Characteristic Analysis Of Primary Pollutant Of Xi’an During2012、2013

An on-line monitoring of water soluble inorganic ions and OC, EC in PM2.5weremonitored by ambient ions monitor and OC/EC online analyzer from6to22August2012in Xi’an. Aerosol precursors (SO2, NO2) and some meteorological parameters were alsomonitored and analyzed. And on this basis, An air quality monitoring and analysis coverthe whole13Air quality monitoring station of Xi’an in2013was conducted after theTechnical Regulation on Ambient Air Quality Index (on trial) carried out.OC, EC and dominant water soluble ions (SO42-, NH4+, NO3-) in PM2.5during hotenvironment in summer were14.34%,5.35%,26.32%,12.90%and11.28%,respectively. TCA, of which the major element was OM, accounted for28.30%of PM2.5.While photochemical reaction led to increasing of secondary organic carbon (SOC) inOM, up to45.30%. The correlation analysis of main water soluble ions demonstratedNO3-,SO42-and NH4+were combined in forms of (NH4)2SO4and NH4NO3. The analysisalso indicated that Mg2+and Ca2+had more than one common source. Furthermore,SOR and NOR were always high showed that a drastic photochemical reaction occurredin the air. Four sources of PM2.5were discovered by the method of factor analysis,including exhaust gas of vehicle and coal, dust of soil and construction, secondarynitrate aerosols and secondary sulfate aerosols.Multivariate regression analysis of PM2.5during haze day showed that the maininfluence of PM2.5was air pressure,visibility,reality humidity,SO2,NO2. Regressionequation was C(PM2.5)=14028.263-83.094l㏑(RH)-2023.366㏑(ATM)-140.911㏑(VIS)+82.212㏑(SO2)+74.141㏑(NO2). Error of regression equation was ideal,theproportion of the error less than40%was8.89%,but the proportion of the error less than20%reached up to70%.In2013, the number of days whose ambient air quality of Xi’an was good is9, thenumber of days whose ambient air quality of Xi’an was moderate is129, the number ofdays whose ambient air quality of Xi’an was lightly polluted is105, the number of days whose ambient air quality of Xi’an was medially polluted is56, the number of dayswhose ambient air quality of Xi’an was heavily polluted is30, the number of dayswhose ambient air quality of Xi’an was severely polluted is36. The number of dayswhose primary pollutant was PM2.5was162, the number of days whose primarypollutant was PM10was112, the number of days whose primary pollutant was O3was78, the number of days whose primary pollutant was NO2was9, the number of dayswhose primary pollutant was CO was1. The primary pollutant of2013wasparticle,ozone pollution was seriously during the high-temperature interval. Thecontamination of PM10and PM2.5、O3was relatively serious in the main urban area.Theseriously polluted areas of ozone was similar with PM10and PM2.5,Ozone had somerelevance to PM10and PM2.5.It maybe had a relevance with secondary photochemicalpollution whose main product was ozone.The daily change rules of O3was unimodaldistribution whose valley value was less obvious; the daily change rule of PM2.5andPM10was similar,their rules was a bi-modal distribution whose valley value and peakvalue was Obvious. Dust weather on march9was caused by the sand air mass fromwest bound of Xinjiang province; The peak concentration of PM10and PM2.5duringdust weather respectively are3141μg/m3and604μg/m3. Central-heating lead to thevalue of PM2.5/PM10rose high in January and February.The higher temperature,higherhumidity and more rainfall lead to the value of PM2.5/PM10in February was higher thanJanuary.dust weather made the value of PM2.5/PM10lower. Then along with thedisappear of dust weather,the temperature rose higher and the end of central heatingseason,the value of PM2.5/PM10rose steadily,the value of PM2.5/PM10declined whenthe temperature went down in November, then maintained at a high level.Thecorrelation between CO,SO2,NO2,PM10and PM2.5was high.The correlation betweenthem had difference.It maybe related to the sources of them.Flue gas emission ofcentral heating was the main source of them,so their correlation were higher.However,the high temperature and strong solar in July,August,September made thephotochemical reaction in the air intensity.It maybe the reason that the correlationbetween O3and other pollutants higher than other period.