Pollution and Risk of PAHs in Surface Sediments from the Tributaries and Their Relation to Anthropogenic Activities, in the Main Urban Districts of Chongqing City, Southwest China

Abstract

Concentrations, sources and risk of 16 priority polycyclic aromatic hydrocarbons (PAHs) were investigated in surface sediments from 19 representative tributaries in a regional scale of Chongqing City. The total concentration of 16 PAHs (ΣPAHs) ranged from 221 to 3205 ng g−1 with a mean of 1055 ng g−1. Most tributaries of the Jialing River exhibited significantly higher ΣPAHs concentrations (mean 1864 ng g−1) compared to those flowing into the Yangtze River (mean 787 ng g−1). Isomeric ratio and hierarchical clustering analysis showed combustion may impact sedimentary PAHs at most center sites of the City, while PAHs at most sites were mixed of petrogenic and pyrogenic sources. Toxicity equivalency concentration for carcinogenic PAH were 2–4 times more than the Dutch limit. More comprehensive assessment of safety is suggested to reduce environmental risk of PAHs in sediments.