Awareness concerning the degradation of groundwater quality and their exacerbating adverse effects due to salinization processes is gaining traction, raising for adequate understanding of the distribution, sources, genesis, and environmental concerns of salinity in groundwater. Saline groundwater is widely distributed all over the world, with an area of 24 million km2 (16% of the total land area on earth) and 1.1 billion people living in the affected areas, especially the arid/semi-arid areas in developing countries. These large-scale groundwater salinization problems are sourced from two major ways: natural and anthropogenic. The natural sources are diversified from connate saline groundwater, seawater intrusion, evaporation, dissolution of soluble salts, membrane filtration process to geothermal origin. The anthropogenic sources include irrigation return flow, road deicing salts, industrial and agricultural wastewater, and gas and oil production activities. The integrated approach of geochemical tracers and multiple isotopes (δ18OH2O, δ2HH2O, δ11B, δ36Cl, δ34Ssulfate, 87Sr/86Sr, and δ7Li) is proved to be useful in the constraints of the origin and transport of solutes in groundwater. Groundwater salinization is often associated with high levels of some toxic elements like arsenic, fluoride, selenium, and boron. Four "triggers" lead to this association: salt effect, competing adsorption, microbial processes, and cation exchange.
Keywords: Distribution; Environmental concerns; Genesis; Geochemical tracers; Groundwater salinization; Stable isotopes.