Geochemical mobility of ions in groundwater from the tropical western coast of Maharashtra, India: implication to groundwater quality

Groundwater quantity and quality are equally important for the sustainable management of water resources in coastal parts of the world. Therefore, it is essential to study the geochemical mobility of ions in groundwater and their spatial variation in western coastal part of Maharashtra, India. A total of sixty-five (65) groundwater samples were collected from different dug and bore wells and spring samples and subjected to physicochemical analysis using standard methods of APHA. The analytical results inferred that groundwater is acidic to alkaline in nature. The order of abundance of ions in the groundwater samples is Ca2+ > Na+ > Mg2+ > K+ and HCO3- > Cl- > SO4-2>NO3- > F-. The piper trilinear diagram reveals that the ground water is of Ca-HCO3 and mixed Ca-Cl-HCO3 types. Gibbs diagrams indicate rock and precipitation dominance which is controlling the groundwater chemistry. As compared with World Health Organization drinking standards, groundwater is good for drinking; however, a few samples surpass the desirable limit of pH, HCO3 and F. Similarly, suitability of groundwater for irrigation purpose is also studied using USSL diagram, SAR and %Na and it was found that all groundwater samples are suitable for irrigation purpose, showing good to excellent quality. Conversely, Kelley's ratio suggests that 78.47% of water samples are unsuitable for irrigation. Multiple linear regressions model is used for predicting the fluoride content and confirming the efficiency of the proposed model based on R (0.72) and RMSE (0.035) values. Furthermore, correlation analysis, cluster and principal component analysis were performed to find the significant parameters that influence groundwater chemistry. The cluster analysis explored that all the parameters are associated with EC and PCA which shows four factors are found to be significant which influenced groundwater chemistry.