Long-term deposition of fly ash regulates bacterial communities in different disturbance zones: Evidence from diversity, network complexity and predictive metabolic function.

The structural diversity and metabolic pathways formed by soil microbial-environmental factor interactions can be used to predict the differences in microbial ecological functions. The storage of fly ash (FA) has caused potential harm to the surrounding soil environment, whereas little is known about bacterial communities and environmental factor interactions in FA-disturbed areas. In this study, we selected two disturbed areas (DW: dry-wet deposition zone, LF: leachate flow zone) and two nondisturbed areas (CSO: control point soil, CSE: control point sediment) as the test areas and used high-throughput sequencing technology to investigate the bacterial communities. The results indicated that (1) FA disturbance significantly increased the electrical conductivity (EC), geometric mean diameter (GMD), soil organic carbon (SOC) and some potentially toxic metals (PTMs) (Cu, Zn, Se and Pb) of DW and LF and significantly decreased the AK of DW and the pH of LF (p < 0.05). (2) The relative abundance of Proteobacteria was significantly increased in the DW (p < 0.05). Similarly, the relative abundances of Proteobacteria and Firmicutes obviously increased in the LF (p < 0.001). Interestingly, the α and β diversity of LF flora and the β diversity of DW flora changed. (3) The order of influence of bacterial community structure was nutrient characteristics > physical properties > PTMs. Among all factors, AK (33.9 %) and pH (44.3 %) were the key environmental limiting factors for the bacterial community in the DW and the LF, respectively. (4) FA perturbation reduced the complexity, connectivity and modularity of the interaction network between bacteria and disturbed them by increasing the metabolic pathways that degrade pollutants. In conclusion, our results revealed the changes in the bacterial community and the main environmental driving factors under different pathways of FA disturbance; this information provides a theoretical basis for ecological environment management.