scholarly journals Spatial distribution of stable water isotopes in alpine snow cover

2013 ◽  
Vol 17 (7) ◽  
pp. 2657-2668 ◽  
Author(s):  
N. Dietermann ◽  
M. Weiler

<p><strong>Abstract.</strong> The aim of this study was to analyse and predict the mean stable water isotopic composition of the snow cover at specific geographic locations and altitudes. In addition, the dependence of the isotopic composition of the entire snow cover on altitude was analysed. Snow in four Swiss catchments was sampled at the end of the accumulation period in April 2010 and a second time during snowmelt in May 2010 and analysed for stable isotope composition of <sup>2</sup>H and <sup>18</sup>O. The sampling was conducted at both south-facing and north-facing slopes at elevation differences of 100 m, for a total altitude difference of approximately 1000 m. The observed variability of isotopic composition of the snow cover was analysed with stepwise multiple linear regression models. The analysis indicated that there is only a limited altitude effect on the isotopic composition when considering all samples. This is due to the high variability of the isotopic composition of the precipitation during the winter months and, in particular in the case of south-facing slopes, an enrichment of heavy isotopes due to intermittent melting processes. This enrichment effect could clearly be observed in the samples which were taken later in the year. A small altitudinal gradient of the isotopic composition could only be observed at some north-facing slopes. However, the dependence of snow depth and the day of the year were significant predictor variables in all models. This study indicates the necessity to further study the variability of water isotopes in the snow cover to increase prediction for isotopic composition of snowmelt and hence increase model performance of residence time models for alpine areas in order to better understand the accumulation processes and the sources of water in the snow cover of high mountains.</p>

2022 ◽  
Vol 12 (2) ◽  
pp. 625
Author(s):  
Tatyana Papina ◽  
Alla Eirikh ◽  
Tatiana Noskova

Stable water isotopes in snowpack and snowfalls are widely used for understanding hydrological processes occurring in the seasonally snow-covered territories. The present study examines the main factors influencing changes of the initial stable water isotopes composition in the seasonal snow cover of the south of Western Siberia. Studies of the isotopic composition of snow precipitation and snow cover, as well as experiments with them, were carried out during two cold seasons of 2019–2021, and laser spectroscopy PICARRO L2130-i (WS-CRDS) was used for the determination of water isotope composition (δ18O and δD). The main changes in the isotopic composition of the snow cover layers in the studied region are associated with the existence of a vertical temperature gradient between the layers and with the penetration of soil moisture into the bottom layers in the absence of soil freezing. During the winter period, the sublimation from the top layer of snow is observed only at the moments of a sharp increase in the daily air temperature. At the end of winter, the contrast between day and night air temperatures determines the direction of the shift in the isotopic composition of the top layer of snow relative to the initial snow precipitation.


2020 ◽  
Vol 32 ◽  
pp. 100739
Author(s):  
L. Nicole Arellano ◽  
Stephen P. Good ◽  
Ricardo Sánchez-Murillo ◽  
W. Todd Jarvis ◽  
David C. Noone ◽  
...  

2019 ◽  
Vol 98 ◽  
pp. 07031
Author(s):  
Arny E. Sveinbjörnsdóttir ◽  
Andri Stefánsson ◽  
Jan Heinemeier

Stable water isotopes of oxygen and hydrogen have been studied in Icelandic natural waters since 1960 for hydrological and geothermal research. All the waters are of meteoric and seawater origin. The measured range in δD and δ18O is large -131 to +3.3‰ and -20.8 to +2.3‰ respectively. Some of the waters are more depleted than any present-day precipitation suggesting a pre-Holocene component in the groundwater. Carbon isotopes of streams, rivers, soil and groundwater have been studied since 1990 in order to evaluate the carbon sources and reactions that possibly influence the carbon systematics of the water. Results show large range of values, for δ13CDIC -27.4 to +4.5‰ and for 14CDIC +0.6 to +118 pMC. Apart from atmospheric, organic and rock leaching, input of gas at depth with similar isotopic composition as the pre-erupted melt of the upper mantle and lower crust beneath Iceland have been identified as sources for carbon in the deeper groundwater.


2016 ◽  
Author(s):  
Harald Sodemann ◽  
Franziska Aemisegger ◽  
Stephan Pfahl ◽  
Mark Bitter ◽  
Ulrich Corsmeier ◽  
...  

