Department of Civil and Environmental Engineering, Louisiana State University, Baton Rouge, LA 70803, USA.
Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, Collaborative Innovation Center of Atmospheric Environment and Equipment Technology, School of Environmental Science and Engineering, Nanjing University of Information Science & Technology, 219 Ningliu Road, Nanjing 210044, China.
Sci Total Environ. 2019 Apr 20;662:297-306. doi: 10.1016/j.scitotenv.2019.01.227. Epub 2019 Jan 22.
Tremendous efforts have been made to reduce the severe air pollution in China since 2013. However, the annual and peak fine particulate matter (PM) concentrations during severe events in winter did not always reduce as expected. This is partially due to the inter-annual variation of meteorology, which affects the emission, transport, transformation, and deposition processes of air pollutants. In this study, the responses of PM and ozone (O) concentrations to changes in emission and meteorology from 2013 to 2015 were investigated based on ambient measurements and the Community Multi-Scale Air Quality (CMAQ) model simulations with anthropogenic emissions. It is found that emission reductions in 2014 and 2015 effectively reduced PM concentrations by 23.9 and 43.5 μg/m, respectively, but was partially counteracted by unfavorable meteorology. The negative effects from unfavorable meteorology were significant in extreme pollution events. For example, in December 2015, unfavorable meteorology caused a great increase (90 μg/m) of PM in Beijing. Reduction of primary PM and gaseous precursors led to 13.4 and 16.5 ppb increase of O-8 h daily concentrations in the summertime in 2014 and 2015 in comparison of 2013, which was likely caused by the increase of solar actinic flux due to PM reduction. In addition, reduction of nitrogen oxides (NOx) emissions in areas with negative NOx-O sensitivity could lead to an increase of O formation when the reduction of volatile organic compounds (VOCs) was not sufficient. This unintended enhanced O formation could also lead to higher O in downwind areas. This study emphasizes the role of meteorology in pollution control, validates the effectiveness of PM control measures in China, and highlights the importance of appropriate joint reduction of NOx and VOCs to simultaneously decrease O and PM for higher air quality.
自 2013 年以来，中国为降低严重的空气污染做出了巨大努力。然而，冬季严重事件期间的年际和峰值细颗粒物（PM）浓度并不总是如预期的那样降低。这部分是由于气象的年际变化，影响了空气污染物的排放、传输、转化和沉积过程。在这项研究中，根据环境监测和带有人为排放的大气多尺度空气质量（CMAQ）模型模拟，研究了 2013 年至 2015 年排放和气象变化对 PM 和臭氧（O）浓度的响应。结果发现，2014 年和 2015 年的减排措施分别有效降低了 23.9 和 43.5μg/m 的 PM 浓度，但部分被不利的气象条件抵消。不利气象条件的负面影响在极端污染事件中非常显著。例如，2015 年 12 月，不利的气象条件导致北京 PM 增加了 90μg/m。与 2013 年相比，2014 年和 2015 年夏季，主要 PM 和气态前体物的减少导致 O-8h 日浓度分别增加了 13.4 和 16.5 ppb，这可能是由于 PM 减少导致太阳光化通量增加所致。此外，在氮氧化物（NOx）-O 敏感性为负的地区减少 NOx 排放，如果挥发性有机化合物（VOCs）的减少不足，可能会导致 O 形成增加。这种意外增强的 O 形成也可能导致下风区的 O 浓度升高。本研究强调了气象在污染控制中的作用，验证了中国 PM 控制措施的有效性，并强调了适当联合减少 NOx 和 VOCs 以同时降低 O 和 PM 以提高空气质量的重要性。
