Spatial and Historical Occurrence, Sources, and Potential Toxicological Risk of Polycyclic Aromatic Hydrocarbons in Sediments of the Largest Chinese Deep Lake

Abstract

Lake sediments are important reservoirs for polycyclic aromatic hydrocarbons (PAHs) in catchments. Knowledge of occurrence, sources, and toxicological risk of PAHs is crucial to abate their pollution and risk. We investigated the spatial and temporal occurrence, sources, and potential toxicological risks of 12 PAHs in the surface sediments and one sediment core of the largest deep lake (Lake Fuxian) of China. Our results indicated the average ΣPAH₁₂ in the surface sediments of this lake was 1550.6 ± 231.4 ng g _dw ^-1 , much higher than those of most Chinese shallow lakes. The average ΣPAH₁₂ in the lake area was higher than that in the estuaries. The average ΣPAH₁₂ in the estuaries of influent rivers was higher than that of the outlet river. Coal combustion, gasoline combustion, and diesel combustion were the major sources, which contributed 68.5%, 19.8%, and 11.8% to the ΣPAH₁₂. The average total benzo[a]pyrene toxic equivalent concentration (TEQ^carc) of the six most carcinogenic PAHs was 317.1 ± 86.3 ngTEQ^carc g^-1 in the surface sediments. The ΣPAH₁₂ increased from 301.7 to 1964.4 ng g _dw ^-1 from 1945 to 2011 and significantly increased with the GDP and population of the catchment. The contribution of coal combustion to the concentrations of PAHs increased gradually with time. The total TEQ^carc, and the percentage of ΣPAH_carc to ΣPAH₁₂ in the sediment core increased from 5.0 to 84.6 ngTEQ^carc g^-1 and from 5.7 to 23.3%, respectively. Our study highlights the importance of such deep waters in burying PAHs and the increasing risk of PAHs from human activities.