Abstract As an intersection that links terrestrial and aquatic ecosystems, river ecosystems are hotspots for nitrogen (N) removal. Nitrification and denitrification processes have been recognized as the primary mechanisms behind permanent N removal in rivers, which can be influenced by a variety of environmental factors. However, in rivers characterized by low carbon to nitrogen (C/N) ratio, the interaction among environmental factors and their effects on the sediment N-removal rates remain to be elucidated. In this study, we conducted six surveys in the Chuanfang River (an urban low C/N ratio river flowing into the Dianchi Lake) to investigate the effects of four categories of environmental variables on sediment N-removal rates (water physicochemical properties, water nutrients, sediment characteristics, and submerged vegetation) and their respective contribution to sediment N-removal rates. The results showed that sediment N-removal rates increased along the river reach, accompanied by a gradual improvement in water quality, sediment fertility, and submerged vegetation. Furthermore, comprehensive results of multiple analysis indicated positive effects of water physicochemical properties (e.g. dissolved oxygen, pH, temperature, etc.), sediment characteristics (e.g. sediment C, N, etc.), and submerged vegetation (e.g. tissue C, N, etc.) on the N-removal rates but emphasized the restriction of water nutrients (e.g. water N, etc.). In addition, the significant negative correlation between nitrification and denitrification in path model signified the decoupled nitrification–denitrification in the Chuanfang River. This study suggested that river ecosystems that received low C/N water had a great N-removal capacity, which could be further enhanced by the improvement of water quality, sediment fertility, and submerged vegetation.

中文翻译：

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低C/N比河流中各类环境因素对沉积物脱氮的贡献

摘要 作为连接陆地和水生生态系统的交汇点，河流生态系统是氮（N）去除的热点。硝化和反硝化过程已被认为是河流中永久性氮去除的主要机制，其可能受到多种环境因素的影响。然而，在以低碳氮（C/N）比为特征的河流中，环境因素之间的相互作用及其对沉积物氮去除率的影响仍有待阐明。在本研究中，我们在川房河（流入滇池的城市低 C/N 比河流）进行了 6 次调查，研究了四类环境变量对沉积物 N 去除率（水理化性质、水养分）的影响。 , 沉积物特征, 和淹没植被）及其各自对沉积物氮去除率的贡献。结果表明，随着河段的沉积物氮去除率增加，水质、沉积物肥力和淹没植被逐渐改善。此外，多重分析的综合结果表明，水的理化性质（如溶解氧、pH、温度等）、沉积物特征（如沉积物 C、N 等）和沉水植被（如组织 C、N、等），但强调了对水养分（如水 N 等）的限制。此外，路径模型中硝化和反硝化之间的显着负相关表明川房河的硝化-反硝化解耦。