Oxygen isotopes in glacier-river water, Austre Okstindbreen, Okstindan, Norway

Theakstone, Wilfred H.

doi:10.3189/172756503781830700

Cited by 22 publications

(12 citation statements)

References 81 publications

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“…When the melting rate is high, water flows through the snowpack with a high velocity, which limits the time of contact between liquid water and ice, thus producing a melt that is closer isotopically to the composition of the melting snow. Theakstone [2003] observed diel variations of the isotopic composition of glacier river water in a period of fine weather, but the diel fluctuations were interrupted by rainfall‐induced events. Our simulation, although not matching the observations perfectly, does reproduce the diel fluctuations such that the δ D of the melt water is higher during a high flow and lower at a low flow.…”

Section: Discussionmentioning

confidence: 98%

Isotopic evolution of snowmelt: A new model incorporating mobile and immobile water

Lee

Feng

Faiia

et al. 2010

Water Resources Research

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[1] Isotopic variations of snowmelt provide important information for understanding snowmelt processes and the timing and contribution of snowmelt to catchments in spring. We report a new model for simulating the isotopic evolution of snowmelt. The model includes a hydraulic exchange between mobile and immobile water, and an isotopic exchange between liquid water (mobile and immobile water) and ice within a snowpack. Since this model is based on the mobile-immobile water conceptualization, which is widely used for describing chemical tracer transport in snow, it allows simultaneous simulations of chemical as well as isotopic variations in snowpack discharge. We also report temporal variations of isotopic composition of a snowpack and snowmelt during artificial rain-on-snow experiments and diel snowmelt cycles observed in spring 2003 at the Central Sierra Snow Laboratory, California. These observations are used to test the newly developed model and to understand physical processes in a seasonal snowpack. Our model simulates the isotopic variations reasonably well, and suggests that exchanges of ice with both mobile and immobile water are important for determining the isotopic composition of the discharge.

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Section: Discussionmentioning

confidence: 98%

Isotopic evolution of snowmelt: A new model incorporating mobile and immobile water

Lee

Feng

Faiia

et al. 2010

Water Resources Research

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“…In proglacial areas, increased water residence times in older sediments promote silicate weathering and increase the acquisition of solutes from crustal sources in active soil layers (Anderson et al ., ; Dragon and Marciniak, ), thus imparting a hydrochemical signature on shallow groundwater discharge that contrasts with that of glacier and snowpack meltwater. Similarly, the isotopic composition of bulk runoff may also reflect variations in the geographical source of river flow (Theakstone, ; Liu et al ., ) because high rates of evaporation in proglacial areas during summer months lead to the progressive enrichment of heavy‐isotope content in active layer soil waters relative to that of precipitation and snowmelt (Cooper et al ., ; Gibson, ).…”

Section: Introductionmentioning

confidence: 99%

Water source dynamics of high Arctic river basins

Blaen¹,

Hannah²,

Milner³

2013

Hydrological Processes

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Arctic river basins are amongst the most vulnerable to climate change. However, there is currently limited knowledge of the hydrological processes that govern flow dynamics in Arctic river basins. We address this research gap using natural hydrochemical and isotopic tracers to identify water sources that contributed to runoff in river basins spanning a gradient of glacierization (0–61%) in Svalbard during summer 2010 and 2011. Spatially distinct hydrological processes operating over diurnal, weekly and seasonal timescales were characterized by river hydrochemistry and isotopic composition. Two conceptual water sources (‘meltwater’ and ‘groundwater’) were identified and used as a basis for end‐member mixing analyses to assess seasonal and year‐to‐year variability in water source dynamics. In glacier‐fed rivers, meltwater dominated flows at all sites (typically >80%) with the highest contributions observed at the beginning of each study period in early July when snow cover was most extensive. Rivers in non‐glacierized basins were sourced initially from snowmelt but became increasingly dependent on groundwater inputs (up to 100% of total flow volume) by late summer. These hydrological changes were attributed to the depletion of snowpacks and enhanced soil water storage capacity as the active layer expanded throughout each melt season. These findings provide insight into the processes that underpin water source dynamics in Arctic river systems and potential future changes in Arctic hydrology that might be expected under a changing climate. Copyright © 2013 John Wiley & Sons, Ltd.

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“…For the δ 18 O fw end‐member of the Atlantic Domain, a representative figure of −14‰ is assumed based on δ 18 O values for northwestern Scandinavian precipitation and runoff: despite strong local variability [ Theakstone , ], these δ 18 O values often appear to fall between ~−13 and −15‰ [ Hammerlund et al ., ; Jonsson et al ., ; Dahlke et al ., ].…”

Section: Setting Material and Methodsmentioning

confidence: 99%

Sea surface density gradients in the Nordic Seas during the Holocene as revealed by paired microfossil and isotope proxies

et al. 2016

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We attempt to assess the Holocene surface‐subsurface seawater density gradient on millennial time scale based on the reconstruction of potential density (σθ) by combining data from dinoflagellate cyst assemblages and planktic foraminiferal (Neogloboquadrina pachyderma (s)) stable oxygen isotopes (δ18Oc). Following several calibration exercises, the likeliness of favorable seasonal preconditioning to open ocean convection is evaluated. The reconstructed σθ values reveal unfavorable conditions for vertical convection in the western Nordic Seas prior to ~7–6.5 ka B.P., with a westward increase and persistence of surface water buoyancy. Active overturning became more likely after 6.5 ka B.P. as suggested by a reduced and recurrently inverted vertical σθ gradient, while intermittent eastward spreading of lower density surface waters continued to modulate the area of potential overturning. Despite some reservation regarding the accuracy of the σθ values reconstructed, the documentation of relative changes of σθ gradients through time and space is suggested as a helpful tool for the appraisal of past overturning likeliness.

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Oxygen isotopes in glacier-river water, Austre Okstindbreen, Okstindan, Norway

Cited by 22 publications

References 81 publications

Isotopic evolution of snowmelt: A new model incorporating mobile and immobile water

Isotopic evolution of snowmelt: A new model incorporating mobile and immobile water

Water source dynamics of high Arctic river basins

Sea surface density gradients in the Nordic Seas during the Holocene as revealed by paired microfossil and isotope proxies

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