HR: 09:15h
AN: B11B-06    [PDF]
TI: Carbon cycle dynamics in the geologic record: Speleothems as a source for new biogeochemical and paleoclimate information
AU: * Frappier, A
EM: A.frappier@unh.edu
AF: CCRC/EOS & Earth Sci., University of New Hapmshire, Durham, NH 03824
AU: Sahagian, D
EM: dork.sahagian@unh.edu
AF: CCRC/EOS & Earth Sci., University of New Hapmshire, Durham, NH 03824
AB: Many of the key outstanding questions in paleoclimate and biogeochemical cycles involve terrestrial ecosystems. Caves provide an important depositional environment for sedimentary archives of past and present terrestrial environmental changes. Until recently, the tools available to the research community have been appropriate for coarse resolution studies, but have been inadequate to address other important questions such as: 1. How have climate changes affect ecosystem carbon cycling in the past? 2. What is the role of tropical ecosystems in climate change and the global carbon cycle? 3. How does disturbance affect below ground carbon processing and export to groundwater? Recent developments in the use of speleothems as a tool for carbon cycle and paleoclimate studies have opened the door for a fresh look at these perennial questions. Our recent carbon isotopic study of a speleothem from Belize indicates that terrestrial carbon cycling may be more sensitive to interannual climatic variability such as El Nino-Southern Oscillation (ENSO) than previously thought. In this case, the geologic record has revealed carbon cycle sensitivity to climate forcing that has not been instrumentally observable over the same period. A number of other studies have revealed intriguing correlations between the speleothem carbon isotopic record and various Earth system processes such as millennial scale climate variations and land use history. These results suggest that our understanding of speleothems as a biogeochemical tool remains largely unexplored. In order to better understand the utility of the speleothem carbon isotopic record, we are conducting a modern process study at the Belize cave site. This will enable us to calibrate the record preserved in speleothems for exploration of past carbon cycle behavior. Our initial analysis suggests that speleothems faithfully record variations in terrestrial ecosystem biogeochemical processes that are measurable in real time, and are thus a valuable research tool with considerable untapped potential.
DE: 1030 Geochemical cycles (0330)
DE: 1040 Isotopic composition/chemistry
DE: 1615 Biogeochemical processes (4805)
DE: 3344 Paleoclimatology
SC: Biogeosciences [B]
MN: 2003 Fall Meeting