Continuous-Flow Analysis of δ17O, δ18O, and δD of H2O on an Ice Core from the South Pole
The δ D and δ 18 O values of water are key measurements in polar ice-core research, owing to their strong and well-understood relationship with local temperature. Deuterium excess, d , the deviation from the average linear relationship between δ D and δ 18 O, is also commonly used to provide informa...
Published in: | Frontiers in Earth Science |
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Main Authors: | , , , , , , , |
Other Authors: | |
Format: | Article in Journal/Newspaper |
Language: | unknown |
Published: |
Frontiers Media SA
2021
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Subjects: | |
Online Access: | http://dx.doi.org/10.3389/feart.2021.640292 https://www.frontiersin.org/articles/10.3389/feart.2021.640292/full |
Summary: | The δ D and δ 18 O values of water are key measurements in polar ice-core research, owing to their strong and well-understood relationship with local temperature. Deuterium excess, d , the deviation from the average linear relationship between δ D and δ 18 O, is also commonly used to provide information about the oceanic moisture sources where polar precipitation originates. Measurements of δ 17 O and “ 17 O excess” (Δ 17 O) are also of interest because of their potential to provide information complementary to d . Such measurements are challenging because of the greater precision required, particularly for Δ 17 O. Here, high-precision measurements are reported for δ 17 O, δ 18 O, and δ D on a new ice core from the South Pole, using a continuous-flow measurement system coupled to two cavity ring-down laser spectroscopy instruments. Replicate measurements show that at 0.5 cm resolution, external precision is ∼0.2‰ for δ 17 O and δ 18 O, and ∼1‰ for δ D. For Δ 17 O, achieving external precision of <0.01‰ requires depth averages of ∼50 cm. The resulting ∼54,000-year record of the complete oxygen and hydrogen isotope ratios from the South Pole ice core is discussed. The time series of Δ 17 O variations from the South Pole shows significant millennial-scale variability, and is correlated with the logarithmic formulation of deuterium excess ( d ln ), but not the traditional linear formulation ( d ). |
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