首页|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

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

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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PM2。5的AAE值分别为 1。58 和 1。55，表明城区PM2。5中明显存在BrC。观测期间，黑碳(BC)和BrC在 370～660nm对PM2。5的吸光贡献分别为58%～90%和10%～42%，表明PM2。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PM2。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(BrCpri)和二次棕碳(BrCsec)的吸光系数。污染天和清洁天BrCpri对BrC吸光系数的贡献(74%～80%和 57%～74%)均高于BrCsec(20%～26%和 26%～43%)，但BrCpri的AAE值(3。42 和3。08)明显低于相应的AAE(BrCsec)(4。22 和 5。15)，这与BrCsec吸光具有较强的波长依赖性有关。此外，σ_BrCsec(370)日变化表明BrCsec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BrCpri和BrCsec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。
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
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 PM2.5 were 1.58 and 1.55 during pollution and clean periods,implying the presence of BrC in urban PM2.5.During the campaign,BC and BrC contributed 58%～90%and 10%～42%to PM2.5 absorption at 370～660 nm,indicating σ_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 to σ_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(BrCpri)and secondary brown carbon(BrCsec)were obtained based on the minimum R squired method(MRS).The contributions of BrCpri to σ_BrC were 74%～80%and 57%～74%during pollution and clean periods,higher than that of BrCsec(20%～26%and 26%～43%).However,The AAE values of BrCpri during pollution and clean periods were 3.42 and 3.08,significantly lower than the corresponding AAE(BrCsec)(4.22 and 5.15),which was related to the strong wavelength dependence of BrCsec light absorption.In addition,the daily variation of σ_BrCsec(370)suggested that BrCsec 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 BrCpri and BrCsec at 370～950 nm were 24.8%and 10.2%during pollution periods,higher than that during clean periods(18.4%and 9.8%),respectively.The results of the potential source contribution function(PSCF)showed that the local emissions were the main sources of BrC during pollution periods in Chongqing,while regional transport from Hunan province and Guizhou province had major impacts of BrC during clean periods.

secondary brown carbonpollution periodslight absorption characteristicradiation absorptionChongqing

邓竞成、彭超、卢培利、李振亮、陈阳、翟崇治、杨复沫、田密

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重庆大学环境与生态学院,重庆 400045

重庆市生态环境科学研究院,重庆 401147

中国环境科学研究院西南分院,重庆 401147

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

中国科学院重庆绿色智能技术研究院,重庆 400714

四川大学建筑与环境学院,四川 成都 610065

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次棕碳 污染天 吸光特性 辐射吸收 重庆

国家自然科学基金资助项目重庆市自然科学基金项目重庆市博士"直通车"科研项目重庆市基本科研业务费计划项目

4230512CSTB2022NSCQ-MSX0504CSTB2022BSXM-JCX0157Cqhky2021jxjl00004

2024

中国环境科学
中国环境科学学会

中国环境科学

CSTPCDCHSSCD北大核心
影响因子：2.174
ISSN：1000-6923
年,卷(期)：2024.44(7)
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