The influence of terrigenous particulate material dissolution on ocean chemistry and global element cycles

Differential weathering of basaltic and granitic catchments from concentration–discharge relationships

The reaction of Ca derived from silicate weathering with CO2 in the world’s oceans to form carbonate minerals is a critical step in long-term climate moderation. Ca is delivered to the oceans primarily via rivers, where it is transported either as dissolved species or within suspended material. The relative importance for climate moderation of riverine dissolved Ca vs. suspended Ca transport stems from the total Ca flux and its climate dependence. Data in the literature suggest that, within uncertainty, global riverine dissolved Ca flux is equal to suspended material Ca flux. To determine how these fluxes depend on temperature and rainfall, a 40 yr field study was performed on 4 catchments

Role of river-suspended material in the global carbon cycle

https://escholarship.org/content/qt47r1w7cp/qt47r1w7cp.pdf?t=pexr5i

Evaluation of accessible mineral surface areas for improved prediction of mineral reaction rates in porous media

In order to evaluate the importance of hydrologic processes in controlling chemical weathering rates, a reactive transport analysis is used to interpret chemical weathering rate data for a range of systems. An analysis of weathering rates for granitic material shows that weathering rates depend most strongly on fluid residence times and fluid flow rates, and depend very weakly on material age. Over moderate fluid residence times from 5 days to 10 yr, characteristic of soils and some aquifers, transport-controlled weathering explains the orders of magnitude variation in weathering rates to a better extent than material age. For fluid residence times greater than 10 yr, characteristic of some aquifers, saprolites, and most marine sediments, a purely thermodynamic-control on chemical weathering rates sustains chemical weathering—this control may be due to clay precipitation, which can drive weathering of primary minerals, or microbial processes which alter the fluid chemistry via the oxidation of organic matter. In addition, this analysis suggests that the apparent time dependence of chemical weathering rates commonly used to model the evolution of Earth's landforms may be attributable to transport-controlled weathering and the evolution of hydrologic properties over time. If hydrologic processes are the primary control on chemical weathering rates, the nature of the temperature dependence of chemical weathering rates is also altered.

The dependence of chemical weathering rates on fluid residence time

The surface area and reactivity of granitic soils: I. Dissolution rates of primary minerals as a function of depth and age deduced from field observations

Is silt the most influential soil grain size fraction

The breaking down of massive rock into smaller grains
and the resultant increase in mineral surface area, is
potentially the most critical step in soil formation. The aim of
this study is to investigate how mineral surface area and
porosity varies during pedogenesis, and how these variations
in conjucnction with mineralogical changes influence soil
mineral reactivity.

Samuel A. Parry

Papers

The surface area and reactivity of granitic soils: I. Dissolution rates of primary minerals as a function of depth and age deduced from field observations

Is silt the most influential soil grain size fraction

Turning rock into soil - Variations in soil mineral reactivity, surface area, and porosity through the critical zone