Spatial distribution and sources of winter black carbon and brown carbon in six Chinese megacities
Spatial distribution and sources of winter black carbon and brown carbon in six Chinese megacities
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中国六大城市冬季黑碳、棕碳空间分布及来源
DOI：
10.1016/j.scitotenv.2020.143075
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发表时间：
2021
影响因子：
9.8
通讯作者：
Cao Junji
中科院分区：
文献类型：
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作者：
Zhang Qian;Shen Zhenxing;Zhang Tian;Kong Shaofei;Lei Yali;Wang Qiyuan;Tao Jun;Zhang Renjian;Wei Peng;Wei Chong;Cui Song;Cheng Tiantao;Ho Steven Sai Hang;Li Ziyi;Xu Hongmei;Cao Junji
吸光碳质气溶胶，包括黑碳（BC）和棕碳（BrC），对气溶胶环境质量和地球辐射影响很大。这里，使用连续空气浓度计在中国六个特大城市（即哈尔滨、北京、西安、上海、武汉和广州）同时开展了一项冬季活动，以表征 PM2.5 中的 BC 和 BrC。先进的气体浓度计和广义加性模型 (GAM) 的组合被用来精确量化这些大城市中的 BC 和 BrC 来源。北方城市BC（babs-BC）和BrC（babs-BrC）平均吸光系数分别为28.6和21.8 Mm−1，分别是南方城市的1.4和2.7倍。在北方城市，BrC 占总人口的比例（>40%），而在南方城市则低至 20%。另一方面，南方城市的BC分数较高，贡献率为62.4%~79.7%，而北方城市的BC分数较低，为53.7%~59.4%。来源解析表明，广州和武汉的液体燃料（例如汽油或柴油）的燃烧对babs-BC占主导地位（>80%）。 GAM 模型中的高 NO2 负荷进一步支持了这一点。在观察到大量初级 babs-BrC 的其他四个城市中，固体燃料（即生物质或煤炭）占 babs-BC 总量的很大一部分。日变化趋势显示，北方城市次生BrC（babs-BrCS）和babs-BrCS/ΔCO的峰值出现在夜间高相对湿度的情况下，这表明次生BrC的形成可能与冬季的水反应有关。相比之下，在南方城市上海和广州，早高峰交通期间车辆尾气的积累导致通过光化学反应形成二次BrC。这项工作的结果可用于开发更有效的实践来控制区域范围内的 BC 和 BrC。
The light-absorbing carbonaceous aerosols, including black carbon (BC) and brown carbon (BrC), influenced heavily on aerosol environmental quality and the Earth's radiation. Here, a winter campaign to characterize BC and BrC in PM2.5was conducted simultaneously in six Chinese megacities (i.e., Harbin, Beijing, Xi'an, Shanghai, Wuhan, and Guangzhou) using continual aethalometers. The combinations of advanced aethalometer and generalized additive model (GAM) were used to precisely quantify the BC and BrC sources in these megacities. The averaged light-absorbing coefficients of BC (babs-BC) and BrC (babs-BrC) were 28.6 and 21.8 Mm−1in northern cities, they were 1.4 and 2.7 times higher than those in southern cities. The BrC dominated the total babs(>40%) in northern cities but low to 20% in southern cities. On the other hand, the BC fractions were high in the southern cities, with the contributions of 62.4–79.7%, whereas much lower values of 53.7–59.4% in the northern cities.Source apportionment showed that the combustion of liquid fuels (e.g., gasoline or diesel) was highly dominant to babs-BC (>80%) in Guangzhou and Wuhan. This was further supported by the high NO2loadings in the GAM model. Solid fuels (i.e., biomass or coal) contributed a substantial portion to total babs-BC in the other four cities where the high abundances of primary babs-BrC were observed. The diurnal trend showed the peaks of secondary-BrC (babs-BrCS) and babs-BrCS/ΔCO in the northern cities occurred at high relative humidity in nighttime, implying the secondary BrC formation was possibly related to aqueous reactions in winter. In contrast, in the southern cities of Shanghai and Guangzhou, the accumulation of vehicle emissions during the morning traffic rush hours lead the formation of secondary BrC through photochemical reactions. The results of this work can be applied for the development of more effective practices to control BC and BrC on regional scale.