2020年天津市两次重污染天气污染特征分析  

Characterization of Two Heavy Pollution Episodes in Tianjin in 2020

作　　者：肖致美 徐虹 蔡子颖 李鹏 刘彬 元洁 郑乃源 唐邈 陈魁 邓小文 XIAO Zhi-mei;XU Hong;CAI Zi-ying;LI Peng;LIU Bin;YUAN Jie;ZHENG Nai-yuan;TANG Miao;CHEN Kui;DENG Xiao-wen(Tianjin Eco-Environ mental Monitoring Center,Tianjin 300191,China;Tianjin Environmental Meteorological Center,Tianjin 300074,China)

机构地区：[1]天津市生态环境监测中心,天津300191 [2]天津市环境气象中心,天津300074

出　　处：《环境科学》2020年第9期3879-3888,共10页Environmental Science

基　　金：天津市科技计划项目(18ZXSZSF00160)。

摘　　要：为了解2020年天津市两次重污染天气污染特征,基于2020年1~2月高时间分辨率的在线监测数据,对天津市2020年1月16~18日(重污染过程Ⅰ)和2020年2月9~10日(重污染过程Ⅱ)进行分析,结果表明,两次重污染过程均呈现前期区域输送和后期本地不利气象条件叠加双重影响的特点,重污染过程期间平均风速均较低,平均相对湿度接近70%,部分时段接近饱和,边界层高度低于300 m,水平和垂直扩散条件均较差.与重污染过程Ⅰ相比,重污染过程Ⅱ主要污染物浓度和污染程度均降低,尤其是NO2浓度下降明显,重污染过程Ⅱ北部地区PM2.5和CO浓度较高.两次重污染过程PM2.5中化学组分浓度和占比发生明显变化,重污染过程Ⅰ二次无机离子(SO4^2-、NO-3和NH^+4)、EC和Ca^2+平均浓度较高,OC和Cl^-平均浓度略低于重污染过程Ⅱ,K^+平均浓度低于重污染过程Ⅱ.与重污染过程Ⅰ相比,受燃烧源增加和移动源大幅降低影响,重污染过程Ⅱ中SO4^2-、OC和K^+在PM2.5中占比明显上升,NO-3和EC在PM2.5中占比明显下降;工业持续生产使重污染Ⅱ中NH^+4和Cl^-在PM2.5中占比相对较高;工地的停工使两次重污染过程中Ca^2+占比均较低.PMF解析结果表明,重污染过程Ⅰ中PM2.5来源为二次离子、燃煤和工业、机动车、扬尘、烟花爆竹及生物质燃烧,贡献率分别为53.8%、20.2%、18.6%、6.3%和1.1%;重污染过程Ⅱ中各源对PM2.5的贡献率分别为48.3%、28.2%、8.7%、2.6%和12.2%.与重污染过程Ⅰ相比,重污染过程Ⅱ燃煤和工业、烟花爆竹及生物质燃烧对PM2.5贡献率明显上升,二次离子、机动车和扬尘贡献率明显下降,尤其是机动车和扬尘,贡献率分别下降53.2%和58.7%.High-resolution online monitoring data from January to February in 2020 was used to study the characterization of two heavy pollution episodes in Tianjin in 2020;the heavy pollution episode that lasted from January 16 to 18,2020(referred to as episodeⅠ)and that from February 9 to 10,2020(referred to as episodeⅡ)were analyzed.The results showed that two heavy pollution episodes were influenced by regional transportation in the early stage and local adverse meteorological conditions in the later stage.During these episodes,the average wind speed was low,the average relative humidity was close to 70%,and relative humidity approached the saturated,the boundary layer heights were below 300 m,and the horizontal and vertical diffusion conditions were poor.Compared to episodeⅠ,the concentration of pollutants decreased during episodeⅡ,especially for the concentration of NO2.During the episodeⅡ,the concentrations of PM2.5 and CO were higher in the north of Tianjin.The chemical component concentrations and their mass ratios to PM2.5 changed significantly in both episodes;the concentrations of secondary inorganic ions(NO-3,SO4^2-,and NH^+4),elemental carbon(EC)and Ca^2+were higher in episodeⅠ,the concentrations of organic carbon(OC)and Cl^-slightly increased in episodeⅡ;and the concentrations of K^+were higher in episodeⅡ.Compared to episodeⅠ,because of the increase in the combustion sources and significant reductions in the number of vehicles,the mass ratios of SO4^2-,OC,and K^+to PM2.5 increased while the mass ratios of NO-3 and EC to PM2.5 decreased in episodeⅡ;the mass ratios of NH^+4 and Cl^-to PM2.5 were relatively higher due to the continuity of the industrial production processes;the mass ratios of Ca^2+to PM2.5 were lower in two heavy pollution episodes because construction activities were halted.Source apportionment of PM2.5 was performed using the positive matrix factorization(PMF)model.In episodeⅠ,the major sources of PM2.5 in Tianjin were secondary sources,industrial and coal combustion,veh

关 键 词：天津 重污染 PM2.5 污染特征 来源解析 

分 类 号：X513[环境科学与工程—环境工程]