Date of Award
Spring 6-15-2025
Document Type
Thesis (Master's)
Department or Program
Earth Sciences
First Advisor
Erich Osterberg
Second Advisor
Meredith Kelly
Third Advisor
Bess Koffman
Abstract
Dust aerosols impact global climate by influencing direct and indirect radiative forcing, serving as cloud condensation nuclei, and supplying trace nutrients to the ocean that affect the marine biological pump. Antarctic ice core dust records show dust deposition changing in step with global climate over the past eight ice-age cycles. However, fewer studies have focused on Antarctic dust deposition during the late Holocene-to-modern period. Notably, 20th-century increases in dust deposition have been observed in ice cores from James Ross Island (JRI) and Dronning Maud Land, with the JRI record hypothesized to reflect desertification and land-use changes in Patagonia. To investigate this dust increase, I test these hypotheses using existing glaciochemical records from a suite of Antarctic ice cores from the South Pole-West Antarctic region over the Common Era. I also investigate this increase by conducting new analyses on archived South Pole Ice Core (SPC-14) samples to better understand the physical and chemical properties of the dust. My combined analysis of existing ice core derived dust records and satellite-based reanalysis data (MERRA-2 Aer-2d) confirm a near tripling of dust deposition within the South Pole-West Antarctic region. I find that the 20th century dust increase is driven primarily by expansion of sheep pastoralism in Patagonia triggering widespread vegetation change and soil erosion. The anthropogenically induced positive shift in the Southern Annular Mode (at ~1955 CE) enhanced the effects of this land use change through amplifying desertification. Novel single-particle and bulk chemical and physical analyses on archived SPC-14 samples were contaminated by small (< 3 µm) aluminum oxide alloy particles. While their origin remains unknown, the absence of these contaminating particles in methodological blanks suggest that they were introduced to the archive samples during storage or transport prior to arriving to the Dartmouth College laboratory facilities. Nevertheless, single particle time-of-flight mass spectrometry (spTOF-ICPMS) shows promise as a useful analytical method in ice core dust studies.
Recommended Citation
Tipton, Lillian D., "Late Holocene to Modern Dust Increases in Antarctic Ice Cores" (2025). Dartmouth College Master’s Theses. 243.
https://digitalcommons.dartmouth.edu/masters_theses/243
