Albite dissolution kinetics as a function of distance from equilibrium: Implications for natural feldspar weathering

Beig, Mikala S.; Lüttge, Andreas

doi:10.1016/j.gca.2005.10.035

Cited by 125 publications

(84 citation statements)

References 64 publications

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“…Even though our R-ΔG data set is still incomplete, the present study suggests that the R-ΔG relation is sigmoidal and highly non-linear, which is in agreement with other studies on feldspars (Hellmann & Tisserand, 2006;Beig & Lüttge, 2006;Burch et al, 1993) and a few other silicate minerals (e.g. Nagy & Lasaga, 1992).…”

Section: Discussionsupporting

confidence: 92%

Albite feldspar dissolution kinetics as a function of the Gibbs free energy at high pCO2

Hellmann¹,

Daval²,

Tisserand³

et al. 2007

Water-Rock Interaction

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Section: Discussionsupporting

confidence: 92%

Albite feldspar dissolution kinetics as a function of the Gibbs free energy at high pCO2

Hellmann¹,

Daval²,

Tisserand³

et al. 2007

Water-Rock Interaction

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“…However, a number of experiments near equilibrium have shown that the actual relationship between r j and DG r deviates from this so-called linear kinetics (Schramke et al, 1987;Nagy et al, 1991;Nagy andLasaga, 1992, 1993;Burch et al, 1993;Gautier et al, 1994;Alekseyev et al, 1997;Cama et al, 2000;Taylor et al, 2000;Beig and Lü ttge, 2006;Hellmann and Tisserand, 2006). As shown below, the linear TST rate law also cannot fit the experimental data of Zhu and Lu (2009).…”

mentioning

confidence: 95%

“…doi: 10.1016/j.gca.2010.04.012 1984; Velbel, 1990;Brantley, 1992;Blum and Stillings, 1995;Drever and Clow, 1995). These hypotheses include the possible armoring effects of the secondary minerals that coat the feldspar grain surfaces (Correns and Von Engelhardt, 1938;Correns, 1940;Helgeson, 1971Helgeson, , 1972Luce et al, 1972;Paces, 1973;Busenberg and Clemency, 1976;Chou and Wollast, 1984;Nugent et al, 1998), the possible effects of the leached layer (Luce et al, 1972;Busenberg and Clemency, 1976;Chou and Wollast, 1984;Hellmann et al, 1990;Brantley and Stillings, 1996;Hellmann, 1997;Nesbitt and Skinner, 2001;Oelkers, 2001), the approach to saturation with respect to feldspars (Burch et al, 1993;Gautier et al, 1994;Oelkers et al, 1994;Oelkers, 2001;Beig and Lü ttge, 2006;Hellmann and Tisserand, 2006), unknown biological effects, and inhibition by adsorbed Al 3+ on feldspar surfaces (Chou and Wollast, 1985;Gautier et al, 1994;Oelkers et al, 1994;Oelkers, 2001).…”

Section: Introductionmentioning

confidence: 99%

Coupled alkali feldspar dissolution and secondary mineral precipitation in batch systems: 4. Numerical modeling of kinetic reaction paths

Zhu

Lü

Zheng

et al. 2010

Geochimica et Cosmochimica Acta

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This paper explores how dissolution and precipitation reactions are coupled in batch reactor experimental systems at elevated temperatures. This is the fourth paper in our series of "Coupled Alkali Feldspar Dissolution and Secondary Mineral Precipitation in Batch Systems". In our third paper, we demonstrated via speciation-solubility modeling that partial equilibrium between secondary minerals and aqueous solutions was not attained in feldspar hydrolysis batch reactors at 90-300°C and that a strong coupling between dissolution and precipitation reactions follows as a consequence of the slower precipitation of secondary minerals ). Here, we develop this concept further by using numerical reaction path models to elucidate how the dissolution and precipitation reactions are coupled. Modeling results show that a quasi-steady state was reached. At the quasi-steady state, dissolution reactions proceeded at rates that are orders of magnitude slower than the rates measured at far from equilibrium. The quasi-steady state is determined by the relative rate constants, and strongly influenced by the function of Gibbs free energy of reaction (DG r ) in the rate laws.To explore the potential effects of fluid flow rates on the coupling of reactions, we extrapolate a batch system (Ganor et al., 2007) to open systems and simulated one-dimensional reactive mass transport for oligoclase dissolution and kaolinite precipitation in homogeneous porous media. Different steady states were achieved at different locations along the one-dimensional domain. The time-space distribution and saturation indices (SI) at the steady states were a function of flow rates for a given kinetic model. Regardless of the differences in SI, the ratio between oligoclase dissolution rates and kaolinite precipitation rates remained 1.626, as in the batch system case (Ganor et al., 2007). Therefore, our simulation results demonstrated coupling among dissolution, precipitation, and flow rates.Results reported in this communication lend support to our hypothesis that slow secondary mineral precipitation explains part of the well-known apparent discrepancy between lab measured and field estimated feldspar dissolution rates (Zhu et al., 2004). Here we show how the slow secondary mineral precipitation provides a regulator to explain why the systems are held close to equilibrium and show how the most often-quoted "near equilibrium" explanation for an apparent field-lab discrepancy can work quantitatively. The substantiated hypothesis now offers the promise of reconciling part of the apparent fieldlab discrepancy.

