The hydrochemistry of meltwaters draining a polythermal‐based, high Arctic glacier, south Svalbard: I. The ablation season

Abstract

Abstract:Solute and runo time-series at Finsterwalderbreen, Svalbard, provide evidence for considerable basal routing of water and the existence of at least two contrasting subglacial chemical weathering environments. The hydrochemistry of a subglacial upwelling provides evidence for a snowmelt-fed subglacial reservoir that dominates bulk runo during recession¯ow. High concentrations of Cl 7 and crustal ions, high pCO 2 and ratios of [ * SO 3 )] close to 0 . 5 indicate the passage of snowmelt through a subglacial weathering environment characterized by high rock:water ratios, prolonged residence times and restricted access to the atmosphere. At higher discharges, bulk runo becomes dominated by icemelt from the lower part of the glacier that is conveyed through a chemical weathering environment characterized by low rock : water ratios, short residence times and free contact with atmospheric gases. These observations suggest that icemelt is routed via a hydrological system composed of basal/ice-marginal, englacial and supraglacial components and is directed to the glacier margins by the ice surface slope. Upwelling water¯ows relatively independently of icemelt to the terminus via a subglacial drainage system, possibly constituting¯ow through a sediment layer. Cold basal ice at the terminus forces it to take a subterranean routing in its latter stages. The existence of spatially discrete¯ow paths conveying icemelt and subglacial snowmelt to the terminus may be the norm for polythermal-based glaciers on Svalbard. Proglacial mixing of these components to form the bulk meltwaters gives rise to hydrochemical trends that resemble those of warm-based glaciers. These hydrochemical characteristics of bulk runo have not been documented on any other glacier on Svalbard to date and have signi®cance for understanding interactions between thermal regime and glacier hydrology. #

Organic carbon flux and particulate organic matter composition in Arctic valley glaciers: examples from the Bayelva River and adjacent Kongsfjorden

“…The manners by which meltwater drains through the glaciers vary in Svalbard (Hodgkins, 1997) and this impacts the meltwater chemistry (Hodson et al, 2002;Wadham et al, 1998). Whether the meltwater flows through supra-, enor sub-glacial channels would have great impact on the nutrients, TSM, and further organic matter in the glacier meltwater.…”

Chemistry of Supraglacial Ponds in the Debris-Covered Area of Lirung Glacier in Central Nepal Himalayas

“…At the outlet point of Lirung debris-covered glacier in central Nepal Himalaya, chemical erosion rate is higher than those reported for the Antarctic, Arctic, and European glaciers (Sharp et al 1995;Wadham et al 1998;Bhatt et al 2000;Green et al 2005). Debris may have played a great role in the release of solute from this catchment.…”

Glacier Biogeochemistry

“…The pressurised water had the sea salt signature of the snowpack, and the chemical weathering signature of weathering in a distributed drainage system. This was evidence that pressurised waters at the bed of the glacier were able to flow through the subglacial debris, and beneath the permafrost that otherwise froze the margins of the glacier to the bed (Wadham et al, 1998). Relatively warm years produced copious melt that was able to hydro-fracture the frozen seal and produce outbursts, while colder years could initially produce only sub-permafrost flow.…”