Unveiling Distribution, Hydrogeochemical Behavior and Environmental Risk of Chromium in Tannery Wastewater

Chromium (Cr)-contaminated tannery wastewater is a major environmental concern, especially in developing countries, such as Pakistan, due to its use for crop irrigation, resulting food-chain contamination and health issues. In this study, we explored the distribution, speciation, hydrogeochemical behavior risks of Cr collected from various tanneries Kasur district Punjab, Pakistan. Tannery samples were taken during summer (TWW-summer; n = 82) winter (TWW-winter; seasons. The results showed that high concentration was observed TWW-winter (mean: 49 ± 32 mg L−1) compared TWW-summer 15 21 L−1). samples, exceeded National Environmental Quality Standard (1 L−1), with total ranging 2.8 125 L−1. Hexavalent (Cr(VI)) trivalent (Cr(III)) concentrations spanned 2.7 2.9 12.4 46 L−1, respectively. Piper plot hydrogeochemistry dominated by Ca-Mg-SO4 Ca-Mg-Cl type water, geochemical modeling indicated presence Cr-iron (Fe)-bearing mineral phases—notably, FeCr2O4, MgCr2O4 Cr(OH)3) may control fate wastewater. risk assessment categorized ‘worst quality’, which not fit irrigation without treatment. This study highlights immediate monitoring, remediation mitigation strategies are required reduce exposure many areas