Nitrous acid (HONO) in a polluted subtropical atmosphere: Seasonal variability, direct vehicle emissions and heterogeneous production at ground surface
Nitrous acid (HONO) in a polluted subtropical atmosphere: Seasonal variability, direct vehicle emissions and heterogeneous production at ground surface
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DOI：
10.1016/j.atmosenv.2015.01.061
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发表时间：
2015-04
影响因子：
5
通讯作者：
Zhengning Xu;Tao Wang;Jueqi Wu;L. Xue;James Chan;Q. Zha;Shengzhen Zhou;P. Louie;C. Luk
中科院分区：
文献类型：
--
作者：
Zhengning Xu;Tao Wang;Jueqi Wu;L. Xue;James Chan;Q. Zha;Shengzhen Zhou;P. Louie;C. Luk
虽然亚硝酸（HONO）在污染大气的化学中起着重要的作用，但其大气丰度和来源仍然没有得到很好的了解。本文报道了在香港郊区的一个地点，在不同的季节，在四个选择的月的环境测量的HONO。分析了这些数据，以阐明季节特征，排放比和异质生产率。HONO月平均浓度变化范围为春末（5月）0.35 ± 0.30 ppbv至深秋（11月）0.93 ± 0.67 ppbv。从午夜到高峰时段，HONO、NOx和交通流量的变化模式相似，表明HONO浓度受到机动车排放的强烈影响。排放比（HONO/NOx）来自对21个新鲜羽流（NO/NOx> 0.80）的分析，范围为0.5- 1.6%。的排放比率的大的变化是由于从车辆排放的黑碳（BC）的NO2的反应，基于HONO/NOx和同时测量的BC之间的强相关性。夜间NO2转化为HONO的平均转化率为0.52 × 10 - 2 h-1，与其它报道值相比相对较低。本文强调了一个大的变化，机动车排放比例和非均匀转换的NO2在地面。光化学模型必须考虑这种变化，以更好地模拟HONO的主要来源和随后的光化学在对流层下部。
Although nitrous acid (HONO) plays an important role in the chemistry of polluted atmospheres, its atmospheric abundances and sources are still not well understood. This paper reports ambient measurements of HONO taken over four select months in different seasons at a suburban site in Hong Kong. The data were analyzed to elucidate the seasonal characteristics, emission ratios and rates of heterogeneous production. The monthly averaged HONO concentrations ranged from 0.35 ± 0.30 ppbv in late spring (May) to 0.93 ± 0.67 ppbv in late autumn (November). The similar variation patterns of HONO, NOx,and traffic flow from midnight to rush hours suggest that the HONO concentration was strongly influenced by vehicle emissions. The emission ratios (HONO/NOx) were derived from an analysis of 21 fresh plumes (NO/NOx> 0.80), with the range of 0.5–1.6%. The large variability in the emission ratios is attributed to the reaction of NO2on black carbon (BC) emitted from vehicles, based on a strong correlation between the HONO/NOxand concurrently measured BC. The mean conversion rate of NO2to HONO on ground surface during nighttime estimated on nine select days was 0.52 × 10−2h−1, which is relatively low compared with other reported values. This paper highlights a large variability in vehicle emission ratios and heterogeneous conversions of NO2at ground surface. Photochemical models must consider this variability to better simulate the primary sources of HONO and subsequent photochemistry in the lower part of the troposphere.