Evolution of nitrogen species air pollutants along trajectories crossing the Los Angeles area
Evolution of nitrogen species air pollutants along trajectories crossing the Los Angeles area
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DOI：
10.1021/es0110630
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发表时间：
2002-09-15
影响因子：
11.4
通讯作者：
Cass, GR
中科院分区：
文献类型：
--
作者：
Hughes, LS;Allen, JO;Cass, GR
环境气溶胶采样进行了钻石吧，米拉洛马，和滨江，CA，近距离观察氨排放对空气质量的影响。这些地点分别位于奇诺乳品区的上风、内和下风处，奇诺乳品区是洛杉矶地区最大的氨排放源。惯性撞击器和散装过滤采样器提供了4-7小时的气溶胶化学成分和粒度分布的测量。日平均细颗粒物质量浓度范围为22.4-143.0 mug m（-3）。在某些日子里，细颗粒物浓度比拟议的24小时联邦标准65 mug m（-3）高出两倍多。硝酸铵是最大的组成部分，细颗粒质量在所有三个网站; 24小时平均细颗粒铵加上硝酸盐浓度范围从11.7到75.4 mug m（-3）。对同一天早晨经过钻石吧空气监测点并于傍晚在米拉洛马附近停滞的单个气团进行了研究。在这两个站点之间，NO被氧化成NO2，并且氨浓度增加了5倍。第二个气团轨迹在清晨停滞在米拉洛马附近，大约24小时后经过滨江现场附近，表明氨浓度随着时间的推移而降低，这与稀释一致，因为空气质量从乳品区的氨源顺风移动。随着时间的推移，空气中的颗粒状NH 4 NO3浓度保持大致恒定，这与NH3相对于HNO 3在乳制品区域顺风处持续过量相一致。
Ambient aerosol sampling was conducted in Diamond Bar, Mira Loma, and Riverside, CA, to observe at close range the effects of ammonia emissions on air quality. These sites are located upwind, within, and downwind, respectively, of the Chino dairy area, the largest single source of ammonia emissions in the Los Angeles area. Inertial impactors and bulk filter samplers provided 4-7-h measurements of aerosol chemical composition and size distribution. Daily average fine particle mass concentrations were in the range 22.4-143.0 mug m(-3). On some days the fine particulate matter concentrations were more than two times greater than the proposed 24-h Federal standard of 65 mug m(-3). Ammonium nitrate was the largest component of fine particle mass at all three sites; 24-h average fine particulate ammonium plus nitrate concentrations ranged from 11.7 to 75.4 mug m(-3). A single air mass was studied as it passed the Diamond Bar air monitoring site in the morning and stagnated near Mira Loma in the evening of the same day. Between these two sites NO was oxidized to NO2, and the ammonia concentration increased by a factor of 5. A second air parcel trajectory, which stagnated near Mira Loma during the early morning and passed near the Riverside site approximately 24 h later, showed a decrease in ammonia concentration over time that is consistent with dilution as the air mass moved downwind from the source of ammonia in the dairy area. Particulate NH4NO3 concentration in that air parcel remained approximately constant over time, consistent with a continued excess of NH3 relative to HNO3 downwind of the dairy area.