Abstract:

Inland seasonal lake basins are an important source of sand-dust in arid region， and their sand-dust emissions can have a great impact on regional climate and ecological environment through a series of terrestrial-atmospheric interactions. In this study， Qingtu Lake， Nanhu Lake and Hongshagang were taken as the research objects. The BSNE dust collectors were used to gather sand-dust to explore the differences of sand-dust horizontal flux and grain size characteristics among different sites. The results showed that the order of the average horizontal sand-dust flux at the five sites was as follows： Qingtu Lake North （612.1 kg·m^-2·a^-1）>Qingtu Lake South （84.6 kg·m^-2·a^-1）>Qingtu Lake East （35.2 kg·m^-2·a^-1）>Hongshagang （11.0 kg·m^-2·a^-1）>South Lake （10.7 kg·m^-2·a^-1）. With increasing height， the horizontal sand-dust fluxes in Qingtu Lake North and Qingtu Lake East decreased rapidly， the decrease rates in Qingtu Lake South and Hongshagang slowed down above 0.5 m and 1 m height， respectively， and the horizontal sand-dust fluxes in South Lake increased at first and then decreased. The grain content of sand-dust was mainly composed of silt and very fine sand， followed by fine sand and clay. Except for Qingtu Lake South， the content of silt increased， the content of fine sand and the average particle size decreased with increasing height. Among five sites， the average particle size of the sand-dust in Qingtu Lake North was the largest， the sorting was the best， the kurtosis distribution was the narrowest and the local material content was the highest， followed by Qingtu Lake East， Nanhu Lake， Qingtu Lake South， and Hongshagang. The differences in dust horizontal flux and particle size among sites were mainly due to the different underlying surface and sand-dust sources， while wind speed， wind direction and vegetation conditions were important reasons for the temporal variation of sand-dust horizontal flux and particle size. With the increasing wind speed， sand-dust horizontal flux increased and average particle size became coarser.

Key words: inland lake basin, sand-dust horizontal flux, grain size characteristics