赤泥自然成土过程中微生物群落的原生演替及成土机制探究

The key of ecological restoration for red mud disposal area is soil genesis. Microorganisms play a dominant role in the pedogenesis of red mud. The natural pedogenesis process of red mud corresponds to the primary succession of microorganisms. However, the research related to microbial community succession or microbial driving forces during natural pedogenesis process of red mud is little. The space-for-time substitution approach will be employed, and the red mud samples in time sequence will be collected from Bayer and sintering process in order to study the relationship between the change of microbial community structure and the physical, chemical and microbial characteristics of red mud in the natural pedogenesis process. In our research, the thresholds of physical and chemical factors which significantly influence the microbial diversity will be defined, and the bacterial and fungal indicators which play an important role in soil genesis will be clarified. Eventually, through comparing the similarities and differences of pedogenesis between the Bayer and sintering process, the rule of microbial community succession during the pedogenesis process of red mud will be found, and the driving forces of red mud pedogenesis exerted from microorganisms will be explored. The results of this research will be benificial to thoroughly understand the relationship between natural pedogenesis process of red mud and the primary succession of microorganisms. Furthermore, it will have some academic value for guiding the soil genesis in red mud yard and improving the ecological restoration theory for mine tailings.

赤泥堆场是典型的原生裸地，其生态修复的关键是赤泥土壤化。在赤泥的自然成土过程中微生物扮演重要角色，赤泥的自然成土过程对应的是微生物群落的原生演替。但是目前对赤泥自然成土过程中微生物群落演替和成土驱动机制的研究鲜有报道。本项目拟采用空间代替时间的方法，在发生自然成土现象的拜耳法和烧结法赤泥堆场采集具有时间序列特征的赤泥样品，通过研究微生物群落结构及多样性变化与赤泥理化生特性之间的关系，阐明影响微生物群落演替的赤泥关键理化因子及其阈值，分析能够表征赤泥成土进程的指示菌种，并通过比较拜耳法和烧结法赤泥成土过程的异同，最终揭示赤泥自然成土过程中微生物群落演替及多样性变化的规律，探究赤泥成土的微生物驱动机制。本研究有助于深入理解赤泥自然成土过程与微生物原生演替过程之间的联系，对指导赤泥堆场土壤化实践和完善尾矿废弃地生态修复理论具有一定学术价值。

氧化铝废渣(赤泥)堆场生态修复的关键是赤泥土壤化。运用空间代替时间的方法，在未采取人工修复措施的拜耳法和烧结法赤泥堆场采集具有时间序列特征的赤泥样品，通过测定其理化生化指标及微生物群落结构变化，研究赤泥的自然成土过程及其微生物驱动机制。结果表明，随赤泥泥龄的增加，其物理指标孔隙度、水稳性团聚体含量、团聚体平均重量直径提升，容重降低；化学指标pH值、电导率、酸中和能力和交换性钠饱和度降低；营养水平指标有机碳、总氮、有效态磷、有效态钾含量提升；微生物生化指标微生物生物量碳、土壤基础呼吸提升，代谢熵降低。细菌和真菌的多样性显著增加，细菌群落结构由产氧光合细菌蓝细菌门占据绝对优势转变为变形菌门和放线菌门占据优势地位，真菌群落结构为子囊菌门中的座囊菌纲、子囊菌纲和散囊菌纲占据优势地位。赤泥自然成土过程中限制微生物群落发展的关键理化因子阈值为：pH值≤10.5、EC≤6.0 mS/cm、ESP≤30、容重≤1.8 g/cm3。细菌在烧结法赤泥成土前期、中期和后期的指示性菌种分别为鞘丝藻属、常丝藻属和Aridibacter，拜耳法赤泥为鞘丝藻属、埃希氏菌属和诺尔氏菌属。真菌在烧结法赤泥成土前期、中期和后期的指示性菌种分别为链格孢属、支顶孢属和弯孢属，拜耳法赤泥为盾壳霉属、球腔菌属和离蠕孢属。微观形态分析表明菌丝、细菌细胞及代谢产物通过对赤泥颗粒的吸附、链接、缠绕及包裹形成物理结构稳定、有一定孔隙的微生物-赤泥聚合体。自然堆置的烧结法和拜耳法赤泥堆场发生了明显的自然成土现象，赤泥自发地由贫营养的极端生境向土壤生境转变，微生物通过提升营养水平、降低盐碱度、改善质地结构等途径参与赤泥的自然成土过程。