Spatial distribution, composition, and source analysis of petroleum pollutants in soil from the Changqing Oilfield, Northwest China

Petroleum contamination surrounding oilfields has attracted more concerns. However, the levels, distribution and source of petroleum of Changqing Oilfield soil still remain lots of knowns, which is important for local environmental protection. Given soil contamination issues in Changqiong Oilfield were investigated. The maximum concentrations of total petroleum hydrocarbons (TPHs), N-alkanes (TNAs) and polycyclic aromatic hydrocarbons (PAHs) were determined to be 1960.29, 96.13 and 0.82 mg/kg, respectively. TPHs were higher in the north than the south of the study area. TPHs decreased in the horizontal and vertical distribution as soil depth and distance from oil wells increased. Source analysis showed that TNAs mainly originated from petroleum, PAHs were controlled by petroleum spills, combustion and traffic. Correlation analysis implied that TPHs residues had an effect on soil environmental quality. This study have important implications for understanding the environmental behavior of petroleum and can provide support for petroleum remediation and risk control. [Display omitted] •TPHs in northern study area (QC, XF) were higher than those in the southern (PCQ).•TPHs levels obviously decreased with increasing soil depth and distance from the oil well.•The sources of TNAs and PAHs are oil leaking, coal combustion and vehicle exhaust.•TPHs residues had a negative effect on soil environmental quality.