AUTHOR=Steig Eric J. , Jones Tyler R. , Schauer Andrew J. , Kahle Emma C. , Morris Valerie A. , Vaughn Bruce H. , Davidge Lindsey , White James W.C. TITLE=Continuous-Flow Analysis of δ17O, δ18O, and δD of H2O on an Ice Core from the South Pole JOURNAL=Frontiers in Earth Science VOLUME=9 YEAR=2021 URL=https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2021.640292 DOI=10.3389/feart.2021.640292 ISSN=2296-6463 ABSTRACT=

The δD and δ¹⁸O 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 δD and δ¹⁸O, is also commonly used to provide information about the oceanic moisture sources where polar precipitation originates. Measurements of δ¹⁷O and “¹⁷O excess” (Δ¹⁷O) 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 Δ¹⁷O. Here, high-precision measurements are reported for δ¹⁷O, δ¹⁸O, and δD 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 δ¹⁷O and δ¹⁸O, and ∼1‰ for δD. For Δ¹⁷O, 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 Δ¹⁷O 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).