State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China.
State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China.
Environ Pollut. 2020 Feb;257:113599. doi: 10.1016/j.envpol.2019.113599. Epub 2019 Nov 9.
Concentrations of 99 volatile organic compounds (VOCs) were continuously measured online at an urban site in Beijing, China, in January, April, July, and October 2016. Characterization and sources of VOCs and their related changes during days with heavy ozone (O) pollution were analysed. The total observed concentration of VOCs (TVOCs) was 44.0 ± 28.9 ppbv. The VOC pollution level has decreased in Beijing but remains higher than in other Chinese cities. Alkanes comprised the highest proportion among seven major sampled VOC groups. The concentrations and sources of ambient VOCs showed obvious temporal variations. Six emission sources were identified by the positive matrix factorization (PMF), including biomass burning, coal combustion, gasoline vehicles, diesel vehicles, solvent usage, and biogenic + secondary emissions. The combustion source was the key control factor for VOC reduction in Beijing. From the potential source contribution function (PSCF) and concentration-weighted trajectory (CWT) model, Beijing, Tianjin, Hebei, Shanxi, Inner Mongolia, Shandong, and Henan were identified as major potential source regions of ambient VOCs. O formation was sensitive to VOCs in Beijing according to the VOC/NOx ratio (ppbC/ppbv, 8:1 threshold). High- and low-O days in July were identified, and high O levels were due to both enhanced VOC emission levels and meteorological conditions favourable to the production of O. These findings provide evidence that the fuel combustion and regional transport have a great impact on concentrations and sources of VOCs in urban Beijing.
2016 年 1 月、4 月、7 月和 10 月，在中国北京的一个城市地区，连续在线测量了 99 种挥发性有机化合物（VOC）的浓度。分析了 VOC 及其相关变化的特征和来源，以及在臭氧（O）污染严重的日子。观测到的总挥发性有机物（TVOCs）浓度为 44.0 ± 28.9 ppbv。北京的 VOC 污染水平有所下降，但仍高于中国其他城市。烷烃是 7 种主要采样 VOC 组中占比最高的。环境 VOC 的浓度和来源表现出明显的时间变化。正矩阵因子化（PMF）确定了 6 个排放源，包括生物质燃烧、煤炭燃烧、汽油车辆、柴油车辆、溶剂使用和生物源+二次排放。燃烧源是北京减少 VOC 的关键控制因素。从潜在源贡献函数（PSCF）和浓度加权轨迹（CWT）模型来看，北京、天津、河北、山西、内蒙古、山东和河南被确定为大气 VOC 的主要潜在源区。根据 VOC/NOx 比（ppbC/ppbv，8:1 阈值），北京的 O 形成对 VOC 敏感。确定了 7 月的高 O 日和低 O 日，高 O 水平是由于 VOC 排放水平的提高和有利于 O 生成的气象条件。这些发现表明，燃料燃烧和区域传输对北京市城区 VOC 的浓度和来源有重大影响。
