Progressively narrow the gap of PM2.5 pollution characteristics at urban and suburban sites in a megacity of Sichuan Basin, China
Progressively narrow the gap of PM2.5 pollution characteristics at urban and suburban sites in a megacity of Sichuan Basin, China
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逐步缩小中国四川盆地特大城市城乡PM2.5污染特征差距
DOI：
10.1016/j.jes.2022.05.017
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发表时间：
2022
影响因子：
6.9
通讯作者：
Fumo Yang
中科院分区：
文献类型：
--
作者：
Ning Wang;Li Zhou;Miao Feng;Tianli Song;Zhuoran Zhao;Danlin Song;Qinwen Tan;Fumo Yang
·成都市主要污染物在大部分季节由SO 42-向NO3-转化。·由于Mn催化的多相反应，SO 4 2−可能更容易在城市地区产生。·除EC外，城市地区的OC浓度高于郊区。·燃烧源和二次气溶胶的贡献从CP到PP增加。目前，我国一些特大城市的细颗粒物污染仍然比较严重，特别是四川盆地。为了了解细颗粒物的成因、来源和影响，我们在2018年7月至2019年5月的典型月份中，在该地区的特大城市成都的一个城市和一个郊区（背景）站点收集了PM 2.5样本，并分析了其化学成分。各站点PM2.5日平均浓度范围为5.6-102.3 μg/m3和4.3-110.4 μg/m3。次生无机物和有机物是两个站点PM2.5的主要成分。PM 2.5中硝酸盐的比例已经超过硫酸盐，成为首要无机成分。在城市地区，由于Mn催化的多相反应，SO2更容易转化为硫酸盐。相反，在大气气溶胶含水量高的郊区，NO2更容易转化.除元素碳外，城市土壤有机碳含量均高于农村。元素Cr和As是主要的癌症风险驱动因素。城市和郊区PM2.5的主要来源均为二次气溶胶（42.9%、32.1%）、燃烧（16.0%、25.2%）和机动车排放（15.2%、19.2%）。从清洁期到污染期，燃烧和二次气溶胶的贡献显著增加。除了加强车辆控制外，城市地区需要限制钢铁冶炼厂的排放，郊区需要在秋冬季节尽量减少煤炭和生物质燃烧。图形摘要
• The dominant pollutant changed from SO 4 2− to NO 3 − in most seasons of Chengdu. • SO 4 2− was likely generated more easily in urban areas due to Mn-catalytic heterogeneous reactions. • OC concentrations were higher in urban areas than in suburban areas, other than EC. • The contribution of combustion origins and secondary aerosols increased from CP to PP. Nowadays, the fine particle pollution is still severe in some megacities of China, especially in the Sichuan Basin, southwestern China. In order to understand the causes, sources, and impacts of fine particles, we collected PM 2.5 samples and analyzed their chemical composition in typical months from July 2018 to May 2019 at an urban and a suburban (background) site of Chengdu, a megacity in this region. The daily average concentrations of PM 2.5 ranged from 5.6-102.3 μg/m 3 and 4.3-110.4 μg/m 3 at each site. Secondary inorganics and organic matters were the major components in PM 2.5 at both sites. The proportion of nitrate in PM 2.5 has exceeded sulfate and become the primary inorganic component. SO 2 was easier to transform into sulfate in urban areas because of Mn-catalytic heterogeneous reactions. In contrast, NO 2 was easily converted in suburbs with high aerosol water content. Furthermore, organic carbon in urban was much greater than that in rural, other than elemental carbon. Element Cr and As were the key cancer risk drivers. The main sources of PM 2.5 in urban and suburban areas were all secondary aerosols (42.9%, 32.1%), combustion (16.0%, 25.2%) and vehicle emission (15.2%, 19.2%). From clean period to pollution period, the contributions from combustion and secondary aerosols increased markedly. In addition to tightening vehicle controls, urban areas need to restrict emissions from steel smelters, and suburbs need to minimize coal and biomass combustion in autumn and winter. Graphical Abstract