中文摘要：

基于珠三角大气超级站2013年11月29日-12月17日大气细颗粒物（PM2.5）质量浓度、主要水溶性离子组分及其重要气态前体物等参数的在线监测结果,揭示了当地冬季大气细颗粒物的理化特性,及细颗粒物二次组分与其气态前体物的相互作用规律,并结合同期南岭背景站PM2.5监测结果,评估长距离输送对珠三角PM2.5污染的影响。观测期间,SO4^2-、NO3^-和NH4^＋的平均浓度分别为24.7、17.3和16.0μg/m^3,占PM2.5中的平均比例之和为64.3%,说明二次转化是珠三角冬季细颗粒物的重要来源。珠三角冬季大气气态NH3平均浓度为13.1μg/m^3,具有足量气态NH3以中和硫酸盐和硝酸盐;大气环境有利于NH4NO3的生成与存在,甚至可以导致NO3-迅速生成,使其浓度高于SO4^2-。不利气象条件下,污染物累积与转化是冬季PM2.5污染的主要成因,个别时段长距离输送的影响显著。

英文摘要：

Based on the online observation of PM2.5, its major water-soluble ions, and their gaseous precursors during November 29^th to December 17^th, 2013, at the atmospheric supersite in the Pearl River Delta （PRD） region, the interaction of the secondary compositions and their precursors was discussed, and physical and chemical properties of atmospheric fine particles were revealed. In combination with the simultaneous PM2.5 measurement at Nanling Background site, the affection of long-term transport on the PM2.5 pollution in PRD was evaluated. During the measurement, average concentrations of SO4^2-, NO3^- and NH4^＋ were 24.7,17.3 and 16.0 μg/m^3 respectively, with total contribution to PM2.5 of 64.3%, indicating the significant role of secondary transformation in PM2.5 pollution. Average concentration of NH3 was 13.1 μg/m^3 and abundant to neutralize sulfate and nitrate; the atmospheric conditions favored the formation and existence of NO3^-, even led to higher concentration of NO3^- than SO4^2-. Accumulation and transformation were major causes for PM2.5 pollution in winter, while long-term transport imposed obvious effect occasionally.