organic compound constituents of ultrafine and accumulation mode particulate matter in the Los Angeles basin
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DOI：
10.1021/es0348389
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发表时间：
2004-03-01
影响因子：
11.4
通讯作者：
Sioutas, C
中科院分区：
文献类型：
--
作者：
Fine, PM;Chakrabarti, B;Sioutas, C
单个有机化合物可用作化学质量平衡受体模型中环境颗粒物 (PM) 主要来源的示踪剂。之前的工作仅检查了 PM2.5，并且通常采用涵盖全天或更长时间的长采样周期。在这项研究中，采用了高流量、低压降的超细颗粒分离器，以收集足够的质量，以便每天进行超细颗粒和累积模式气溶胶的有机形态形成。直径在0.18至2.5μm之间的颗粒被收集在石英纤维冲击基底上，0.18μm以下的超细颗粒被在下游的高容量过滤器上收集。在五个工作日内对四个每日时间段样本（早上、中午、晚上和夜间）进行采样，以形成每个昼夜周期的每周平均组合。在两个季节的两个地点进行了采样；夏季（八月）和冬季（一月）样本在洛杉矶市中心附近的城市地点（南加州大学）和加利福尼亚州里弗赛德的顺风内陆地点采集。藿烷用作车辆排放的有机标记物，被发现主要以超细模式存在。左旋葡聚糖是木材燃烧的指标，在两个尺寸范围内都进行了定量，但更多的是在累积模式颗粒中存在。光化学二次有机气溶胶形成的指标 1,2-苯二甲酸主要以积累模式被发现，并且随着地点、季节和一天中的时间而变化，正如人们对光化学产品的预期一样。还考虑了颗粒胆固醇和其他有机酸的大气变化。通过检查单个有机化合物的昼夜变化、尺寸分级和相互关系，可以更好地了解这些示踪剂的来源和大气命运，并可以评估它们作为分子标记的效用。
Individual organic compounds can be used as tracers for primary sources of ambient particulate matter (PM) in chemical mass balance receptor models. Previous work has examined PM2.5 only and usually over long sampling periods encompassing entire days or longer. In this study, a high-flow-rate, low-pressure-drop ultrafine particle separator was deployed to collect sufficient mass for organic speciation of ultrafine and accumulation mode aerosol on a diurnal basis. Particles between 0.18 and 2.5 mum in diameter were collected on a quartz-fiber impaction substrate,and ultrafine particles below 0.18 mum were collected downstream on a high-volume filter. Four daily time period samples (morning, midday, evening, and overnight) were sampled over five weekdays to form a weekly average composite for each diurnal period. Sampling was conducted at two sites over two seasons; summer (August) and winter (January) samples were collected at both an urban site near downtown Los Angeles (University of Southern California) and a downwind, inland site in Riverside, CA. Hopanes, used as organic markers for vehicular emissions, were found to exist primarily in the ultrafine mode. Levoglucosan, an indicator of wood combustion, was quantified in both size ranges, but more was present in the accumulation mode particles. An indicator of photochemical secondary organic aerosol formation, 1,2-benzenedicarboxylic acid, was found primarily in the accumulation mode and varied with site, season, and time of day as one would expect for a photochemical product. The atmospheric variations of particulate cholesterol and other organic acids were also considered. By examining the diurnal variation, size-fractionation, and intercorrelations of individual organic compounds, the sources and atmospheric fate of these tracers can be better understood and their utility as molecular markers can be assessed.