Date of Award

Spring 5-10-2019

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Quaternary and Climate Studies

Advisor

Paul A. Mayewski

Second Committee Member

Andrei Kurbatov

Third Committee Member

Alexander More

Abstract

Ice core archives provide the most direct and detailed evidence of past climate and atmospheric conditions, however, traditional ice core sampling (~1-cm resolution) does not provide significant environmental detail in low accumulation and compressed ice core sites. Advances in ice core sampling techniques allows for the capability to detect environmental signals in compressed ice found deeper in the core using finer sampling resolutions. Using the Climate Change Institute’s W.M. Keck Laser Ice Facility non-destructive, ultra-high-resolution, continuously sampled laser ablation-inductively coupled plasma-mass spectrometer (LA-ICP-MS) sampling on ice cores, we are able to resolve proxies for both climatological and meteorological scale events while preserving the core (Sneed et al., 2015). Ice-core analysis by LA-ICP-MS provides resolution (121-μm) necessary to achieve a robust measure of variability for select glacio-chemical species preserved in ice cores. Elements are measured using single element or multi-element line scans, producing a continuous, miniscule laser ablated profile along the length of the ice sample. We measure select glacio-chemical species using the LA-ICP-MS sampling technique for 20-m of the Colle Gnifetti ice core, drilled in the Swiss-Italian Alps, and ~0.7-m of the Allan Hills ice core, drilled in Antarctica. These two ice cores, though drilled at quite different locations, demonstrate the advantages of ultra-high-resolution sampling for ice core records. For the Allan Hills ice core, we can detect environmental signals and potentially annual layers at the depth ~125-m, which is established as an age of ~1-Ma old (Higgins et al., 2015). For the 2013 Colle Gnifetti ice core, we established a strong correlation between equivalent species from the LA-ICP-MS data and traditionally sampled ICP-MS and revealed climate proxies related to Saharan dust, Atlantic moisture, and anthropogenic inputs that can extend our understanding of air mass sources transported to the European Alps region over the last ~2000 years. Since the Colle Gnifetti LA-ICP-MS ice core record is the longest, multi-element ultra-high-resolution analysis yet constructed, yielding a total of ~5,000,000 samples, we developed a computer program using Python to easily pre-process the extensive samples collected to generate a structured compilation of data. This program allows the user to input files containing the vast amounts of machine output data by the LA-ICP-MS system along with lab notes, to create a more functional output with graphs, figures, statistical information and analysis reports. This thesis encompasses the application of the LA-ICP-MS analysis on two diverse ice cores and the development of a novel computer program to assist in data processing from the LA-ICP-MS system output.

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