Physical and Chemical Characterization of Dust Deposited in the Turan Lowland (Central Asia)

Abstract

The desiccation of the Aral Sea ranks among the largest man-made ecological catastrophes and has become a global symbol for the overexploitation of limited resources and the environmental and socio-economic consequences caused thereby. Formerly the fourth largest inland lake, large parts of the Aral Sea have been transformed into a salty desert – the Aralkum. The exposed lake bed sediments are subject to wind erosion, resulting in white sand and dust storms which have been tracked over several hundred kilometres using remote sensing images. Dust deposition data, on the other hand, requires excessive field work over prolonged periods of time and thus is scarce. But this kind of ground-based monitoring provides valuable insights into the physical and chemical composition of the transported material. The dust transported from the Aralkum contains, among other things, salts, heavy metals and agrochemicals deposited in the Aral Sea over decades. It can contribute to soil salinization, damage crops and technical infrastructure and impair the human health in the region surrounding the Aralkum, making the analysis of the aeolian dust deposition highly relevant. In the study presented here passive dust deposition data from 23 meteorological stations in the Turan lowland have been collected between 2003 and 2012 and analyzed for their grain size, mineralogical, and chemical characterization in order to identify the influence the newly formed Aralkum has on the Central Asian dust dynamic.