The spatiotemporal variability of snowpack and snowmelt water ¹⁸O and ²H isotopes in a subarctic catchment
Noor, Kashif; Marttila, Hannu; Klöve, Björn; Welker, Jeffrey M.; Ala-aho, Pertti (2023-01-03)
Noor, K., Marttila, H., Klöve, B., Welker, J. M., & Ala-aho, P. (2023). The spatiotemporal variability of snowpack and snowmelt water ¹⁸O and ²H isotopes in a subarctic catchment. Water Resources Research, 59, e2022WR033101. https://doi.org/10.1029/2022WR033101
© 2022. American Geophysical Union. All Rights Reserved. This is the peer reviewed version of the following article: Noor, K., Marttila, H., Klöve, B., Welker, J. M., & Ala-aho, P. (2023). The spatiotemporal variability of snowpack and snowmelt water ¹⁸O and ²H isotopes in a subarctic catchment. Water Resources Research, 59, e2022WR033101, which has been published in final form at https://doi.org/10.1029/2022WR033101. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.
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https://urn.fi/URN:NBN:fi-fe202301162895
Tiivistelmä
Abstract
This study provides a detailed characterization of spatiotemporal variations of stable water ¹⁸O and ²H isotopes in both snowpack and meltwater in a subarctic catchment. We performed extensive sampling and analysis of snowpack and meltwater isotopic compositions at 11 locations in 2019 and 2020 across three different landscape features: (a) forest hillslope, (b) mixed forest, and (c) open mires. The vertical isotope profiles in the snowpack’s layered stratigraphy presented a consistent pattern in all locations before snowmelt, and isotope profiles homogenized during the peak melt period; represented by a 1–2‰ higher δ¹⁸O value than prior to melting. Our data indicated that the liquid-ice fractionation was the prime reason that caused the depletion of heavy isotopes in initial meltwater samples prior to the peak melt period. The liquid-ice fractionation was influenced by snowmelt rate, with higher fractionation during slow melt. The kinetic liquid-ice fractionation was evident only in close examination of meltwater lc-excess values, not δ¹⁸O values alone. Meltwater was isotopically heavier and more variable than the depth-integrated snowpack; the weighted mean of meltwater isotope values was higher by 0.62–1.33‰ δ¹⁸O than the weighted mean of snowpack isotope values in forest hillslope and mixed forest areas, and 1.51–6.37‰ δ¹⁸O in open mires. Our results reveal close to 3.1‰ δ¹⁸O disparity between the meltwater and depth-integrated snowpack isotope values prior to the peak melt period, suggesting that proper characterization of meltwater δ¹⁸O and δ²H values is vital for tracer-based ecohydrological studies and models.
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