Hydrogeochemical Processes Affecting the Quality of Groundwater Resources of the Medial Part of Nuq Plain (West of Kerman Province)

The Nugh plain, with an area of some 3600 km2, is located in the southeast Iran (west of Kerman Province). Its geographical coordinates include 55°32´ - 56°03´eastern longitude and  30°61´ - 31°23´ northern latitude. The purpose of this study is to identify and assess the processes affecting the chemical characteristics of groundwater in the medial part of Nuq Plain situated in the west of Kerman province. For this purpose, 22 samples were taken from pumping wells and the concentrations of heavy metals  along with  ions and some other elements were determined by ICP –MS  and other common methods. At the end, isoconcentration maps were prepared and the samples were analysed statistically (using CA and PCA methods). The concentration of heavy metals (Mo, Ag, Pb, Mn and Fe), Major ions(Na+, Ca2+  Mg2+, Cl-, SO42- and HCO3-)  and also EC and pH were determined. In order to identify the affecting processes, isoconcentration maps were drawn and interpreted; statistical techniques of principal component analysis (PCA) and Cluster Analysis (CA) were employed; saturation indices of halite, calcite, aragonite, dolomite and gypsum were calculated and assessed and also choloroalkaline indices were determined. The above-mentioned parameters indicated that the processes affecting hydrogeochemical characteristics of the groundwater included evaporation and evaporite dissolution, calcite and gypsum precipitation, sulfide oxidation, desorption of heavy metals, common ion effect precipitation, silicate hydrolysis and ion exchange.