Document Type : Original Research Paper
Authors
1 M.Sc., Hydrogeologist Base Studies section of Water Resources Department, North Khorasan Regional Water Company, Bojnord, Iran
2 Assistant Professor, Faculty of Earth Sciences, Shahrood University of Technology, Shahrood, Iran
Abstract
Shoghan plain is one of the sub-catchments of the central Kavir, in NorthKhorasanProvince which experiences semi-arid to arid climate. With the exception of its eastern part, the quality of water in Shoghan aquifer is very low, unacceptable even for agricultural use. One of the main factors that deteriorate the quality of groundwater is local geology which comprises mostly sedimentary rocks and in particular evaporites. In order to study the effects of geological formations on the quality of groundwater, 31 water samples were collected from different parts of the aquifer in 2009 and were analyzed for acidity, electrical conductivity and major ions. In the second step, ion distribution maps were prepared and geological characteristics were rechecked in the field. There is a clear impact of geology on the distribution of ions. A combination of ions cross plots and saturation indices of gypsum, halite, calcite and dolomite minerals show that the dissolution of these minerals and weathering of silicate minerals is commonplace in the aquifer. Due to high concentrations of sodium in the groundwater of the area, reverse ion exchange is one of the chemical processes controlling the chemical composition of groundwater.
Keywords
)