Effect of pH and organic ligands on the kinetics of smectite dissolution at 25°C

Голубев, С. В.; Bauer, Andreas; Pokrovsky, Oleg S.

doi:10.1016/j.gca.2006.06.1557

Cited by 135 publications

(74 citation statements)

References 72 publications

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“…The thermodynamic modeling demonstrates that the presence of carbonate is essential to buffer the pH, allowing Fe-rich montmorillonite to precipitate. This result is consistent with experimental studies on smectite dissolution rates as a function of pH (Bauer and Berger, 1998, Golubev et al 2006and Rozalén et al, 2008. These authors showed that dissolution of smectite at 25°C occurs preferentially at pH < 6, indicating that smectites are more stable in neutral solutions.…”

Section: Conditions Of Iron-rich Montmorillonite Formationsupporting

confidence: 91%

Conditions and mechanism for the formation of iron-rich Montmorillonite in deep sea sediments (Costa Rica margin): Coupling high resolution mineralogical characterization and geochemical modeling

Charpentier

Buatier

Jacquot³

et al. 2011

Geochimica et Cosmochimica Acta

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Wheat. Conditions and mechanism for the formation of iron-rich Montmorillonite in deep sea sediments (Costa Rica margin): Coupling high resolution mineralogical characterization and geochemical modeling. Geochimica et Cosmochimica Acta, Elsevier, 2011Elsevier, , 75 (6), pp.1397Elsevier, -1410Elsevier, . 10.1016Elsevier, /j.gca.2010 Conditions and mechanism for the formation of iron- AbstractIron-rich smectite is commonly described in the diagenetic fraction of deep-sea sediment, as millimeter to centimeter aggregates dispersed in the sediment, or as a coating on sedimentary particles or nodules. This study examines several factors to elucidate formation mechanisms of a particular iron-rich smectite and its potential transformation to glauconite. The study combines a detailed mineralogical investigation on natural samples and a chemical modeling approach to assess mineralogical reactions and pathways.Transmission electron microscopy (TEM) observations and analytical electron microscopy (TEM-AEM) analyses were conducted on microtomed samples of millimeter-to centimeter-long green grains. These grains are widespread in pelagic calcareous sediment from the Costa Rica margin. They are composed of pyrites that are partially dissolved and are surrounded by amorphous or very poorly crystallized iron-rich particles. Iron-rich montmorillonite grows from an amorphous precursor and its formation requires the input of Si, O, Mg, K, Na and Ca; our results suggest that these inputs are supported by the dissolution of sedimentary phases such as volcanic glasses, siliceous fossils and silicates.Thermodynamic modeling of fluid-sediment interactions was conducted with the geochemical computer code PhreeqC, using mineralogical and pore fluid compositions from sediment samples and calculated estimates for thermodynamic constants of smectites that are not maintained by the computer code. Simulations confirm the possibility that the green grains are the product of pyrite alteration by seawater under oxidizing conditions. The extent of smectite production is controlled by the kinetics of pyrite dissolution and fluid migration. The absence of aluminum in the Costa Rica margin system explains the formation of an iron-rich montmorillonite instead of glauconite, whereas the presence of calcite that buffers the system explains the formation of an iron-rich montmorillonite instead of iron oxides.

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Section: Conditions Of Iron-rich Montmorillonite Formationsupporting

confidence: 91%

Conditions and mechanism for the formation of iron-rich Montmorillonite in deep sea sediments (Costa Rica margin): Coupling high resolution mineralogical characterization and geochemical modeling

Charpentier

Buatier

Jacquot³

et al. 2011

Geochimica et Cosmochimica Acta

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“…Comparison among the other examined ligands indicates that the effectiveness of organic ligands such as oxalate and succinate having two functional groups is higher on the dissolution process as compared to that of the monofunctional organic ligands (formate, acetate, propionate, lactate and butyrate). This result is in agreement with the previously reported data that propose compounds with higher functional groups promote dissolution to a much higher extent than monofunctional ligands (Golubev et al, 2006;Stumm, 1997). Over the experimental period, the the ligands are titrated in the solution reaching the concentration indicated in 5 th column of table 3.2 at 60h.…”

Section: Resultssupporting

confidence: 92%

Mineral CO2 sequestration by environmental biotechnological processes

Salek

Kleerebezem

Jonkers

et al. 2013

Trends in Biotechnology

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“…Organic acids may also chelate with formerly organic-bound surface cations (Golubev et al 2006;Wang et al 2014;Kleber et al 2015) or compete with binding sites and directly displace MAOM via ligand exchange (Oburger et al 2009;Keiluweit et al 2015). These processes can affect both metal oxides and silicate clays, although the potential for MAOM destabilization through this mechanism is generally greater among the former (Golubev et al 2006).…”

Section: Direct Destabilization Pathwaysmentioning

confidence: 99%

Minerals in the rhizosphere: overlooked mediators of soil nitrogen availability to plants and microbes

et al. 2018

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Despite decades of research progress, ecologists are still debating which pools and fluxes provide nitrogen (N) to plants and soil microbes across different ecosystems. Depolymerization of soil organic N is recognized as the rate-limiting step in the production of bioavailable N, and it is generally assumed that detrital N is the main source. However, in many mineral soils, detrital polymers constitute a minor fraction of total soil organic N. The majority of organic N is associated with clay-sized particles where physicochemical interactions may limit the accessibility of N-containing compounds. Although mineralassociated organic matter (MAOM) has historically been considered a critical, but relatively passive, reservoir of soil N, a growing body of research now points to the dynamic nature of mineral-organic associations and their potential for destabilization. Here we synthesize evidence from biogeoscience and soil ecology to demonstrate how MAOM is an important, yet overlooked, mediator of bioavailable N, especially in the rhizosphere. We highlight several biochemical strategies that enable plants and microbes /doi.org/10.1007/s10533-018-0459-5 to disrupt mineral-organic interactions and access MAOM. In particular, root-deposited low-molecularweight exudates may enhance the mobilization and solubilization of MAOM, increasing its bioavailability. However, the competitive balance between the possible fates of N monomers-bound to mineral surfaces versus dissolved and available for assimilation-will depend on the specific interaction between mineral properties, soil solution, mineral-bound organic matter, and microbes. Building off our emerging understanding of MAOM as a source of bioavailable N, we propose a revision of the Schimel and Bennett (Ecology 85:591-602, 2004) model (which emphasizes N depolymerization), by incorporating MAOM as a potential proximal mediator of bioavailable N.123 Biogeochemistry (2018) 139:103-122 https:/

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Effect of pH and organic ligands on the kinetics of smectite dissolution at 25°C

Cited by 135 publications

References 72 publications

Conditions and mechanism for the formation of iron-rich Montmorillonite in deep sea sediments (Costa Rica margin): Coupling high resolution mineralogical characterization and geochemical modeling

Conditions and mechanism for the formation of iron-rich Montmorillonite in deep sea sediments (Costa Rica margin): Coupling high resolution mineralogical characterization and geochemical modeling

Mineral CO2 sequestration by environmental biotechnological processes

Minerals in the rhizosphere: overlooked mediators of soil nitrogen availability to plants and microbes

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