深圳冬季大气气态硝酸和硝酸盐气粒分配特征

利用双通道在线气体和气溶胶分析仪（MARGA）在深圳冬季同时观测了PM_2.5和PM₁₀中水溶性无机离子及气态前体物浓度变化，以探究气态硝酸（HNO₃）和颗粒态硝酸盐（pNO₃^-）的气粒分配特征.结果表明，气态硝酸和颗粒态硝酸盐总和TNO₃（TNO₃=HNO₃+pNO₃^-）中，气态HNO₃、细颗粒NO₃^-和粗颗粒NO₃^-三个部分的占比分别为9.6%、56.8%和33.6%.TNO₃浓度日变化呈现双峰特征，上午峰值来自于细颗粒态NO₃^-增加，由交通早高峰排放NO_x转化生成所致；白天光化学反应使TNO₃的3个部分浓度均增加，TNO₃在下午17：00达到全天峰值.相关分析表明，低温有利于NO₃^-以NH₄NO₃存在于细颗粒态；TNO₃浓度较高时，细颗粒态NO₃^-占比亦升高.

Characteristics of gas-particle partitioning of gaseous nitric acid and particle nitrate in Shenzhen in winter

In this study, the dual-channel online gas and aerosol analyzer (MARGA) was used to simultaneously observe water-soluble inorganic ions and their gaseous precursors in PM_2.5 and PM₁₀ in Shenzhen in winter, in order to explore the gas-particle partitioning characteristic of gaseous nitric acid (HNO₃) and particle nitrate (pNO₃^-). It was shown that gaseous nitric acid, fine-particle nitrate and coarse-particle nitrate accounted for 9.6%, 56.8% and 33.6% of total nitrate (TNO₃,=HNO₃+ pNO₃^-), respectively. The diurnal variation of TNO₃ concentration presented a curve of two peaks. The peak in the morning was related to the increase of fine NO₃^- caused by NO_x from vehicles in the morning rush hour. The photochemical reaction in the daytime increased the concentration of three components of TNO₃, so the TNO₃ concentration reached the highest level of the day at 17:00. The analysis suggested that low temperature was beneficial for NO₃^- to exist in fine particles as NH₄NO₃. When the concentration of TNO₃ was high, the proportion of NO₃^- in fine particles also increased.