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1. Measurements of ¹⁸ O ¹⁸ O and ¹⁷ O ¹⁸ O in the atmosphere and the role of isotope-exchange reactions: ¹⁸ O ¹⁸ O AND ¹⁷ O ¹⁸ O IN THE ATMOSPHERE

   https://doi.org/10.1029/2012JD017992  

   Yeung, Laurence Y.; Young, Edward D.; Schauble, Edwin A. (September 2012, Journal of Geophysical Research: Atmospheres)
2. Variability and Controls on δ ¹⁸ O, d‐excess, and ∆′ ¹⁷ O in Southern Peruvian Precipitation

   https://doi.org/10.1029/2020JD034009  

   Aron, Phoebe G.; Poulsen, Christopher J.; Fiorella, Richard P.; Levin, Naomi E.; Acosta, Rene P.; Yanites, Brian J.; Cassel, Elizabeth J. (December 2021, Journal of Geophysical Research: Atmospheres)

   Abstract The isotopic composition of precipitation is used to trace water cycling and climate change, but interpretations of the environmental information recorded in central Andean precipitation isotope ratios are hindered by a lack of multi‐year records, poor spatial distribution of observations, and a predominant focus on Rayleigh distillation. To better understand isotopic variability in central Andean precipitation, we present a three‐year record of semimonthly δ¹⁸O_pand δ²H_pvalues from 15 stations in southern Peru and triple oxygen isotope data, expressed as ∆′¹⁷O_p, from 32 precipitation samples. Consistent with previous work, we find that elevation correlates negatively with δ¹⁸O_pand that seasonal δ¹⁸O_pvariations are related to upstream rainout and local convection. Spatial δ¹⁸O_pvariations and atmospheric back trajectories show that both eastern‐ and western‐derived air masses bring precipitation to southern Peru. Seasonal d‐excess_pcycles record moisture recycling and relative humidity at remote moisture sources, and both d‐excess_pand ∆′¹⁷O_pclearly differentiate evaporated and non‐evaporated samples. These results begin to establish the natural range of unevaporated ∆′¹⁷O_pvalues in the central Andes and set the foundation for future paleoclimate and paleoaltimetry studies in the region. This study highlights the hydrologic understanding that comes from a combination of δ¹⁸O_p, d‐excess_p, and ∆′¹⁷O_pdata and helps identify the evaporation, recycling, and rainout processes that drive water cycling in the central Andes. 

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3. Equatorial Undercurrent Influence on Surface Seawater δ ¹⁸ O Values in the Galápagos

   https://doi.org/10.1029/2022GL102074  

   Conroy, Jessica_L; Murray, Nicole_K; Patterson, Gillian_S; Schore, Aiden_I_G; Ikuru, Ima; Cole, Julia_E; Chillagana, David; Echeverria, Fernando (February 2023, Geophysical Research Letters)

   Abstract Stable isotopes of oxygen (δ¹⁸O) in seawater reflect the combined influences of ocean circulation and atmospheric moisture balance. However, it is difficult to disentangle disparate ocean and atmosphere influences on modern seawater δ¹⁸O values, partly because continuous time series of seawater δ¹⁸O are rare. Here we present a nearly nine‐year, continuous record of seawater δ¹⁸O values from the Galápagos. Seawater δ¹⁸O values faithfully track sea surface salinity and salinity along the equator at 50 m depth. Zonal current velocity within the Equatorial Undercurrent (EUC), directly west of the Galápagos, is strongly correlated with Galápagos surface seawater δ¹⁸O values with a 1‐month lag. Reconstructions of Galápagos seawater δ¹⁸O values could thus provide a window into past variations in the strength of the EUC, an important influence on large‐scale tropical Pacific climate. 

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4. Branching Ratio Measurements for Vacuum Ultraviolet Photodissociation of ¹² C ¹⁶ O

   https://doi.org/10.1021/jp400412n  

   Gao, Hong; Song, Yu; Chang, Yih-Chung; Shi, Xiaoyu; Yin, Qing-Zhu; Wiens, Roger C.; Jackson, William M.; Ng, C. Y. (July 2013, The Journal of Physical Chemistry A)
5. A 600 kyr reconstruction of deep Arctic seawater δ ¹⁸ O from benthic foraminiferal δ ¹⁸ O and ostracode Mg ∕ Ca paleothermometry

   https://doi.org/10.5194/cp-19-555-2023  

   Farmer, Jesse R.; Keller, Katherine J.; Poirier, Robert K.; Dwyer, Gary S.; Schaller, Morgan F.; Coxall, Helen K.; O'Regan, Matt; Cronin, Thomas M. (January 2023, Climate of the Past)

   Abstract. The oxygen isotopic composition of benthic foraminiferal tests (δ18Ob) is one of the pre-eminent tools for correlating marine sediments and interpreting past terrestrial ice volume and deep-ocean temperatures. Despite the prevalence of δ18Ob applications to marine sediment cores over the Quaternary, its use is limited in the Arctic Ocean because of low benthic foraminiferal abundances, challenges with constructing independent sediment core age models, and an apparent muted amplitude of Arctic δ18Ob variability compared to open-ocean records. Here we evaluate the controls on Arctic δ18Ob by using ostracode Mg/Ca paleothermometry to generate a composite record of the δ18O of seawater (δ18Osw) from 12 sediment cores in the intermediate to deep Arctic Ocean (700–2700 m) that covers the last 600 kyr based on biostratigraphy and orbitally tuned age models. Results show that Arctic δ18Ob was generally higher than open-ocean δ18Ob during interglacials but was generally equivalent to global reference records during glacial periods. The reduced glacial–interglacial Arctic δ18Ob range resulted in part from the opposing effect of temperature, with intermediate to deep Arctic warming during glacials counteracting the whole-ocean δ18Osw increase from expanded terrestrial ice sheets. After removing the temperature effect from δ18Ob, we find that the intermediate to deep Arctic experienced large (≥1 ‰) variations in local δ18Osw, with generally higher local δ18Osw during interglacials and lower δ18Osw during glacials. Both the magnitude and timing of low local δ18Osw intervals are inconsistent with the recent proposal of freshwater intervals in the Arctic Ocean during past glaciations. Instead, we suggest that lower local δ18Osw in the intermediate to deep Arctic Ocean during glaciations reflected weaker upper-ocean stratification and more efficient transport of low-δ18Osw Arctic surface waters to depth by mixing and/or brine rejection. 

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