深圳市冬季PM2.5中水溶性有机物的来源特征

Source characteristics of water-soluble organic matters in PM_(2.5) in the winter of Shenzhen

利用连续液化采样器(PILS)-超声雾化器-气溶胶化学组分检测仪(ACSM)联用系统,对深圳市冬季PM_(2.5)中水溶性组分进行在线连续观测,获取高时间分辨率的水溶性有机物(WSOM),SO_4^(2-),NO_3^-,NH_4^+和Cl^-浓度信息以及WSOM的质谱结构信息.分析结果表明:PM_(2.5)中水溶性组分的总质量浓度变化范围为4.0～117μg/m^3,平均浓度为20.1μg/m^3,其中WSOM(25.2%)和SO_4^(2-)(22.4%)是最主要的贡献组分.ACSM质谱显示WSOM具有氧化态有机气溶胶(OOA)的质谱特征,其氧碳比(O/C)的平均值达到(0.60±0.09),且WSOM与二次无机离子(SO_4^(2-)+NO_3^-)和钾(K)有强相关性,与黑碳(BC)的相关性较弱,表明了观测期间WSOM主要来源于二次反应产生的二次有机气溶胶(SOA)和生物质燃烧,与机动车等一次排放没有明显关系.

In this study,a combined system of particle-into-liquid sampler(PILS)-Nebulizer-aerosol chemical speciation monitor(ACSM)was applied in the on-line measurement of water-soluble components in PM2.5 in winter in Shenzhen.High temporal resolution concentrations of WSOM,sulfate,nitrate,ammonium and chloride and their mass spectra were simultaneously obtained.The mass concentration of the water-soluble species in PM2.5 ranged from 4.0~117μg/m3,with an average of 20.1μg/m3,and sulfate and WSOM were the most abundant components.The characteristics of the mass spectrum of WSOM was similar to that of oxygenated organic aerosols,and the average O/C was 0.60±0.09.We found that WSOM strongly correlated with secondary inorganic ions(SO4 2-+NO3-)and potassium(K),while the correlation with black carbon(BC)weakened.All evidence showed that the contribution of secondary organic aerosol(SOA)and biomass burning to WSOM was much greater than local primary emission in winter of Shenzhen.