随着经济与城市的快速发展，水环境问题已经成为全球最重要的环境问题之一，《2021年中国生态环境状况公报》显示，全国地表水监测的3632个国考断面中，主要污染指标为化学需氧量、高锰酸盐指数和总磷。黄河流域整体水质良好，干流水质为优，但部分支流水质较差。涑水河是黄河的一级支流，2020年运城市环境状况公报显示，涑水河流域地表水主要污染指标为化学需氧量（Chemical Oxygen Demand，COD）、五日生化需氧量和总磷，其中45.45％的断面化学需氧量年均值超过地表水Ⅲ类标准。由此可见，COD超标是涑水河水质管理面临的主要问题。然而，各环境要素对COD超标的贡献不明，且由于其水体具有咸水特征，环境因子对底泥微生物碳源利用及有机物释放的影响机制不清楚。本研究主要分析了涑水河流域的水体水质时空分布特征，探究了底泥微生物碳源利用及环境因子对其的影响机制，底泥微生物碳源利用与水体中COD含量关系研究，以及不同温度和盐度胁迫下底泥对水体COD的影响规律，主要结论如下：

(1) 分析了涑水河流域3月、7月和10月的水质指标时空分布特征。涑水河研究区的溶解氧浓度较高，溶解氧与叶绿素浓度和pH值高度相关，Pearson。涑水河研究区总氮污染严重，部分样点的总氮含量为劣Ⅴ类水标准，且枯水期3月和10月比丰水期7月污染更为严重。除了硝池外，其余地点的氨氮与总磷的污染较轻。涑水河研究区COD与TOC (Total Organic Carbon，总有机碳)浓度高度相关，并且硝池与伍姓湖部分的COD污染较其余地点更加严重，部分样点浓度为劣Ⅴ类水标准。

(2) 通过底泥培养实验研究不同温度和盐度梯度下底泥有机物释放对上覆水COD浓度的影响。结果表明，随着培养时间的延长，整体来说上覆水中的COD浓度先增加后下降。在盐度一定的情况下，随着温度的增加，上覆水中的COD浓度增加，这可能是温度使得底泥微生物代谢活性增强，生成的易溶于水的有机物进入上覆水中导致；在温度一定的情况下，随着盐度的增加，上覆水中的COD浓度也增加，可能是因为高盐度使得细胞破裂，内容物进入水中，有机质含量上升。上覆水体中的COD浓度与底泥中的总碳含量相关系数R²值为0.59。底泥中的微生物通过代谢可以将底泥中难溶于水的蛋白质、碳水化合物、脂类等降解成易溶于水的氨基酸、脂肪酸和糖类等，增加上覆水COD浓度。

(3)分析了底泥微生物碳源利用多样性和代谢活性，探究咸水条件下底泥微生物碳源利用机制。底泥微生物的碳源利用实验表明，随着培养时间的延长，底泥微生物的AWCD (Average Well Color Development, 单孔颜色平均变化率)逐渐升高，当培养时间达192小时，各样点AWCD值排序为：硝池中>张留庄>伍姓湖南2>姚暹渠>伍姓湖北1>涑水河。所有地点的Shannon-Wiener指数与AWCD值相关性系数均在0.6以上，表明底泥微生物对碳源的利用率与多样性指数高度相关。涑水河样点处高效利用碳源的底泥微生物种类数最少，硝池中样点处高效利用碳源的底泥微生物种类数最多。主成分分析和聚类分析结果均表明姚暹渠与伍姓湖北1的底泥微生物碳源利用相似度较高。水体COD浓度与培养192h时的AWCD值线性拟合的R²为0.58，相关度较高，表明COD污染较严重的样点底泥微生物群落对碳源的代谢利用活性较强。

本研究分析了涑水河流域水体水质和底泥参数的时空分布特征，探究了不同温度和盐度梯度条件下，底泥有机质释放规律，日后研究可以在该底泥培养的过程中测定底泥微生物群落的功能多样性与代谢活性，使联系更为紧密。本研究也对底泥微生物碳源利用进行了分析，可以设计灭菌的底泥作为对照，将矿物质对有机物的吸附与解吸一并考虑研究。

