西南地区工业主导城市重污染期间PM_(2.5)污染特征及形成机制

Characteristics and formation mechanism of PM_(2.5) pollution during heavy pollution in an industrial-dominated city in Southwest China

为研究长江上游典型工业城市重庆市长寿区雾霾污染特征和形成机制,在雾霾持续污染时段分别在城区和工业区站点开展了细颗粒物(PM_(2.5))及其重要前体物的观测分析.结果显示,观测期间长寿区PM_(2.5)平均浓度为(71.78±38.44)μg/m^(3),雾霾污染时期PM_(2.5)日均值最高达到193μg/m^(3).雾霾污染相比非污染时期PM_(2.5)的各类化学组分均有所增加,其中有机颗粒物(OM)和二次无机气溶胶(SIAs)的迅速增长是导致雾霾污染发生的最主要因素.雾霾污染时期硫氧化比(SOR)和氮氧化比(NOR)显著上升,相比清洁天增幅分别为64%和55%,并且相对湿度(RH)较高的环境下对于SOR、NOR和气溶胶的吸湿增长均具有一定的促进作用.二次有机气溶胶(SOAs)同样在雾霾污染时期表现出显著的增长趋势,相比清洁天增加了13.03μg/m^(3),评估SOAP的结果发现甲苯、对-二甲苯和邻-二甲苯等芳香烃对SOA的形成具有显著的贡献.主成分分析(PCA)和spearman相关性分析表明了PM_(2.5)中化学组分主要的3种来源,分别为工业源、地壳源和扬尘源,其中工业源是PM_(2.5)中化学成分最重要的来源.来源解析结果表明,长寿区及周边临近地区是PM_(2.5)、SIAs、总有机碳(TOC)、二氧化硫(SO_(2))、二氧化氮(NO_(2))和总挥发性有机物(TVOCs)重要的潜在源区,本地污染源排放对于雾霾的形成具有重要的贡献.

To study the characteristics and formation mechanisms of haze pollution in Changshou District,a typical industrial city in the upper reaches of the Yangtze River,observational analyses of fine particulate matter (PM_(2.5)) and its important precursors were conducted separately in urban and industrial areas during periods of continuous haze pollution.The results showed that the mean concentration of PM_(2.5) in Changshou District during the observation period was (71.78±38.44)μg/m^(3),with the highest daily mean reaching 193μg/m^(3) during haze pollution episodes.Compared to non-polluted periods,various chemical components of PM_(2.5)increased during haze pollution,with rapid growth of organic matter (OM) and secondary inorganic aerosols (SIAs) being the primary factors contributing to haze pollution.During haze pollution episodes,the sulfur oxidation ratio (SOR) and nitrogen oxidation ratio(NOR) significantly increased,with increases of 64%and 55%,respectively,compared to clean days,and higher relative humidity (RH)environments played a promoting role in the hygroscopic growth of SOR,NOR,and aerosols.Secondary organic aerosols (SOAs) also showed a significant increasing trend during haze pollution periods,with an increase of 13.03μg/m^(3) compared to clean days.Evaluation of SOAP revealed that aromatics such as toluene,o-xylene,and m-xylene significantly contributed to SOA formation.Principal component analysis (PCA) and Spearman correlation analysis identified three main sources of chemical components in PM_(2.5),namely industrial sources,crustal sources,and dust sources,with industrial sources being the most important contributor to PM_(2.5)chemical composition.Source apportionment results indicated that Changshou District and its surrounding areas are important potential source regions for PM_(2.5),SIAs,total organic carbon (TOC),sulfur dioxide (SO_(2)),nitrogen dioxide (NO_(2)),and total volatile organic compounds (TVOCs),with local emissions from pollution sources playing a crucial role in haze formation.