Types and Source Apportionment of Polycyclic Aromatic Hydrocarbons (PAHs) in Soil-Groundwater of a Closed Coking Plant in Shanxi Province, China

Abstract

To clarify the impact of coking industry activities on the soil-groundwater Polycyclic aromatic hydrocarbon (PAH) occurrence, a typical coking site in Shanxi Province was taken as the study area, and soil and groundwater samples were collected to analyze the pollution level, composition, and distribution of PAHs in soil-groundwater. The sources of PAHs in the study area were identified based on the positive matrix decomposition model (PMF); the health risks of PAHs were calculated based on the carcinogenic and non-carcinogenic health risk model from the Technical Guidelines for Risk Assessment of Soil Pollution for Construction Land (HJ 25.3-2019) and toxicity equivalent quantity (TEQ). The results showed that ∑PAHs of soil ranged from 0 to 6077.7 mg/kg, with an average value of 198.02 mg/kg; ∑PAHs of groundwater ranged from 0 to 18.30 mg/L, with an average value of 9.39 mg/L. In horizontal distribution, ∑PAH content and types in the tar processing area were much higher than those in the surrounding area, and PAHs might migrate to the southwest through infiltration; in vertical distribution, ∑PAH content reached a peak at 5 m underground. According to the PMF model results, four primary sources of ∑PAHs were identified, which were the coking production source (55.0%), coal and petroleum combustion source (22.6%), atmospheric deposition source (13.1%) and residents living source (9.3%). The total average ∑PAH carcinogenic and non-carcinogenic health risks of soil in the study area were 7.05 × 10−6 and 0.695; the average TEQBaP−∑PAHs was 1.650 mg·TEQ/g; as for groundwater, they were 3.08 × 10−6 and 32.04; the average TEQBaP−∑PAHs was 9.390 μg·TEQ/L, indicating that PAHs both in soil and groundwater had potential health risks. This study provides a basis for the same coking site type for pollution control, secondary utilization, and data support for future site restoration.