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  Polynuclear aromatic hydrocarbons(PAHs) and black carbon(BC) in sediments are powerful tools in the identification of the combustion process throughout geologic history.In this study,combustion-derived PAHs and BC were carefully investigated in sediments from the Global Stratotype Section and Point of the Permian-Trias sic(P/Tr) boundary in Meishan, China.Quantitative analyses of combustion-derived PAHs and BC demonstrate anomalously high concentrations in the boundary event beds that coincide with the mass extinction horizon.The prevalence of parent polynuclear aromatics(e.g., phenanthrene) in PAHs,together with non-metric multidimensional scaling analysis,confirms that the PAHs are mainly derived from vegetation burning instead of having a coal and/or oil origin.BC detected in sediment occurs in various forms from large irregular charcoal particles to fine aciniform soot,with an equivalent reflectance of up to 3.5%.The results strongly suggest that a wildfire occurred during the P/Tr boundary,which served as one of the possible triggers of mass extinction on land.The wildfire occurrence indicates that the O_2 concentration of the atmosphere during(or before) the P/Tr mass extinction was probably >17%.The temporal coincidence of the mass extinction with intensive volcanic eruption,marine anoxia and wildfire events in the region of the Meishan section provides new insight into the mechanisms of the P/Tr biotic crisis. Our results show that wildfires could have played an important role in the collapse of the ecosystem in the Meishan P/Tr events.……