Vehicle exhausts contribute high near-UV absorption through carbonaceous aerosol during winter in a fast-growing city of Sichuan Basin, China
Vehicle exhausts contribute high near-UV absorption through carbonaceous aerosol during winter in a fast-growing city of Sichuan Basin, China
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在中国四川盆地快速发展的城市，冬季汽车尾气通过碳质气溶胶产生高近紫外线吸收
DOI：
10.1016/j.envpol.2022.119966
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发表时间：
2022
影响因子：
8.9
通讯作者：
Fumo Yang
中科院分区：
文献类型：
--
作者：
Song Liu;Tianzhi Luo;Li Zhou;Tianli Song;Ning Wang;Qiong Luo;Gang Huang;Xia Jiang;Shuhua Zhou;Yang Qiu;Fumo Yang
碳质气溶胶对气候有重大影响，但它们的来源和各自对光吸收的贡献各不相同，仍然知之甚少。在这项工作中，2021年冬季，在四川盆地南部快速发展的城市宜宾的三个城市站点，中国采集了基于过滤器的PM2.5样本。分析了PM2.5的组成特征、光吸收特性和碳质气溶胶的来源。冬季全市PM2.5平均浓度为87.4±31.0μg/m3。碳质气溶胶含量最高，占PM2.5总量的42.5%。源解析结果表明，车辆排放是冬季PM2.5的主要来源，对PM2.5的贡献率为34.6%。用简化的双组分模型计算了黑碳(BC)和褐碳(BRC)的光吸收系数。采用最优角吸收指数(AAE、BC)的最小二乘线性回归方法，计算了碳质气溶胶对BC和BRC的光吸收系数。BC和BRC在405 nm处的平均吸收分别为51.6±21.5 mm−1和17.7±8.0 mm−1，平均AAEBC=0.82±0.02。在405 nm处，BRC对碳质吸收的贡献率达到26.1%。根据PM2.5源解析和BRC在405 nm处的质量吸收截面(MAC)值，车辆排放是冬季BRC的主要来源，贡献率高达56.4%。因此，在这个快速发展的城市，机动车排放减排应该是提高大气能见度的首要和有效的途径。·宜宾市冬季PM2.5以碳质气溶胶为主。·应用一种改进的基于AAE的方法来评估气溶胶的光吸收。·BRC对405 nm碳质气溶胶吸收的贡献率为26%。·在这座快速发展的城市，汽车尾气成为BRC的主要来源。
Carbonaceous aerosols pose significant climatic impact, however, their sources and respective contribution to light absorption vary and remain poorly understood. In this work, filter-based PM 2.5 samples were collected in winter of 2021 at three urban sites in Yibin, a fast-growing city in the south of Sichuan Basin, China. The composition characteristics of PM 2.5 , light absorption and source of carbonaceous aerosol were analyzed. The city-wide average concentration of PM 2.5 was 87.4 ± 31.0 μg/m 3 in winter. Carbonaceous aerosol was the most abundant species, accounting for 42.5% of the total PM 2.5 . Source apportionment results showed that vehicular emission was the main source of PM 2.5 during winter, contributing 34.6% to PM 2.5 . The light absorption of black carbon (BC) and brown carbon (BrC) were derived from a simplified two-component model. We apportioned the light absorption of carbonaceous aerosols to BC and BrC using the Least Squares Linear Regression with optimal angstrom absorption exponent of BC (AAE BC ). The average absorption of BC and BrC at 405 nm were 51.6 ± 21.5 Mm −1 and 17.7 ± 8.0 Mm −1 , respectively, with mean AAE BC = 0.82 ± 0.02. The contribution of BrC to the absorption of carbonaceous reached 26.1% at 405 nm. Based on the PM 2.5 source apportionment and the mass absorption cross-section (MAC) value of BrC at 405 nm, vehicle emission was found to be the dominant source of BrC in winter, contributing up to 56.4%. Therefore, vehicle emissions mitigation should be the primary and an effective way to improve atmospheric visibility in this fast-developing city. • Carbonaceous aerosol was the dominate species of PM 2.5 during winter in Yibin city. • An improved AAE-based method was applied to evaluate aerosol light absorption. • The contribution of BrC to carbonaceous aerosol absorption at 405 nm was 26%. • Vehicle emission became the dominant source of BrC in this fast-growing city.