Characteristics of Chinese aerosols determined by individual-particle analysis

Tropospheric aerosols that originate in China and are transported over the North Pacific Ocean have potentially significant impacts on regional and gl obal climate. These aerosols are complex mixtures of soil dust and anthropo genic particles from a variety of sources, including fossil fuel combustion , biomass burning, mining, smelting, and other industrial processes, plus r eaction products of heterogeneous processes that affect these particles dur ing transport. In the coastal marine atmosphere, these particles could be f urther mixed with marine aerosols. To provide examples of the diversity of chemical and physical properties of east Asian aerosols in the spring, indi vidual aerosol particle samples were collected in April and May 1999 in thr ee different environments in China: Qingdao on the coast of the East China Sea, Beijing in the northeast interior, and Mount Waliguan in remote northw estern China. Results reveal that aerosols in this region are complex and h eterogeneous. In addition to significant differences in aerosol composition and size distributions among the samples, each sample contains a large num ber of polyphase aggregates. Many of the particles also have irregular shap es; for a number of the particle types, the irregular shapes should persist even at high ambient RH. Because composition, degree and nature of polypha se aggregation, and shape all effect aerosol radiative properties, the comp lex state of cast Asian aerosols presents a challenge for the modeling of a erosol radiative forcing in the region.