Phytostabilization of acidic mine tailings with biochar, biosolids, lime, and locally-sourced microbial inoculum: Do amendment mixtures influence plant growth, tailing chemistry, and microbial composition?

Authors: Trippe, Kristin; Manning, Viola; Reardon, Catherine - Kate; Klein, Ann; Weidman, Clara; Ducey, Thomas; Novak, Jeffrey; Watts, Donald - Don; Rushmiller, Hannah; Spokas, Kurt; IPPOLITO, JAMES - Colorado State University; JOHNSON, MARK - Us Environmental Protection Agency (EPA)

Submitted to: Applied Soil Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/23/2021
Publication Date: 3/15/2021
Citation: Trippe, K.M., Manning, V., Reardon, C.L., Klein, A.M., Weidman, C.S., Ducey, T.F., Novak, J.M., Watts, D.W., Rushmiller, H.C., Spokas, K.A., Ippolito, J.A., Johnson, M.G. 2021. Phytostabilization of acidic mine tailings with biochar, biosolids, lime, and locally-sourced microbial inoculum: Do amendment mixtures influence plant growth, tailing chemistry, and microbial composition? Applied Soil Ecology. 165. Article 103962. https://doi.org/10.1016/j.apsoil.2021.103962.
DOI: https://doi.org/10.1016/j.apsoil.2021.103962

Interpretive Summary: Abandoned mine lands present persistent environmental challenges to ecosystems and economies; reclamation an important step for overcoming these challenges. Phytostabilization is an elegant and cost-effective reclamation strategy, however, establishing plants on severely degraded soils is problematic, often requiring soil amendment additions. We evaluated whether amendment mixtures composed of lime, biochar, biosolids, and locally effective microbes (LEM) could alleviate the constraints that hinder phytostabilization success. We hypothesized that 1) plants grown in tailings amended with lime, biochar, and biosolids (LBB) would establish faster and grow larger than plants grown in tailings amended with lime only, and 2) the LEM source would influence microbial community function and structure in amended mine tailings. We conducted a greenhouse study that simulated in situ conditions to measure the influence of LBB-LEM amendment blends on plant growth, plant nutrients, metal concentrations, microbial function, and microbial community structure. Blue wildrye [Elymus glaucus Buckley ssp. Jepsonii (Burtt Davy) Gould] was grown in tailings collected from the Formosa mine site amended with various combinations of LBB-LEM. The above and below ground biomass of plants grown in mine tailings amended with LBB was 3 to 4 times larger than the biomass of plants grown in tailings amended only with lime. Although the LEM source did not influence immediate plant growth, it did affect nutrient content and altered the rhizosphere community membership. As such, it is not yet clear if LEM-driven alterations in microbial membership will advance mine reclamation strategies by improving long-term growth.

Technical Abstract: Abandoned mine lands (AMLs) pose an ongoing and serious threat to ecosystems, water resources, and human health. In the United States, it is estimated that over 500,000 AMLs contribute to this threat; however financial resources to remediate these sites are severely limited. Therefore, cost effective, simple strategies that simultaneously address the chemical and biological drivers of mine pollution are needed to remediate degraded mine soils. Phytostabilization is one such method, however, the ability of plants to grow in severely degraded mine soils is limited. Here, we conducted a greenhouse study using mine waste from the Formosa mine to evaluate the influence of blended soil amendments on plant growth and compared it to traditional approaches for mine remediation. We also evaluated if inoculating the amendment blends with locally effective microbes influenced plant growth or changed the composition of the microbial community. We found that plants grown in mine waste amended with biochar, biosolids, and lime grew larger than plants grown in mine waste amended only with lime. Although inoculation of the amendment blend did not improve plant growth, it did influence the microbial community adjacent to plant roots. Overall the trial showed that blended amendments alleviate the chemical and biological constraints associated with AMLs and are more effective than current remediation strategies in supporting plant growth.