Geochemical characteristics and behaviors of polycyclic aromatic hydrocarbons (PAHs) in soil, water, and sediment near a typical nonferrous smelter

Purpose A comprehensive study was conducted to investigate the presence, geochemical characteristics, and behaviors of polycyclic aromatic hydrocarbons (PAHs) in soil, water, and sediment near a typical nonferrous smelter. Methods A total of 50 samples were collected and analyzed by gas chromatograph-mass spectrometer (GC–MS) for the presence and levels of 16 PAHs. Molecular diagnostic ratios (DRs) and principal component analysis—multiple linear regression analysis (PCA-MLR) were used to determine the source apportionment of PAHs. Fugacity model was used to estimate the exchange and migration between sediment and water. The toxic equivalent quantity (TEQ) and risk quotient (RQ) were applied to determine potential risk. Results The concentration of Σ 16 PAHs in soil ranged from 44.62 to 2547 ng g −1 (mean 629.6 ± 664.4 ng g −1 ) and consisted mainly of 4- to 5-ringed PAHs. The concentration of Σ 16 PAHs in water ranged from 20.34 to 702.7 ng L −1 (mean 97.63 ± 152.9 ng L −1 ), mainly consisting of 2- to 3-ringed PAHs. The highest concentrations of Σ 16 PAHs were found in sediments, which ranged from 44.52 to 6040 ng g −1 (mean 1537 ± 1698 ng g −1 ) and mainly consisted of 4- to 6-ringed compounds. PCA-MLR analysis identified three, two, and three principal components in soil, water, and sediment with a cumulative variance of 94.23%, 90.09%, and 87.48%, respectively. The result of sediment–water exchange showed that the low molecular weight (LMW) (2- to 3-ringed) PAHs were essentially in equilibrium between sediment and water, while the medium molecular weight (MMW) (4-ringed) and high molecular weight (HMW) (5- to 6-ringed) PAHs tended to sink from the water to sediments. Conclusion The sources of PAHs were slightly different in different media and different ring numbers. Coal combustion and traffic emissions from industrial activities of smelters were the primary contributors. The highest concentration levels of Σ 16 PAHs were found in sediment, followed by soil and water. In this area, sediments would serve as a sink more than a source of PAHs and sediments were potentially at environmental risk. Therefore, more attention should be paid to the sediment.