Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology, International Institute for Earth System Science, Nanjing University, Nanjing, 210023, China.
Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology, International Institute for Earth System Science, Nanjing University, Nanjing, 210023, China; Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing, 210023, China.
Environ Pollut. 2021 Jan 15;269:116163. doi: 10.1016/j.envpol.2020.116163. Epub 2020 Nov 27.
Nitrogen dioxide (NO) is one of the most important air pollutants that highly affect the formation of secondary fine particles and tropospheric ozone. In this study based on hourly NO observations from June 2014 to May 2019 and a regional air quality model (WRF-CMAQ), we comprehensively analyzed the spatiotemporal variations of NO concentrations throughout China and in 12 urban agglomerations (UAs) and quantitatively showed the anthropogenic and meteorological factors controlling the interannual variations (IAVs). The ground observations and tropospheric columns show that high NO concentrations are predominantly concentrated in UAs such as Beijing-Tianjin-Hebei (BTH), the Shandong Peninsula (SP), the Central Plain (CP), Central Shaanxi (CS), and the Yangtze River Delta (YRD). For different UAs, the NO IAVs are different. The NO increased first and then decreased in 2016 or 2017 in BTH, YRD, CS, and Cheng-Yu, and decreased from 2014 to 2019 in Harbin-Changchun, CP, SP, Northern Slope of Tianshan Mountain, and Beibu-Gulf, while increased slightly in the Pearl River Delta (PRD) and Hohhot-Baotou-Erdos-Yulin (HBEY). The NO IAVs were primarily dominated by emission changes. The net wintertime decreases of NO in BTH, Yangtze River Middle-Reach, and PRD were mostly contributed by emission reductions from 2014 to 2018, and the significant increase in the wintertime in HBEY was also dominated by emission changes (93%). Weather conditions also have an important effect on the NO IAVS. In BTH and HBEY, the increases of NO in winter of 2016 are mainly attributed to the unfavorable weather conditions and for the significant decreases in the winter of 2017, the favorable weather conditions also play a very important role. This study provides a basic understanding on the current situation of NO pollution and are helpful for policymakers as well as those interested in the study of tropospheric ozone changes in China and downwind areas.
二氧化氮（NO）是最重要的空气污染物之一，对二次细颗粒物和对流层臭氧的形成有很大影响。本研究基于 2014 年 6 月至 2019 年 5 月的每小时 NO 观测数据和区域空气质量模型（WRF-CMAQ），全面分析了中国各地以及 12 个城市群（UA）的 NO 浓度时空变化，并定量显示了控制年际变化（IAVs）的人为和气象因素。地面观测和对流层柱表明，高浓度的 NO 主要集中在北京-天津-河北（BTH）、山东半岛（SP）、中原（CP）、关中（CS）和长江三角洲（YRD）等城市群。对于不同的 UA，NO 的 IAV 不同。2016 年或 2017 年，BTH、YRD、CS 和成渝的 NO 先增加后减少，而哈尔滨-长春、CP、SP、天山北坡和北部湾的 NO 则从 2014 年减少到 2019 年，而珠三角（PRD）和呼和浩特-包头-鄂尔多斯-榆林（HBEY）则略有增加。NO 的 IAV 主要受排放变化的控制。BTH、长江中游和珠三角冬季 NO 的净减少主要归因于 2014 年至 2018 年的减排，而 HBEY 冬季 NO 的显著增加也主要归因于排放变化（93%）。天气条件对 NO 的 IAV 也有重要影响。在 BTH 和 HBEY，2016 年冬季 NO 的增加主要归因于不利的天气条件，而 2017 年冬季 NO 的显著减少，有利的天气条件也起到了非常重要的作用。本研究为了解当前 NO 污染状况提供了基础，并为决策者以及对中国和下风区对流层臭氧变化感兴趣的研究人员提供了帮助。
