مهدی رحمتی

Despite the great extent of Urmia Playa Lake (UPL), researchers have rarely ever studied the development of playa surfaces and their vulnerability to dust emission. Therefore, we aimed the current research to study the formation of UPL surfaces and how their physicochemical, mineralogical and geomorphological characteristics affect their susceptibility to wind erosion. An area of 41 km2 was chosen including lands from UPL and adjacent Agricultural Lands (AL). Different playa surfaces were identified on different geomorphic surfaces and mapped using Landsat images. Later, 75 soil samples from depth of 0–5 cm of di fferent map units were collected and subjected to physicochemical analysis. Soil Erodible Fraction (EF) was also measured as an index for the wind erodibility of the examined soil surfaces. X-Ray Diffraction (XRD) and X-Ray Fluorescence (XRF) analysis of soil samples from three playa surfaces with significantly different EF values were also conducted. Major reasons for the development of different playa surfaces were found to be basically related to geomorphic surfaces on which they have developed, size and mineralogical composition of the sediments as well as the landscape position and depth to the groundwater. Statistical analysis of EF of different playa surfaces and AL showed that Salt Crusts (SC)hadthelowestmeanEFvalueduetotheformationofathinlayerofsaltonitssurfaceasithasdevelopedon low stand geomorphic surface being fine-textured by nature and rich in Na, Mg and Cl ions. Abandoned Agricultural lands (AA) and AL had the highest mean EF values. High sand content of soils with anthropogenic origin along with conventional tillage practices resulting in soil organic matter loss and over grazing were the majorreasonsoftheirhighEF.Therefore,thesesurfacesneedtobemonitoredcarefullyandtobeofhighpriority of conservation and dust control programs in the region.