Hydrochemistry of meltwaters draining a polythermal-based, high-Arctic glacier, south Svalbard: II. Winter and early Spring

• Published in: Hydrological processes 2000-07, Vol.14 (10), p.1767-1786
• Main Authors: Wadham, J. L., Tranter, M., Dowdeswell, J. A.
• Format: Article
• Language: English
• Subjects: Earth sciences; Earth, ocean, space; Exact sciences and technology; Geochemistry; glacier; hydrochemistry; Hydrology; Hydrology. Hydrogeology; ion exchange; Mineralogy; polythermal-based; Silicates; subglacial drainage; Svalbard; Water geochemistry; winter
• ISSN: 0885-6087; 1099-1085
• DOI: 10.1002/1099-1085(200007)14:10<1767::AID-HYP103>3.0.CO;2-Q

The hydrochemistry of naled and upwelling water sampled from the forefields of Finsterwalderbreen, Svalbard, during spring are used for the first time to infer the hydrology of overwinter meltwaters at a polythermal‐based glacier. Hydrochemical variations in naled are explained in terms of different water sources and their chemical alteration during freezing. Two water sources to naled are identified: surficially routed snowmelt and subglacial water. Naled that results from the freezing of the former is enriched in atmospherically derived ions such as Na+ and Cl−, and is believed to be formed during winter warm periods. Naled of subglacial origin contains relatively high proportions of crustally derived solute. It reflects the freezing of subglacial meltwaters that continue to issue from a subterranean upwellling during winter. An increasing dominance of SO2−4 Mg2+, Na+ and Cl− in subglacial naled with increasing distance from the upwelling reflects the progressive freezing of this water body and the associated removal of Ca2+ and HCO − 3 by calcite precipitation. These spatial trends are accentuated by the leaching of soluble ions from the naled close to its source by subsequent upwelling waters. The chemistry of spring upwelling waters, also of subglacial origin, strongly reflects this process. Meltwater produced by geothermal heating of glacier basal ice is believed to be the principal source of water to the subglacial drainage system during winter. Solute acquisition by this meltwater is limited by a scarcity of proton suppliers. Evolution of this dilute meltwater carries an imprint of ion exchange processes. Some stored subglacial water from the end of the previous ablation season may supplement the basal meltwater component in early winter. Copyright © 2000 John Wiley & Sons, Ltd.