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The effect of pH, grain size, and organic ligands on biotite weathering rates

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The effect of pH, grain size, and organic ligands on biotite weathering rates. / Bray, Andrew W.; Oelkers, Eric H.; Bonneville, Steeve; Wolff-Boenisch, Domenik; Potts, Nicola J.; Fones, Gary; Benning, Liane G.

In: Geochimica et Cosmochimica Acta, Vol. 164, 01.09.2015, p. 127-145.

Research output: Contribution to journalArticle

Harvard

Bray, AW, Oelkers, EH, Bonneville, S, Wolff-Boenisch, D, Potts, NJ, Fones, G & Benning, LG 2015, 'The effect of pH, grain size, and organic ligands on biotite weathering rates', Geochimica et Cosmochimica Acta, vol. 164, pp. 127-145. https://doi.org/10.1016/j.gca.2015.04.048

APA

Bray, A. W., Oelkers, E. H., Bonneville, S., Wolff-Boenisch, D., Potts, N. J., Fones, G., & Benning, L. G. (2015). The effect of pH, grain size, and organic ligands on biotite weathering rates. Geochimica et Cosmochimica Acta, 164, 127-145. https://doi.org/10.1016/j.gca.2015.04.048

Vancouver

Bray AW, Oelkers EH, Bonneville S, Wolff-Boenisch D, Potts NJ, Fones G et al. The effect of pH, grain size, and organic ligands on biotite weathering rates. Geochimica et Cosmochimica Acta. 2015 Sep 1;164:127-145. https://doi.org/10.1016/j.gca.2015.04.048

Author

Bray, Andrew W. ; Oelkers, Eric H. ; Bonneville, Steeve ; Wolff-Boenisch, Domenik ; Potts, Nicola J. ; Fones, Gary ; Benning, Liane G. / The effect of pH, grain size, and organic ligands on biotite weathering rates. In: Geochimica et Cosmochimica Acta. 2015 ; Vol. 164. pp. 127-145.

Bibtex

@article{0d59a429c94f4937825c270c6a322f6e,
title = "The effect of pH, grain size, and organic ligands on biotite weathering rates",
abstract = "Biotite dissolution rates were determined at 25 °C, at pH 2–6, and as a function of mineral composition, grain size, and aqueous organic ligand concentration. Rates were measured using both open- and closed-system reactors in fluids of constant ionic strength. Element release was non-stoichiometric and followed the general trend of Fe, Mg > Al > Si. Biotite surface area normalised dissolution rates (ri) in the acidic range, generated from Si release, are consistent with the empirical rate law: Turn MathJaxon where kH,i refers to an apparent rate constant, aH+ designates the activity of protons, and xi stands for a reaction order with respect to protons. Rate constants range from 2.15 × 10−10 to 30.6 × 10−10 (molesbiotite m−2 s−1) with reaction orders ranging from 0.31 to 0.58. At near-neutral pH in the closed-system experiments, the release of Al was stoichiometric compared to Si, but Fe was preferentially retained in the solid phase, possibly as a secondary phase. Biotite dissolution was highly spatially anisotropic with its edges being ∼120 times more reactive than its basal planes. Low organic ligand concentrations slightly enhanced biotite dissolution rates. These measured rates illuminate mineral–fluid–organism chemical interactions, which occur in the natural environment, and how organic exudates enhance nutrient mobilisation for microorganism acquisition.",
keywords = "NE/C004566/1, RCUK, NERC",
author = "Bray, {Andrew W.} and Oelkers, {Eric H.} and Steeve Bonneville and Domenik Wolff-Boenisch and Potts, {Nicola J.} and Gary Fones and Benning, {Liane G.}",
note = "This study was enabled by funding from the UK Natural Environment Research Council Weathering Science Consortium (NE/C004566/1) and The Geological Society of London William George Fearnsides Fund, both of which the authors are extremely grateful for.",
year = "2015",
month = "9",
day = "1",
doi = "10.1016/j.gca.2015.04.048",
language = "English",
volume = "164",
pages = "127--145",
journal = "Geochimica et Cosmochimica Acta",
issn = "0016-7037",
publisher = "Elsevier Limited",

}

RIS

TY - JOUR

T1 - The effect of pH, grain size, and organic ligands on biotite weathering rates

AU - Bray, Andrew W.

AU - Oelkers, Eric H.

AU - Bonneville, Steeve

AU - Wolff-Boenisch, Domenik

AU - Potts, Nicola J.

AU - Fones, Gary

AU - Benning, Liane G.

N1 - This study was enabled by funding from the UK Natural Environment Research Council Weathering Science Consortium (NE/C004566/1) and The Geological Society of London William George Fearnsides Fund, both of which the authors are extremely grateful for.

PY - 2015/9/1

Y1 - 2015/9/1

N2 - Biotite dissolution rates were determined at 25 °C, at pH 2–6, and as a function of mineral composition, grain size, and aqueous organic ligand concentration. Rates were measured using both open- and closed-system reactors in fluids of constant ionic strength. Element release was non-stoichiometric and followed the general trend of Fe, Mg > Al > Si. Biotite surface area normalised dissolution rates (ri) in the acidic range, generated from Si release, are consistent with the empirical rate law: Turn MathJaxon where kH,i refers to an apparent rate constant, aH+ designates the activity of protons, and xi stands for a reaction order with respect to protons. Rate constants range from 2.15 × 10−10 to 30.6 × 10−10 (molesbiotite m−2 s−1) with reaction orders ranging from 0.31 to 0.58. At near-neutral pH in the closed-system experiments, the release of Al was stoichiometric compared to Si, but Fe was preferentially retained in the solid phase, possibly as a secondary phase. Biotite dissolution was highly spatially anisotropic with its edges being ∼120 times more reactive than its basal planes. Low organic ligand concentrations slightly enhanced biotite dissolution rates. These measured rates illuminate mineral–fluid–organism chemical interactions, which occur in the natural environment, and how organic exudates enhance nutrient mobilisation for microorganism acquisition.

AB - Biotite dissolution rates were determined at 25 °C, at pH 2–6, and as a function of mineral composition, grain size, and aqueous organic ligand concentration. Rates were measured using both open- and closed-system reactors in fluids of constant ionic strength. Element release was non-stoichiometric and followed the general trend of Fe, Mg > Al > Si. Biotite surface area normalised dissolution rates (ri) in the acidic range, generated from Si release, are consistent with the empirical rate law: Turn MathJaxon where kH,i refers to an apparent rate constant, aH+ designates the activity of protons, and xi stands for a reaction order with respect to protons. Rate constants range from 2.15 × 10−10 to 30.6 × 10−10 (molesbiotite m−2 s−1) with reaction orders ranging from 0.31 to 0.58. At near-neutral pH in the closed-system experiments, the release of Al was stoichiometric compared to Si, but Fe was preferentially retained in the solid phase, possibly as a secondary phase. Biotite dissolution was highly spatially anisotropic with its edges being ∼120 times more reactive than its basal planes. Low organic ligand concentrations slightly enhanced biotite dissolution rates. These measured rates illuminate mineral–fluid–organism chemical interactions, which occur in the natural environment, and how organic exudates enhance nutrient mobilisation for microorganism acquisition.

KW - NE/C004566/1

KW - RCUK

KW - NERC

U2 - 10.1016/j.gca.2015.04.048

DO - 10.1016/j.gca.2015.04.048

M3 - Article

VL - 164

SP - 127

EP - 145

JO - Geochimica et Cosmochimica Acta

JF - Geochimica et Cosmochimica Acta

SN - 0016-7037

ER -

ID: 3141548