Effects of mine tailings on the structure and diversity of microbial communities in riparian soils

Mine tailing contamination from dam failures severely impacts riparian ecosystems and their interlinkages. This study assessed the effects of the Córrego do Feijão Mine (CFM) dam rupture on microbial communities across a 200 km sampling area. Biochemical, pedological, and ecological parameters were measured, including bacterial phylogeny, abundance, and diversity. The collapsed dam and surrounding areas exhibited the lowest microbial diversity and cultured colony-forming units (CFU) compared to reference sites. Metal concentrations significantly influenced pedological and biological parameters, especially bacterial composition, metabolic quotient, respiration, enzymatic activities, and nitrogen cycling. Ecotoxicity tests revealed greater inhibition of dehydrogenase activity in heavily contaminated areas, indicating a higher sensitivity of Arthrobacter globiformis compared to Azospirillum brasilense. The Pseudomonadaceae and Acidobacteriaceae families, along with the Proteobacteria, Acidobacteriota, Actinobacteriota, and Firmicutes phyla, were the most abundant, demonstrating resilience to post-spill environmental conditions. Changes in microbial activities suggest a potential reduction or loss of ecosystem services, compromising soil functionality and quality. These findings aid in selecting the most suitable local soil microorganisms for biomonitoring and bioremediation in mining sludge-contaminated sites.