With the rapid development of the economy and cities, water environmental problems have become one of the most important environmental problems in the world. According to the 2021 China Ecological Environment Status Bulletin, the main pollution indicators in 3632 national surface water monitoring sections are chemical oxygen demand, permanganate index, and total phosphorus. The overall water quality in the Yellow River Basin is good, with the main stream having excellent water quality, but some tributaries have poor water quality. The Sushui River is a primary tributary of the Yellow River. According to the 2020 Environmental Status Bulletin of Yuncheng City, the main pollution indicator of surface water in the Sushui River Basin is Chemical Oxygen Demand, COD）、 Five day biochemical oxygen demand and total phosphorus, of which 45.45% of the annual average chemical oxygen demand of the cross-section exceeds the Class III standard for surface water. It can be seen from this that, Excessive COD is the main problem facing water quality management in the Sushui River. However, the contribution of various environmental factors to excessive COD is unclear, and due to the saltwater characteristics of their water bodies, the impact mechanism of environmental factors on the utilization of microbial carbon sources and organic matter release in sediment is not clear. This study mainly analyzed the spatiotemporal distribution characteristics of water quality in the Sushui River Basin, explored the utilization of microbial carbon sources in sediment and the impact mechanism of environmental factors on it, studied the relationship between microbial carbon source utilization in sediment and COD content in water, and studied the impact of sediment on water COD under different temperature and salinity stresses. The main conclusions are as follows:

(1) Analyzed the spatiotemporal distribution characteristics of water quality indicators in the Sushui River Basin in March, July, and October. The dissolved oxygen concentration in the Sushui River research area is relatively high, and dissolved oxygen is highly correlated with chlorophyll concentration and pH value, Pearson。 The total nitrogen pollution in the Sushui River research area is severe, and the total nitrogen content of some sampling points is inferior to the Class V water standard. The pollution is more severe in the dry season of March and October than in the wet season of July. Except for the nitrate tank, the pollution of ammonia nitrogen and total phosphorus in other locations is relatively light. The COD and Total Organic Carbon (TOC) concentrations in the Sushui River research area are highly correlated, and the COD pollution in the nitrate tank and Wuxing Lake is more severe than in other locations, with some sampling points having concentrations below the Class V water standard.

(2) The effect of organic matter release from sediment on COD concentration in overlying water under different temperature and salinity gradients was studied through sediment cultivation experiments. The results showed that with the extension of cultivation time, the overall COD concentration in the overlying water first increased and then decreased. Under a constant salinity, as the temperature increases, the COD concentration in the overlying water increases. This may be due to the temperature enhancing the metabolic activity of sediment microorganisms, resulting in the generation of water-soluble organic compounds entering the overlying water; At a constant temperature, as the salinity increases, the COD concentration in the overlying water also increases. This may be due to high salinity causing cell rupture and the contents entering the water, resulting in an increase in organic matter content. The correlation coefficient R2 between the COD concentration in the overlying water and the total carbon content in the sediment is 0.59. Microorganisms in the sediment can degrade insoluble proteins, carbohydrates, lipids, etc. in the sediment into easily soluble amino acids, fatty acids, and sugars through metabolism, increasing the COD concentration in the overlying water.

(3) Analyzed the diversity and metabolic activity of microbial carbon source utilization in sediment, and explored the mechanism of microbial carbon source utilization in sediment under saline water conditions. The carbon source utilization experiment of sediment microorganisms showed that with the extension of cultivation time, the average well color development (AWCD) of sediment microorganisms gradually increased. When the cultivation time reached 192 hours, the AWCD values of various points were ranked as follows: in the nitrate pool>Zhangliuzhuang>Wuxing Hunan 2>Yaoxianqu>Wuxing Hubei 1>Sushui River. The correlation coefficient between the Shannon Wiener index and AWCD values of all locations is above 0.6, indicating a high correlation between the utilization efficiency of sediment microorganisms for carbon sources and the diversity index. The sediment microbial species that efficiently utilize carbon sources at the Sushui River sampling point are the least, while the sediment microbial species that efficiently utilize carbon sources at the sampling point in the nitrate tank are the most. The results of principal component analysis and cluster analysis indicate that there is a high similarity in the utilization of microbial carbon sources in the sediment of Yaoxian Canal and Wuxing Hubei 1. The R2 of the linear fit between the COD concentration in the water and the AWCD value at 192 hours of cultivation is 0.58, indicating a high correlation. This indicates that the microbial community in the sediment of the sample points with severe COD pollution has a strong metabolic activity towards carbon sources.

This study analyzed the spatiotemporal distribution characteristics of water quality and sediment parameters in the Sushui River Basin, and explored the release patterns of organic matter in sediment under different temperature and salinity gradient conditions. Future research can determine the functional diversity and metabolic activity of sediment microbial communities during the cultivation process of the sediment, making the connection more closely connected. This study also analyzed the utilization of microbial carbon sources in sediment, and sterilized sediment can be designed as a control to consider the adsorption and desorption of minerals on organic matter.