State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control, College of Environmental Science and Engineering, Nankai University, Tianjin, 300071, China.
State Environmental Protection Key Laboratory of Urban Ambient Air Particulate Matter Pollution Prevention and Control, College of Environmental Science and Engineering, Nankai University, Tianjin, 300071, China.
Environ Pollut. 2016 Nov;218:757-769. doi: 10.1016/j.envpol.2016.07.072. Epub 2016 Aug 25.
From November 2014 to October 2015, the concentrations of volatile organic compounds (VOCs), O and NOx were simultaneously monitored by using online instruments at the air monitoring station belonged to Tianjin Environmental Protection Bureau (TEPB). The results indicated that VOCs concentrations were higher in autumn and lower in spring, while O concentrations were higher in summer, and lower in winter. The diurnal variations of VOCs and NOx (NO plus NO) showed opposite tendency comparing to that of O. The concentrations of alkanes were higher (the average of 18.2 ppbv) than that of aromatics (5.3 ppbv) and alkenes (5.2 ppbv), however, the alkenes and aromatics made larger contributions to ozone because of their high reactivity. Tianjin belonged to the VOC-limited region during most of seasons (except summer) according to the VOC/NOx ratios (the 8:1 threshold). The automobile exhaust, industrial emission, liquefied petroleum gas/natural gas (LPG/NG), combustion, gasoline evaporation, internal combustion engine emission and solvent usage were identified as major sources of VOCs by Positive Matrix Factorization (PMF) model in Tianjin, and the contributions to VOCs for the entire year were 23.1%, 19.9%, 18.6%, 10.6%, 8.7%, 5.4% and 4.7%, respectively. The conditional probability function (CPF) analysis indicated that the contributing directions of automobile exhaust and industrial emission were mainly affected by source distributions, and that of other sources might be mainly affected by wind direction. The backward trajectory analysis indicated that the trajectory of air mass originated from Mongolia, which reflected the features of large-scale and long-distance air transport, and that of beginning in Jiangsu, Shandong and Tianjin, which showed the features of small-scale and short-distance. Tianjin, Beijing, Hebei and Northwest of Shandong were identified as major potential source-areas of VOCs by using potential source contribution function (PSCF) and concentration-weighted trajectory (CWT) models.
从 2014 年 11 月到 2015 年 10 月，天津环境保护局（TEPB）的空气监测站使用在线仪器同时监测挥发性有机化合物（VOCs）、O 和氮氧化物（NOx）的浓度。结果表明，VOCs 浓度在秋季较高，春季较低，而 O 浓度在夏季较高，冬季较低。VOCs 和 NOx（NO 加 NO）的日变化与 O 的日变化相反。烷烃的浓度较高（平均为 18.2ppbv），而芳烃（5.3ppbv）和烯烃（5.2ppbv）的浓度较低，但由于其高反应性，烯烃和芳烃对臭氧的贡献更大。根据 VOC/NOx 比值（8:1 阈值），天津在大多数季节（夏季除外）属于 VOC 限制区。正矩阵因子化（PMF）模型识别出天津的 VOC 主要来源为汽车尾气、工业排放、液化石油气/天然气（LPG/NG）、燃烧、汽油蒸发、内燃机排放和溶剂使用，全年对 VOCs 的贡献率分别为 23.1%、19.9%、18.6%、10.6%、8.7%、5.4%和 4.7%。条件概率函数（CPF）分析表明，汽车尾气和工业排放的贡献方向主要受源分布的影响，其他源的贡献方向可能主要受风向的影响。后向轨迹分析表明，空气团的轨迹起源于蒙古，反映了大规模、远距离的空气传输特征，而起源于江苏、山东和天津的轨迹则显示了小规模、短距离的特征。潜在源贡献函数（PSCF）和浓度加权轨迹（CWT）模型确定天津、北京、河北和山东西北部为 VOCs 的主要潜在源区。
