Interactions of calcareous suspended sediment with glacial meltwater: a field test of dissolution behaviour

摘要: Abstract Dissolution of calcite and associated interactions suspended sediment with aqueous solution were investigated in a tributary-free 600 m reach the main meltstream draining Tsanfleuron glacier, Switzerland, over 24-h cycle during which solute concentrations varied inversely discharge. Downflow, calcium, strontium, alkalinity increased because dissolution. Using flow-through times from salt-dilution gauging, consistent small sulphate excess at downstream site was observed. Given slowness supply by pyrite oxidation, this can be attributed to mixing around 1% ion-rich water (seeping till banks) meltstream. Calcite dissolution is normally directly proportional exposed surface area mineral, yet only increase observed when factor 25 1.3 g/l peak flow. The displays little variation size distribution total load, contains 30–40% minimum specific (S) 0.25 m2/g sediment. Application Plummer–Wigley–Parkhurst (PWP) model predicts rates broadly similar those found lower given value S. At higher loads predicted are too high. This discrepancy reduced use Buhmann–Dreybrodt (B–D) takes explicit account hydration carbon dioxide, problem mass transfer H2CO3 volume solutions considered. remaining implies less interaction than expected particles turbulent meltwater high concentrations. effects proglacial modification geochemistry case strong decrease PCO2 accompanied an ion but decreases Mg/Ca Sr/Ca, values characteristic low water–rock ratio subglacial environments till. Nevertheless, distinctive chemical imprint chemistry non-congruent mineral glacial weathering remain. In contrast, terrains where scarce, it will tend dissolve congruently, contributing significantly solutes, its limited CO2 reaction kinetics.