Retired chemically polluted sites in southern Jiangsu Province, China, are characterized by dense nonaqueous phase liquids (DNAPLs) and extremely thick aquifers (>30 m), which pose substantial challenges for determining investigation and remediation depths during redevelopment and exploitation. This study constructed a 2D groundwater transport model using TMVOC to systematically investigate the migration, diffusion, and natural attenuation processes of two typical DNAPLs—1,2-dichloroethane (DCE) and carbon tetrachloride (CTC)—under three scenarios: individual transport, mixed transport, and heterogeneous aquifer conditions, with a simulation period of 35 years. In individual transport scenarios, DCE and CTC showed distinct migration behaviors. DCE achieved a maximum vertical transport distance of 14.01 m and a downstream migration distance of 459.58 m, while CTC reached 13.57 m vertically and 453.51 m downstream. When transported as a mixture, their migration was inhibited: DCE’s vertical and downstream distances decreased to 13.76 m and 440.46 m, respectively; and CTC’s to 13.23 m and 420.32 m, likely due to mutual solvent effects that altered their physicochemical properties such as viscosity and solubility. Under natural attenuation conditions, both DNAPLs ceased downstream transport by the end of the 6th year. DCE concentrations dropped below its risk control value (0.81 mg/L) by the 14th year, and CTC (with a risk control value of 0.23 mg/L) by the 11th year. By the 10th year, DCE’s downstream plume had retreated to 48.65 m, and CTC’s to 0.95 m. In heterogeneous aquifers, vertical upward transport of DCE and CTC increased to 14.82 m and 14.22 m, respectively, due to the partial absence of low-conductivity silt layers, while their downstream distances decreased to 397.99 m and 354.11 m, constrained by low-permeability lenses in the migration path. These quantitative results clarify the dynamic differences in DNAPL transport under varying conditions, highlighting the impacts of multicomponent interactions, natural attenuation, and aquifer heterogeneity. They provide critical references for risk management, scientific determination of remediation depths, and safe exploitation of retired chemically polluted sites with similar hydrogeological characteristics.

Antibiotic residues in aquatic environments exhibit high environmental persistence and pose potential ecological risks, highlighting the need for efficient and low-cost advanced treatment technologies. In this study, nitrogen-doped sea buckthorn wood-derived carbon catalysts (NSBC-x) were prepared from sea buckthorn wood waste through a ball-milling–nitrogen-doping–pyrolysis strategy and applied to catalytic ozonation for tetracycline (TTCH) degradation. The pyrolysis temperature significantly affected the catalytic performance of the materials, with NSBC-800 exhibiting the highest activity. Under an initial TTCH concentration of 50 ppm, a catalyst dosage of 0.10 g L⁻¹, and an ozone flow rate of 0.10 L min⁻¹, NSBC-800 achieved a TTCH removal efficiency of 94.72%. Reactive-species quenching experiments indicated that superoxide radicals (O₂^·−) and singlet oxygen (¹O₂) were the predominant reactive species in the system. The superior catalytic performance of NSBC-800 may be attributed to the synergistic effects of nitrogen-containing active sites, structural defects, accessible pore channels, and a moderately graphitized carbon framework, which collectively facilitate ozone adsorption, interfacial electron transfer, and reactive oxygen species (ROS) generation.