Bauxite residue disposal areas (BRDAs) are typically bare of vegetation with high salinity and alkalinity. However, spontaneous encroachment of vegetation indicated that natural weathering processes had transformed the residue tailings into a soil-like material. Here we investigate the development of bacterial communities and their geochemical drivers in bauxite residue, using Illumina high-throughput sequencing technology. Bauxite residue from weathered sites had lower pH and exchangeable sodium percentages (ESP), but greater organic carbon and nitrogen concentrations.Following natural processes, the diversity of the bacterial community significantly increased and hierarchical clustering separated un-weathered from older weathered sites. Taxonomic analysis revealed that long-term weathering processes encouraged populations of Proteobacteria, Chloroflexi, Acidobacteria and Planctomycetes, whilst reducing populations of Firmicutes and Actinobacteria.LEfSe analysis revealed that the biomarker changed considerably in older weathered residues compared with that of un-weathered residue. Amongst all the residue properties, variation in total organic carbon (TOC), total nitrogen (TN), available phosphorus (AP) and pH, showed significant effects on the diversity and structures of the bacterial community. The results have demonstrated that natural weathering processes stimulate the dynamic development of bacterial communities in bauxite residue, and may provide a hypothetical basis for the application of microbes at disposal areas to improve soil conditions.
HIGHLIGHT:► Development of microbial communities in bauxite residue disposal areas following long-term natural processes was investigated. ► Natural processes promoted the diversity of bacterial communities in bauxite residue. ► Bacterial community structure significantly differed in weathered disposal areas ► pH, TOC, TN and AP may be the most important factors influencing bacterial community structure in bauxite residue.
