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 con-centrations, toxicity risks, and sources of polycyclic aromatic hydrocarbons (PAHs). The average concentrations of sigma 16PAHs, seven carcinogenic PAHs (carPAHs), and carcinogenic toxic equivalents (TEQcar) in the surface sediments and sediment core were 1634.50 +/- 488.56 ng g-1 and 436.72 +/- 128.17 ng g- 1, 67.18-293.65 ng g-1 and 91.07-265.90 ng g-1, and 34.89 +/- 13.17 ng g-1 and 36.99 +/- 7.52 ng g-1, respectively. The sigma 16PAHs and carPAHs concentrations in surface sediments were higher in the southern lake. The sigma 16PAHs and TEQcar in the sediment core peaked in the 2010s and 1980s. The spatiotemporal variations in TEQcar and carPAHs were similar. Positive matrix factorization revealed that traffic emissions contributed 35.71 % of the TEQcar, whereas coal and biomass combustion contributed 12.89 % in the surface sediments. The contribution of gasoline and fossil fuel to TEQcar 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.