Are Minor and Trace Elements Useful Indicators of Chemical Weathering Processes and Flow-Routing in Subglacial Hydrological Systems?

In Alpine glacierised catchments, snowand icemelt are chemically enriched and modified during transit though subglacial hydrological systems by distinct bio-geochemical weathering reactions. The nature and extent of these reactions are dictated by waters source and meltwater routing. This chemical modification of meltwaters has been applied in hydrochemical and hydroglacial studies, based mainly on the determination of dissolved major ions. In this study we present seasonal variations in the concentration of minor and trace elements in bulk-meltwaters and in-situ meltwaters from Haut Glacier d’Arolla, Switzerland, and investigate their utility for solute-provenance and flow-routing studies. On seasonal timescales the dissolved concentration of many minor and trace elements (e.g. Sr, Rb, Al, Co) are controlled by hydrological parameters such as water residence time and water-rock ratios. However, Li, Be, Mn, Fe, As and Cd appear to be affected by physico-chemical controls such as sorption, (oxi)hydroxide formation and coprecipitation reactions, rather than water residence time alone. Nevertheless, seasonal changes of dissolved minor and trace element concentration ratios reveal important information about solute sources, the nature of weathering processes, and temporal changes in weathering reactions which are associated with hydrological conditions.