Zhao Yu, Wu Can, Wang Yi-Qian, Chen Yu-Bao, Lü Shao-Jun, Wang Fang-Lin, Du Wei, Liu Shi-Jie, Ding Zhi-Jian, Wang Ge-Hui
Key Laboratory of Geographic Information Sciences, Ministry of Education, School of Geographic Sciences, East China Normal University, Shanghai 200241, China.
Institute of Eco-Chongming, Shanghai 200062, China.
Huan Jing Ke Xue. 2021 Jul 8;42(7):3127-3135. doi: 10.13227/j.hjkx.202012002.
To investigate the pollution characteristics and sources of atmospheric brown carbon (BrC) in Chongming Island, a background site of the Yangtze River Delta (YRD) region in China, PM samples collected from December 2018 to January 2019 were analyzed to determine their chemical compositions and optical properties. The results showed that the light absorption coefficient (Abs) of BrC extracted by methanol at 365 nm was (5.39±3.33) M·m, which was 1.3 times of the water extracted BrC. Both increased significantly with the increase of pH values, suggesting that less acidic conditions can enhance the light absorption ability of BrC. In winter, both Abs and MAE (mass absorption efficiency) were higher in the nighttime than in the daytime. A strong linear correlation observed between Abs and levoglucosan (=0.72) indicated that many light absorbing substances in Chongming Island were derived from biomass burning emissions. During the campaign, nitro-aromatic compounds (NACs) and PAHs accounted for (1.5±1.1) ng·m and (8.3±4.7) ng·m, respectively, contributing to 0.1% and 0.067% of the absorption of the total BrC at 365 nm, respectively. Positive matrix factorization (PMF) analysis further showed that biomass and fossil fuel combustions were the main sources of BrC in Chongming Island in winter, accounting for 56% of the total BrC, followed by secondary formation, accounting for 24% of the total BrC, with road dust contributing only 6%.
为了研究中国长江三角洲（YRD）地区背景站点崇明岛大气棕碳（BrC）的污染特征和来源，对2018年12月至2019年1月采集的PM样本进行了分析，以确定其化学成分和光学性质。结果表明，甲醇在365nm处提取的BrC的光吸收系数（Abs）为（5.39±3.33）M·m，是水提取的BrC的1.3倍。两者均随pH值的升高而显著增加，表明酸性较弱的条件可增强BrC的光吸收能力。在冬季，Abs和MAE（质量吸收效率）在夜间均高于白天。Abs与左旋葡聚糖之间观察到强线性相关性（=0.72），表明崇明岛的许多光吸收物质来自生物质燃烧排放。在采样期间，硝基芳烃化合物（NACs）和多环芳烃（PAHs）分别占（1.5±1.1）ng·m和（8.3±4.7）ng·m，分别占365nm处总BrC吸收的0.1%和0.067%。正矩阵分解（PMF）分析进一步表明，生物质和化石燃料燃烧是冬季崇明岛BrC的主要来源，占总BrC的56%，其次是二次形成，占总BrC的24%，道路扬尘仅占6%。
