HR: 15:25h
AN: PP53A-08    [Abstracts]
TI: Late Quaternary Environmental Changes Inferred from the stable Oxygen Isotope Composition of Aquatic Insects (Chironomidae: Diptera) and Stable Hydrogen Isotope Composition of bulk sediments from Idavain Lake, Southwest Alaska
AU: * Wang, Y
EM: ftyw@uaf.edu
AF: Department of Geology & Geophysics, University of Alaska Fairbanks, Reichardt Building, 900 Yukon Drive P.O. Box 755780, Fairbanks, AK 99775, United States
AU: * Wang, Y
EM: ftyw@uaf.edu
AF: Alaska Stable Isotope Facility, Water and Environmental Research Center, University of Alaska Fairbanks, 306 Tanan Loop Duckering Building University of Alaska Fairbanks PO Box 755910, Fairbanks, AK 99775, United States
AU: Finney, B
EM: finney@peakpeak.com
AF: Institute of Marine Science/School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, 245 O'Neill Bldg. PO Box 757220 University of Alaska Fairbanks, Fairbanks, AK 99775-7220, United States
AU: Wooller, M J
EM: ffmjw@uaf.edu
AF: Alaska Stable Isotope Facility, Water and Environmental Research Center, University of Alaska Fairbanks, 306 Tanan Loop Duckering Building University of Alaska Fairbanks PO Box 755910, Fairbanks, AK 99775, United States
AU: Wooller, M J
EM: ffmjw@uaf.edu
AF: Institute of Marine Science/School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, 245 O'Neill Bldg. PO Box 757220 University of Alaska Fairbanks, Fairbanks, AK 99775-7220, United States
AB: Several techniques are available to examine the isotopic composition of historic lake waters, providing data that can subsequently be used to examine environmental changes. Recently-developed techniques are the stable oxygen isotope analysis of subfossil chironomid (Diptera: Chironomidae) head capsules (mostly chitin) preserved in lake sediments and stable hydrogen isotope analyses directly on bulk sediments. An advantage of using δ¹⁸O of chironomids is that the chitinous chironomid headcapsules preserve well in lake sediments, retaining the stable oxygen isotope signature of the lake in which they lived. An advantage of δD analyses of bulk sediments is that a sediment core can be analyzed relatively easily and when the %C (total organic carbon) and %H profiles correlate the data can be used to infer past δD changes of the organics in the sediments. We present results from these analyses of a lake sediment core from Idavain Lake (58°46'N, 155°57'W, 223m above sea level) in southwest Alaska in concert with other paleolimnological proxies, including δ¹⁵N, δ¹³C, LOI, magnetic susceptibility, organic content and opal concentrations for a better understanding of paleolimnological changes since deglaciation for the region. Our preliminilary result shows that downcore shifts of δ¹⁸O analyzed from chironomid head capsules coincide well with LOI and pollen changes. The δD of sediments and TOM showed large magnitude changes and reflected the relative lake level changes during the record. This study aim to test the correlation between stable isotope analyese on chiornomid head capsules, lake water, and bulk sediments. In the addition, our study will add to the relatively small database of paleoenvironmental reconstructions from terrestrial sites in Southwest Alaska.
DE: 4870 Stable isotopes (0454, 1041)
DE: 4942 Limnology (0458, 1845, 4239)
DE: 4950 Paleoecology
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting