Ice Core Chemistry: Enhanced Sea Ice Proxy and Micrometer Resolution Analysis
This dissertation is in two parts. The first presents an expanded examination of a proxy for sea ice extent around Antarctica. Maximum and mean concentrations of sodium, non-sea salt sulfate, and methylsullfonate are measured on six ice cores. Four cores were collected as part of the International T...
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DigitalCommons@UMaine
2013
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| Online Access: | https://digitalcommons.library.umaine.edu/etd/2015 https://digitalcommons.library.umaine.edu/context/etd/article/3048/viewcontent/SneedSB2013_OCR.pdf |
| Summary: | This dissertation is in two parts. The first presents an expanded examination of a proxy for sea ice extent around Antarctica. Maximum and mean concentrations of sodium, non-sea salt sulfate, and methylsullfonate are measured on six ice cores. Four cores were collected as part of the International Trans-Antarctic Scientific Expedition (ITASE), one collected at South Pole, and one drilled at Siple Dome. Sea ice data are retrieved from the Australian Antarctic Data Centre. Correlations are calculated between maximum and mean chemistry and maximum, mean, and minimum sea ice extent in 36-10° sectors around the Antarctic continent. Correlations vary on a temporal scale due to seasonality, on a spatial scale as a result of atmospheric circulation patterns, and as a positive or negative correlation due to relative influences of local site conditions, source strength, and transport efficiency. The second section of this dissertation is the development of a laser ablation inductively coupled mass spectrometry LA-ICP-MS) method for the analysis of ice cores. The new system builds on work initially completed at the Alfred Wegener Institute, Bremenhaven, Germany. Improvements include a cold cell that can hold up to one meter of ice which reduces sample preparation time, reduced sample resolution, and a simplified technique to calibrate between measured intensity and concentration. Validation of the new system is carried out by testing the repeatability of measurements, identification of annual signals in the chemical record preserved in ice cores at depths where the original sample resolution prohibited identification, comparison of LA-ICP-MS concentrations with original measurements, examination of previously determined conductivity and particle concentration relative to LA-ICP-MS elemental measurements. Ice cores are from Greenland, South Pole, and the Swiss Alps. Selected co-authored papers are included as supplemental material as an appendix in pocket. |
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