ELEMENTAL CHARACTERISTICS OF SEDIMENTS FROM LAKE SUGAN IN QAIDAM BASIN AND THE STRONG WIND (DUST STORM) EVENTS

As a hydrologically closed lake, Lake Sugan located at the northern margin of the Qaidam Basin would be employed to study dust storm history in the northeastern Qinghai-Tibetan Plateau. The elemental compositions were analyzed for three types of samples, namely,lake surface deposits,settled sand and dust and the surface sediments from the eastern catchment, respectively. The results indicate that different samples derive from a homologous source. Al and Ti exhibit a stable gain-loss pattern during the period of the dust emission and deposition. However, Fe is enriched in the lake sediment, which possibly results from element loss by HCl treatment. Elemental characteristics of the six typical dust storms show that there are apparently positive correlations between the elemental fluxes of settled materials (Al, Fe and Ti) and the mean 10 min wind velocity and the variation coefficients (Cv) of the wind velocity. Fluxes of Al, Fe and Ti linearly increase with the increasing wind strength and the fluctuation amplitude of wind velocity. Al, Fe and Ti fluxes of the lake sediments from Lake Sugan are in line with annual day numbers (frequency) of strong wind observed at the Lenghu Meteorological Station since 1957, and therefore Al, Fe and Ti fluxes of the lake sediments organic matter and carbonate were removed from should be used as indicators of strong wind and dust storm. On this basis, we can reconstruct dust storm sequence and history of dust emission for the study area.