华北平原典型工业城市秋、冬季大气细颗粒物污染特征

Characteristics of fine particulate matter during autumn and winter in a typical industrial city in the North China Plain

济宁市是位于华北平原大气污染传输通道上的工业城市,为研究其秋、冬季细颗粒物(PM2.5)的污染特征,在市区的3个站点进行了PM2.5的同步滤膜采样。采样期为2018年10月15日至2019年1月31日,涵盖非采暖期和采暖期(自2019年11月15日始),共270个小流量滤膜样品。研究结果表明,济宁市秋、冬季PM2.5平均质量浓度为(98.9±48.8)µg/m^(3),采暖期PM2.5质量浓度(107.1±52.8)µg/m^(3)显著高于非采暖期(77.4±27.8)µg/m^(3)。PM2.5的化学组成以二次无机气溶胶、有机碳和元素碳为主,占比分别为52.4%、10.9%和7.5%。S、Cl、K、Ca、Fe和Si元素平均质量浓度之和占元素总平均质量浓度的78.8%,是PM2.5中的主要元素。采暖期PM2.5的主要化学组分质量浓度显著高于非采暖期。二次有机碳是有机碳的重要来源,占比78.9%。PM2.5中Zn和Pb的富集因子较高,说明燃煤及相关工业对PM2.5中重金属的贡献较为显著,ρ(NO3^(−))/ρ(SO4^(2−))比值分析表明,济宁市整体受流动源影响较大。本研究可为查明华北平原典型工业城市的PM2.5污染来源成因提供依据。

Jining is an industrial city located in the North China Plain on a main transport route resulting in high levels of air pollution.To characterize fine particulate matter(PM2.5)in Jining during autumn and Winter,a series of sampling and chemical analyses were conducted.A total of 270 minute volume samples of PM2.5 were collected at three sites from October 15,2018 to January 31,2019.PM2.5 components,including water-soluble ions,carbonaceous,and elements were measured.The average PM2.5 concentration in Jining during the observation period was(98.9±48.8)µg/m^(3).The mass loading of PM2.5 was higher during the heating periods(107.1±52.8)µg/m^(3) than the non-heating periods(77.4±27.8µg/m^(3)).The main components of PM2.5 were secondary inorganic compounds(NH4^(+),NO3^(−) and SO4^(2−)),organic carbon and element carbon accounting for 52.4%,10.9% and 7.5% of PM2.5,respectively.The sum of the average concentrations of S,Cl,K,Ca,Fe,and Si accounted for 78.8% of the total element average concentration and were the main elements in PM2.5.The concentrations of PM2.5 and the major chemical components were significantly higher in the heating periods than in the non-heating periods.The estimated secondary organic compounds(SOC)results show that secondary organic compounds accounted for 78.9% of organic carbon,and therefore is an important contributor of organic carbon.The enrichment factor(EF)is usually used as an indicator to evaluate the contribution of anthropogenic sources and the enrichment factors of Zn and Pb in PM2.5 were high,mainly due to emissions from coal burning and coal-related industries.ρ(NO3^(−))/ρ(SO4^(2−))shows that Jining is greatly affected by the flow source.