杭州冬季大气细颗粒物污染特征及形成机制  

Pollution characteristics and formation mechanism of atmospheric fine particulate matter in Hangzhou during winter

作　　者：陆晔宇 张思[1] 张轲 陈玉宝 吴灿 李睿[1] 王格慧 LU Ye-yu;ZHANG Si;ZHANG Ke;CHEN Yu-bao;WU Can;LI Rui;WANG Ge-hui(Key Laboratory of Geographic Information Sciences,Ministry of Education,School of Geographic Sciences,East China Normal University,Shanghai 200241,China)

机构地区：[1]华东师范大学地理科学学院,地理信息科学教育部重点实验室,上海200241

出　　处：《中国环境科学》2024年第4期1936-1944,共9页China Environmental Science

基　　金：华北平原高氨环境大气棕碳区域污染特征与二次成因国家自然科学基金-重点项目(42130704)。

摘　　要：为探究杭州市冬季大气细颗粒物的污染特征及形成机制,采集2019年12月~2020年1月PM_(2.5)样品,根据天气条件将采样期分为无雨期、多雨期和少雨期,比较分析各个时期SOA(二次有机气溶胶)的形成机制,结合稳定碳同位素技术确定污染来源.结果显示,多雨期PM_(2.5)的pH值为(2.2±0.6),比其它时期低1~2个pH值单位,这归因于降水对NH_(3)(g)的有效去除.二元羧酸类化合物的分子组成与其它地区类似,C_(2)(草酸)>C_(4)(丁二酸)>Ph(邻苯二甲酸),但mGly(甲基乙二醛)与Gly(乙二醛)的比例高得多,表明杭州冬季的SOA主要来源于生物排放的光化学氧化.特异性稳定碳同位素组成结果也表明,大部分二元羧酸在多雨期富集δ^(13)C,可能是因为POA(一次有机气溶胶)的气相分解增强和VOCs(挥发性有机化合物)的气相氧化减少.To investigate the pollution characteristics and formation mechanism of fine particulate matter in Hangzhou in winter,atmospheric PM_(2.5) samples were collected on a daily basis from December 2019 to January 2020.According to the weather conditions,the sampling period was classified as dry,rainy and less-rainy periods,and the differences in chemical characteristics and formation mechanisms of dicarboxylic acids and related secondary organic aerosols(SOA)during the three periods were investigated.pH values of PM_(2.5) during the rainy periods were 2.2±0.6,which were 1~2 units lower than those in the dry and less-raining periods,mainly due to the effective removal of NH_(3)(g)by precipitation.Being similar to those in other cities,dicarboxylic acids of PM_(2.5) in Hangzhou during winter were dominated by oxalic acid,followed by malonic and succinic acids,but the much higher ratio of methglyoxal to glyoxal observed in the city suggested that SOA in Hangzhou during winter were mostly derived from photochemical oxidation of biogenic emissions.Compound-specific stable carbon isotope composition results further showed that most of the detected diacids and related SOA in Hangzhou were enriched in ^(13)C during the rainy days but depleted in ^(13)C during the non-rainy and less-rainy periods,which can be ascribed to an enhanced aerosol-phase decomposition of primary organic aerosols(POA)and a decreased gas-phase oxidation of volatile organic compounds(VOCs).

关 键 词：无机离子 二元羧酸 稳定碳同位素 污染来源 

分 类 号：X513[环境科学与工程—环境工程]