针对三峡库区中小河流河口泥沙沉积易造成内源污染的问题，以常年回水区典型中小河流泥溪河与朱衣河为研究对象，通过泥沙淤积调查、泥沙理化特性分析以及环境风险评估开展研究。研究表明：泥溪河与朱衣河河口均有显著泥沙沉积，泥沙中粉粒占76%以上；泥溪河泥沙氮磷含量从研究河段上游至河口呈增高趋势，朱衣河泥沙总有机碳含量从上游至河口呈下降趋势；两研究河段泥沙综合污染指数最高分别为0.7和0.8，风险较低，但有机氮质量分数最高分别为0.110 7%和0.103 1%，存在轻度过量；泥沙多金属的潜在生态风险指数最高分别为68.07和123.94，污染程度为低。目前两研究河段整体水环境风险较低，研究结果为大型水库区域的中小河流管理与生态保护提供了科学依据。

[Objective] Significant sediment deposition occurs at the estuaries of small and medium-sized rivers in the Three Gorges Reservoir Area （TGRA）， which can easily lead to endogenous pollution. Investigating the water environment pollution risks associated with sediment deposition in these typical rivers is of great significance for the water environment protection of the TGRA. [Method] Taking the Nixi River and Zhuyi River—typical small and medium-sized rivers located in the perennial backwater zone—as study subjects， this study evaluated the water environment pollution risks through sediment deposition surveys and analyses of the physicochemical properties， nutrient contents， and heavy metals in the sediments. [Results] （1） Significant sediment deposition was observed at the estuaries of both rivers， with silt accounting for over 76% of the sediment. Sampling sites closer to the estuaries exhibited higher proportions of clay and silt， and lower proportions of sand. （2） In the Nixi River， the spatial distribution of total nitrogen， hydrolyzable nitrogen， and available phosphorus showed a consistent trend， increasing from the upstream section to the estuary. Conversely， in the Zhuyi River， the average total organic carbon content in the sediment was higher than that in the Nixi River， but it decreased from upstream to the estuary. （3） The maximum comprehensive sediment pollution indices for the two rivers were 0.7 and 0.8， respectively， indicating a low overall risk. However， the maximum mass fractions of organic nitrogen reached 0.110 7% and 0.103 1%， respectively， indicating slight exceedance and a potential risk of release into the water body. Organic pollution in the Nixi River was primarily affected by the confluence and reservoir water level fluctuations， whereas in the Zhuyi River， it was mainly driven by human activities in the upstream urban areas of the bay. （4） The maximum potential ecological risk indices for multiple heavy metals were 68.07 and 123.94， respectively， indicating low pollution levels. [Conclusion] The overall water environment risk in the Nixi and Zhuyi rivers is currently low. However， sudden water quality deterioration occasionally occurs， primarily caused by the exceedance of phosphorus-containing substances and easily oxidizable small molecules. Further improvement and management of the water environment require not only controlling agricultural non-point source pollution but also emphasizing sediment dredging and endogenous pollution control. Additionally， comprehensive measures must be implemented in the Zhuyi River to reduce low-molecular-weight pollutants and prevent sudden water pollution incidents.