Chemical characteristics and source apportionments of volatile organic compounds (VOCs) before and during the heating season at a regional background site in the North China Plain
Chemical characteristics and source apportionments of volatile organic compounds (VOCs) before and during the heating season at a regional background site in the North China Plain
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华北平原区域背景点采暖季前及采暖季挥发性有机物(VOCs)化学特征及来源解析
DOI：
10.1016/j.atmosres.2021.105778
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发表时间：
2021-07-30
影响因子：
5.5
通讯作者：
Wang, Yao
中科院分区：
文献类型：
--
作者：
Han, Tingting;Ma, Zhiqiang;Wang, Yao
我们于2017年10月12日至12月31日在华北平原的一个区域本底站调查了挥发性有机化合物（VOCs）的特征和来源。该研究的独特之处在于首次在中国北方的区域背景站点上确定了VOCs的排放源及其对臭氧形成的影响。采暖期前（NHP，10月12日至11月14日）VOCs的平均总混合比为16.0 +/- 10.0 ppbv，该值比采暖期（HP，11月15日至12月31日）高43%。烷烃是总VOCs的主要贡献者，范围从59.9%到67.1%，在HP和NHP。在HP之前观察到相对湿度（RH）和温度（T）依赖性，并且在相对低的T（-4 ° C至5 ° C）和高RH（60%）条件下观察到高VOC混合比。高混合比的挥发性有机化合物观察到的RH 2 m s-1）之前的HP，而高的混合比被发现在HP期间，突出本地源排放在HP期间的重要作用。此外，西南风在高风速（4米秒-1）是必不可少的区域运输的污染物。在高压前和高压过程中，烯烃对洛自由基损失率（LOH）和臭氧生成潜势（OFP）的贡献分别高达48.8%~ 62.9%和49.7%~ 64.4%。乙烯的OFP和洛在高压前和高压过程中都呈现出较高的水平，说明烯烃在SDZ位点O3的形成中起着重要作用。采用正矩阵分解（PMF）模型对燃煤、液化石油气（LPG）和天然气（NG）的使用、机动车尾气和汽油挥发4种VOCs排放源进行了解析，其贡献率分别为45.4%、15.8%、23.4%和15.4%。浓度加权轨迹（CWT）分析表明，高压前主要潜在污染源分布在上店子以南和西南部，污染带沿着衡水-保定-廊坊-北京。高CWT值主要分布在一个小的区域在SDZ南部的HP期间，强调本地排放和运输的作用，从周边地区，特别是北京市区。
We investigated the characteristics and sources of volatile organic compounds (VOCs) at a regional background station on the North China Plain from 12 October to 31 December 2017. This study is unique in that emission sources of VOCs and their influence on ozone formation were identified for the first time at a regional background site in North China. The average total mixing ratio of VOCs was 16.0 +/- 10.0 ppbv before the heating period (NHP, 12 October to 14 November), and this value was 43% higher than that during the heating period (HP, November 15 to 31 December). Alkanes were the dominant contributors to total VOCs and ranged from 59.9% to 67.1% during the HP and NHP. Relative humidity (RH) and temperature (T) dependence were observed before the HP, and high VOC mixing ratios were observed at relatively low T (-4 degrees C to 5 degrees C) and high RH ( 60%) conditions. High mixing ratios of VOCs were observed under RH 2 m s-1) before the HP, whereas a high mixing ratio was found during the HP, highlighting the important role of local source emissions during the HP. In addition, southwest winds at high wind speeds ( 4 m s-1) were essential for the regional transport of pollutants. The contributions of alkenes to LOH (OH radical loss rate) and OFP (ozone formation potential) before and during the HP were as high as 48.8%-62.9% and 49.7% -64.4%, respectively. The OFP and LOH of ethene presented higher levels before and during the HP, elucidating the significant role of alkenes in the formation of O3 at SDZ site. Four emission sources of VOCs, including coal burning, liquefied petroleum gas (LPG) and natural gas (NG) usage, vehicular emissions and gasoline evaporation, were resolved using a positive matrix factorization (PMF) model, with contributions of 45.4%, 15.8%, 23.4% and 15.4%, respectively. The concentration weighted trajectory (CWT) analysis indicated that the main potential source regions were located to the south and southwest of Shangdianzi (SDZ) before the HP, and they were characterized by a narrow pollution band along Hengshui-Baoding-Langfang-Beijing. High CWT values were primarily distributed in a small region in southern SDZ during the HP, emphasizing the role of local emissions and transport from surrounding regions, especially urban areas of Beijing.