Increasing concerns over future anthropogenic effects on climate change as a result of increasing greenhouse gases generate concomitant efforts to better characterize recent climate in order to more accurately predict climate in the future. To this end, a multiproxy study of climate variability in western Ireland from lacustrine sediment was undertaken. The interpretation of paleoclimate records derived from lacustrine carbonate minerals is difficult without a good understanding of the mechanisms that generate variation in isotope values of modern surface waters. Variation in surface waters are ultimately incorporated into lacustrine sediment records conflated by temperature. Therefore, a study of the spatial distribution of ä<sup>18</sup>O and äD values of lake and river waters from 144 locations in Ireland has been conducted to provide insight into the behavior of lakes and rivers in Ireland, including source, recycling and loss through evapotranspiration. A 7.6 m sediment core was recovered from Lough Inchiquin that provides evidence for rapid and long-term climate change from the Late Glacial to the Holocene. This was determined using carbon and oxygen isotope analyses of lacustrine calcite as well as carbon from bulk organic sediment fractions. Several significant climate perturbations were identified in the ä<sup>18</sup>O<sub>calcite</sub> record such as the Oldest Dryas, Younger Dryas, and the 8.2 ka cold event. A previously undescribed climate anomaly between 7,300 to 6,700 cal. yr B.P. characterized by low ä<sup>18</sup>O</span><sub>calcite</sub> values with high frequency variability. Variations in carbon isotopes of calcite and bulk organics from the Late Glacial to the Holocene are significant in magnitude (~12) and have similar trends that record temporal shifts in the relative contributions of carbon from the weathering of limestone versus the weathering of terrestrial organic matter. ä<sup>13</sup>C<sub>calcite</sub> and ä<sup>13</sup>C<sub>org</sub> suggest a rapid recovery of terrestrial vegetation following the Younger Dryas. Change in Ää<sup>13</sup>C<sub>calcite - org</sub> documents a rapid increase in exogenous fluxes of carbon into the lake at ~9 ka.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:SSU.etd-04202005-143729 |
| Date | 22 April 2005 |
| Creators | Diefendorf, Aaron F. |
| Contributors | Smol, John, Pratt, Brian R., Patterson, William P., Holmden, Chris, Ansdell, Kevin M. |
| Publisher | University of Saskatchewan |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://library.usask.ca/theses/available/etd-04202005-143729/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Saskatchewan or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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