The delivery of precipitation to southwestern China is largely through monsoon circulation which has evolved with changing insolation forcing during the Holocene and will likely continue to change in response to greenhouse gas increases. Additionally, southwestern China has a long history of human activity including mining, metallurgy, agriculture, and pollution. Here, high-resolution sampling of a sediment core from Lake Xing Yun in the Yunnan Province (24°10N, 102°46E), a drought sensitive lake that behaves as a closed basin, provides a sub-decadal record of changing climate and human activity in the late Holocene. We use δ18O and δ13C measurements of authigenic carbonate precipitated from the lake water and magnetic susceptibility values to document the timing, direction, and magnitude of moisture changes associated with variations in monsoon strength. We use δ13C and δ15N measurements on organic matter and carbon to nitrogen ratios to assess the impact of human activity on the Xing Yun watershed and sediment trace metal concentrations in investigate regional mining and smelting intensity.
The 2,500 year record highlights several transition periods related to both human and climate forcing. The rise of metallurgy and intensive mining practices occurs at 900 AD, much later than historical records indicate. A number of proxies including δ13C values and C/N ratio show a marked shift at 1600 AD, the time in which many Han immigrants from the north settled and worked the land in the Yunnan Province. The most pronounced feature of the record is a rapid transition to a substantially drier climate that took place over 50 years and persisted from 1360-1880 AD as an expression of the Little Ice Age (LIA). This project demonstrates that complex human and climate interactions have been taking place for thousands of years and have the potential to illuminate discontinuities in Chinese historical records and learn lessons that might apply to future climate change.
| Identifer | oai:union.ndltd.org:PITT/oai:PITTETD:etd-04202011-141146 |
| Date | 06 June 2011 |
| Creators | Hillman, Aubrey L |
| Contributors | Patrick Manning, Daniel Bain, Mark Abbott, Michael Rosenmeier |
| Publisher | University of Pittsburgh |
| Source Sets | University of Pittsburgh |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.pitt.edu/ETD/available/etd-04202011-141146/ |
| Rights | restricted, 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 Pittsburgh 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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