Date of Award

Summer 8-22-2019

Level of Access

Open-Access Thesis

Degree Name

Doctor of Philosophy (PhD)

Department

Earth Sciences

Advisor

Paul A. Mayewski

Second Committee Member

Andrei Kurbatov

Third Committee Member

Kirk Maasch

Additional Committee Members

Jefferson Simoes

Daniel Dixon

Abstract

The research presented in this dissertation utilizes high-resolution records of major and trace elements, major ions, and stable water isotopes covering the last ~2000 years from the SPRESSO South Pole ice core to reconstruct past climate variability and evaluate anthropogenic impacts. The dissertation is in three parts. The first section demonstrates major reorganization of atmospheric circulation during the period 1400-1700 CE, and shows that this atmospheric reorganization occurred in two steps: ~1400-1425 CE and ~1650-1700 CE. Major declines in dust and SO42- concentrations are observed ~1400 CE suggesting poleward contraction and intensification of westerly air flow. The changes in stable water isotopes, deuterium excess, NO3- concentration and accumulation rate characterize a second shift in atmospheric reorganization between 1650-1700 CE. The period since ~1650 CE is characterized by increased marine air mass incursions to South Pole, reduction of the katabatic winds, a poleward shift in the moisture source, and a sea ice decrease in the Weddell Sea. The second part of the dissertation presents a high-resolution (~9 samples/year), continuous record of natural and anthropogenic source arsenic (As) deposition over the last ~2000 years. We show that volcanic and terrestrial biogenic emissions are a major natural source for As. We suggest that early human smelting activities could have contributed to the As deposition as early as 225 CE. The most significant anthropogenic source As enrichment in the record, starting in 1975 CE, is associated with increased copper production in Chile and at least partially to coal combustion from throughout the Southern Hemisphere. The third part of the dissertation describes a record of barium deposition at the South Pole. Significant enrichment observed since 1980 CE is attributed to local pollution from activities at Amundsen-Scott South Pole Station.

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