大理河沉积物微生物碳源利用特征及其影响因素

沉积物是河流生态系统中氮磷等物质循环的重要场所，而微生物是河流生态系统的重要组成部分，探究沉积物中微生物群落碳源利用特征和功能多样性对于河流生态环境保护具有重要意义。利用Biolog Eco微平板法、基于主成分分析、冗余分析阐明了大理河流域沉积物中微生物群落碳源利用强度和功能多样性变化特征及其影响因素。结果表明：（1）从流域上游到流域下游，沉积物中微生物碳源利用强度逐渐降低，与上游相比，支流、中游、下游沉积物中微生物碳源利用强度分别降低了13.4%、30.5%、30.7%。（2）沉积物中微生物群落功能多样性存在差异，沉积物中微生物群落功能多样性（Shannon-Wiener多样性指数）表现为上游 > 支流 > 中游 > 下游，常见物种优势度（Simpson多样性指数）则表现为下游 > 支流 > 中游 > 上游。（3）与微生物代谢活动相关性较高碳源为糖类，其次是氨基酸类，聚合物类、羧酸类、胺类、酚酸类与微生物代谢活动相关性较低。（4）沉积物中全氮、氨氮、硝氮、有机碳含量是影响微生物群落功能多样性和碳源利用特征差异的主要因素。流域沉积物中合适的碳、氮水平对维持河流水生态健康具有重要的意义。

Characteristics and influencing factors of microbial carbon source utilization in Dali River sediments

Sediment is an important place for the circulation of nitrogen and phosphorus in river ecosystems, and microorganisms are an important part of river ecosystems. It is of great significance to explore the carbon source utilization characteristics and functional diversity of microbial communities in sediments for river ecological environmental protection. In this study, the Biolog Eco microplate method, principal component analysis and redundancy analysis were used to elucidate the variation characteristics and influencing factors of carbon source utilization intensity and functional diversity of microbial communities in the sediments of the Dali River Basin. The results show that:(1) from the upstream to the downstream of the watershed, the utilization intensity of microbial carbon sources in the sediments gradually decrease. Compare with the upstream, the utilization intensity of microbial carbon sources in the tributaries, midstream and downstream sediments decrease by 13.4%, 30.5%, and 30.7%. (2) There are differences in the functional diversity of microbial communities in sediments. The functional diversity of microbial communities in sediments (Shannon-Wiener diversity index) is upstream > tributaries > midstream > downstream, and common species dominance (Simpson diversity index) is shown as downstream > tributary > midstream > upstream. (3) Carbohydrates are highly correlated with microbial metabolic activity; amino acids, polymers, carboxylic acids, amines, and phenolic acids are less correlated with microbial metabolic activity. (4) The contents of total nitrogen, ammonia nitrogen, nitrate nitrogen and organic carbon in the sediments are the main factors affecting the functional diversity of microbial communities and differences in carbon source utilization characteristics. Appropriate carbon and nitrogen levels in river basin sediments are of great significance to maintain the ecological health of river water.