Sediment record in pollution, toxicity risk, and source assignment of polycyclic aromatic hydrocarbons (PAHs) in Erhai Lake, Southwest China.

Surface sediments and sediment core had been collected from Erhai Lake, Southwest China to study the concentrations, toxicity risks, and sources of polycyclic aromatic hydrocarbons (PAHs). The average concentrations of ΣPAHs, seven carcinogenic PAHs (carPAHs), and carcinogenic toxic equivalents (TEQ) in the surface sediments and sediment core were 1634.50 ± 488.56 ng g and 436.72 ± 128.17 ng g, 67.18-293.65 ng g and 91.07-265.90 ng g, and 34.89 ± 13.17 ng g and 36.99 ± 7.52 ng g, respectively. The ΣPAHs and carPAHs concentrations in surface sediments were higher in the southern lake. The ΣPAHs and TEQ in the sediment core peaked in the 2010s and 1980s. The spatiotemporal variations in TEQ and carPAHs were similar. Positive matrix factorization revealed that traffic emissions contributed 35.71 % of the TEQ, whereas coal and biomass combustion contributed 12.89 % in the surface sediments. The contribution of gasoline and fossil fuel to TEQ significantly increased from 19.2 % (1890s) to 66.5 % (1990s), that of benz[a]pyrene (coal combustion) decreased, and those of benz[b]fluoranthene and indeno[1,2,3-cd]pyrene (petroleum combustion and traffic emissions) increased from 1.92 % to 3.93 % and from 1.54 % to 2.52 % in the sediment cores, respectively, owing to changes in energy consumption.