北京市远郊冬季铵盐颗粒物的单颗粒质谱研究

2016年冬季使用单颗粒气溶胶质谱仪（SPAMS）于在北京市平谷区西柏店村进行大气颗粒物的在线观测.以m/z18NH₄]⁺为特征离子提取含铵盐颗粒物，分析其时间变化特征、粒径分布、化学组分、混合状态和可能来源.含铵盐颗粒物约占观测期间所有颗粒物的31%，分为NH₄-OC（49.9%），NH₄-EC（5.6%），NH₄-ECOC（8.9%），NH₄-HOC（1.4%），NH₄-K（9.3%），NH₄-NaK（21.7%）和NH₄-FeK（2.5%）7种主要类别.铵盐主要以硫酸铵、硫酸氢铵和硝酸铵的形态存在，且更易于和含碳类物质发生内混.煤炭和生物质燃烧是铵盐颗粒物的主要来源.后向轨迹分析表明，清洁期气团主要来自采样点北方和西北方的长距离传输，灰霾期气团主要来自西北向的区域传输.潜在源贡献因子分析（PSCF）表明含铵盐颗粒物主要来自本地和周边区域的排放，以及西北方向的长距离传输.

Single-particle characterization of ammonium-containing particles during wintertime in suburb of Beijing

A Single Particle Aerosol Mass Spectrometer (SPAMS) was deployed on a rural site of Beijing during the winter of 2016. Ammonium-containing particles were identified using the ion signal peaking at m/z 18, and their temporal variation, size distribution, mixing state, and possible source of ammonium-containing particles were analyzed. Approximately 31% of particles in the SPAMS dataset were identified as ammonium-containing particles. Using an ART-2a clustering algorithm, the ammonium-containing particle dataset could be clustered to seven major particles types, such as NH₄-OC(49.9%), NH₄-EC(5.6%), NH₄-ECOC(8.9%), NH₄-HOC(1.4%), NH₄-K(9.3%), NH₄-NaK(21.7%), and NH₄-FeK(2.5%). Ammonium, which internally mixed with carbonaceous particles, existed in the form of ammonium sulfate, ammonium bisulfate, and ammonium nitrate. Coal and biomass burning were the major sources of ammonium-containing particles. During the clear period, air masses transport from the north and northwest of the sampling site; while during the haze period, air masses were mainly from the northwest. The potential source contribution function (PSCF) analysis showed that the ammonium-containing particles were mainly from local and regional emissions near the sampling site, and from the long-range transport in the northwest.