Spatial distribution and health risk assessment of soil petroleum hydrocarbons at an oil refinery in northwest China

Abstract

Abstract In the present study, the concentrations of six petroleum hydrocarbons, including n-alkane hydrocarbons (total petroleum hydrocarbons [TPH] (C6–C9) and (C10–C40)), BTEX(benzene, toluene, ethylbenzene, and m- and p-xylene), in 261 soil (0–14 cm), 31 groundwater, and 4 soil gas samples were measured to determine their spatial distribution and human health risks. The study integrated the model by Johnson and Ettinger and the HJ 25.3–2019 technical standards for risk assessment of soil contamination with localized parameters using Chinese demographic characteristics and site features to determine Health risk assessments. The results revealed that TPH (C6–C9) was the main contaminant in oil refineries, and the m- and p-xylene concentrations exceeded the screening values in groundwater and soil gas but not in soil. According to the spatial distribution characteristics, the contaminants were mainly concentrated in the refining workshop and around the storage tank, and the migration ability of linear-chain petroleum hydrocarbons in the soil was stronger than that of BTEX. TPH (C6–C9), TPH (C10–C40), and benzene in soil and groundwater pose a threat to human health. The pathway of steam invasion in soil gas and the carcinogenic risk and hazard quotient assessment of benzene in soil gas were 0–4 and 1–3 orders of magnitude higher than those in soil. Aliphatic hydrocarbons [AHCs] (C10–C12) had the highest non-carcinogenic risk among all TPH (C10–C40) parts. The present study provides a reference to accurately determine the toxicological parameters of TPH (C6–C9) and TPH (C10–C40) and to improve the BTEX risk assessment methods.