Environ Geochem Health. 2026 Jan 3;48(2):74. doi: 10.1007/s10653-025-02965-0.
ABSTRACT
This study examines the hydrogeochemical behavior and salinization processes affecting groundwater in the Kujang area, Eastern Odisha, India. Groundwater was very hard during both pre-monsoon (PRM) and post-monsoon (POM) periods due to elevated total hardness (TH). The chemical composition displayed high concentrations of Na⁺, Cl⁻, Mg2⁺, electrical conductivity (EC), total dissolved solids (TDS), and TH, reflecting saltwater-freshwater mixing within the coastal aquifer. The ionic dominance sequence Mg2⁺ > Na⁺ > Ca2⁺ > K⁺ = Cl⁻ > HCO3⁻ > SO42⁻ indicates saline influence. Multivariate statistical analyses (PCA and correlation), combined with the Base Exchange Index (BEX), Seawater Mixing Index (SMI), and ionic ratios, suggested the effects of seawater intrusion. Additional factors contributing to groundwater salinity include over-pumping, agricultural return flow, and wastewater infiltration. Simpson’s ratio [Cl⁻/(HCO3⁻ + CO32⁻)] suggests that most samples fall within moderate to injurious contamination categories. The Hydrochemical Facies Evolution (HFE) diagram revealed that 86% of PRM and 64% of POM samples were affected by seawater intrusion and cation exchange. Vertical Electrical Sounding (VES) profiles demonstrated heterogeneous subsurface conditions with saline horizons at both shallow and deeper levels. Entropy water quality index (EWQI) analysis revealed that 55% (PRM) and 42% (POM) of groundwater samples with EWQI > 100 were categorized as poor to extremely poor. Therefore, the groundwater quality was found to be largely unsuitable for drinking purposes. This is the first integrated EWQI-VES-based assessment for the Kujang Block, providing a comprehensive understanding of groundwater salinization and insights for sustainable aquifer management.
PMID:41483421 | DOI:10.1007/s10653-025-02965-0