Jia Zhi-Hai, Gu Yao, Kong Cui-Li, Song Jiang-Bang, Meng He, Shi Lai-Yuan, Wu Jian-Hui, Liu Bao-Shuang
Laoshan Branch of Qingdao Ecology and Environment Bureau, Qingdao 266061, 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 300350, China.
Huan Jing Ke Xue. 2023 Apr 8;44(4):1962-1973. doi: 10.13227/j.hjkx.202205040.
The ambient concentration of ozone is high in Qingdao, and ozone pollution episodes occur frequently in summer. The refined source apportionment of ambient volatile organic compounds (VOCs) and their ozone formation potential (OFP) during ozone pollution episodes and non-ozone pollution periods can play an important role in effectively reducing air ozone pollution in coastal cities and continuously improving ambient air quality. Therefore, this study applied the online VOCs monitoring data with hourly resolution in summer (from June to August) in 2020 in Qingdao to analyze the chemical characteristics of ambient VOCs during the ozone pollution episodes and non-ozone pollution periods and conducted the refined source apportionment of ambient VOCs and their OFP using a positive matrix factorization (PMF) model. The results showed that the average mass concentration of ambient VOCs in Qingdao in summer was 93.8 μg·m, and compared with that during the non-ozone pollution period, the mass concentration of ambient VOCs during the ozone pollution episodes increased by 49.3%, and the mass concentration of aromatic hydrocarbons increased by 59.7%. The total OFP of ambient VOCs in summer was 246.3 μg·m. Compared with that in the non-ozone pollution period, the total OFP of ambient VOCs in the ozone pollution episodes increased by 43.1%; that of alkanes increased the most, reaching 58.8%. M-ethyltoluene and 2,3-dimethylpentane were the species with the largest increase in OFP and its proportion during the ozone pollution episodes. The main contributors of ambient VOCs in Qingdao in summer were diesel vehicles (11.2%), solvent use (4.7%), liquefied petroleum gas and natural gas (LPG/NG) (27.5%), gasoline vehicles (8.9%), gasoline volatilization (26.6%), emissions of combustion- and petrochemical-related enterprises (16.4%), and plant emissions (4.8%). Compared with that in the non-ozone pollution period, the contribution concentration of LPG/NG in the ozone pollution episodes increased by 16.4 μg·m, which was the source category with the largest increase. The contribution concentration of plant emissions increased by 88.6% in the ozone pollution episodes, which was the source category with the highest increase rate. In addition, emissions from combustion- and petrochemical-related enterprises were the largest contributor to the OFP of ambient VOCs in summer in Qingdao, with its OFP and contribution proportion being 38.0 μg·mand 24.5%, respectively, followed by that of LPG/NG and gasoline volatilization. Compared with the non-ozone pollution period, the total contributions of LPG/NG, gasoline volatilization, and solvent use to the increase in OFP for ambient VOCs in the ozone pollution episodes were 74.1%, which were the main contribution source categories.
青岛地区臭氧环境浓度较高，夏季臭氧污染事件频发。对臭氧污染事件和非臭氧污染时期环境挥发性有机化合物（VOCs）及其臭氧生成潜势（OFP）进行精细化源解析，对于有效降低沿海城市大气臭氧污染、持续改善环境空气质量具有重要作用。因此，本研究运用青岛市2020年夏季（6月至8月）小时分辨率的在线VOCs监测数据，分析臭氧污染事件和非臭氧污染时期环境VOCs的化学特征，并采用正定矩阵因子分解（PMF）模型对环境VOCs及其OFP进行精细化源解析。结果表明，青岛市夏季环境VOCs的平均质量浓度为93.8 μg·m，与非臭氧污染时期相比，臭氧污染事件期间环境VOCs的质量浓度增加了49.3%，芳烃质量浓度增加了59.7%。夏季环境VOCs的总OFP为246.3 μg·m。与非臭氧污染时期相比，臭氧污染事件期间环境VOCs的总OFP增加了43.1%；烷烃增加最多，达到58.8%。间乙基甲苯和2,3 - 二甲基戊烷是臭氧污染事件期间OFP及其占比增加幅度最大的物种。青岛市夏季环境VOCs的主要贡献源为柴油车（11.2%）、溶剂使用（4.7%）、液化石油气和天然气（LPG/NG）（27.5%）、汽油车（8.9%）、汽油挥发（26.6%）、燃烧及石化相关企业排放（16.4%）和植物排放（4.8%）。与非臭氧污染时期相比，臭氧污染事件期间LPG/NG的贡献浓度增加了16.4 μg·m，是增加幅度最大的源类别。臭氧污染事件期间植物排放的贡献浓度增加了88.6%，是增加速率最高的源类别。此外，燃烧及石化相关企业排放是青岛市夏季环境VOCs的OFP的最大贡献源，其OFP和贡献比例分别为38.0 μg·m和24.5%，其次是LPG/NG和汽油挥发。与非臭氧污染时期相比，臭氧污染事件期间LPG/NG、汽油挥发和溶剂使用对环境VOCs的OFP增加的总贡献率为74.1%，是主要贡献源类别。
