Source apportionment of PM2.5 and sulfate formation during the COVID-19 lockdown in a coastal city of southeast China
Source apportionment of PM2.5 and sulfate formation during the COVID-19 lockdown in a coastal city of southeast China
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DOI：
10.1016/j.envpol.2021.117577
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发表时间：
2021-06-13
影响因子：
8.9
通讯作者：
Chen, Jinsheng
中科院分区：
文献类型：
--
作者：
Hong, Youwei;Xu, Xinbei;Chen, Jinsheng
揭示PM2.5的化学成分和来源的变化对于理解气溶胶化学和排放控制策略非常重要。COVID-19大流行期间，在中国东南沿海城市进行了PM2. 5中水溶性无机离子、元素、有机碳（OC）和元素碳（EC）的高时间分辨表征。结果显示，封城期间PM2. 5平均浓度由46. 2 μ g m（-3）降至24. 4 μ g m（-3），低于2019年同期（PM2. 5：37. 1 μ g m（-3））。在CLD期间，SO2、NO2、PM10、OC、EC和BC等污染物浓度也下降了27.3%~ 67.8%，而O3浓度上升了28.1%。虽然SO2在CLD期间从4.94 μ g m（-3）下降到1.59 μ g m（-3），但SO 42-的浓度（6.63 μ g m（-3））与非封锁期间的浓度（5.47 μ g m（-3））相当，这归因于硫酸盐氧化速率（SOR）的增加（16.0%）。O-x（O-3+NO2）与SO 42-呈正相关，表明受光化学氧化的影响。SO 42-与Fe、Mn的相关系数为0.557，表明过渡金属离子对氧化有催化作用。正矩阵分解（PMF）结果表明，在PM2.5的形成过程中，二次有机碳（SOC）的贡献增加，而交通、扬尘和工业等一次污染源的贡献分别减少了9%、8.5%和8%。本研究强调了在相对清洁的条件下，PM2.5的化学组成和形成机制对人为排放控制的全面和非线性响应。
Revealing the changes in chemical compositions and sources of PM2.5 is important for understanding aerosol chemistry and emission control strategies. High time-resolved characterization of water-soluble inorganic ions, elements, organic carbon (OC), and elemental carbon (EC) in PM2.5 was conducted in a coastal city of southeast China during the COVID-19 pandemic. The results showed that the average concentration of PM2.5 during the city lockdown (CLD) decreased from 46.2 mu g m(-3) to 24.4 mu g m(-3), lower than the same period in 2019 (PM2.5: 37.1 mu g m(-3)). Concentrations of other air pollutants, such as SO2(,) NO2, PM10, OC, EC, and BC, were also decreased by 27.3%-67.8% during the CLD, whereas O3 increased by 28.1%. Although SO2 decreased from 4.94 mu g m(-3)to 1.59 mu g m(-3) during the CLD, the concentration of SO42- (6.63 mu g m(-3)) was comparable to that (5.47 mu g m(-3)) during the non-lockdown period, which were attributed to the increase (16.0%) of sulfate oxidation rate (SOR). O-x (O-3+NO2) was positively correlated with SO42-, suggesting the impacts of photochemical oxidation. A good correlation (R-2 = 0.557) of SO42- and Fe and Mn was found, indicating the transition-metal ion catalyzed oxidation. Based on positive matrix factorization (PMF) analysis, the contribution of secondary formation to PM2.5 increased during the epidemic period, consisting with the increase of secondary organic carbon (SOC), while other primary sources including traffic, dust, and industry significantly decreased by 9%, 8.5%, and 8%, respectively. This study highlighted the comprehensive and nonlinear response of chemical compositions and formation mechanisms of PM2.5 to anthropogenic emissions control under relatively clean conditions.