Microscopic comparison of aerosol particles collected at an urban site in North China and a coastal site in Japan
Microscopic comparison of aerosol particles collected at an urban site in North China and a coastal site in Japan
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华北城市站点和日本沿海站点收集的气溶胶颗粒的显微比较
DOI：
10.1016/j.scitotenv.2019.03.163
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发表时间：
2019
影响因子：
9.8
通讯作者：
Weijun Li
中科院分区：
文献类型：
--
作者：
Liang Xu;Daizhou Zhang;Weijun Li
为了了解日本和中国气溶胶颗粒的理化特性，利用透射电子显微镜分析了在两个截然不同的环境地点（即春季的华北大陆地点（T1）和日本沿海地点（T2））收集的单个气溶胶颗粒。 2014年3月20日至23日，T1的平均PM2.5浓度（52μg/m3）远高于T2（20μg/m3）。我们的研究表明，硫有机物（S-OM）颗粒在T1和T2均最丰富，并且仅在T1时观察到单个球形初级有机物（POM）颗粒。 T1处观察到更多的人为飞灰和金属颗粒，这与T1处的空气污染较T2处一致，并且由于区域工业排放的影响，T1处气溶胶成分的整体复杂性超过了T2处。对 S-OM 颗粒的进一步检查表明，S-OM 涂层颗粒占 T2 时观察到的颗粒总数的 29.6%，但在 T1 时仅占 8.6%。然而，T2 时 OM 涂层的平均厚度大于 T1 时，表明 T2 时的颗粒比 T1 时的颗粒老化时间更长。这些比较表明，硫酸盐上的 OM 涂层厚度取决于空气团的传输距离和大气氧化剂的浓度，但不应用于代表污染水平。与日本沿海空气相比，华北城市气溶胶颗粒物不仅浓度较高，而且气溶胶成分更为复杂。
In order to understand the physicochemical properties of aerosol particles in Japan and China, transmission electron microscopy was used to analyze individual aerosol particles collected at two very different environmental sites, i.e., a continental site (T1) in North China and a coastal site (T2) in Japan in springtime. The average PM2.5concentration (52 μg/m3) at T1 was much higher than T2 (20 μg/m3) from 20 to 23 March 2014. Our study shows that sulfur-organic matter (S-OM) particles were the most abundant at both T1 and T2, and individual spherical primary organic matter (POM) particles were only observed at T1. More anthropogenic fly ash and metal particles were observed at T1, consistent with the heavier air pollution at T1 than T2, and the overall complexity of aerosol composition at T1 exceeded that at T2, due to the influence of regional industrial emissions. Further examination of S-OM particles suggest that S-OM coated particles accounted for 29.6% of total observed particles at T2 but only 8.6% at T1. However, the average thickness of OM coating was larger at T2 than at T1, indicating that the particles at T2 had aged longer than those at T1. These comparisons suggest that the OM coating thickness on sulfate depends on the transport distance of the air mass and on the concentration of atmospheric oxidants but should not be used to represent pollution levels. Compared with the coastal air in Japan, we know that urban aerosol particles in North China not only attain high concentrations but also have more complex aerosol components.