Centre for Microscopy, Characterisation and Analysis , University of Western Australia , 35 Stirling Hwy , Crawley 6009 , Australia.
National Synchrotron Radiation Research Centre , Hsinchu Science Park , Hsinchu 300 , Taiwan.
Environ Sci Technol. 2019 Dec 3;53(23):13720-13731. doi: 10.1021/acs.est.9b04526. Epub 2019 Nov 20.
The formation of water-stable aggregates in finely textured and polymineral magnetite Fe ore tailings is one of the critical processes in eco-engineering tailings into soil-like substrates as a new way to rehabilitate the tailings. Organic matter (OM) amendment and plant colonization are considered to be effective in enhancing water-stable aggregation, but the underlying mechanisms have not yet been elucidated. The present study aimed to characterize detailed changes in physicochemistry, Fe-bearing mineralogy, and organo-mineral interactions in magnetite Fe ore tailings subject to the combined treatments of OM amendment and plant colonization, by employing various microspectroscopic methods, including synchrotron-based X-ray absorption fine structure spectroscopy and nanoscale secondary ion mass spectroscopy. The results indicated that OM amendment and plant colonization neutralized the tailings' alkaline pH and facilitated water-stable aggregate formation. The resultant aggregates were consequences of ligand-promoted bioweathering of primary Fe-bearing minerals (mainly biotite-like minerals) and the formation of secondary Fe-rich mineral gels. Especially, the sequestration of OM (rich in carboxyl, aromatic, and/or carbonyl C) by Fe-rich minerals via ligand-exchange and/or hydrophobic interactions contributed to the aggregation. These findings have uncovered the processes and mechanisms of water-stable aggregate formation driven by OM amendment and plant colonization in alkaline Fe ore tailings, thus providing important basis for eco-engineered pedogenesis in the tailings.
在将细纹理和多矿物磁铁矿铁尾矿制成类似土壤的基质的生态工程中，水稳定团聚体的形成是关键过程之一，这是一种修复尾矿的新方法。有机质（OM）的添加和植物定殖被认为可以有效增强水稳定团聚体，但潜在机制尚未阐明。本研究旨在通过各种微光谱方法，包括同步加速器基于 X 射线吸收精细结构光谱和纳米二次离子质谱，来表征在 OM 添加和植物定殖联合处理下磁铁矿铁尾矿的物理化学、含铁矿物学和有机-矿物相互作用的详细变化。结果表明，OM 添加和植物定殖使尾矿的碱性 pH 值中和，并促进了水稳定团聚体的形成。所得的团聚体是原生含铁矿物（主要是类云母矿物）的配体促进生物风化和次生富铁矿物凝胶形成的结果。特别是，富含羧基、芳基和/或羰基 C 的 OM 通过配体交换和/或疏水性相互作用被富铁矿物螯合，这有助于团聚体的形成。这些发现揭示了 OM 改良和植物定殖驱动碱性铁矿尾矿中水稳定团聚体形成的过程和机制，从而为尾矿的生态工程成土作用提供了重要依据。
