A multiple stable isotope record of Late Quaternary limnological changes and chironomid paleoecology from northeastern Iceland |
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| Authors: | Matthew Wooller Yiming Wang Yarrow Axford |
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| Institution: | (1) Alaska Stable Isotope Facility, Water & Environmental Research Center, University of Alaska Fairbanks, Fairbanks, AK 99775, USA;(2) School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, AK 99775, USA;(3) Department of Geology & Geophysics, University of Alaska Fairbanks, Fairbanks, AK 99775, USA;(4) Institute of Arctic and Alpine Research and Department of Geological Sciences, University of Colorado, Boulder, CO 80309, USA |
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| Abstract: | We present results from multiple stable isotope analyses (δ18O of chironomid larval head capsules, chironomid adult thoraxes and other insect remains and δD, δ13C, δ15N of total organic matter—TOM) of a lake sediment core (04-SVID-03) taken from Stora Vidarvatn in northeastern Iceland to
reconstruct past environmental, limnological and δ18O of past lake water changes during the Holocene. Core 04-SVID-03 represents a ∼12,000 cal. yrs BP to present record. Large
magnitude changes in δ18O occurred during the Holocene at the site. Downcore shifts in δ18O of chironomids did not correlate with measurements of the δ13C and δ15N of chironomid head capsules, implying that the δ18O changes were not primarily driven by changes in chironomid diet during the Holocene. The δD of TOM provided a proxy of relative
lake-water δD changes at the site and also showed large magnitude changes during the record. This approach was supported by
analyses of a modern training set where δDTOM analyses were conducted using surface sediments from a suite of freshwater lakes over a large latitudinal gradient. The magnitude
of changes in both the δ18O and δD and the relatively negative δ18O values throughout much of the core suggest that the proxies represent more paleoenvironmental information than solely temperature.
Additional possible influences on lake-water isotopic composition are discussed, including changes in the seasonality of precipitation,
in the patterns of air masses supplying precipitation to Iceland and in the dominant mode of the North Atlantic Oscillation. |
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| Keywords: | Chironomids Stable isotopes Carbon Nitrogen Oxygen Hydrogen |
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