Centre for Mined Land Rehabilitation, Sustainable Minerals Institute, The University of Queensland, Brisbane, Queensland 4072, Australia.
Centre for Mined Land Rehabilitation, Sustainable Minerals Institute, The University of Queensland, Brisbane, Queensland 4072, Australia.
J Hazard Mater. 2022 Apr 5;427:127860. doi: 10.1016/j.jhazmat.2021.127860. Epub 2021 Nov 20.
Organic matter (OM) amendments and plant colonization can accelerate mineral weathering and soil formation in metal mine tailings for ecological rehabilitation. However, the weathering effects may dissolve uranium (U)-bearing minerals (e.g., ianthinite) and increase U dissolution in porewater and seepages. The present study aimed to characterize the U solubility and distribution among different fractions and investigate if biochar (BC) could decrease soluble U levels and facilitate U immobilization in the OM-amended and plant-colonized tailings. A native plant species, Red Flinders grass (Iseilema vaginiflorum) was cultivated in the tailings for four weeks, which were amended with sugarcane residue (SR) with or without BC addition. The results showed that OM amendment and plant colonization increased porewater U concentrations by almost 10 folds from ~ 0.2 mg L to > 2.0 mg L. The BC addition decreased porewater U concentrations by 40%. Further micro-spectroscopic analysis revealed that U was immobilized through adsorption onto BC porous surfaces, via possibly complexing with oxygen-rich organic groups. Besides, the BC amendment facilitated U sequestration by secondary Fe minerals in the tailings. These findings provide important information about U biogeochemistry in Cu-tailings mediated by BC, OM and rhizosphere interactions for mitigating potential pollution risks of tailings rehabilitation.
有机物（OM）改良和植物定殖可以加速金属尾矿的矿化和土壤形成，从而促进生态恢复。然而，风化作用可能会溶解含铀矿物（如铀石），并增加孔隙水中和渗流中的铀溶解。本研究旨在描述 U 在不同形态之间的溶解度和分布，并探讨生物炭（BC）是否可以降低可溶 U 水平并促进 OM 改良和植物定殖尾矿中的 U 固定。本研究选用本地植物红弗林德斯草（Iseilema vaginiflorum）在尾矿中进行了四周的培养，这些尾矿添加了甘蔗渣（SR），并添加或不添加 BC。结果表明，OM 改良和植物定殖使孔隙水中 U 的浓度增加了近 10 倍，从约 0.2mg/L 增加到>2.0mg/L。BC 的添加使孔隙水中 U 的浓度降低了 40%。进一步的微观光谱分析表明，U 通过吸附在 BC 的多孔表面上而被固定，可能与富氧有机基团发生络合。此外，BC 的添加促进了尾矿中次生铁矿物对 U 的固定。这些发现为 BC、OM 和根际相互作用介导的 Cu 尾矿中 U 的生物地球化学提供了重要信息，对于减轻尾矿修复的潜在污染风险具有重要意义。
