Soils and the Local Weathering Environment

O2) change tremendously on time-scales that are infinitesimally short geologically (minutes to days) and reactions frequently occur in thin films and on grain services. 

2 Variable Chemistry of Soil Fluids, a Complicating Factor 

Weathering rates are most sensitive to the throughput of water. In soils, this is a decidedly discontinuous process. Typically, water flows through soil following rainfall or snowmelt. Once saturated, the flux of water is largely dependent on the physical properties of the soil and not on the rate of supply. Water that cannot be accommodated by flow through the soil. 

Groundwater environments can be represented as a simple flow-through system. For the situation where chemical weathering of mineral grains is transport controlled, the weathering rate of a mineral should be directly dependent on the rate of throughput of water. For the situation where rates are controlled by surface 

Soil water flow is decidedly episodic. During dry times the water solutions in the soil are probably fairly concentrated and not very reactive. Time-averaged reaction rates should be roughly proportional to the fraction of time reacting minerals are in contact with thermodynamically imdersaturated (and reactive) water. In a study of the relationship between denudation rate and runoff for rivers draining igneous and metamorphic rock in Kenya, Dunne (1978) obtains the relationship of (denudation rate in tons/km per year) = 0.28 (runoff in mm/ year)°.  

Freezing, which also produces residual fluids with elevated concentrations of dissolved solutes, presumably does not have as significant 

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