The Effect of Dissolved Humic Acids on Aluminosilicate Formation and Associated Carbon Sequestration

Rouff, Ashaki A.; Phillips, Brian L.; Cochiara, Stacey G.; Nagy, Kathryn L.

doi:10.1155/2012/430354

Cited by 10 publications

(16 citation statements)

References 43 publications

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“…Most peaks in the sample of montmorillonite shocked with projectile velocity 4.49 km/s are still intact but have decreased in intensity, except for the large 001 peak at 2θ ~ 5 o (Figure a) which has increased in intensity. Additionally, there is a large “hump” feature around 22° indicating the presence of an amorphous phase [ Ohashi et al ., ; Musić et al ., , and references therein; Rouff et al ., ]. All of nontronite's signature peaks are also intact but decreased in intensity in the XRD of the sample shocked to 3.27 km/s (Figure b).…”

Section: Resultsmentioning

confidence: 97%

“…Each sample shocked to maximum velocity showed evidence of structural deformation and/or partial amorphization as indicated by their XRD, CL, or Raman data. In the XRD of shocked montmorillonite, the large hump feature at 2θ ~22° indicates the presence of an amorphous phase in the shocked sample, likely allophane, a poorly crystalline clay that often forms from Al‐smectites [ Ohashi et al ., ; Rouff et al ., ]. Prehnite seemed to show the most resistance to shock alteration, while kaolinite and chlorite show the strongest evidence for structural deformation by the loss of most peaks in their respective XRD data.…”

Section: Discussionmentioning

confidence: 99%

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Experimental investigation into the effects of meteoritic impacts on the spectral properties of phyllosilicates on Mars

et al. 2013

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[1] Phyllosilicates have been identified in some of the most highly cratered Noachian terrains on Mars. To study the effects of such impacts on the properties of phyllosilicates, we experimentally shocked six phyllosilicate minerals relevant to the Martian surface: montmorillonite, nontronite, kaolinite, prehnite, chlorite, and serpentine. The shock-treated samples were analyzed with X-ray diffraction (XRD), near-and mid-infrared (NIR and MIR) spectroscopy, Raman spectroscopy, cathodoluminescence (CL), and the shock pressures and temperatures in some were modeled using Autodyn modeling software. XRD data show that the structure of each mineral, except prehnite, underwent partial structural deformation or amorphization. We also found that while the NIR spectra of shocked samples were very similar to that of the original sample, the MIR spectra changed significantly. This may explain some of the discrepancies between CRISM/OMEGA data (NIR) and TES/THEMIS (MIR) observations of phyllosilicates on Mars. Quartz was identified as a secondary phase in the XRD of shocked chlorite.

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Section: Resultsmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

Experimental investigation into the effects of meteoritic impacts on the spectral properties of phyllosilicates on Mars

et al. 2013

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“…Hetero-epitaxial growth of Fe(II)–Al(III)-LDH at the Al-oxide surface may be hindered by HS due to surface masking or due to interactions between HS and Fe(II)–Al(III)-LDH crystallites poisoning their growth. A further possibility is that HS limit the availability of Fe(II) and Al(III) for precipitation as Fe(II)–Al(III)-LDH by forming HS-Fe(II) or HS-Al(III) complexes [ 77 – 79 ]. HS surface complexes may additionally hinder the supply of Al needed for Fe(II)–Al(III)-LDH formation by blocking surface sites of Al dissolution, or by limiting inner-sphere metal-surface interactions which may promote dissolution of the sorbent [ 80 ].…”

