Role of ion chemistry and hydro-geochemical processes in aquifer salinization-a case study from a semi-arid region of Haryana, India

Abstract

In the present study, a total of sixty groundwater samples, twenty each for the premonsoon, monsoon and post monsoon seasons of 2018, were collected from selected locations in the Mewat district of Haryana, India. Electrical conductivity (EC) was measured at the site and total dissolved solids (TDS) were estimated. Samples were analysed for anions (chloride, sulphate, and bicarbonate) and cations (calcium, potassium, magnesium, and sodium). Multiple regression analysis was performed to analyse the data and report the dominant ions. Piper trilinear diagram and Gibbs plots were used to find out the water type and the factors controlling the chemistry of the groundwater, respectively. The saturation index of CaCO3, CaSO4 and NaCl was determined, using the PHREEQC MODEL. Sodium and calcium among cations, and chloride among the anions, had the highest degree of affinity and strong significance for all three seasons. The calcium-chloride water type dominated for all three seasons and Gibbs plot depicted that most of the Na+/Na+ + Ca2+ and Cl-/Cl- + HCO3- ratios show the weathering of rocks to form minerals as the major reason behind the ionic chemistry of the groundwater. The highest level of dissolution is encountered in the case of NaCl, followed by CaSO4, whereas CaCO3 depicts precipitation. The geochemical aspects of weathering, evaporation and ion exchange are the major processes responsible for high salinity, and anthropogenic activities are leading to its expansion. The findings from this study will be useful in management and remediation of groundwater salinity of the region.