Triple oxygen isotope distributions in meteoric waters, plant waters and laboratory precipitated calcite

Triple oxygen isotopes;Paleoclimate;Stable isotope geochemistry;Carbonates;Meteoric water;Plant water;Earth & Planetary Sciences

Li, Shuning

Johns Hopkins University

关键词: Triple oxygen isotopes;    Paleoclimate;    Stable isotope geochemistry;    Carbonates;    Meteoric water;    Plant water;    Earth & Planetary Sciences;   

Others  :  https://jscholarship.library.jhu.edu/bitstream/handle/1774.2/38025/A2.2%20VSMOW-SLAP%20normalization.xlsx?sequence=3&isAllowed=y

瑞士|英语

来源: JOHNS HOPKINS DSpace Repository

【 摘 要 】

Triple oxygen isotope variations in meteoric waters demonstrate kinetic fractionation effects in hydrologic and biogeochemical cycles on the Earth surface. Recent advances in the ability to measure small differences in the deviation from expected relationships between 18O/16O and 17O/16O ratios (17O-excess or Δ17O) in waters and minerals provide the opportunity to extend the utility of triple oxygen isotopes to hydrologic and paleoclimatological studies. The major objective of this thesis is to explore the variation of triple oxygen isotope deviation in meteoric and plant waters and its response to different kinetic fractionation processes that are functions of environmental conditions. The first detailed study in this thesis reports on the variation in Δ17O of tap waters from the U.S. and provides a predictive map for Δ17O of meteoric waters in the United States. This is the first continental-scale study of variation in Δ17O of meteoric waters and it documents the influence of latitude on Δ17O of meteoric waters. The second study explores triple oxygen isotope fractionation associated with evapotranspiration by presenting new Δ17O data on plant waters from central Kenya and comparing these data to modeled results. This chapter provides a framework that will facilitate a more accurate view of the Δ17O variation in plant waters that contribute to triple oxygen isotope variations in the atmosphere, hydrosphere and biosphere. Lastly, the thesis includes Δ17O data from an experimental study on synthetic carbonates that was performed to evaluate triple oxygen isotope fractionation during the precipitation of calcite from water. In sum, this dissertation provides a suite of baseline datasets that will be critical for interpreting triple oxygen isotopes in water and geologic materials in studies of environmental conditions on the past and present Earth.