焦作市大气重污染过程单颗粒气溶胶特征分析

Single Particle Analysis during Heavy Air Pollution Wpisodes in Jiaozuo

利用单颗粒气溶胶飞行时间质谱(SPAMS)于2015年12月9-30日对焦作市高新区监测站新办公楼观测站大气单颗粒粒径及其化学组成进行了在线测量,共采集到具有粒径信息的颗粒物9 391 749个,其中有正负质谱图的颗粒2 189 337个,其粒径主要集中在0.2~2.0μm。利用自适应共振神经网络分类方法(Art-2a)对SPAMS采集的数据进行了成分分类,最终确定了8类颗粒物,焦作市监测期间占比前三的成分分别为有机碳(46.6%)、元素碳(16.1%)和富钾颗粒(11.8%),这3类颗粒物占比达70%以上,左旋葡聚糖(5.7%)、富硅(5.1%)和重金属(4.1%)占比相当,钠钾颗粒占比最少,仅为2.2%。监测期间PM_(2.5)源解析结果显示首要污染源为燃煤源,其次为工业工艺源,第三是机动车尾气,三者分别占32.6%、24%和16.6%,紧随其后的为扬尘源(13%),二次无机源稍低于扬尘源,为9.7%,生物质燃烧仅占3%。并对多次出现严重污染天气的监测过程进行了分析,第一次污染过程PM_(2.5)质量浓度出现爆表,严重污染天气持续时间长,PM_(2.5)质量浓度最高达551μg/m^3,并且多次出现迅速上升的趋势,在此次污染过程中主要污染源为燃煤源和工业工艺源;第二次污染过程空气质量略有好转,但严重污染持续时间也较长,PM_(2.5)质量浓度最高达345μg/m^3,机动车尾气大体上呈现PM_(2.5)质量浓度出现高峰时,比例随之增大,说明本次空气质量变差和机动车尾气有着密切的关系。

To investigate the chemical composition and possible source at the new office building monitoring station in Jiaozuo High-tech zone,a single particle aerosol mass spectrometry(SPAMS) was deployed to measure the particle size and changes of single particle species from Dec.9th to 30 th in 2015.A total of 9 391 749 particles in the size range of 0.2~2.0μm was collected,2 189 337 particles with both positive and negative spectrums were characterized by the Art-2a neural network algorithm.8 types of particles were classified as organic carbon(OC) ,elemental carbon(EC) ,EC and OC combined particles(ECOC) ,Na-K containing particles(Na K) ,K-rich particles(K) ,Levoglucosan particles(LEV) ,heavy metal particles(HM) and Si-rich particles(SIO) .The results revealed that more than 70% particles were OC(46.6%) ,EC(16.1%) and K(11.8%) ,LEV,SIO and HM accounted for almost equivalent proportion as 5.7%,5.1%,4.1%,respectively,while Na K was the lowest one with the proportion of 2.2%.Coal combustion,industrial source and vehicle exhaust were the most abundant particle sources,the percentages of these three sources were 32.6%,24% and 16.6% respectively.Dust,secondary inorganic source and biomass burning were the following PM_(2.5) major source with the percentages of 13%,9.7% and 3%,respectively.During on-line monitoring by SPAMS,two haze pollution episodes were observed and analyzed,PM_(2.5) concentration wasextremely high and the highest concentration reached 551 μg/m^3 during the first haze pollution period.And the primary pollution sources in this period were coal burning and industrial source.In the second haze pollution period,the air quality turned to be better whereas the haze pollution still lasted a long time,with the highest PM_(2.5) concentration of 345 μg/m^3.As the mass concentration of PM_(2.5) increased,the percentage of vehicle exhaust raised,suggested that haze pollution in this period was caused by vehicle exhaust.