『Abstract
Uplift of the Himalayas has been proposed to have locally accelerated
chemical weathering, thus leading to enhanced CO2
sequestration and global cooling. This hypothesis assumes that
rapid erosion exposes fresh, highly reactive minerals at Earth's
surface. Empirical studies quantifying the relationship between
erosion and weathering have produced apparently conflicting results,
where the nature of the relationship is dependent on the weathering
regime of the sampled landscapes. We derive a quantitative model
that defines this relationship across the range of weathering
regimes, from supply-limited to kinetically limited conditions.
The model matches trends in field data collected by others and
reconciles apparently conflicting results. The model also demonstrates
that, as erosion rates increase, potential increases in weathering
rate from the exposure of fresher materials are offset by the
decrease in the total volume of minerals exposed due to thinner
regolith. We conclude that the relationship between weathering
and erosion is one of diminishing returns, in which increases
in erosion rate lead to progressively smaller increases in weathering
rate; indeed, at the highest erosion rates, weathering rates may
decline. The ability, therefore, of accelerated uplift and erosion
to stimulate greater CO2 sequestration may
be significant in landscapes eroding at rates of 100-102
t km-2yr-1. However, where erosion rates
are greater than 102 t km-2yr-1,
increases in denudation may not be matched by increases in chemical
weathering. Finally, our results suggest that watersheds with
regolith thicknesses of 〜0.5 m will yield the greatest solute
fluxes.』
Introduction
Model
Formulation
Assumptions
Parameterization
Results and discussion
Acknowledgments
References cited