Variations and sources of nitrous acid (HONO) during a severe pollution episode in Beijing in winter 2016
Variations and sources of nitrous acid (HONO) during a severe pollution episode in Beijing in winter 2016
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2016年冬季北京严重污染期间亚硝酸（HONO）的变化及来源
DOI：
10.1016/j.scitotenv.2018.08.133
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发表时间：
2019
影响因子：
9.8
通讯作者：
He Hong
中科院分区：
文献类型：
--
作者：
Zhang Wenqian;Tong Shengrui;Ge Maofa;An Junling;Shi Zongbo;Hou Siqi;Xia Kaihui;Qu Yu;Zhang Hongxing;Chu Biwu;Sun Yele;He Hong
HONO是OH自由基的重要前体物，在大气化学中起着重要作用，但其来源和形成机制仍不确定，尤其是在复杂的大气污染过程中。在这项研究中，在2016年12月16日至23日的严重污染事件期间，在北京市区，通过定制的仪器测量了HONO混合比。根据PM2.5的水平，测量分为三个阶段：I（雾霾），II（重度雾霾）和III（清洁）。这一污染事件的特点是高水平的NO（75 ± 39和94 ± 40 ppbV期间分别为I和II）和HONO（高达10.7 ppbV）。在夜间，两次灰霾天气的平均非均质转换频率分别为0.0058和0.0146 h-1，不是形成HONO的重要途径。机动车排放对夜间环境HONO的贡献率分别为52%（±16）%和40%（±18）%。在高NOx条件下，NO与OH的均相反应的贡献应该重新考虑，并且在这次污染事件中对HONO源的贡献可能是明显的。此外，HONO与PM2.5在第一和第二阶段呈正相关，这表明HONO和灰霾颗粒物之间存在潜在的化学联系。
HONO is an important precursor of OH radical and plays a key role in atmospheric chemistry, but its source and formation mechanism remain uncertain, especially during complex atmospheric pollution processes. In this study, HONO mixing ratios were measured by a custom-made instrument during a severe pollution event from 16 to 23 December 2016, at an urban area of Beijing. The measurement was divided into three periods: I (haze), II (severe haze) and III (clean), according to the levels of PM2.5. This pollution episode was characterized by high levels of NO (75 ± 39 and 94 ± 40 ppbV during periods I and II, respectively) and HONO (up to 10.7 ppbV). During the nighttime, the average heterogeneous conversion frequency during the two haze periods were estimated to be 0.0058 and 0.0146 h−1, and it was not the important way to form HONO. Vehicle emissions contributed 52% (±16)% and 40% (±18)% to ambient HONO at nighttime during periods I and II. The contribution of homogeneous reaction of NO with OH should be reconsidered under high-NOxconditions and could be noticeable to HONO sources during this pollution event. Furthermore, HONO was positively correlated with PM2.5during periods I and II, suggesting a potential chemical link between HONO and haze particles.