HOLOCENE HYDROCLIMATE IN HIGH ARCTIC SVALBARD USING THE HYDROGEN ISOTOPE COMPOSITION OF LEAF WAXES

The Arctic hydrological cycle will likely intensify in the future, with implications for ice sheets and sea level rise. To predict and understand these changes, it is necessary to study the Holocene hydroclimate of the High Arctic, which we have interpreted from preserved leaf waxes in lake sediments. Leaf waxes are part of the protective coating that covers plant leaves and are produced to control moisture loss and protect from pathogens. These hydrocarbons, which are produced by both terrestrial and aquatic plants, are preserved in lake sediment and have been shown to record the hydrogen isotopic composition of plant source water during photosynthesis. The hydrogen isotopic composition of plant source water is controlled by the moisture source, temperature, and air mass trajectories of precipitation, plus evaporative enrichment. We present a Holocene record of the hydrogen isotopic composition of leaf waxes extracted from a sediment core from the closed-basin lake Austre Nevlingen, in northern Svalbard.

Initial results suggest that hydrogen isotopes of terrestrial plant waxes, identified by 28 carbon chain length, and of aquatic plant waxes, identified by 22 carbon chain length, both experience a rapid decrease at the beginning of the Holocene, followed by a ²H-enrichment, and relatively stable values during the middle Holocene. Toward the middle-late Holocene, terrestrial plant waxes are more rapidly and extremely ²H-depleted, indicating a decrease in temperature or a change in moisture sources. After this depletion, terrestrial plant waxes become ²H-enriched, indicating warmer temperatures or a shift to more proximal moisture sources. Finally, at the end of the Holocene, terrestrial leaf wax hydrogen isotopes rapidly decrease and then experience a small increase. We will compare the Austre Nevlingen record to an existing leaf wax hydrogen isotope record from Haklyutvatnet on northwestern Svalbard, which will provide insights into regional similarities and differences and shed light on leaf wax hydrogen isotope interpretations.