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“…These hypotheses include the possible armoring effects of the secondary minerals that coat the feldspar grain surfaces (Correns and Von Engelhardt, 1938;Correns, 1940;Helgeson, 1971Helgeson, , 1972Luce et al, 1972;Paces, 1973;Busenberg and Clemency, 1976;Chou and Wollast, 1984;Nugent et al, 1998), the possible effects of the leached layer (Luce et al, 1972;Busenberg and Clemency, 1976;Chou and Wollast, 1984;Hellmann et al, 1990;Brantley and Stillings, 1996;Hellmann, 1997;Nesbitt and Skinner, 2001;Oelkers, 2001), approach to saturation with respect to feldspars (Burch et al, 1993;Gautier et al, 1994;Oelkers et al, 1994;Oelkers, 2001;Beig and Luttge, 2006;Hellmann and Tisserand, 2006), biological effects, inhibition of adsorbed Al 3+ on feldspar surfaces (Chou and Wollast, 1985;Gautier et al, 1994;Oelkers et al, 1994;Oelkers, 2001).…”

Section: Introductionmentioning

confidence: 99%

Alkali feldspar dissolution and secondary mineral precipitation in batch systems: 3. Saturation states of product minerals and reaction paths

Zhu¹,

Lü²

2009

Geochimica et Cosmochimica Acta

113

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In order to evaluate the complex interplay between dissolution and precipitation reaction kinetics, we examined the hypothesis of partial equilibria between secondary mineral products and aqueous solutions in feldspar-water systems. Speciation and solubility geochemical modeling was used to compute the saturation indices (SI) for product minerals in batch feldspar dissolution experiments at elevated temperatures and pressures and to trace the reaction paths on activity-activity diagrams. The modeling results demonstrated: (1) the experimental aqueous solutions were supersaturated with respect to product minerals for almost the entire duration of the experiments; (2) the aqueous solution chemistry did not evolve along the phase boundaries but crossed the phase boundaries at oblique angles; and (3) the earlier precipitated product minerals did not dissolve but continued to precipitate even after the solution chemistry had evolved into the stability fields of minerals lower in the paragenesis sequence. These three lines of evidence signify that product mineral precipitation is a slow kinetic process and partial equilibria between aqueous solution and product minerals were not held. In contrast, the experimental evidences are consistent with the hypothesis of strong coupling of mineral dissolution/precipitation kinetics [e.g., Zhu C., Blum A. E. and Veblen D. R. (2004a) Feldspar dissolution rates and clay precipitation in the Navajo aquifer at Black Mesa, Arizona, USA. In Water-Rock Interaction (eds. R. B. Wanty and R. R. I. Seal). A.A. Balkema, Saratoga Springs,. In all batch experiments examined, the time of congruent feldspar dissolution was short and supersaturation with respect to the product minerals was reached within a short period of time. The experimental system progressed from a dissolution driven regime to a precipitation limited regime in a short order. The results of this study suggest a complex feedback between dissolution and precipitation reaction kinetics, which needs to be considered in the interpretation of field based dissolution rates.

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Albite dissolution kinetics as a function of distance from equilibrium: Implications for natural feldspar weathering

Cited by 125 publications

References 64 publications

Albite feldspar dissolution kinetics as a function of the Gibbs free energy at high pCO2

Albite feldspar dissolution kinetics as a function of the Gibbs free energy at high pCO2

Coupled alkali feldspar dissolution and secondary mineral precipitation in batch systems: 4. Numerical modeling of kinetic reaction paths

Alkali feldspar dissolution and secondary mineral precipitation in batch systems: 3. Saturation states of product minerals and reaction paths

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