School of Nuclear Science and Technology, University of South China, Hengyang 421001, China; Department of Nuclear Reactor Engineering, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.
School of Nuclear Science and Technology, University of South China, Hengyang 421001, China.
J Environ Sci (China). 2019 Aug;82:155-168. doi: 10.1016/j.jes.2019.02.017. Epub 2019 Feb 27.
To understand the physical and chemical characteristics, particle size distribution and sources of size-separated aerosols in Lhasa, which is located on the Tibetan Plateau (TP), six sizes of aerosol samples were collected in Lhasa in 2014. Ca, NH, NO, SO and Cl were the dominant ions. The ratio of cation equivalents (CE) to anion equivalents (AE) for each particle size segment indicated that the atmospheric aerosols in Lhasa were alkaline. SO and NO could be neutralized by Ca, but could not be neutralized by NH, according to the [NH]/[NO + SO] and [Ca]/[NO + SO] ratios. Mobile sources were dominant in PM, PM and PM, while stationary sources were dominant in the other three size fractions according to the [NO]/[SO] ratios. The particle size distribution of all water-soluble ions during monsoon and non-monsoon periods was characterized by a bimodal distribution due to the different sources and formation mechanisms, and it was revealed that different ions had different sources in different seasons and different particle size segments by combining particle size distribution with correlation analysis. Source analysis of aerosols in Lhasa was performed using the Principal component analysis (PCA) for the first time, which revealed that combustion sources, motor vehicle exhaust, photochemical reaction sources and various types of dust were the main sources of Lhasa aerosols. Furthermore, Lhasa's air quality was also affected by long-distance transmission, expressed as pollutants from South Asia and West Asia, which were transmitted to Lhasa according to backward trajectory analysis.
为了了解位于青藏高原（TP）上的拉萨市大气气溶胶的物理化学特性、粒径分布及来源，于 2014 年在拉萨市采集了六个粒径段的气溶胶样品。Ca、NH、NO、SO 和 Cl 是主要的离子。各粒径段的阳离子当量（CE）与阴离子当量（AE）比值表明拉萨大气气溶胶呈碱性。根据[NH]/[NO+SO]和[Ca]/[NO+SO]比值，SO 和 NO 可以被 Ca 中和，但不能被 NH 中和。PM、PM 和 PM 中以移动源为主，而其他三个粒径段中以固定源为主。根据[NO]/[SO]比值，季风期和非季风期所有水溶性离子的粒径分布均呈双峰分布，这是由于不同的来源和形成机制所致。通过结合粒径分布和相关分析，表明不同的离子在不同的季节和不同的粒径段有不同的来源。首次利用主成分分析（PCA）对拉萨市气溶胶进行源分析，结果表明燃烧源、机动车尾气、光化学反应源和各种扬尘是拉萨市气溶胶的主要来源。此外，根据后向轨迹分析，拉萨的空气质量还受到远距离传输的影响，表现为来自南亚和西亚的污染物传输到拉萨。
