巢湖百年来沉积物碳氮同位素指示的有机质来源变化

Lakes are one of the ecosystems most closely related to human being. Changes in sedimentary organic matter will significantly influence the ecological environment of lakes. Therefore，investigating the sources and change of sedimentary organic matter has become a key focus in lake environmental research. Chaohu Lake，a representative case of severe eutrophication，is used in this study to explore the changes in sedimentary organic matter over the past century. The study measured content of ²¹⁰Pb and ¹³⁷Cs，TOC，TN，δ¹³C，δ¹⁵N of each layer in three sediment cores length by 30~35 cm，and calculated proportion of three different source of each layer in Chaohu Lake by employing MixSIAR Bayesian mixed model. The study found that the sedimentary environment of Chaohu Lake has remained relatively stable，with an average sedimentation rate of 0.22~0.38 cm·a^-1. Over the past century，the organic matter content in sediments has increased significantly：the average TOC and TN concentrationsi from 0.26% and 0.054% in the bottom layers（1900s）to 0.86% and 0.13% in the surface layers（2020s），representing increases of 2.3-fold and 1.41-fold，respectively. The organic matter in the sediments primarily derived from three sources：sewage，algae，and soil. Additionally，the contribution of organic matter from thress sources has changed significantly over the last century. The proportions of organic matter derived from sewage and algae increased by 0.71-fold and 0.76 folds，respectively，while the proportion from soil decreased by 59%. This study provides new scientific insights into the environmental evolution，management，and remediation of Chaohu Lake and offers valuable scientific guidance for its environmental management，governance，and ecological restoration efforts.