Effects of the Three-year Action Plan on pollution characteristics and sources of environmentally persistent free radicals in the atmosphere
DING Jia-le1, CHEN Qing-cai1, ZHANG Zi-meng1, HAN Yue-mei2
1. School of Environmental Science and Engineering, Shaanxi University of Science and Technology, Xi'an, 710021, China; 2. Key Laboratory of Aerosol Chemistry and Physics, State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710061, China
Abstract:The concentration characteristics, species type, and potential sources of environmentally persistent free radicals (EPFRs) in atmospheric PM2.5 of Xi'an were investigated during, before, and after the implementation of the Three-year Action Plan for Winning the Blue Sky Battle, using Electron paramagnetic resonance spectroscopy (EPR). Results showed that the mean concentration of EPFRs after the implementation of the plan (5.03×1014spins/m3) decreased 29.9% compared with that before the implementation (7.18×1014spins/m3), which suggests that EPFRs were effectively controlled due to the implementation of the Three-year Action Plan. The mean concentration of EPFRs in winter (8.61×1014spins/m3) was 2.8times that in summer (3.10×1014spins/m3), and the main type was the free radicals affected by oxygen-containing functional groups near the carbon atoms. Correlations and parallel factor analysis revealed that coal combustion (35.3%), traffic emission (30.0%), and dust (27.8%) were the main sources of EPFEs in atmospheric PM2.5 of Xi'an. Traffic emission was the most dominant source of EPFRs in winter season (45.8%), whereas the EPFRs was strongly correlated with O3 in summer season and the contribution of secondary sources was 2.2~5.7times that of other seasons. The contribution of coal combustion to EPFRs decreased significantly (13.7%) after the implementation of the plan, indicating that policies such as clean heating, total coal consumption control, and comprehensive improvement of coal-fired boilers were very effective. The contributions of traffic emission, dust, and secondary sources slightly increased (3.70%, 3.00%, and 7.00%, respectively), suggesting that the comprehensive controlling of dust, motor vehicle emission for green travel, as well as O3 and VOCs should be the primary focus for future pollution control. The contributions of coal combustion (42.9%) and dust (33.4%) to EPFRs were relatively high on heavy pollution days, whereas the contributions of traffic emission (31.7%) and secondary sources (8.95%) were relatively high on clean days, suggesting that in addition to reduce heavy pollution days, the health impact of EPFRs on clean days also warrant further attention.
丁佳乐, 陈庆彩, 张梓萌, 韩月梅. “三年行动计划”对大气环境持久性自由基污染特征和来源的影响[J]. 中国环境科学, 2023, 43(10): 5041-5051.
DING Jia-le, CHEN Qing-cai, ZHANG Zi-meng, HAN Yue-mei. Effects of the Three-year Action Plan on pollution characteristics and sources of environmentally persistent free radicals in the atmosphere. CHINA ENVIRONMENTAL SCIENCECE, 2023, 43(10): 5041-5051.
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