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Full text release has been delayed at the author's request until August 03, 2026

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Carbon and Hydrogen Isotopes of Diatom Derived C20 Highly Branched Isoprenoid (HBI) in North American Lakes

Naake, Hans
http://orcid.org/0009-0000-1878-1958
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1721230442729165

Abstract Details

2024, MS, University of Cincinnati, Arts and Sciences: Geology.
The hydrogen isotopic composition (δ2H) of lipid biomarkers extracted from lake sediment serves as a valuable tool for tracking changes in the hydrologic cycle by reflecting changes in the δ2H of their source water. However, interpreting these changes is complicated by the mixture of terrestrial and aquatic lipids preserved in lake sediments, which present δ2H values influenced by different source waters (i.e. precipitation and lake water). Highly branched isoprenoids (HBI) produced by diatoms are suggested as a proxy for lake water hydrogen isotopic composition (δ2Hlw) that avoid terrestrial interferences. The controls on hydrogen isotope fractionation between HBI and its lake water source (ε2HHBI/lw) must be better constrained to improve the utility of HBI as a proxy for δ2Hlw. Here we measure ε2HHBI/lw across a broad study area comprising 48 lakes spanning 10 US states. We analyzed sediment, water filter, and sediment trap samples to evaluate the consistency of ε2HHBI/lw across the study area and identify factors controlling its variability. We observed a consistent and significant disparity in ε2HHBI/lw between sediment and water filter samples, suggesting that sedimentary ε2HHBI/lw values are not solely dictated by the hydrogen isotopic composition of HBI (δ2HHBI) in the water column during the sampling season (May-June). Furthermore, consistent with prior smaller-scale studies, we observed a standard deviation of ±30‰ in ε2HHBI/lw across the study area, comparable to that of widely accepted precipitation proxies such as plant waxes. These results demonstrate that δ2HHBI can be used to track changes in δ2Hlw through time. They also show that the effectiveness of δ2HHBI as a tool for reconstructing paleohydrology can be improved by developing a set of criteria to enable carful site selection that targets lakes with more consistent ε2HHBI/lw values, which are best suited for such studies.
Aaron Diefendorf, Ph.D. (Committee Chair)
Dylan Ward, Ph.D. (Committee Member)
Thomas Lowell, Ph.D. (Committee Member)
43 p.
Geology
Diatom; Isotopes; Lakes; Hydrogen; Carbon; Highly Branched Isoprenoid

Recommended Citations

Citations

  • Naake, H. (2024). Carbon and Hydrogen Isotopes of Diatom Derived C20 Highly Branched Isoprenoid (HBI) in North American Lakes [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1721230442729165

    APA Style (7th edition)

  • Naake, Hans. Carbon and Hydrogen Isotopes of Diatom Derived C20 Highly Branched Isoprenoid (HBI) in North American Lakes. 2024. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1721230442729165.

    MLA Style (8th edition)

  • Naake, Hans. "Carbon and Hydrogen Isotopes of Diatom Derived C20 Highly Branched Isoprenoid (HBI) in North American Lakes." Master's thesis, University of Cincinnati, 2024. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1721230442729165

    Chicago Manual of Style (17th edition)

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© 2024, all rights reserved.
This open access ETD is published by University of Cincinnati and OhioLINK.
Release 3.2.12