兰州市冬季大气沉降尘粒度特征及来源解析

A study of the characteristics and source of the atmospheric deposition dust in Lanzhou

通过对兰州市冬季大气沉降尘颗粒的粒度分布特征及参数的分析,认识其可能来源及对环境的影响．从实验结果发现兰州市大气沉降尘粒径主要为10-50μm,各个采样点的PM2.5和PM10贡献突出,说明兰州市颗粒物污染严重．研究表明兰州市大气中可吸入颗粒物的来源主要为生活燃煤和汽车、工厂产生的废气;粒径<50μm的颗粒物主要来源于空气搬运作用迁移而来的黄土粉尘等;粒径>50μm的颗粒物主要是由人为引入或由特大尘暴使大颗粒物近源搬运的结果．不同的功能区中,工业区内污染最大,其次为生活区和其他区．从整体看兰州市的4个行政区内大气沉降尘粒度特征有较大的相似性,除了受生活、汽车、工业以及黄土高原的影响外,兰州城市整体布局存在较大缺陷,工业区和生活区混杂、密集,布局不合理．

Grain size distributional characteristics and parameters of the atmospheric deposition dust in Lanzhou have been analyzed to study the sources and the influence on the environment. It has been shown that the grain size of atmospheric deposition dust in Lanzhou is in the range of 10-50 μm from the experiment results and the particles PM2.5 and PM10 stand out at different sample locations. The conclusion is that the grain pollution is very heavy in this city. The research indicates the sources of atmospheric breathing particles in Lanzhou are mainly the coal-burning for daily living, the combustion gas of automobiles and the exhausted gas of industries. The particles with a grain size less than 100 μm mainly come from the loess particles carried by the air. The particles with a grain size more than 100 μm mainly come fromhuman activities or are carried by the greatest dust storm from the nearby areas. In the different function areas, industrial pollution is the heaviest, following pollution from living and other sources. On the whole, for the 4 districts in Lanzhou, there is a great comparability in the characteristics of the atmospheric deposition dust, which is affected by, apart from daily life, automobiles, industries and the Loess Plateau, the deficient distribution of the city proper characterized by the unreasonable mixed distribution of living areas and industries.