Mobilization and retardation of reduced manganese in sandy aquifers: Column experiments, modeling and implications

摘要: Abstract Manganese enrichment is common in various sedimentary environments, e.g. deep ocean floor, shallow environments where the overlying water column oxic and phreatic aquifers, which Mn aquatic geochemistry controlled by redox conditions. In many cases, aquifers recharged organic-rich waters contain high amounts of dissolved 2+ that was mobilized from Mn-oxides during microbial oxidation organic matter under low-oxygen Thus, identification quantification processes controlling mobilization speciation great practical importance as a geochemical tool for sustainable management aquifers. This study uses experiments to quantify role adsorption precipitation retarding sandy Flow-through columns were packed with pristine sediment artificial solutions containing different concentrations. Outflow analyzed simulated using transport-reaction model. The results used demonstrate on three experimental data showed solids main control breakthrough behavior. Nevertheless, up 20% entered precipitated MnCO 3 . rate ( k p  = 0.04 h −1 ) found be ∼3 orders magnitude slower than  = 10–200 h ). Given slow mineral-precipitation kinetics, flow critical determining potential immobilizing within an aquifer. A scale-up retardation time natural aquifer conditions, suggests responsible prolonged observed An important conclusion this environmental response perturbation hydro-geochemical regime might delayed several decades.