Interannual Variability in Carbon Export to the Deep Arctic Ocean

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). The effects of anthropogenically-driven climate change are predicted to be most rapidly and most acutely felt in the Arctic. Two major manifestations of this change are a reduction in sea-ice cover and the destabilization of permafrost soils, both of which will likely alter the arctic carbon cycle. In particular, marked changes in terrestrial carbon fluxes to the ocean and in marine productivity seem inevitable but the overall response of the carbon system in the face of rapidly changing hydrographic and biogeochemical conditions remain unknown. Answers to these questions are crucial to our understanding of whether the Arctic will serve as a net carbon dioxide (CO2) source or sink to the atmosphere, as well as how coastal and pelagic ecosystems will be perturbed in response to climate change. This project will conduct a detailed examination of flux, sources, mode of delivery, and fate of carbon exported to the deep Arctic Ocean during two consecutive years that coincided with record sea-ice minima (2007-2009). The core sample suite for this investigation stems from time-series sediment traps deployed on a physical oceanographic mooring array in the Canada Basin. By comparing observed fluxes and geochemical characteristics of particulate organic carbon and related biogenic components during this time interval with observations from a prior, more ice-replete period (2004- 2005), and by comparing fluxes for locations currently under seasonal versus perennial ice cover, this research seeks to determine how biogeochemical fluxes to the deep Arctic Ocean vary in response to sea-ice and hydrographic conditions and identify the sources of particulate organic carbon (POC), and the mechanisms of supply to the deep Arctic Ocean. To do this, multiple geochemical tracer approaches will be combined with biogeochemical flux data and synchronous hydrographic measurements to delineate mechanisms that govern carbon export to the deep basin and establish the provenance of this carbon. This will enabale us to gauge future shifts in this system and predict how the arctic carbon cycle may be modified in the face of the climate changes which have been set in motion.