| 摘要: |
| 摘要：三峡大坝建设显著改变了长江水沙通量，但其对沉积物中微生物介导的多功能性（碳氮磷循环）的影响尚未明确。本研究基于16S扩增子测序、共现网络分析和结构方程模型，探究三峡大坝对上下游沉积物细菌群落组成、多样性及多功能性的影响。结果表明，上游沉积物细菌群落以假单胞菌门（~ 25.5%）为主，下游以脱硫杆菌门（~ 24.8%）为主。三峡大坝显著降低下游沉积物的细菌α多样性，且α多样性与水分（减少约35.39%）、阳离子交换量（~ 49.64%）和溶解性有机碳（~ 49.88%）的减少显著相关。结构方程模型显示，沉积物细菌α多样性能通过减少细菌网络相互作用，显著降低沉积物多功能性。本研究揭示了三峡大坝对下游沉积物生态功能的负面影响，建议通过长期监测沉积物中溶解性有机碳和阳离子交换量，以优化水文管理，减缓生物多样性损失。 |
| 关键词: 三峡大坝 沉积物 物质循环 细菌群落组成 生态多功能性 |
| DOI： |
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| 基金项目:长江水利委员会水文局科技创新基金资助项目（SWJ-24CJX05） |
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| Effect of Three Gorges Dam on bacterial diversity and multifunctionality of sediments in the upsteam and downstream of the Yangtze River |
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zhengkaikai, Peng chunlan, Gao qianhong, Yan haitao, Yan jinbo
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Three Gorges Hydrology and Water Resources Survey Bureau, Hydrology Bureau of Changjiang Water Resources Commission
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| Abstract: |
| Abstract: The construction of the Three Gorges Dam has significantly altered water and sediment fluxes in the Yangtze River, yet its impact on microbially mediated multifunctionality (carbon, nitrogen, and phosphorus cycling) in sediments remains unclear. This study employed 16S amplicon sequencing, co-occurrence network analysis, and structural equation modeling to investigate the effects of the dam on bacterial community composition, diversity, and multifunctionality in upstream and downstream sediments. Results revealed that upstream sediments were dominated by Proteobacteria (~25.5%), while downstream sediments were dominated by Desulfobacterota (~24.8%). The dam significantly reduced bacterial α-diversity in downstream sediments, which was closely correlated with reductions in moisture (~35.4%), cation exchange capacity (~49.6%), and dissolved organic carbon (~49.9%). Structural equation modeling indicated that reduced α-diversity directly impaired ecological functions and indirectly decreased multifunctionality by weakening bacterial network interactions. This study highlights the adverse ecological impacts of the Three Gorges Dam on downstream sediment functions and recommends long-term monitoring of dissolved organic carbon and cation exchange capacity, alongside optimized reservoir management, to mitigate biodiversity loss. |
| Key words: Three Gorges Dam Sediment Material circulation Bacterial community composition Ecological |
