Hydrology and hydrochemistry of a deglaciating high-Arctic catchment, Svalbard

摘要

The impact of deglaciation on contemporary hydrological and biogeochemical functioning in the Rieperbreen-Foxfonna catchment in western Svalbard was observed in 2007-2008. An overall negative mass balance was observed during 2007; mass loss was high below the equilibrium line altitude (ELA), but spatially patchy mass increases due to superimposed ice and firn were evident above the ELA. Runoff from above the ELA was almost exclusively routed through low gradient, hydraulically inefficient supraglacial flowpaths, which fed steeper, highly efficient supraglacial and englacial/subglacial channels downstream. As interaction with debris-rich environments (subglacial and proglacial) was minimal and transit times were rapid below the ELA, runoff from supraglacial sources had a low solute content. In addition, two further parallel hydrological pathways existed: snowmelt-fed springs emerging from the glacier's contemporary marginal moraines, and multiple shallow intermittent streams within recent moraines throughout the glacier forefield and along its northern moraine flank. Runoff from these additional pathways flowed through highly reactive sediments composed of shale, carbonate and sandstones. Their intense chemical and physical weathering meant moraines were important sources of solute contribution to the catchment's bulk runoff chemistry. Ecological succession at the glacier margin is therefore highly likely to be dependent upon nutrient acquisition by hydrological processes within moraines as the catchment undergoes deglaciation.