『（Abstract）
The central control of mineral weathering rates on biogeochemical
systems has motivated studies of dissolution for more than 50
years. A complete physical picture that explains widely observed
variations in dissolution behavior is lacking, and some data show
apparent serious inconsistencies that cannot be explained by the
largely empirical kinetic “laws.” Here, we show that mineral dissolution
can, in fact, be understood through the same mechanistic theory
of nucleation developed for mineral growth. In principle, this
theory should describe dissolution but has never been tested.
By generalizing nucleation rate equations to include dissolution,
we arrive at a model that predicts how quartz dissolution processes
change with undersaturation from step retreat, to defect-driven
and homogeneous etch pit formation. This finding reveals that
the “salt effect,” recognized almost 100 years ago, arises from
a crossover in dominant nucleation mechanism to greatly increase
step density. The theory also explains the dissolution kinetics
of major weathering aluminosilicates, kaolinite and K-feldspar.
In doing so, it provides a sensible origin of discrepancies reported
for the dependence of kaolinite dissolution and growth rates on
saturation state by invoking a temperature-activated transition
in the nucleation process. Although dissolution by nucleation
processes was previously unknown for oxides or silicates, our
mechanism-based findings are consistent with recent observations
of dissolution (i.e., demineralization) in biological minerals.
Nucleation theory may be the missing link to unifying mineral
growth and dissolution into a mechanistic and quantitative framework
across the continuum of driving force.
(Keywords): silica; kinetics; mineralization』
(Introduction)
Methods
Dissolution experiments
Atomic force microscopy (AFM) imaging
Results
Discussion
Dissolution at dislocation
Dissolution by nucleation of vacancy islands
Nucleation theory also explains silicate dissolution kinetics
Broad implications for other families of crystalline materials
(Acknowledgments)
(References)