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首页> 外文期刊>Atmospheric chemistry and physics >Volatile organic compounds at a rural site in Beijing: influence of temporary emission control and wintertime heating
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Volatile organic compounds at a rural site in Beijing: influence of temporary emission control and wintertime heating

机译：北京农村地区的挥发性有机物：临时排放控制和冬季取暖的影响

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While residential coal/biomass burning might be a major and underappreciated emission source for PMsub2.5/sub, especially during winter, it is not well constrained whether burning solid fuels contributes substantially to ambient volatile organic compounds (VOCs), which are precursors to secondary organic aerosols (SOAs) that typically have a higher contribution to particulate matter during winter haze events. In this study, ambient air samples were collected in 2014 from 25?October to 31?December at a rural site on the campus of the University of Chinese Academy of Sciences (UCAS) in northeastern Beijing for the analysis of VOCs. Since temporary intervention measures were implemented on 3–12?November to improve the air quality for the Asian-Pacific Economic Cooperation (APEC) summit held on 5–11?November in Beijing, and wintertime central heating started on 15?November in Beijing after the APEC summit, this sample collection period provided a good opportunity to study the influence of temporary control measures and wintertime heating on ambient VOCs. As a result of the temporary intervention measures implemented during 3–12?November (period II), the total mixing ratios of non-methane hydrocarbons averaged 11.25 ppb, approximately 50 % lower than the values of 23.41 ppb in period I (25?October–2?November) and 21.71 ppb in period III (13?November–31?December). The ozone and SOA formation potentials decreased by ～?50 % and ～?70 %, respectively, during period II relative to period I, with the larger decrease in SOA formation potentials attributed to more effective control over aromatic hydrocarbons mainly from solvent use. Back trajectory analysis revealed that the average mixing ratios of VOCs in southerly air masses were 2.3, 2.3 and 2.9 times those in northerly air masses during periods I, II and III, respectively; all VOC episodes occurred under the influence of southerly winds, suggesting much stronger emissions in the southern urbanized regions than in the northern rural areas. Based on a positive matrix factorization (PMF) receptor model, the altered contributions from traffic emissions and solvent use could explain 47.9 % and 37.6 % of the reduction in ambient VOCs, respectively, during period II relative to period I, indicating that the temporary control measures on vehicle emissions and solvent use were effective at lowering the ambient levels of VOCs. Coal/biomass burning, gasoline exhaust and industrial emissions were among the major sources, and they altogether contributed 60.3 %, 78.6 % and 78.7 % of the VOCs during periods I, II and III, respectively. Coal/biomass burning, mostly residential coal burning, became the dominant source, accounting for 45.1 % of the VOCs during the wintertime heating period, with a specifically lower average contribution percentage in southerly air masses (38.2 %) than in northerly air masses (48.8 %). The results suggest that emission control in the industry and traffic sectors is more effective in lowering ambient reactive VOCs in non-heating seasons; however, during the winter heating season reducing emissions from residential burning of solid fuels would be of greater importance and would have health co-benefits from lowering both indoor and outdoor air pollution.
机译：虽然居民燃煤/生物质燃烧可能是PM 2.5 的主要排放源且未被充分认识，尤其是在冬季，但燃烧固体燃料是否对环境挥发性有机化合物（VOC）产生实质性影响并没有得到很好的限制。是次级有机气溶胶（SOA）的前体，通常在冬季雾霾天气中对颗粒物的贡献更大。在这项研究中，2014年10月25日至12月31日在北京东北的中国科学院大学（UCAS）校园内的一个农村站点收集了环境空气样本，用于分析VOC。自从11月3日至12日实施临时干预措施以改善11月5日至11日在北京举行的亚太经济合作组织（APEC）峰会的空气质量之后，冬季集中供热于11月15日至11月在北京开始在APEC峰会期间，这个采样期为研究临时控制措施和冬季取暖对周围VOC的影响提供了一个很好的机会。由于在11月3日至12日（第二阶段）实施了临时干预措施，非甲烷碳氢化合物的总混合比平均为11.25 ppb，比第一阶段的23.41 ppb的值低约50％（10月25日）。 –第三阶段（11月11日– 12月31日）– 11月2日– 21 ppb。相对于时期I，时期II中的臭氧和SOA形成潜力分别降低了约50％和70％，其中SOA形成潜力的下降主要归因于对溶剂的有效控制，这主要是由于溶剂的使用。反向轨迹分析表明，在第一，第二和第三阶段，南气团中VOC的平均混合比分别是北气团中VOC的2.3、2.3和2.9倍;所有的VOC事件均发生在南风的影响下，这表明南部城市化地区的排放量要比北部农村地区大得多。根据正矩阵分解（PMF）受体模型，交通排放和溶剂使用的变化贡献可以解释在第二阶段相对于第一阶段，分别减少了47.9％和37.6％的环境VOC，表明临时控制车辆排放和溶剂使用方面的措施有效降低了挥发性有机化合物的环境水平。煤炭/生物质燃烧，汽油废气和工业排放是主要来源，在第一，第二和第三阶段，它们分别占VOC的60.3％，78.6％和78.7％。煤炭/生物质燃烧，主要是居民用燃煤，成为主要来源，在冬季取暖期间占挥发性有机化合物的45.1％，与南部空气质量（48.8％）相比，南部空气质量（38.2％）的平均贡献率特别低％）。结果表明，工业和交通部门的排放控制在降低非供暖季节的环境活性VOC方面更有效。然而，在冬季取暖季节，减少住宅燃烧固体燃料的排放将具有更大的重要性，并通过降低室内和室外空气污染而带来健康上的共同利益。

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