State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China; Eco-Environmental Research Department, Nanjing Hydraulic Research Institute, Nanjing, 210098, China.
State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China.
Chemosphere. 2023 Aug;331:138832. doi: 10.1016/j.chemosphere.2023.138832. Epub 2023 May 5.
Discovering the complexity and improving the stability of microbial networks in urban rivers affected by combined sewer overflows (CSOs) is essential for restoring the ecological functions of urban rivers, especially to improve their ability to resist CSO impacts. In this study, the effects of sediment remediation on the complexity and stability of microbial networks was investigated. The results revealed that the restored microbial community structure using different approaches in the river sediments differed significantly, and random matrix theory showed that sediment remediation significantly affected microbial networks and topological properties; the average path distance, average clustering coefficient, connectedness, and other network topological properties positively correlated with remediation time and weakened the small-world characteristics of the original microbial networks. Compared with other sediment remediation methods, regulating low dissolved oxygen (DO) shifts the microbial network module hubs from Actinobacteria and Bacteroidetes to Chloroflexi and Proteobacteria. This decreases the positive association of networks by 17%-18%, which intensifies the competitiveness among microorganisms, further weakening the influence and transmission of external pressure across the entire microbial network. Compared with that of the original sediment, the vulnerability of the restored network was reduced by more than 36%, while the compositional stability was improved by more than 12%, with reduced fluctuation in natural connectivity. This microbial network succession substantially increased the number of key enzyme-producing genes involved in nitrogen and sulfur metabolism, enhancing nitrification, denitrification, and assimilatory sulfate reduction, thereby increasing the removal rates of ammonia, nitrate, and acid volatile sulfide by 43.42%, 250.68% and 2.66%, respectively. This study comprehensively analyzed the succession patterns of microbial networks in urban rivers affected by CSOs before and after sediment remediation, which may provide a reference for reducing the impact of CSO pollution on urban rivers in the subsequent stages.
揭示受合流制污水溢流（CSO）影响的城市河流中微生物网络的复杂性和稳定性，并改善其稳定性，对于恢复城市河流的生态功能至关重要，特别是提高其抵御 CSO 影响的能力。本研究探讨了底泥修复对微生物网络复杂性和稳定性的影响。结果表明，采用不同方法对河流底泥进行修复，恢复后的微生物群落结构存在显著差异，随机矩阵理论表明，底泥修复显著影响微生物网络和拓扑性质；平均路径长度、平均聚类系数、连通性等网络拓扑性质与修复时间呈正相关，减弱了原始微生物网络的小世界特征。与其他底泥修复方法相比，调节低溶解氧（DO）将微生物网络模块枢纽从放线菌和拟杆菌转移到绿弯菌门和变形菌门。这使得网络的正关联减少了 17%-18%，加剧了微生物之间的竞争，进一步削弱了整个微生物网络对外界压力的影响和传递。与原始底泥相比，修复网络的脆弱性降低了 36%以上，而组成稳定性提高了 12%以上，自然连通性的波动减小。这种微生物网络演替显著增加了参与氮和硫代谢的关键酶产生基因的数量，增强了硝化、反硝化和同化硫酸盐还原作用，从而使氨、硝酸盐和酸可挥发性硫化物的去除率分别提高了 43.42%、250.68%和 2.66%。本研究全面分析了受 CSO 影响的城市河流底泥修复前后微生物网络的演替模式，为后续阶段减少 CSO 污染对城市河流的影响提供了参考。
