The Mixing of Asian Dust with Pollution Aerosol and the Transformation of Aerosol Components during the Dust Storm over China

Abstract Extensive and continuing sampling, monitoring and analyzing aerosols for the last ten years were performed at 10 representative sites (desert, rural, urban, and island) in China to investigate the characteristics, composition, source, and long-range transport of aerosols over East Asia. In particular, fine and coarse particulate samples collected under normal conditions, as well as samples taken during specific events like haze-fog, rain, and dust storm were characterized for their elemental and ionic compositions and for the organic markers to study the variation of characteristics and the different formation mechanisms of aerosols in dust, haze, and clear days. Several techniques have been developed for the differentiation of local and remote PM. The ratios of Ca/Al and Mg/Al can be used to distinguish and estimate the contributions of mineral particles from different dust sources and from local or remote sources. The spatial variation of the visual range over entire China is achieved, which demonstrated that almost all areas of the central and eastern China, especially all of those urban clusters were covered by heavy haze with very poor visibility. The results demonstrated that there has been tremendous heavy air pollution over entire China and a new weather pattern of haze is shown over many China cities. The high concentration of the soluble salts with high hygroscopicity, especially, ammonium salt, sulfate salt was the formation mechanism of the new weather pattern in China. Sulfate emitted from Taklimakan Desert was found most from the primary dust aerosol, which is due to the paleo-ocean source of this largest desert in Asia. Sulfate transported to Eastern China and Pacific would be much more than previous estimation. The mixing and interaction of Asian dust with the heavy anthropogenic aerosol during the long range transport of China aerosol would have an significant impact on the environment of downstream local cities as well as the global climate change. Asian dust not only delivered large amounts of mineral elements but also carried several times high concentration of pollution elements to the open ocean. Dust not only serves as surface carrier for the formation of sulfate and nitrate, but also can provide the limiting nutrients, Fe(II) to the oceans, which would has far-reaching impact on the global biogeochemical cycle.