Abstract. Stable water isotopes are powerful indicators of meteorological processes on a broad range of scales, reflecting evaporation, condensation, and airmass mixing processes. With the recent advent of fast laser-based spectroscopic methods it has become possible to measure the stable isotopic composition of atmospheric water vapour in situ at high temporal resolution, enabling to tremendously extend the measurement data base in space and time. Here we present the first set of airborne spectroscopic stable water isotopes measurements over the western Mediterranean. Measurements have been acquired by a customised Picarro L2130-i cavity-ring down spectrometer deployed onboard of the Dornier 128 D-IBUF aircraft together with a meteorological flux measurement package during the HyMeX SOP1 field campaign in Corsica, France during September and October 2012. Taking into account memory effects of the air inlet pipe, the typical time resolution of the measurements was about 15–30 s, resulting in an average horizontal resolution of about 1–2 km. Cross-calibration of the water vapour measurements from all humidity sensors showed good agreement in most flight conditions but the most turbulent ones. In total 21 successful stable isotope flights with 59 flight hours have been performed. Our data provide quasi-climatological autumn average conditions of the stable isotope parameters δD, δ18O and d-excess during the study period. A time-averaged perspective of the vertical stable isotope composition reveals for the first time the mean vertical structure of stable water isotopes over the Mediterranean at high resolution. A d-excess minimum in the overall average profile is reached in the region of the boundary layer top due to precipitation evaporation, bracketed by higher d-excess values near the surface due to non-equilibrium fractionation and above the boundary layer due to the non-linearity of the d-excess definition. Repeated flights along the same pattern reveals pronounced day-to-day variability due to changes in the large-scale circulation. During a period marked by a strong inversion at the top of the marine boundary layer, vertical gradients in stable isotopes reached up to 25.4 ‰ 100 m−1 for δD.


2017 ◽  
Vol 11 (4) ◽  
pp. 1733-1743 ◽  
Author(s):  
Pirmin Philipp Ebner ◽  
Hans Christian Steen-Larsen ◽  
Barbara Stenni ◽  
Martin Schneebeli ◽  
Aldo Steinfeld

Abstract. Stable water isotopes (δ18O) obtained from snow and ice samples of polar regions are used to reconstruct past climate variability, but heat and mass transport processes can affect the isotopic composition. Here we present an experimental study on the effect of airflow on the snow isotopic composition through a snow pack in controlled laboratory conditions. The influence of isothermal and controlled temperature gradient conditions on the δ18O content in the snow and interstitial water vapour is elucidated. The observed disequilibrium between snow and vapour isotopes led to the exchange of isotopes between snow and vapour under non-equilibrium processes, significantly changing the δ18O content of the snow. The type of metamorphism of the snow had a significant influence on this process. These findings are pertinent to the interpretation of the records of stable isotopes of water from ice cores. These laboratory measurements suggest that a highly resolved climate history is relevant for the interpretation of the snow isotopic composition in the field.


2018 ◽  
Author(s):  
Yonatan Ganot ◽  
Ran Holtzman ◽  
Noam Weisbrod ◽  
Anat Bernstein ◽  
Hagar Siebner ◽  
...  

Abstract. The spreading of reverse-osmosis desalinated seawater (DSW) in the Israeli Coastal Aquifer was studied using groundwater modeling and stable water isotopes as tracers. The DSW produced at the Hadera seawater reverse osmosis (SWRO) desalination plant is recharged into the aquifer through infiltration pond at the managed aquifer recharge (MAR) site of Menashe, Israel. The distinct difference in isotope composition between DSW (δ18O = +1.41; δ2H = +11.34 ‰) and the natural groundwater (δ18O = −4.48 to −5.43 ‰; δ2H = −18.41 to −22.68 ‰) makes the water isotopes a preferable tracer compared to widely-used chemical tracers, such as chloride. Moreover, this distinct difference can be used to simplify the system to a binary mixture of two end members: desalinated seawater and groundwater. This approach is especially robust when spatial data of stable water isotopes in the aquifer is scarce. A calibrated groundwater flow and transport model was used to predict the DSW plume distribution in the aquifer after 50 years of MAR with DSW. The results show that after 50 years 94 % of the recharged DSW was recovered by the production wells at the Menashe MAR site. The presented methodology is useful for predicting the distribution of reverse-osmosis desalinated seawater in various downstream groundwater systems.


