Groundwater hydro-geochemistry, irrigation and drinking quality, and source apportionment in the intensively cultivated area of Sutlej sub-basin of main Indus basin

In the present study, multivariate statistical tools together with graphical methods and ionic inter-relationships have been utilised to comprehend the source apportionment of ions and various geochemical processes involved in the evolution of groundwater in aquifers of intensively cultivated Sutlej sub-basin of the main Indus basin, India. Fifty groundwater samples were taken in January 2020 from fifty rural habitations of the Jalalabad block of Punjab where people mainly depend on groundwater to fulfil drinking and irrigation needs. The collected samples were analysed for 16 water quality parameters by adopting the standard protocols. The average cationic abundance followed the descending order: Na+  > Ca2+  > Mg2+  > K+ and average anionic abundance followed the descending order: HCO3− > SO42− > Cl− > NO3− > F−. Sodium (Na+) and bicarbonate (HCO3−) are the most abundant cation and anion, respectively. Almost all the samples have sodium and bicarbonate content in excess of the permissible limit. Fluoride content ranged between 0.03 mg L−1 and 5.24 mg L−1, and 44% of samples had fluoride content excessive of permissible limit of 1.5 mg L−1. As per the water quality index, 92% of samples are unfit for drinking. The majority of the groundwaters have high to medium salinity and low to medium alkalinity. Na–HCO3 is the most abundant hydrochemical facies followed by Na–Ca–HCO3 and Na–Mg–HCO3 type. Principal component analysis indicated that NO3− and K+ in groundwater are potentially of mixed origin contributed primarily by irrigation return flows and the dissolution of saltpetre (nitre), however, fluoride is of geogenic origin. An inverse relation between fluoride (F−) and calcium (Ca2+) has been observed in correlation as well as principal component analysis, which can be explained by the removal of calcium through calcite (CaCO3) precipitation and dissolution of fluorite (CaF2) releasing F− in these alkaline and Na–HCO3 type of groundwaters. Gibbs plots, along with other ionic cross plots, suggest that rock weathering followed by the ion exchange process are the primary mechanisms regulating groundwater chemistry.