Simultaneously on-line measurements of major water-soluble inorganic ions and gaseous pollutants were performed from March 5 to 12,2017 in Wuhan,using a gas-aerosol collector(GAC) and ion chromatograph (IC),aiming to track the chemical characteristics and reaction mechanism of secondary inorganic components in fine particles (PM2.5).The results showed that there was an obvious quadratic transformation process between water-soluble ions in PM2.5 and their gas-phase precursors,which was the important source of PM2.5.As the dominant ionic components of PM2.5 (accounting for 40％-70％),the average concentrations of NO3-、SO42-、NH4+ were 24.3,16.9 and 15.0 μg/m3 respectively.The average fine sulfate and nitrate oxidation ratios (SOR and NOR) were SOR =0.52,NOR =0.27,revealing the remarkable characteristics of quadratic pollution.The correlation analysis showed that NH4+ got well relations with NO3-and SO42-,and the environment was rich of ammonia,NH3 in atmosphere could neutralize sulfate and nitrate.%运用大气PM2.5水溶性组分及其气态前体物在线监测系统(GAC-IC)于2017年3月5-12日对武汉市大气PM2.5中水溶性组分进行了在线监测,分析了PM2.5中主要水溶性离子的化学特征和作用机制.结果表明:实验期间武汉市大气PM2.5中水溶性组分与气态前体物间存在明显的二次转化过程,二次反应是PM2.5的重要来源.监测期间,PM2.5中NO3-、SO42-和NH4+的平均质量浓度分别为24.3、16.9、15.0μg/m3,是PM2.5中重要的水溶性无机离子,占PM2.5质量浓度的40％～70％.硫氧化率(SOR)和氮氧化率(NOR)平均值分别为0.52和0.27,表现出较为明显的二次污染特征.通过相关性分析发现:监测点位周边大气PM2.5中NH4+与NO3-、SO2-有良好的相关性,且表现为富氨状态,大气中铵能较好地中和SO42-和NO3-.
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