Characterization of the number and chemical size distribution as well as hygroscopicity of fine and ultrafine particles in Beijing, China

这里所描述的项目是北京大学大气环境模拟国家重点实验室和德国莱比锡对流层研究所的联合调查。这个为期三年的项目的主要目标是确定北京高度污染的城市气溶胶的数量大小分布、吸湿性和化学大小分布。北京是一个拥有1500多万居民的城市，正处于向现代化城市过渡的时期。北京的气溶胶主要由三种类型的颗粒组成，即国内燃煤产生的含碳气溶胶，急剧增加的汽车、公共汽车和卡车交通排放的气溶胶，以及中国沙漠地区的细尘。这些气溶胶的结合与由于高光化学作用而形成的二次气溶胶的结合产生了可见的颗粒空气污染。由于北京的气溶胶的大小依赖特性，特别是小于100纳米的气溶胶的大小范围尚不清楚，因此尚无法估计颗粒污染对人类呼吸道疾病可能产生的强烈影响。为了更好地了解未来北京城市气溶胶对人类健康的影响，必须研究粒径相关的气溶胶物理和化学性质，直至超细粒径范围。具体来说，将确定3纳米以下的尺寸分布，20-250纳米范围内的吸湿性，以及直径10纳米以下的化学成分。数量大小分布将在连续的基础上运行，并将在两年期间提供每日、每周和季节性变化，而其他属性则在两次密集活动中进行测量，一次在夏季，一次在冬季。

The project described here is a joint investigation between the State Key Laboratory for Atmospheric Environmental Simulation at the Peking University, Beijing, China, and the Institute for Tropospheric Research, Leipzig, Germany. The major goal of this three-year project is to determine number size distributions, hygroscopic properties, and chemical size distributions of the highly polluted urban aerosol in Beijing. Beijing is a town with more than 15 million inhabitants and it is in the period of transition to a modern city. The aerosol in Beijing consists mainly of three types of particles, the carbonaceous aerosol from domestic coal burning, the emission from the drastically increasing car, bus, and truck traffic, and the fine dust from desert regions in China. The combination of these aerosols in combination with secondary aerosol formation due to the high photochemistry creates a visible particulate air pollution. Since sizedependent aerosol properties especially in the size range smaller than 100 nm are unknown for Beijing, an estimate of the possible strong influence of the particulate pollution on human airway diseases cannot be made yet. To understand better the impact of the Beijing urban aerosol on human health in future, sizedependent physical and chemical aerosol properties down to the ultrafine size range has to be investigated. Specifically, numer size distributions down to 3 nm, hygroscopic properties in the size range 20-250 nm, and chemical composition down to 10 nm in diameter will be determined. The number size distribution will be operated on a continuous base and will provide diurnal, weekly, and seasonal variations over a two year period, while the other properties are measured during two intensive campaigns, one in summer and one in winter time.