HONO Budget and Its Role in Nitrate Formation in the Rural North China Plain
HONO Budget and Its Role in Nitrate Formation in the Rural North China Plain
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HONO预算及其在华北平原农村硝酸盐形成中的作用
DOI：
10.1021/acs.est.0c01832
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发表时间：
2020
影响因子：
11.4
通讯作者：
Yujing Mu
中科院分区：
文献类型：
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作者：
Chaoyang Xue;Chenglong Zhang;Can Ye;Pengfei Liu;Valéry Catoire;Gisèle Krysztofiak;Hui Chen;Yangang Ren;Xiaoxi Zhao;Jinhe Wang;Fei Zhang;Chongxu Zhang;Jingwei Zhang;Junling An;Tao Wang;Jianmin Chen;Jörg Kleffmann;Abdelwahid Mellouki;Yujing Mu
亚硝酸(HONO)是对流层羟基自由基(OH)的主要前体，可加速二次污染物的形成。然而，HONO的来源并不是很清楚，特别是在污染地区。基于在中国平原北部农村地区进行的一次全面的冬季田间活动，采用箱式模式(MCMv3.3.1)模拟了白天HONO的收支和硝酸盐的形成。我们发现HONO光解是初级OH的主要来源，贡献率超过92%。观测到的白天HONO可以用模式中已知源很好地解释。NO2在地面上的非均相转化和NO与OH的均相反应是主要的HONO来源，对白天HONO的贡献率分别超过36%和34%。颗粒硝酸盐的光解和NO2在气溶胶表面的反应的贡献在清洁时期(2%)可以忽略不计，在污染时期(8%)略高。在农村地区，由于HONO的快速光解，相对较高的OH水平显著加速了气相反应，导致白天硝酸盐和其他二次污染物的快速形成。
Nitrous acid (HONO) is a major precursor of tropospheric hydroxyl radical (OH) that accelerates the formation of secondary pollutants. The HONO sources, however, are not well understood, especially in polluted areas. Based on a comprehensive winter field campaign conducted at a rural site of the North China Plain, a box model (MCM v3.3.1) was used to simulate the daytime HONO budget and nitrate formation. We found that HONO photolysis acted as the dominant source for primary OH with a contribution of more than 92%. The observed daytime HONO could be well explained by the known sources in the model. The heterogeneous conversion of NO2on ground surfaces and the homogeneous reaction of NO with OH were the dominant HONO sources with contributions of more than 36 and 34% to daytime HONO, respectively. The contribution from the photolysis of particle nitrate and the reactions of NO2on aerosol surfaces was found to be negligible in clean periods (2%) and slightly higher during polluted periods (8%). The relatively high OH levels due to fast HONO photolysis at the rural site remarkably accelerated gas-phase reactions, resulting in the fast formation of nitrate as well as other secondary pollutants in the daytime.