Groundwater risk-based zoning in a representative chemical park along the Yangtze river: Health risk assessment, source apportionment, and multi-scenario contaminant transport modeling.

Groundwater contamination in the Yangtze River basin and its potential impacts have raised widespread concern in recent years. However, existing approaches for comprehensively assessing the diffusion risks of groundwater contaminants have shown limited efficacy and failed to provide systematic scientific support for region-specific and differentiated risk management. We investigated groundwater contamination characteristics, health risks, source apportionment, and hydrodynamic dispersion in a representative riverfront chemical industrial park in the Yangtze River basin to delineate management zones for targeted risk control. Heavy metals, NH3-N, and volatile organic compounds were identified as key contaminants, with Mn, NH3-N, and aniline showing exceedance rates of 72%, 43%, and 13% and maximum concentrations of 66.1, 192, and 16.0 mg/L, respectively. Further, the pollutants were predominantly distributed in the central production cluster and in Quaternary loose-rock pore water. Health risk analysis showed a higher mean potential carcinogenic risk for children (4.80 × 10-5) than adults (3.89 × 10-6). Similarly, non-carcinogenic risk was higher for children (1.74) than adults (0.90). Source apportionment attributed 93.4% of the pollutants to long-term leakage from wastewater treatment plants and groundwater convergence. Based on these findings, the area was divided into health-risk, discharge, potential-source, and lateral rainfall-recharge zones, and green redevelopment, surface hardening, hydraulic capture, in situ bioremediation, and in situ vertical barrier construction were proposed as control strategies. These findings may facilitate groundwater risk management and serve as a reference for the remediation of similar chemical industrial parks.