巢湖百年来沉积物碳氮同位素指示的有机质来源变化
- Changes in Organic Matter Sources Indicated by Carbon and Nitrogen Isotopes in Sediments of Chaohu Lake over the Past Century.
- 基金项目：中国地质调查局项目长江流域重点区生态地质调查（No.DD20221778）；国家自然科学基金（No.41971007；42261144741）
- 摘要：湖泊是与人类密切相关的生态系统之一。湖泊沉积物有机质变化是影响湖泊生态环境的重要因素，研究沉积物有机质来源和变化成为湖泊环境科学研究的核心问题之一。本研究以富营养化严重的巢湖为典型案例，根据3根30~35 cm的沉积柱的放射性测年、TOC、TN、δ13C、δ15N测试数据，利用MixSIAR贝叶斯混合模型，分析了巢湖近百年来沉积物有机质含量、来源及其占比变化。研究发现，巢湖沉积环境较为稳定，平均沉积速率为0.22 ~0.38 cm/yr。近百年来，沉积物有机质显著增加：TOC、TN平均含量分别从底层(1900s)的0.26%、0.054%增加到表层(2020s)的0.86%、0.13%，分别增加了2.3倍、1.41倍。沉积物有机质主要由污水、藻类和土壤三个端元构成，且近百年来不同来源有机质占比显著变化，污水和藻类来源有机质占比分别增加0.71倍和0.76倍；但土壤来源有机质平均占比下降了59%。本研究为巢湖环境演变、环境治理及管理提供了新的科学参考。
- Abstract：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/yr. 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.
