State Key Laboratory of Cryosphere Sciences, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China; Institute for Geophysics and Meteorology, University of Cologne, Cologne D, 50923, Germany.
State Key Laboratory of Cryosphere Sciences, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China.
Environ Pollut. 2019 Mar;246:79-88. doi: 10.1016/j.envpol.2018.11.101. Epub 2018 Dec 1.
Pollutants, which are usually transported from urban cities to remote glacier basins, and aerosol impurities affect the earth's temperature and climate by altering the radiative properties of the atmosphere. This work focused on the physicochemical properties of atmospheric pollutants across the urban and remote background sites in northwest China. Information on individual particles was obtained using transmission electron microscopy (TEM) and energy dispersive X-ray spectrometry (EDX). Particle size and age-dependent mixing structures of individual particles in clean and polluted air were investigated. Aerosols were classified into eight components: mineral dust, black carbon (soot)/fly ash, sulfates, nitrates, NaCl salt, ammonium, organic matter, and metals. Marked spatial and seasonal changes in individual particle components were observed in the study area. Aerosol particles were generally found to be in the mixing state. For example, salt-coated particles in summer accounted for 31.2-44.8% of the total particles in urban sites and 37.5-74.5% of the total particles in background sites, while in winter, almost all urban sites comprised >50%, which implies a significant effect on the radiative forcing in the study area. We found that in PM section, the internally mixed black carbon/organic matter particles clearly increased with diameter. Moreover, urban cities were characterized by atmospheric particles sourced from anthropogenic activities, whereas background locations exhibited much lower aerosol concentrations and increased particle density, originating from natural crustal sources (e.g., mineral dust and NaCl salt), which, together with air mass trajectory analysis, indicates a potential spatial transport process and routes of atmospheric transport from urban cities to background locations. Thus, this work is of importance in evaluating atmospheric conditions in northwest China and northeast Tibetan Plateau regions, to discover the transport processes and facilitate improvements in climatic patterns concerning atmospheric impurities.
污染物通常从城市输送到偏远的冰川盆地，气溶胶杂质通过改变大气的辐射特性来影响地球的温度和气候。本工作重点研究了中国西北地区城市和偏远背景站点大气污染物的物理化学特性。使用透射电子显微镜（TEM）和能量色散 X 射线能谱（EDX）获得了有关单个颗粒的信息。研究了清洁和污染空气中单个颗粒的粒径和年龄依赖性混合结构。气溶胶被分为八个成分：矿物尘、黑碳（烟尘）/飞灰、硫酸盐、硝酸盐、NaCl 盐、铵、有机物和金属。在所研究的区域观察到个体颗粒成分的明显的空间和季节性变化。气溶胶颗粒通常处于混合状态。例如，夏季城市站点中盐涂层颗粒占总颗粒的 31.2-44.8%，背景站点中占 37.5-74.5%，而冬季几乎所有城市站点都超过 50%，这意味着对研究区域的辐射强迫有重大影响。我们发现，在 PM 部分，内部混合的黑碳/有机物颗粒的直径明显增加。此外，城市地区的大气颗粒主要来自人为活动，而背景位置的气溶胶浓度较低，颗粒密度增加，源于自然地壳源（如矿物尘和 NaCl 盐），结合气团轨迹分析，表明存在大气传输的潜在空间传输过程和路径，从城市到背景位置。因此，这项工作对于评估中国西北地区和东北青藏高原地区的大气条件、发现传输过程以及促进大气杂质的气候模式改进具有重要意义。
