The occurrence, spatial distribution, seasonal variation, sources, and ecological risks of polycyclic aromatic hydrocarbons (PAHs) in overlying water and surface sediments from Tiaozi River, which is an urban river running through the downtown of Siping City, a traditional industrial city of northeastern China, were investigated. The total PAH concentrations (ΣPAHs) in water varied from 473.5 to 2674.3 ng/L with a mean value of 1272.6 ng/L and ranged from 601.5 to 2906.3 ng/g with a mean value of 1534.4 ng/g in sediments. Both the individual and total PAH concentrations in water and sediments decreased from upstream to downstream, and the average ΣPAHs between the four seasons in water and sediments decreased in the following order of winter> autumn> spring> summer. The composition of the PAHs was characterized by an abundance of PAHs from 2 rings to 4 rings, and the predominant components were naphthalene, chrysene, and benzo(a)anthracene. The identification of the source indicated that coal combustion could be the main contributor to the PAHs. The equivalent toxic concentrations of benzo[a]pyrene in the water ranged from 11.5 to 33.1 ng/L, which were much higher than the concentration limit, suggesting that PAHs in the water could cause potential risks. The risk assessment of PAHs in sediments also showed that PAHs could cause negative effects on aquatic organisms in this river.
Keywords: Polycyclic aromatic hydrocarbons; risk assessment; seasonal variation; source; spatial distribution.