Insights into different nitrate formation mechanisms from seasonal variations of secondary inorganic aerosols in Shanghai
Insights into different nitrate formation mechanisms from seasonal variations of secondary inorganic aerosols in Shanghai
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从上海次生无机气溶胶季节变化洞察不同硝酸盐形成机制
DOI：
10.1016/j.atmosenv.2016.09.012
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发表时间：
2016
影响因子：
5
通讯作者：
Jiang Shuqin
中科院分区：
文献类型：
--
作者：
Tao Ye;Ye Xingnan;Ma Zhen;Xie Yuanyuan;Wang Ruyu;Chen Jianmin;Yang Xin;Jiang Shuqin
通过分析[NO3−]/[SO42−]和[NH4+]/[SO42−]的相关性，提出了四季形成细颗粒物硝酸盐的主要机制。2013年4月至2014年1月在上海收集了粒径分解气溶胶。夏季硝态氮细颗粒物浓度低于硫酸盐浓度的十分之一，冬季硝态氮细颗粒物浓度高于硫酸盐。受老化海盐气溶胶的影响，秋季[Na+]/[NH4+]的摩尔比达到53±49%，氯离子损耗非常显著（0.83）。春季，[NH4+]/[SO42−]>2的硝酸盐浓度明显增加，表明硫酸盐被完全中和。在夏季，夜间n2o5水解主导了细颗粒物硝酸盐的形成。[NH4+]/[SO42−]与[NH4+]/[SO42−]之间的线性回归错误地表征了秋冬季硝酸盐形成的阈值，因为存在大量的na2so4和NH4Cl。将函数方程中的游离铵代入，确定冬季气溶胶与春季气溶胶具有相同的硝态氮形成机制。在游离硫酸盐的基础上，可以看出秋季n2o5的均相中和和水解机制都参与其中。
The dominant mechanisms for the formation of fine particulate nitrate during four seasons were proposed by evaluating the correlations between [NO3−]/[SO42−] and [NH4+]/[SO42−]. Size-resolved aerosols were collected in Shanghai from April 2013 to January 2014. The concentration of fine particulate nitrate was below one tenth of the concentration of sulfate in summer, whereas fine particulate nitrate dominated over sulfate in winter. Influenced by aged sea salt aerosols, the molar ratio of [Na+]/[NH4+] reached 53 ± 49% and the depletion of chloride was very significant (0.83) during autumn. In spring, the increase of nitrate concentration became evident for [NH4+]/[SO42−]>2, indicating that sulfate is fully neutralized. During summertime, nighttime hydrolysis of N2O5dominated the fine particulate nitrate formation. The thresholds of [NH4+]/[SO42−] for nitrate formation in autumn and winter were wrongly characterized by the linear regression between [NO3−]/[SO42−] and [NH4+]/[SO42−], because considerable amounts of Na2SO4and NH4Cl were present. Replaced by free ammonium in the function equation, it was established that the winter and spring aerosols shared the same nitrate formation mechanism. On the basis of free sulfate, it was evident that both homogeneous neutralization and hydrolysis of N2O5mechanisms were involved during autumn.