Dissolved
organic matter (DOM) plays an important role in soil
structure and biogeochemical function development, which are fundamental
for the eco-engineering of tailings-soil formation to underpin sustainable
tailings rehabilitation. In the present study, we have characterized
the DOM composition and its molecular changes in an alkaline Fe ore
tailing primed with organic matter (OM) amendment and plant colonization.
The results demonstrated that microbial OM decomposition dramatically
increased DOM richness and average molecular weight, as well as its
degree of unsaturation, aromaticity, and oxidation in the tailings.
Plant colonization drove molecular shifts of DOM by depleting the
unsaturated compounds with a high value of nominal oxidation state
of carbon (NOSC), such as tannin-like and carboxyl-rich polycyclic-like
compounds. This may be partially related to their sequestration by
secondary Fe–Si minerals formed from rhizosphere-driven mineral
weathering. Furthermore, the molecular shifts of DOM may have also
resulted from plant-regulated microbial community changes, which further
influenced DOM molecules through microbial–DOM interactions.
These findings contribute to the understanding of DOM biogeochemistry
and ecofunctionality in the tailings during early pedogenesis driven
by OM input and pioneer plant/microbial colonization, providing an
important basis for the development of strategies and technologies
toward the eco-engineering of tailings-soil formation.
Ferroelectric domain morphology and structure in Li-doped (K,Na)NbO3 ceramics J. Appl. Phys. 112, 052005 (2012) Room temperature ferroelectric and magnetic investigations and detailed phase analysis of Aurivillius phase Bi5Ti3Fe0.7Co0.3O15 thin films J. Appl. Phys. 112, 052010 (2012) Electric field induced phase instability in typical (Na,K)(Nb,Sb)O3-LiTaO3 ceramics near orthorhombic and tetragonal phase boundary Appl. Phys. Lett. 101, 092906 (2012) Effects of Gd substitution on microstructures and low temperature dielectric relaxation behaviors of SrTiO3 ceramics J. Appl. Phys. 112, 034114 (2012) Additional information on Appl. Phys. Lett.
Pioneer plants play an important role in ecoengineering Fe ore tailings into soil for sustainable mine site rehabilitation. However, root-driven mineral weathering and secondary mineral formation remain poorly understood in tailings, despite being prerequisites for aggregate formation and pedogenesis. The present study aimed at characterizing the direct role of plant roots in tailing mineral weathering and secondary mineral formation in a compartmented cultivation system. It was found that root activities accelerated the weathering of biotite-like minerals via Fe(II) oxidation coupled with Fe(III) and Si dissolution. Numerous nanosized Fe−Si short-range-ordered (SRO) minerals and vermiculite were neoformed in the tailings after root interactions, as revealed by various microspectroscopic analyses. The Fe−Si-SRO minerals may have resulted from co-precipitation of dissolved Fe(III) and Si on mineral surfaces under alkaline and circumneutral pH conditions. Among the three plant species, Sorghum spp. (Gramineae plant) root developed most extensively in the tailings, possibly leading to more efficient mineral weathering and secondary mineral formation than Atriplex amnicola (halophyte plant) and Acacia chisholmii (leguminous plant). Overall, the study has elucidated the rhizosphere effects on tailing mineral (biotite dominant) weathering and secondary Fe−Si mineral formation, justifying pioneer plant roles in eco-engineering Fe ore tailings into soil.
The neutralization of strongly alkaline
pH conditions and acceleration
of mineral weathering in alkaline Fe ore tailings have been identified
as key prerequisites for eco-engineering tailings-soil formation for
sustainable mine site rehabilitation. Acidithiobacillus
ferrooxidans has great potential in neutralizing alkaline
pH and accelerating primary mineral weathering in the tailings but
little information is available. This study aimed to investigate the
colonization of A. ferrooxidans in
alkaline Fe ore tailings and its role in elemental sulfur (S0) oxidation, tailings neutralization, and Fe-bearing mineral weathering
through a microcosm experiment. The effects of biological S0 oxidation on the weathering of alkaline Fe ore tailings were examined
via various microspectroscopic analyses. It is found that (1) the A. ferrooxidans inoculum combined with the S0 amendment rapidly neutralized the alkaline Fe ore tailings;
(2) A. ferrooxidans activities induced
Fe-bearing primary mineral (e.g., biotite) weathering and secondary
mineral (e.g., ferrihydrite and jarosite) formation; and (3) the association
between bacterial cells and tailings minerals were likely facilitated
by extracellular polymeric substances (EPS). The behavior and biogeochemical
functionality of A. ferrooxidans in
the tailings provide a fundamental basis for developing microbial-based
technologies toward eco-engineering soil formation in Fe ore tailings.
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