[Clay ratio as a tracer to assess the origin of soil-derived dust].

The objectives of this research are to characterise the mineralogy of soil-derived dust in Northern China and to set up the mineralogical signature to trace their origin. Mineral composition of aerosol particles is investigated at five sites (Aksu, Dunhuang, Yulin, Tongliao and Changwu) during the intensive field campaign period of ACE-Asia. The results show that the Kaolinite (K) to Chlorite (C) ratio is sensitive to the regional origin of Asian dust. Western source areas (represent by Aksu) displayed the lowest K/ C ratio of 0.3 (in average), while it was found that to increase up to 0.70 (in average) as moving towards north source areas (represent by Yulin). By studying transported dust in a depositional area representative of the Chinese Loess Plateau, the usefulness of the K/C ratio to retrieve the origin of the dust by associating it with back air-mass trajectories is checked. Compared the mineralogical data between Asian dust and Sahara dust, it is shown that K/C ratio is also a good signature to identify the source areas on the global scale.