【摘要】 2012年8月6日—22日利用大气细颗粒物水溶性组分在线监测分析系统和大气气溶胶OC/EC在线分析仪在线分析了西安PM2.5中的水溶性无机离子和OC、EC,并结合气溶胶前体物SO2、NO2和部分气象参数的监测数据进行了分析。结果表明,PM2.5中OC、EC和主要水溶性组分SO2-4、NH+4和NO-3的比重分别为:14.34%、5.35%、26.32%、12.90%和11.28%;以有机物(OM)为主要成分的总碳气溶胶(TCA)在PM2.5中的质量分数为28.30%,其中光化学反应导致OM中二次组分(SOC)高达45.30%;对主要水溶性组分之间的相关性分析发现,NO-3、SO2-4、NH+43种主要组分之间的结合形态为(NH4)2SO4和NH4NO3,对Mg2+和Ca2+的相关分析反映其有多种共同源;此外,硫氧化率(SOR)和氮氧化率(NOR)均较高,表明大气中存在较强的光化学反应。PM2.5的各组分因子分析得到4个主要来源(机动车尾气和燃煤、土壤建筑尘和生物质燃烧、二次硝酸盐气溶胶、二次硫酸盐气溶胶)。更多还原

【Abstract】 The water soluble inorganic ions and OC,EC in PM2. 5in Xi’an were monitored by an on-line ambient ions monitor and OC /EC online analyzer from 6 to 22 August 2012. Aerosol precursors( SO2,NO2) and some meteorological parameters were also monitored and analyzed. The results showed that OC,EC and dominant water soluble ions( SO2-4,NH+4,NO-3) in PM2. 5were 14. 34%,5. 35%,26. 32%,12. 90% and 11. 28%,respectively. TCA,of which the major element was OM,accounted for 28. 30% of PM2. 5. While photochemical reaction led to increasing of secondary organic carbon( SOC) in OM,up to 45. 30%. The correlation analysis of main water soluble ions demonstrated that NO-3,SO2-4and NH+4were combined in forms of( NH4)2SO4and NH4NO3.The analysis also indicated that Mg2 +and Ca2 +had more than one common source. Furthermore,SOR and NOR were always high which showed that a drastic photochemical reaction occurred in 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,secondary nitrate aerosols and secondary sulfate aerosols.更多还原