Li Huan, Tang Gui-Qian, Zhang Jun-Ke, Liu Qin, Yan Guang-Xuan, Cheng Meng-Tian, Gao Wen-Kang, Wang Ying-Hong, Wang Yue-Si
Faculty of Geosciences and Environmental Engineering, Southwest Jiaotong University, Chengdu 611756, China.
State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China.
Huan Jing Ke Xue. 2020 Oct 8;41(10):4364-4373. doi: 10.13227/j.hjkx.202003303.
To explore the characteristics of water-soluble inorganic ions (WSIIs) in PM during the process of continuous improvement of air quality in Beijing in recent years, a continuous collection of PM sample campaign was conducted in Beijing from 2017 to 2018. The PM mass concentration and WSIIs were then determined. The results showed that the average concentration of PM in Beijing was (77.1±52.1) μg ·m, with the highest and lowest values during spring [(102.9±69.1) μg ·m]and summer [(54.7±19.9) μg ·m], respectively. The average concentration of WSIIs was (31.7±30.1) μg ·m, accounting for 41.1% of the PM mass, and the seasonal contributions were: autumn (45.9%) > summer (41.9%) > spring (39.9%) ≥ winter (39.2%). SNA was an important component of the WSIIs that accounted for 86.0%, 89.5%, 74.6%, and 73.0% of the total WSIIs during spring, summer, autumn, and winter, respectively. With an increase in temperature, the concentration of NO increased initially and then decreased, while the concentration of SO increased. When the relative humidity was less than 90%, the concentrations of both NO and SO increased with an increase in relative humidity. With the aggravation of pollution, the overall contribution of WSIIs in PM increased significantly, and the evolution characteristics of different ions were different. Among them, the concentration and contribution of NO continued to increase, while the contributions of SO and the ions from dust (Mg, Ca, and Na) decreased. During the observation period, the primary sources of WSIIs were secondary conversion, combustion source, and dust. The control of coal combustion and motor vehicles is critical to reduce the emission of WSIIs. The backward trajectory analysis showed that the air masses from the south and west of Beijing corresponded to the high PM concentration and proportion of WSIIs, and the contribution of secondary ions was significant. However, the concentrations and proportions of the air masses from the northwest and north were relatively low, but the contribution of Ca was high.
为探究近年来北京空气质量持续改善过程中细颗粒物（PM）中水溶性无机离子（WSIIs）的特征，于2017年至2018年在北京开展了PM样品的连续采集活动。随后测定了PM质量浓度和WSIIs。结果表明，北京PM的平均浓度为（77.1±52.1）μg·m³，春季[(102.9±69.1) μg·m³]最高，夏季[(54.7±19.9) μg·m³]最低。WSIIs的平均浓度为（31.7±30.1）μg·m³，占PM质量的41.1%，季节贡献为：秋季（45.9%）＞夏季（41.9%）＞春季（39.9%）≥冬季（39.2%）。硫氮化合物（SNA）是WSIIs的重要组成部分，分别占春、夏、秋、冬四季WSIIs总量的86.0%、89.5%、74.6%和73.0%。随着温度升高，NO浓度先升高后降低，而SO浓度升高。当相对湿度小于90%时，NO和SO浓度均随相对湿度增加而升高。随着污染加剧，PM中WSIIs的总体贡献显著增加，不同离子的演变特征不同。其中，NO的浓度和贡献持续增加，而SO和沙尘离子（Mg、Ca和Na）的贡献降低。在观测期内，WSIIs的主要来源是二次转化、燃烧源和沙尘。控制煤炭燃烧和机动车对减少WSIIs排放至关重要。后向轨迹分析表明，来自北京南部和西部的气团对应着高PM浓度和WSIIs比例，二次离子的贡献显著。然而，来自西北和北部的气团浓度和比例相对较低，但Ca的贡献较高。
