Source apportionment of polycyclic aromatic hydrocarbons in soils of wetlands in the Liao River Delta, Northeast China

The polycyclic aromatic hydrocarbons (PAHs) of 55 surface soil samples from the wetlands in the Liao River Delta, Northeast China were measured in order to apportion their sources. The total concentrations of 16 US EPA priority PAHs and alkyl-PAHs in this region ranged 106–3148 ng g−1 (dry weight) (average: 550 ± 565 ng g−1) and 54–5564 ng g−1 (average: 517 ± 838 ng g−1), respectively. Based on the positive matrix factorization analysis of alkylated and parent PAHs, six sources of PAHs were identified including petroleum (23%), biomass burning (23%), air–soil exchange (18%), coal combustion (17%), traffic emission (14%) and biogenic origin (6%). The positive correlation between low molecular weight (LMW) PAHs and TOC contents could demonstrate a potential positive influence of TOC on the accumulations of LMW PAHs in soils by the air–soil exchange. The petrogenic PAHs may pose a limited harmful effect on aquatic organisms although they were abundant in the area.