Abundant NH3 in China Enhances Atmospheric HONO Production by Promoting the Heterogeneous Reaction of SO2 with NO2
Abundant NH3 in China Enhances Atmospheric HONO Production by Promoting the Heterogeneous Reaction of SO2 with NO2
复制标题
中国丰富的NH3通过促进SO2与NO2的非均相反应提高大气中HONO的产量
DOI：
10.1021/acs.est.9b04196
复制
发表时间：
2019-12-17
影响因子：
11.4
通讯作者：
Zhang, Hongliang
中科院分区：
文献类型：
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作者：
Ge, Shuangshuang;Wang, Gehui;Zhang, Hongliang
在中国的灰霾天气中经常观测到高浓度的HONO，由于一些未知的来源和形成机制，目前的模式低估了HONO的浓度。结合实验室模拟和中国西安和北京的现场测量，我们发现NH3可以通过在吸湿颗粒的水相中SO2与NO2的还原-氧化来显著促进HONO的形成（例如，NaCl）。在气溶胶阶段形成的HONO浓度呈指数增长（R-2 = 0.91）与NH3水平的箱条件下和线性增长与NH3水平在两个中国城市。NO_2在NaCl颗粒上的吸收系数为2.0 × 10 ~（-5）~ 1.7 × 10 ~（-4），比在水滴上的吸收系数大3-4个数量级。研究结果进一步表明，气溶胶相生成的HONO占室内总HONO的4-33%，说明气溶胶相生成是我国大气中HONO的重要来源，尤其是在灰霾期间。由于NH3、SO2和NO2在我国大量共存，NH3对HONO生成的积极作用会增强我国大气的氧化能力，造成严重的二次气溶胶污染。我们的工作表明，NH3排放控制是减轻中国空气污染的当务之急。
High levels of HONO have frequently been observed in Chinese haze periods and underestimated by current models due to some unknown sources and formation mechanisms. Combining lab-chamber simulations and field measurements in Xi'an and Beijing, China, we found that NH3 can significantly promote HONO formation via the reduction-oxidation of SO2 with NO2 in the aqueous phase of hygroscopic particles (e.g., NaCl). Concentrations of HONO formed in the aerosol phase showed an exponential increase (R-2 = 0.91) with NH3 levels under the chamber conditions and a linear growth with NH3 levels in the two Chinese cities. The uptake coefficient of NO2 on NaCl particles ranged from 2.0 x 10(-5) to 1.7 x 10(-4), 3-4 orders of magnitude larger than that on water droplets. Our results further showed that HONO formed from the aerosol phase accounted for 4-33% of the total in the chamber, indicating that aerosol-phase formation is an important source of HONO in China, especially in haze periods. Since NH3, SO2, and NO2 abundantly coexist in China, the positive effect of NH3 on HONO formation could enhance the atmospheric oxidizing capacity in the country, causing severe secondary aerosol pollution. Our work suggests that NH3 emission control is imperative for mitigating air pollution in China.