Surface water and groundwater contaminations and the resultant hydrochemical evolution in the Yongxiu area, west of Poyang Lake, China

Major-ion and stable hydrogen and oxygen isotopic compositions were employed in this study of surface water and groundwater contaminations and their impacts on intrinsic hydrochemical evolution in the Yongxiu area, west of Poyang Lake, South China. A total of 36 samples were collected from surface water and groundwater in the study area where water pollution risk is high due to the fertilizer use for farmland and the waste drainage from a nearby silicon industry site. The results show that the surface water bodies have been badly polluted and are characterized by low pH values (minimum 2.85) and high concentrations of chemical compounds such as Cl⁻, Na⁺, NH₄-N, NO₃-N and TDS. Groundwater has also been polluted with the similar specific contaminates, as both surface water and groundwater may have similar contamination sources, and groundwater is recharged from the precipitation infiltration and surface water leakage as indicated by oxygen-18 and deuterium compositions due to the thin unsaturated zone in the area. The acidification and the intrusion of contamination further lead to hydrogeochemical reactions and changed hydrochemical type of groundwater from Ca–Mg–HCO₃ to Ca–Mg–Na–Cl. The data evaluation methods and results of this study could be useful to the water sustainable usage management in this area and other environmental-vulnerable areas.