Dissolution kinetics of rock-water interactions and its implications

Abstract

Chemical dissolution of bed rock/minerals plays a ce ntral role in determining the geochemistry of natural waters. The major source of dissolved species to nat ural water is the rocks coming in contact with water. As soon as the rocks come into contact with water, water– rock reaction starts and moves forward towards equilibrium by dissolving or leaching bedrock minerals into the solution. By this mechanism, major cations, anions, silica and other essential nutrients are released into the hydrosphere. The solute concentration in the water system is proportional to th e reacti vity of the bedrock minerals constituting the catchment. Thus, the chemical composition of natural waters is a direct indication of the geology of their catchment. Dissolution kinetics of rocks and minerals is important in u nderstanding different rates of chemical weathering of various lithologies, development of soils, production of secondary porosity in the rocks, triggering of lan dslides and sequestration of atmospheric carbon dio xide. Recent studies on mineral weathering phenomena in inter-terrestrial materials and under space weathering conditions reveal the differences in chemical weathe ring under different physical and chemical conditions.