Sulfate and nitrate elevation in reverse-transport dust plumes over coastal areas of China
Sulfate and nitrate elevation in reverse-transport dust plumes over coastal areas of China
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DOI：
10.1016/j.atmosenv.2022.119518
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发表时间：
2022-11
影响因子：
5
通讯作者：
Wenshuai Li;Yuxuan Qi;W. Qu;W. Qu;Jinhui Shi;Daizhou Zhang;Yingchen Liu;Feng Wu;Yuanyuan M
中科院分区：
文献类型：
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作者：
Wenshuai Li;Yuxuan Qi;W. Qu;W. Qu;Jinhui Shi;Daizhou Zhang;Yingchen Liu;Feng Wu;Yuanyuan M
由于粉尘气溶胶具有较高的吸湿性，在其上形成的硫酸盐和硝酸盐对颗粒的理化性质有很大的影响。沙尘反向输送（DRT）事件可能发生在中国东部，当沙尘羽经历由亚洲高压或气旋引起的明显转向时，导致沙尘羽在一个地方重新出现，但混入了人为污染物。在本研究中，在沿海城市青岛发现了三个DRT事件。根据水溶性离子和粉尘示踪金属的质量浓度估算了DRT事件期间收集的pm2.5中二次硫酸盐和硝酸盐的含量。几个关键因素，包括气溶胶的非均相反应，空气中的光化学转化，以及尘埃羽中前体的丰度，影响了尘埃羽的老化。在空气中有充足的铵态和高浓度氧化剂的条件下，青岛南部发生DRT时，硫酸盐和硝酸盐在中/高湿条件下有效生成。次生硫酸盐/硝酸盐占总浓度的比例超过90%，其中20.8% ~ 43.1%的次生硝酸盐是在粉尘颗粒上形成的。相反，当DRT发生在青岛北部，相对湿度低，[NH4+]/[SO42−]比低时，硫酸盐和硝酸盐的生长较小。这项研究揭示了大陆大气中尘埃羽状物中硫酸盐和硝酸盐的有效形成方式。
Sulfate and nitrate formed on dust aerosols can considerably affect particles' physicochemical properties due to their high hygroscopicity. Dust reverse-transport (DRT) events can occur in eastern China when dust plumes undergo a distinct turn caused by Asian highs or cyclones, resulting in the re-appearance of the dust plume in one place but with anthropogenic pollutants mixed in. In this study, three DRT events were identified at a coastal city, Qingdao. The secondary sulfate and nitrate in PM2.5collected during the DRT events were estimated according to the mass concentration of water-soluble ions and dust tracer metal. Several key factors, including heterogeneous reactions on aerosols, photochemical conversions in the air, and precursors’ abundance in dust plumes, affected the aging of dust plumes. In the presence of adequate ammonium and high-level oxidants in the air, sulfate and nitrate were efficiently produced under moderate/high humidity conditions when DRT events occurred to the south of Qingdao. The proportions of the secondary sulfate/nitrate in total concentrations exceeded 90%, in which 20.8%–43.1% of secondary nitrate was formed on dust particles. In contrast, when the DRT occurred to the north of Qingdao with low relative humidity and low [NH4+]/[SO42−] ratio, the growth of sulfate and nitrate was small. This study reveals a manner of efficient sulfate and nitrate formation in dust plumes in the continental atmosphere.