基于在线观测的重庆冬季棕碳吸光特性、来源及辐射效应研究:二次转化影响  

Characteristics of light absorption,sources,and radiative effects of brown carbon aerosol in Chongqing during winter based on on-line measurement:Implications of secondary formation

作　　者：邓竞成[1,2,3] 彭超 卢培利 李振亮[2,3,4] 陈阳 翟崇治[2,3,4] 杨复沫 田密 DENG Jing-cheng;PENG Chao;LU Pei-li;LI Zhen-liang;CHEN Yang;ZHAI Chong-zhi;YANG Fu-mo;TIAN Mi(College of Environment and Ecology,Chongqing University,Chongqing 400045,China;Chongqing Academy of Eco-Environmental Science,Chongqing 401147,China;Chongqing Branch Academy of Chinese Research Academy of Environmental Sciences,Chongqing 401147,China;Key Laboratory for Urban Atmospheric Environment Integrated Observation&Pollution Prevention and Control of Chongqing,Chongqing 401147,China;Research Center for Atmospheric Environment,Chongqing Institute of Green and Intelligent Technology,Chinese Academy of Sciences,Chongqing 400714,China;College of Architecture and Environment,Sichuan University,Chengdu 610065,China)

机构地区：[1]重庆大学环境与生态学院,重庆400045 [2]重庆市生态环境科学研究院,重庆401147 [3]中国环境科学研究院西南分院,重庆401147 [4]城市大气环境综合观测与污染防控重庆市重点实验室,重庆401147 [5]中国科学院重庆绿色智能技术研究院,重庆400714 [6]四川大学建筑与环境学院,四川成都610065

出　　处：《中国环境科学》2024年第7期3553-3562,共10页China Environmental Science

基　　金：国家自然科学基金资助项目(4230512);重庆市自然科学基金项目(CSTB2022NSCQ-MSX0504);重庆市博士“直通车”科研项目(CSTB2022BSXM-JCX0157);重庆市基本科研业务费计划项目(Cqhky2021jxjl00004)。

摘　　要：2023年1月20~2月21日在重庆典型城区开展棕碳气溶胶(BrC)多波段吸光系数的在线观测,分析污染天和清洁天BrC的吸光特性及其环境效应.结果显示,污染天和清洁天PM_(2.5)的AAE值分别为1.58和1.55,表明城区PM_(2.5)中明显存在BrC.观测期间,黑碳(BC)和BrC在370~660nm对PM_(2.5)的吸光贡献分别为58%~90%和10%~42%,表明PM_(2.5)吸光系数主要受BC影响,但BrC的贡献也不容忽视.污染天BrC在370nm的吸光系数σ_BrC(370)[(35.30±8.21)Mm-1]为清洁天[(14.28±7.10)Mm-1]的2.47倍,且其对PM_(2.5)的吸光贡献(10%~42%)也高于清洁天(8%~41%).值得注意的是,污染天AAEBrC值范围为3.2~4.7,整体低于清洁天(3.6~4.9),这可能与不同时段BrC的组分差异有关.基于最小相关系数法(MRS)获取一次棕碳(BrC_(pri))和二次棕碳(BrC_(sec))的吸光系数.污染天和清洁天BrC_(pri)对BrC吸光系数的贡献(74%~80%和57%~74%)均高于BrC_(sec)(20%~26%和26%~43%),但BrC_(pri)的AAE值(3.42和3.08)明显低于相应的AAE(BrC_(sec))(4.22和5.15),这与BrC_(sec)吸光具有较强的波长依赖性有关.此外,σ_BrC_(sec)(370)日变化表明BrC_(sec)生成可能主要受夜间高湿条件下液相反应的影响.BrC相对BC的辐射吸收贡献在短波段较为显著,随着波长范围增加明显减少.污染天BrC_(pri)和BrC_(sec)在370~950nm的辐射吸收贡献分别为24.8%和10.2%,清洁天分别为18.4%和9.8%.潜在源分析(PSCF)结果表明,污染天BrC主要来源于重庆本地排放,清洁天BrC受来自湖南省和贵州省的区域传输影响.To investigate the light absorption characteristics and environmental effects of brown carbon(BrC)during pollution and clean periods,the light absorption coefficients of BrC were obtained by Aethalometer(AE33)from 20th January 2023 to 21st February 2023 in Chongqing.The results showed that the AAE values of PM_(2.5) were 1.58 and 1.55 during pollution and clean periods,implying the presence of BrC in urban PM_(2.5).During the campaign,BC and BrC contributed 58%~90%and 10%~42%to PM_(2.5) absorption at 370~660 nm,indicatingσ_abs was mainly affected by BC,but the contribution of BrC can not be ignored.The light absorption coefficient of BrC at 370 nm[σ_BrC(370)]was(35.30±8.21)Mm-1 during pollution periods,2.47 times higher than that during clean periods[(14.28±7.10)Mm-1],and its contribution toσ_abs(10%~42%)was higher than those during clean periods(8%~41%).It is worth noting that the AAEBrC values during pollution periods ranged from 3.2 to 4.7,generally lower than those during clean periods(3.6~4.9),which might be related to the difference of BrC components during the different periods.The light absorption coefficients of primary brown carbon(BrC_(pri))and secondary brown carbon(BrC_(sec))were obtained based on the minimum R squired method(MRS).The contributions of BrC_(pri) toσ_BrC were 74%~80%and 57%~74%during pollution and clean periods,higher than that of BrC_(sec)(20%~26%and 26%~43%).However,The AAE values of BrC_(pri) during pollution and clean periods were 3.42 and 3.08,significantly lower than the corresponding AAE(BrC_(sec))(4.22 and 5.15),which was related to the strong wavelength dependence of BrC_(sec) light absorption.In addition,the daily variation ofσ_BrC_(sec)(370)suggested that BrC_(sec) production might be mainly affected by the liquid-phase reaction under high humidity conditions at night.The radiative absorption contribution of BrC relative to BC was more significant in short wavelengths and decreased obviously with increasing wavelengths.The radiative absorption contributions of BrC_(pr

关 键 词：次棕碳 污染天 吸光特性 辐射吸收 重庆 

分 类 号：X513[环境科学与工程—环境工程]