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A 2500 Year Lake Sediment Record of Drought and Human Activity From Southwestern China

Hillman, Aubrey L (2011) A 2500 Year Lake Sediment Record of Drought and Human Activity From Southwestern China. Master's Thesis, University of Pittsburgh.

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    Abstract

    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°10'N, 102°46'E), 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.


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    Item Type: University of Pittsburgh ETD
    ETD Committee:
    ETD Committee TypeCommittee MemberEmailORCID
    Committee ChairAbbott, Markmabbott1@pitt.edu
    Committee MemberBain, Danieldbain@pitt.edu
    Committee MemberRosenmeier, Michaelmrosenme@pitt.edu
    Committee MemberManning, Patrickpmanning@pitt.edu
    Title: A 2500 Year Lake Sediment Record of Drought and Human Activity From Southwestern China
    Status: Unpublished
    Abstract: 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°10'N, 102°46'E), 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.
    Date: 06 June 2011
    Date Type: Completion
    Defense Date: 30 March 2011
    Approval Date: 06 June 2011
    Submission Date: 20 April 2011
    Access Restriction: 5 year -- Restrict access to University of Pittsburgh for a period of 5 years.
    Patent pending: No
    Institution: University of Pittsburgh
    Thesis Type: Master's Thesis
    Refereed: Yes
    Degree: MS - Master of Science
    URN: etd-04202011-141146
    Uncontrolled Keywords: China; landscape change; metallurgy; paleoclimate; paleolimnology; trace metals
    Schools and Programs: Dietrich School of Arts and Sciences > Geology and Planetary Science
    Date Deposited: 10 Nov 2011 14:39
    Last Modified: 23 May 2012 15:51
    Other ID: http://etd.library.pitt.edu/ETD/available/etd-04202011-141146/, etd-04202011-141146

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