Title Chemical weathering and solute export by meltwater in a maritime Antarctic glacier basin
Author Hodson, A.J.; Heaton, T.; Langford, H.; Newsham, K.
Author Affil Hodson, A.J., University of Sheffield, Department of Geography, Sheffield, United Kingdom. Other: NERC, British Geological Survey, United Kingdom; British Antarctic Survey, United Kingdom
Source Biogeochemistry (Dordrecht), 98(1-3), p.9-27, . Publisher: Springer, Dordrecht - Boston - Lancaster, International. ISSN: 0168- 2563
Publication Date Apr. 2010
Notes In English. 57 refs. Ant. Acc. No: 91592. GeoRef Acc. No: 310442
Index Terms carbon isotopes; chemical composition; river basins; geochemistry; geomorphology; glacial geology; glaciers; hydrogeochemistry; isotopes; meltwater; oxygen; sediments; talus; weathering; Antarctica--Signy Island; acid rock drainage; Antarctica; C-13/C-12; carbon; chemical weathering; chromatograms; clastic sediments; denudation; drainage basins; erosion features; hydrochemistry; ice caps; ion chromatograms; isotope ratios; monitoring; moraines; N-15/N-14; nitrogen; O- 18/O-16; organic compounds; oxidation; pyrite; S-34/S-32; Scotia Sea Islands; Signy Island; Signy Island ice cap; solute transport; South Orkney Islands; stable isotopes; subglacial environment; sulfides; sulfur; talus slopes; transport; Tuva Glacier; water-rock interaction
Abstract Solute yields, laboratory dissolution data and both chemical and isotopic markers of rock weathering reactions are used to characterise the biogeochemistry of glacial meltwaters draining a maritime Antarctic glacier. We find that delayed flowpaths through ice-marginal talus and moraine sediments are critical for the acquisition of solute from rock minerals because delayed flowpaths through subglacial sediments are absent beneath this small, cold-based glacier. Here the mechanisms of weathering are similar to those reported in subglacial environments, and include sub-oxic conditions in the early summer and increasingly oxic conditions thereafter. Up to 85% of the NO3- and 65% of the SO42- are most likely produced by bacterially mediated reactions in these ice marginal sediments. However, reactive pyrite phases are sparse in the host rocks, limiting the export of Fe, SO42- and cations that may be removed by weathering once pyrite oxidation has taken place. This means that dissolution of Ca2+ and Na+ from carbonate and silicate minerals dominate, producing moderate cationic denudation yields from Tuva Glacier (163 #1S#AKmeq+-2 a-1) compared to a global range of values (94-4,200 #1S#AKmeq+ km-2 a-1). Overall, crustally derived cations represent 42% of the total cationic flux, the rest being accounted for by snowpack sources. Copyright 2009 Springer Science+Business Media B.V.
URL http://hdl.handle.net/10.1007/s10533-009-9372-2
Publication Type journal article
Record ID 65007155