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Holocene Paleoenvironmental History from Stable Isotopes in Lake Sediment, North-Central Washington State

Nelson, Daniel B (2005) Holocene Paleoenvironmental History from Stable Isotopes in Lake Sediment, North-Central Washington State. Master's Thesis, University of Pittsburgh. (Unpublished)

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Population growth in the Pacific Northwest has led to increased demand for water resources. Current understanding of the natural cycle of moisture availability is limited, however, by the short duration for which instrumental climate data are available. Here, a detailed paleoenvironmental study from Castor Lake in north-central Washington State is presented to examine the frequency, duration, and magnitude of droughts, lake system dynamics, and other climate events during the past ~16,000 years. The combined use of stable isotope measurements of endogenic carbonate and organic sediment with trace element analysis and standard sedimentological methodologies provides a more coherent basis for understanding environmental change through this period than would be possible through the application of a single technique. Results show that the region was significantly affected by the Younger Dryas cold reversal between approximately 12,500 cal yr BP and 11,500 cal yr BP. The period from approximately 8,200 cal yr BP to 5,900 cal yr BP contains evidence for prolonged aridity, as lake-levels declined and water column stratification broke down. The period spanning the last ~6,000 years is characterized by relative climate stability, but the highly resolved sediment proxy data for this interval reveal several drought events larger than anything experienced in the historic record, with some episodes persisting well over a century. Furthermore, the past fifty-years appear to be anomalously wet in the context of the long-term record obtained from Castor Lake. Preparation for large drought events may therefore be inadequate because water resource allocation laws were written during this interval. Future large-scale drought events are inevitable, however, given the frequency with which they are observed to occur in the past, and the increasing influence of anthropogenic warming.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Nelson, Daniel Bdbn1@pitt.eduDBN1
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairAbbott, Markmabbott1@pitt.eduMABBOTT1
Committee MemberStewart, Brianbstewart@pitt.eduBSTEWART
Committee MemberRosenmeier, Michaelmrosenme@pitt.eduMROSENME
Date: 2 February 2005
Date Type: Completion
Defense Date: 16 November 2004
Approval Date: 2 February 2005
Submission Date: 10 December 2004
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Geology and Planetary Science
Degree: MS - Master of Science
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: carbonate; climate; drought; geology; Holocene; isotope; lake; Pacific Northwest; paleoclimate; PDO; PDSI; sediment; trace element; Washington
Other ID:, etd-12102004-063021
Date Deposited: 10 Nov 2011 20:10
Last Modified: 15 Nov 2016 13:54


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