Understanding the relationship between suspended particulate matter (SPM), sediment organic C, N stable isotopes, and lake trophic state index (TSI) is essential for managing lake pollution and eutrophication. According to the δ13C, δ15N, and C/N we found that the organic C in SPM and sediment of Caohai Lake primarily originated from macrophytes, while N was sourced from chemical fertilizers, phytoplankton, and aquatic plants. Total nitrogen, total phosphorus, NO3−-N, oxidation reduction potential, and Chl.a were identified as key factors influencing the sources and variations of SPM and sediment organic C and N stable isotopes in Caohai Lake, with a significant linear correlation observed between C, N stable isotopes, and TSI in sediments. To mitigate eutrophication in Caohai Lake, it is recommended that farmers apply fertilizers judiciously to minimize nutrient loss and that aquatic plants be regularly harvested to reduce N release from plant residues.

中文翻译：

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利用稳定同位素特征识别高原湖泊悬浮颗粒物和沉积物中受营养状况影响的有机碳和氮的来源


了解悬浮颗粒物 (SPM)、沉积物有机 C、N 稳定同位素和湖泊营养状态指数 (TSI) 之间的关系对于管理湖泊污染和富营养化至关重要。根据δ13C、δ15N和C/N发现，草海SPM和沉积物中的有机C主要来源于水生植物，而N则来源于化肥、浮游植物和水生植物。总氮、总磷、NO3−-N、氧化还原电位和叶绿素被确定为影响草海湖SPM和沉积物有机C、N稳定同位素来源和变化的关键因素，且两者之间存在显着的线性相关性。沉积物中的 C、N 稳定同位素和 TSI。为了缓解草海湖的富营养化，建议农民合理施肥，尽量减少养分损失，并定期收获水生植物，减少植物残留物的氮释放。