Characteristics and source tracing of pollution in soil and groundwater of a retired coking plant in Shanxi Province.

Coking plants represent a significant industrial pollution source, exerting profound impacts on soil and groundwater quality while posing substantial risks to ecosystems and human health. This study investigated the contamination characteristics and spatial distribution of pollutants in soil and groundwater at a decommissioned coking plant in Shanxi Province, China, providing science-based recommendations for remediation. Key findings reveal severe soil contamination, with benzene, benzo(a)pyrene (BaP), and petroleum hydrocarbons (PHs) identified as the predominant pollutants. Spatially, the contamination exhibited a "patchy" pattern, primarily concentrated in the production, storage, and sewage treatment areas, due to production emissions, improper raw material storage, and wastewater leakage. Vertical profiling demonstrated pollutant accumulation primarily in surface and fill layers, with distinct migration depths observed: ammonia nitrogen (NH3-N) > benzene > polycyclic aromatic hydrocarbons (PAHs) > PHs. Targeted and graded removal measures based on the depth of vertical transport of contaminants in the soil. The groundwater remediation strategy prioritizes controlling the migration and treatment of benzene, naphthalene (NAP), and NH3-N contamination. This study enhances the understanding of contaminant distribution and transport mechanisms in soil and groundwater at coking sites and offers practical insights for developing remediation strategies applicable to similar sites.