Section: Discussionmentioning

confidence: 99%

Effects of humic substances on Fe(II) sorption onto aluminum oxide and clay

et al. 2018

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We studied the effects of humic substances (HS) on the sorption of Fe(II) onto Al-oxide and clay sorbents at pH 7.5 with a combination of batch kinetic experiments and synchrotron Fe K-edge EXAFS analyses. Fe(II) sorption was monitored over the course of 4 months in anoxic clay and Al-oxide suspensions amended with variable HS types (humic acid, HA; or fulvic acid, FA) and levels (0, 1, and 4 wt%), and with differing Fe(II) and HS addition sequences (co-sorption and pre-coated experiments, where Fe(II) sorbate was added alongside and after HS addition, respectively). In the Al-oxide suspensions, the presence of HS slowed down the kinetics of Fe(II) sorption, but had limited, if any, effect on the equilibrium aqueous Fe(II) concentrations. EXAFS analyses revealed precipitation of Fe(II)–Al(III)-layered double hydroxide (LDH) phases as the main mode of Fe(II) sorption in both the HA-containing and HA-free systems. These results demonstrate that HS slow down Fe(II) precipitation in the Al-oxide suspensions, but do not affect the composition or stability of the secondary Fe(II)–Al(III)-LDH phases formed. Interference of HS with the precipitation of Fe(II)–Al(III)-LDH was attributed to the formation organo-Al complexes HS limiting the availability of Al for incorporation into secondary layered Fe(II)-hydroxides. In the clay systems, the presence of HA caused a change in the main Fe(II) sorption product from Fe(II)–Al(III)-LDH to a Fe(II)-phyllosilicate containing little structural Al. This was attributed to complexation of Al by HA, in combination with the presence of dissolved Si in the clay suspension enabling phyllosilicate precipitation. The change in Fe(II) precipitation mechanism did not affect the rate of Fe(II) sorption at the lower HA level, suggesting that the inhibition of Fe(II)–Al(III)-LDH formation in this system was countered by enhanced Fe(II)-phyllosilicate precipitation. Reduced rates of Fe(II) sorption at the higher HA level were attributed to surface masking or poisoning by HA of secondary Fe(II) mineral growth at or near the clay surface. Our results suggest that HS play an important role in controlling the kinetics and products of Fe(II) precipitation in reducing soils, with effects modulated by soil mineralogy, HS content, and HS properties. Further work is needed to assess the importance of layered Fe(II) hydroxides in natural reducing environments.

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“…Exchange acidities of humic substances, approximating COOH content, range widely but generally fall within the range of 1500-5000 mmol c /kg (Stevenson, 1985). Polyvalent cations (e.g., Al 3+ , Fe 3+ ) may form multi-dentate complexes (mono-, di-and tri-dentate) with humic substances, but bidentate complexes are believed to be the most prevalent (Rouff et al, 2012).…”

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confidence: 99%

Nature, properties and function of aluminum–humus complexes in volcanic soils

2016

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Andosols (or Andisols) possess several distinctive properties that are rarely found in other groups of soils. These properties are largely due to the dominance of short-range-ordered minerals (allophane, imogolite and ferrihydrite) and/or metal-humus complexes (Al/Fe-humus complexes) in their colloidal fraction. While several papers have extensively reviewed the nature and properties of short-range-ordered minerals, there is no comprehensive review of the genesis, characteristics and management implications of Al-humus complexes, the dominant form of active Al in non-allophanic Andosols. In this review, we survey the chemical characteristics of Al-humus complexes and discuss the pedogenic environment favoring their formation in non-allophanic Andosols. The role of Al-humus complexes in carbon cycling and soil organic carbon accumulation is emphasized as an important mechanism controlling organic dynamics in Andosols. While non-allophanic Andosols share many common properties with allophanic Andosols, they display several distinct characteristics associated with Al-humus complexes, such as strong acidity and high exchangeable Al content that impair agricultural productivity due to Al phytotoxicity. Thus, we focus on the role of Al-humus complexes in regulating aqueous Al 3+ solubility and release/retention kinetics, Al phytotoxicity, phosphorus dynamics, and suppression of soil-borne diseases. Knowledge of these soil properties as related to Al-humus complexes is necessary to develop effective soil management practices to assure sustainable agricultural productivity in non-allophanic Andosols. Finally, future research needs are identified concerning the role of Al-humus complexes in regulating soil biogeochemical processes.

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The Effect of Dissolved Humic Acids on Aluminosilicate Formation and Associated Carbon Sequestration

Cited by 10 publications

References 43 publications

Experimental investigation into the effects of meteoritic impacts on the spectral properties of phyllosilicates on Mars

Experimental investigation into the effects of meteoritic impacts on the spectral properties of phyllosilicates on Mars

Effects of humic substances on Fe(II) sorption onto aluminum oxide and clay

Nature, properties and function of aluminum–humus complexes in volcanic soils

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