The characteristics of dissolved organic matter in river sediments, affected by microorganisms, are of great significance to water management strategies. Based on three-dimensional excitation and emission matrix fluorescence, ultraviolet–visible spectroscopy, and high-throughput sequencing technology, this study jointly analyzed the composition and transformation mechanisms of dissolved organic matter as well as the microbial community structure in sediments of the Beiyun River, the main river within a basin with extreme water shortages. Moreover, we evaluated N and P contents in sediments to identify parameters to reflect potential eutrophication risks. Our results demonstrated that the content of dissolved organic matter in sediments was between 30.2 and 49.9 g/kg in the Tongzhou area of the Beiyun River. Humic substances were the largest components of dissolved organic matter in the sediments, followed by protein-like substances and soluble microbial byproducts. Furthermore, the proportion of humic matter decreased from upstream to downstream. The proportion of carbonyl, carboxyl, hydroxyl, and ester substituents on the aromatic structures of dissolved organic matter was significantly higher in the upstream, whereas the proportion of substances with aliphatic chain substituents on their aromatic structures was relatively low. The variation in downstream sediment microbial communities was much greater than that in the upstream (analyzed at the phylum level). Proteobacteria was the most abundant phylum (47.97%), which was closely related to the aromaticity of the dissolved organic matter in sediments. The N and P contents in the sediments of the Beiyun River were high and exhibited active transformation. The maximum fluorescence intensity of fulvic-acid-like components in the sediments [F_max(C4)] can indirectly reflect the potential risk of eutrophication in the Beiyun River. Therefore, our results provide a theoretical basis for the assessment of water quality and pollution control in the Beiyun River and other water-deficient regions worldwide.

受微生物影响的河流沉积物中溶解有机物的特征对水管理策略具有重要意义。本研究基于三维激发和发射矩阵荧光，紫外可见光谱和高通量测序技术，共同分析了北云河沉积物中溶解性有机物的组成和转化机理以及微生物群落结构，流域内严重缺水的主要河流。此外，我们评估了沉积物中的N和P含量，以确定可反映潜在富营养化风险的参数。我们的结果表明，北云河通州地区沉积物中溶解有机物的含量在30.2至49.9 g / kg之间。腐殖质是沉积物中溶解有机物的最大成分，其次是蛋白质样物质和可溶性微生物副产物。此外，腐殖质的比例从上游降低到下游。在上游，溶解的有机物的芳族结构上的羰基，羧基，羟基和酯取代基的比例明显较高，而在其芳族结构上具有脂族链取代基的物质的比例相对较低。下游沉积物微生物群落的变化远大于上游（在门水平进行分析）。腐殖质的比例从上游降低到下游。在上游，溶解的有机物的芳族结构上的羰基，羧基，羟基和酯取代基的比例明显较高，而在其芳族结构上具有脂族链取代基的物质的比例相对较低。下游沉积物微生物群落的变化远大于上游（在门水平进行分析）。腐殖质的比例从上游降低到下游。在上游，溶解的有机物的芳族结构上的羰基，羧基，羟基和酯取代基的比例明显较高，而在其芳族结构上具有脂族链取代基的物质的比例相对较低。下游沉积物微生物群落的变化远大于上游（在门水平进行分析）。变形杆菌是最丰富的门（47.97％），与沉积物中溶解的有机物的芳香性密切相关。北云河沉积物中氮和磷含量较高，并表现出活跃的转化作用。沉积物中富里酸样成分的最大荧光强度[F _max（C4）]可以间接反映北云河富营养化的潜在风险。因此，我们的研究结果为评估北云河及世界其他缺水地区的水质和污染控制提供了理论基础。