Application of Phragmites australis in bioremediation of Acid mine drainage: Enhancing water quality and remodeling aqueous microbial communities

Abstract

Acid Mine Drainage (AMD) is a significant global environmental challenge, while phytoremediation emerges as a promising bioremediation strategy for AMD treatment. In this study, Phragmites australis, Miscanthus lutarioriparius, and Pennisetum alopecuroides were used to assess their seed germination exposed to AMD to screen the excellent resistant species used for AMD phytoremediation. Our results suggested that compared to the other two species, Phragmites australis exhibited more tolerant characteristics, including its shortened mean germination time, higher fresh weight, increased tillering number, higher chlorophyll content, and superior seedling growth across all AMD concentrations. A 30-day cultivation of Phragmites australis plantlets can improve water quality by enhancing pH levels and effectively reducing the concentrations of metals (iron (Fe), nickel (Ni), and lead (Pb)) and sulfate (SO₄^2-) in AMD samples. Phragmites australis plantlets significantly remodeled the AMD microbial community by enhancing bacterial diversity, altering taxonomic composition, and enriching functional genes (e.g., acid resistance, metal tolerance, and sulfur metabolism), highlighting a key phytotolerance mechanism against AMD stress. This study reveals that Phragmites australis tolerates and remediates AMD through metal accumulation and translocation in plant tissues, formation of reddish-brown precipitates and white crystalline deposits, and substantial restructuring of aquatic microbial communities. These synergistic effects collectively enhance AMD water quality through both physicochemical and biological processes, establishing Phragmites australis as an effective phytoremediation candidate for AMD remediation.