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IMPACT OF SUBGLACIAL GEOTHERMAL ACTIVITY ON MELTWATER QUALITY IN THE JÖKULSÁ Á SÓLHEIMASANDI SYSTEM, SOUTHERN ICELAND

1996; Wiley; Volume: 10; Issue: 4 Linguagem: Inglês

10.1002/(sici)1099-1085(199604)10

1099-1085

Damian Lawler, Helgi Björnsson, Mallory K. Dolan,

Climate change and permafrost

Hydrological ProcessesVolume 10, Issue 4 p. 557-577 Research Article IMPACT OF SUBGLACIAL GEOTHERMAL ACTIVITY ON MELTWATER QUALITY IN THE JÖKULSÁ Á SÓLHEIMASANDI SYSTEM, SOUTHERN ICELAND D. M. LAWLER, Corresponding Author D. M. LAWLER School of Geography, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK (Email: [email protected])School of Geography, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK===Search for more papers by this authorH. BJÖRNSSON, H. BJÖRNSSON Science Institute, University of Iceland, Dunhaga 5, 107 Reykjavík, IcelandSearch for more papers by this authorM. DOLAN, M. DOLAN Quality Department, North West Water, Dawson House, Great Sankey, Warrington WA5 3LW, UKSearch for more papers by this author D. M. LAWLER, Corresponding Author D. M. LAWLER School of Geography, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK (Email: [email protected])School of Geography, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK===Search for more papers by this authorH. BJÖRNSSON, H. BJÖRNSSON Science Institute, University of Iceland, Dunhaga 5, 107 Reykjavík, IcelandSearch for more papers by this authorM. DOLAN, M. DOLAN Quality Department, North West Water, Dawson House, Great Sankey, Warrington WA5 3LW, UKSearch for more papers by this author First published: April 1996 https://doi.org/10.1002/(SICI)1099-1085(199604)10:4 3.0.CO;2-OCitations: 18AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Abstract The influence of subglacial geothermal activity on the hydrochemistry of the Jökulsá á Sólheimasandi glacial meltwater river, south Iceland, is discussed. A radio echosounding and Global Positioning System survey of south-west Myrdalsjökull, the parent ice-cap of the valley glacier Sólheimajökull, establishes the geometry and position of a subglacial caldera. A cauldron in the ice-cap surface at the basin head is also defined, signifying one location of geothermally driven ablation processes. Background H2S concentrations for the Jökulsá meltwaters in summer 1989 show that leakage of geothermal fluids into the glacial drainage network takes place throughout the melt season. Chemical geothermometry (Na+/K+ ratio) applied to the bulk meltwaters tentatively suggests that the subglacial geothermal area is a high-temperature field with a reservoir temperature of ≈289–304°C. A major event of enhanced geothermal fluid injection was also detected. Against a background of an apparently warming geothermal reservoir, the event began on Julian day 205 (24 July) with a burst of subglacial seismic activity. Meltwater hydrochemical perturbations followed on day 209 and peaked on day 213, finally leading to a sudden and significant increase in flow on day 214. The hydrochemical excursions were characterized by strong peaks in meltwater H2S, SO2−4 and total carbonate concentrations, transient decreases in pH, small increases in Ca2+ and Mg2+ and sustained increases in electrical conductivity. The event may relate to temporary invigoration of the subglacial convective hydrothermal circulation, seismic disturbance of patterns of groundwater flow and geothermal fluid recruitment to the subglacial drainage network, or a cyclic ‘sweeping out’ of the geothermal zone by the annual wave of descending groundwater. Time lags between seismic events and meltwater electrical conductivity responses suggest mean and maximum intraglacial throughflow velocities of 0.032–0.132 m s−1, respectively, consistent with a distributed drainage system beneath Sólheimajökull. Because increases in flow follow hydrochemical perturbations, the potential exists to use meltwater hydrochemistry to forecast geothermally driven flood events in such environments. Citing Literature Volume10, Issue4April 1996Pages 557-577 RelatedInformation