Environmental Behavior of PAHs in Dianchi Lake Distributions, Sources and Risk Assessment of Polycyclic Aromatic Hydrocarbons in Surface Sediments from Dianchi Lake,China

Polycyclic aromatic hydrocarbons (PAHs) in the priority controlling list of US EPA were systematically evaluated in surface sediments in Dianchi Lake and its estuaries. Total PAH concentrations (ΣPAHs) varied from 210 to 11,070 ng/g dry weight (d.w.) in Dianchi Lake, and from 230 to 12,271 ng/g d.w. in the estuaries. ΣPAHs in sediments from Caohai section were higher than those from Waihai section. The occurrences of PAHs in the Lake were closely related to the distributions of rivers, indicating that the river runoff was an important pathway of PAHs into the Lake. Compared with the US Sediment Quality Guidelines (SQGs), ΣPAHs in most area were below the effect range low (ERL), which implied that the adverse biological effects would occur rarely. The toxic equivalent concentrations of potentially carcinogenic PAHs (TEQcarc) varied from 19 to 967 ng TEQ/g d.w., and the higher values were found in northern Caohai area. The proportions of the toxic equivalent quantity (TEQcarc) to the total TEQs in sediments were all above 96%, suggesting that the carcinogenicity of PAHs could be occurred. Significantly positive correlations between total organic carbon (TOC) and less molecular weight PAHs (2, 3-ring) (LPAHs) were observed in the Lake. Diagnostic ratios showed that the primary source of PAHs in Dianchi Lake and most estuaries is biomass combustion, but is petroleum combustion or petrogenic origin in several other estuaries.