Organic Material Inputs Regulate the Watershed Biomarker Deposition in the Middle Reaches of Yangtze River From 1885 to 2019

The increased anthropogenic stress potentially influences the sedimentary record in the watershed ecological environment in the recent century. Here, the spatiotemporal occurrence of lipid marker monomers, i.e., n C 12 – n C 37 alkanes and polycyclic aromatic hydrocarbons (PAHs) associated with elements including nitrogen (N), carbon (C), hydrogen (H), and sulfur (S) in the 210 Pb‐dated sediments of the Poyang watershed was investigated. The age of sediment cores was determined to be 1885–2019 by the CRS model. The 134‐year sediment deposition occurred over different stages. The high‐ring PAHs were dominant, and the main sources were biomass combustion and automobile exhaust emissions from 1885 to 2019 without marked change. On a centennial scale, the long‐chain monomers of n ‐alkanes were dominant and found to originate from herbs. Increased terrigenous C input enhanced n ‐alkanes and PAH deposition in the watershed and influenced the ratios of C/N and C/H. The environmental indicator analysis revealed that the restoration of forests and eutrophication of water bodies caused by anthropogenic activities and climate change from wet to drought conditions resulted in the relative contribution of autochthonous organisms and vascular plants from 1885 to 2019.