محمد فاریابی

Salt playas are among the most important sources of groundwater salinity and contamination in arid and semi-arid regions. In this study, the quality of groundwater in the Kavir-e Daranjir district was investigated using hydrochemical and statistical methods. For this purpose, 52 samples were collected from the abstraction wells. These samples were analyzed using standard methods to determine major ions, trace elements, and coliform bacteria. Spatial distribution maps of physicochemical parameters, bivariate diagrams, and ion ratios were used to identify factors affecting the salinity and contamination of groundwater. Statistical methods, such as cluster analysis and factor analysis, were also used for this purpose. The results of this study showed that chloride and sodium are the dominant ions in all water samples. The electrical conductivity has a wide range of variations (1450–27,300 μS/cm) which indicates salinity and quality degradation of groundwater. Based on the ionic ratios such as Cl/HCO3 and Na/(Na + Cl), most groundwater samples are contaminated by saline water. Geochemical processes such as groundwater mixing, dissolution of halite and gypsum, and reverse ion exchange have affected groundwater quality. Groundwater nitrate concentration is consistent with fecal coliform bacteria, which indicates groundwater contamination by the sewage of residential areas. The trace elements ratios such as Li/Cl and Br/Cl, also indicates that the groundwater has been affected by domestic sewage and brines resulting from dissolution of halite. Multivariate statistical analysis such as cluster analysis and factor analysis also confirm these findings. According to the results of this research, the control of extraction from abstraction wells (to prevent further intrusion of saline water) and the collection and treatment of domestic sewage plays an important role in the sustainable management of groundwater resources in the region.