Diffusion chemical dissolution weathering

Incongruent mass transfer in the case of parabolic kinetics based on diffusion control can be readily explained by differences in the diffusion coefficients of chemical species. However, the proposed mechanisms invoked to explain linear kinetics involve the dissolution of the bulk silicate phase, which, over extended periods, should result in the chemical components being transferred to solution from the silicate in their stoichiometric ratios (25). However, many field studies have shown that silicates weather incongruently in nature (27). This is supported by our studies of ground waters associated with vitric rhyolite tuffs. 

In this book we considered mass transfer and elemental migration between the atmosphere, hydrosphere, soils, rocks, biosphere and humans in earth s surface environment on the basis of earth system sciences. In Chaps. 2, 3, and 4, fundamental theories (thermodynamics, kinetics, coupling model such as dissolution kinetics-fluid flow modeling, etc.) of mass transfer mechanisms (dissolution, precipitation, diffusion, fluid flow) in water-rock interaction of elements in chemical weathering, formation of hydrothermal ore deposits, hydrothermal alteration, formation of ground water quality, seawater chemistry. However, more complicated geochemical models (multi-components, multi-phases coupled reaction-fluid flow-diffusion model) and phenomenon (autocatalysis, chemical oscillation, etc.) are not considered. 

One factor that is also discarded is the weathering material testing by immersion in water. The continuous contact with this fluid creates the constant penetration of water onto inner layers of polymer, but it allows the depletion of degradation products by their diffusion towards outer limits of sample and their dissolution in degradation environment. This scenario can be applied to any material, if the migration of stabilizers is the main process through which specimens are exposed to the fast chemical alterations [42 14]. 

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