2017 ◽  
Author(s):  
Pirmin P. Ebner ◽  
Hans Christian Steen-Larsen ◽  
Barbara Stenni ◽  
Martin Schneebeli ◽  
Aldo Steinfeld

Abstract. Stable water isotopes (δ18O) obtained from snow and ice samples of polar regions are used to reconstruct past climate variability, but heat and mass transport processes can affect the isotopic composition. Here we present an experimental study on the effect on the snow isotopic composition by airflow through a snow pack in controlled laboratory conditions. The influence of isothermal and controlled temperature gradient conditions on the δ18O content in the snow and interstitial water vapor is elucidated. The observed disequilibrium between snow and vapor isotopes led to exchange of isotopes between snow and vapor under non-equilibrium processes, significantly changing the δ18O content of the snow. The type of metamorphism of the snow had a significant influence on this process. These findings are pertinent to the interpretation of the records of stable isotopes of water from ice cores. These laboratory measurements suggest that a highly resolved history is relevant for the interpretation of the snow isotopic composition in the field.


2009 ◽  
Vol 55 (191) ◽  
pp. 485-498 ◽  
Author(s):  
K.E. Sinclair ◽  
S.J. Marshall

AbstractThe effects of temperature and seasonal air-mass trajectories on stable water isotopes in alpine snowpacks are investigated using meteorological and snow-pit data at two alpine field sites in the Canadian Rocky Mountains: Haig Glacier, Alberta, and Opabin Glacier, British Columbia. Snow pits were sampled through three accumulation seasons (October–June, 2004/05, 2005/06 and 2006/07) for δ18O, δD, temperature and density. The isotopic characteristics of precipitation over these time periods, including the local meteoric waterline and average δ18O, δD and deuterium excess, were defined using this dataset. Individual snowfall events over the three seasons were identified in the accumulation records from both sites and then fit to snow-pit stratigraphies to determine their mean isotopic characteristics. A trajectory classification was produced for all events, and the key meteorological characteristics of each trajectory class were investigated using data from alpine field sites and a suite of meteorological records from the region. An analysis of the relative influences of temperature and air-mass trajectory on snow isotope ratios reveals some separation in mean δ18O between storm classes. However, the separation appears to be driven primarily by the mean temperature of each class rather then being a direct effect of vapour pathway.


2017 ◽  
Vol 10 (8) ◽  
pp. 3125-3144 ◽  
Author(s):  
Rike Völpel ◽  
André Paul ◽  
Annegret Krandick ◽  
Stefan Mulitza ◽  
Michael Schulz

Abstract. We present the first results of the implementation of stable water isotopes in the Massachusetts Institute of Technology general circulation model (MITgcm). The model is forced with the isotopic content of precipitation and water vapor from an atmospheric general circulation model (NCAR IsoCAM), while the fractionation during evaporation is treated explicitly in the MITgcm. Results of the equilibrium simulation under pre-industrial conditions are compared to observational data and measurements of plankton tow records (the oxygen isotopic composition of planktic foraminiferal calcite). The broad patterns and magnitude of the stable water isotopes in annual mean seawater are well captured in the model, both at the sea surface as well as in the deep ocean. However, the surface water in the Arctic Ocean is not depleted enough, due to the absence of highly depleted precipitation and snowfall. A model–data mismatch is also recognizable in the isotopic composition of the seawater–salinity relationship in midlatitudes that is mainly caused by the coarse grid resolution. Deep-ocean characteristics of the vertical water mass distribution in the Atlantic Ocean closely resemble observational data. The reconstructed δ18Oc at the sea surface shows a good agreement with measurements. However, the model–data fit is weaker when individual species are considered and deviations are most likely attributable to the habitat depth of the foraminifera. Overall, the newly developed stable water isotope package opens wide prospects for long-term simulations in a paleoclimatic context.


2018 ◽  
Author(s):  
Paolo Benettin ◽  
Till H. M. Volkmann ◽  
Jana von Freyberg ◽  
Jay Frentress ◽  
Daniele Penna ◽  
...  

Abstract. Stable water isotopes are widely used in ecohydrology as tracers of the transport, storage, and mixing of water on its journey through landscapes and ecosystems. Evaporation leaves a characteristic signature on the isotopic composition of the water that is left behind, such that in dual-isotope space, evaporated waters plot below the Local Meteoric Water Line (LMWL) that characterizes precipitation. Soil and xylem water samples can often plot below the LMWL as well, suggesting that they have also been influenced by evaporation. These soil and xylem water samples frequently plot along linear trends in dual-isotope space. These trendlines are sometimes termed evaporation lines and their intersection with the LMWL is sometimes interpreted as the isotopic composition of the precipitation source water. Here we use numerical experiments based on established isotope fractionation theory to show that these trendlines are often by-products of the seasonality in evaporative fractionation and in the isotopic composition of precipitation. Thus, they are often not true evaporation lines, and, if interpreted as such, can yield highly biased estimates of the isotopic composition of the source water.


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