Historical records of polycyclic aromatic hydrocarbon deposition in a shallow eutrophic lake:Impacts of sources and sedimentological conditions

Sediment core samples collected from Lake Chaohu were analyzed for 15 priority polycyclic aromatic hydrocarbons(PAHs)to assess the spatial and temporal distributions of the PAHs during lacustrine sedimentary processes and regional economic development.Assessing the PAH sedimentary records over an approximately 100-year time span,we identified two stages in the PAH inputs and sources(before the 1970 s and after the 1970s)in the eastern lake region near a village,whereas three stages(before the 1950 s,1950s–1990s and after the1990s)were identified in the western lake region near urban and industrial areas.Rapid increases in the PAH depositional fluxes occurred during the second stage due to increased human activities in the Lake Chaohu basin.The composition and isomeric ratios of the PAHs revealed that pyrolysis is the main source of PAHs in this lake.Strong positive relationships between PAH concentration and the total organic carbon concentration,sediment grain size(< 4 μm),as well as the local population and Gross Domestic Product indicated that the sedimentary conditions impact the depositional characteristics of the PAHs;simultaneously,socioeconomic activities,such as energy consumption and the levels of urban industrialization and civilization,affect both the composition and abundance of the PAHs.