Experimental study investigating the abiotic dissolution kinetics of iron during lithogenic particle-water interactions in high-energy regions
Here we address the abiotic processes leading to dissolution of Fe caused by agitation during high-energy continental freshwater transport (rivers, ravines, torrents) and on wave impacted coastal regions, such as beaches. To explore these processes, as a first approximation, we have investigated the dissolution kinetics of isolated pure minerals (olivine, pyroxene and plagioclase) in distilled water and synthetic seawater, in shaken closed system batch reactors. Fe results are supported by Mn, Cu, Ni, Cu, Zn and Pb concentrations. Preliminary results suggest simultaneous release and removal processes occurring throughout the experiments, with release processes predominating during the start of the experiments and removal processes predominating towards the end. Stages and degree of release differ between freshwater and seawater experiments. Secondary mineral phases were detected in particles recovered at the end of the experiments, which may play an important role in the removal of Fe from solution (direct incorporation and/or adsorption). Fe isotopic ratios are used to interpret geochemical processes. Our data are fitted to a model that considers mineral dissolution kinetics, combined with Fe2+ oxidation rates and Fe3+ precipitation rates.