Spatial variation of polycyclic aromatic hydrocarbons (PAHs) in surface sediments from rivers in hilly regions of Southern China in the wet and dry seasons

Seasonal variations of polycyclic aromatic hydrocarbons (PAHs) in the surface sediments from 13 rivers in hilly regions of southern China were studied. Concentrations of PAHs analyzed in the wet season were higher than those analyzed in the dry season, with residues ranging from 74.3 to 1930.9 ng g−1 dw in the wet season and from 96.9 to 1388.9 ng g−1 dw in the dry season. The primary contributors were 3- and 4-ringed congeners accounting for 59.8% ± 10.1% and 58.3% ± 9.3% of the identified PAHs in the wet and the dry seasons, respectively. Proximity to sources and locations susceptible to high atmospheric depositional inputs results in high concentrations of PAH. Diagnostic ratios have indicated that the sources of PAHs in different seasons make no apparent difference. Furthermore, a principal component analysis and multiple linear regression (PCA-MLR) studies indicate that combustion sources such as vehicle emissions and coal combustion are the primary sources of PAHs. Toxicological risk assessments based on TEQcare suggested that Benzo[a]pyrene, benz[a]anthracene, dibenz[a,h]anthracene could pose high ecological risks in this area.