Tailings particle size effects on pollution and ecological remediation: A case study of an iron tailings reservoir

The particle size distribution in tailings notably influences their physical properties and behavior. Despite this, our understanding of how the distribution of tailings particle sizes impacts in situ pollution and ecological remediation in in-situ environment remains limited. In this study, an iron tailings reservoir was sampled along a particle flow path to compare the pollution characteristic and microbial communities across regions with different particle sizes. The results revealed a gradual reduction in tailings particle size along the flow direction. The predominant mineral composition shifts from minerals such as albite and quartz to layered minerals. Total nitrogen, total organic carbon, and total metal concentrations increased, whereas the acid-generating potential decreased. The region with the finest tailings particle size exhibited the highest microbial diversity, featuring metal-resistant microorganisms such as KD4-96, Micrococcaceae, and Acidimicrobiia. Significant discrepancies were observed in tailings pollution and ecological risks across different particle sizes. Consequently, it is necessary to assess tailings reservoirs pollution in the early stages of remediation before determining appropriate remediation methods. These findings underscore that tailings particle distribution is a critical factor in shaping geochemical characteristics. The responsive nature of the microbial community further validated these outcomes and offered novel insights into the ecological remediation of tailings.