ORGANIC CARBON CYCLING IN LAMINATED SEDIMENTS FROM COASTAL LACUSTRINE AND MARINE ENVIRONMENTS, EASTERN CANADIAN ARCTIC

The study of modern processes and past changes in polar regions is critical due to the close linkages of high latitude environments to the global climate system. The terrestrial organic carbon pool of the Arctic appears to have increased in recent times due to the CO2 fertilization effect brought about by fossil fuels (Sauer 2001). Little is known however about long-term changes in terrestrial carbon cycling under natural climate variations, particularly in coastal lakes and inlets which have undergone glacial-isostatic rebound. Paleoenvironmental proxies, such as microfossil and isotopic analyses have been useful in reconstructing paleovegetation from these settings however recent developments in the use of lipid biomarkers in fossil organic matter provide a relatively new paleoenvironmental indicator (Conte 2003). In this study lipid biomarkers, C/N values, and stable carbon/nitrogen isotopic analyses of laminated lacustrine and marine sediments will be used to understand changes in terrestrial/marine carbon cycling in arctic coastal sedimentary basins. Undisturbed surface cores were recovered from basins on Cornwallis and Devon Island in the central Canadian arctic archipelago. The core records, spanning approximately the last millennium, will allow evaluation of climatic and other environmental influences on organic carbon deposition through the reported Medieval Warm Period, Little Ice Age and 20th Century Warming. Preliminary data from sediment core tops suggest recent increases in both carbon deposition and primary productivity in open marine basins relative to fully emergent land-locked lakes. The total lipid concentration of open marine basins is significantly higher than values from isolated lakes indicative of higher productivity in the oceans. Fatty acids and sterols from lake sediments are being analyzed to determine distinctive shifts in marine and terrestrial organic deposition through time.