COI Funded Project: The Dynami The Dynamic Land/Sea Margin: Links between Climate Change, Permafrost Stability and Terrestrial Organic Carbon Export from the Mackenzie River, Canadian Arctic Exchange c Land/Sea Margin
Project Funded: 2005
Key Words: Arctic Ocean, Carbon, Nearshore Processes, Climatology, Sedimentology
Arctic coastal environments have been identified as among the most vulnerable regions to anthropogenically-driven climate change. Given this, it is important to fully understand the interplay between the natural processes that maintain the prevailing conditions in the Arctic , and to determine the sensitivity of these processes to anthropogenically-driven perturbation in order to better predict how such future changes may affect this region. The Arctic Ocean receives input from many major and minor rivers on the Eurasian and North American continents. The collective drainage area of these rivers contains half of the global soil carbon inventory and drain low-lying wetland tundra and underlying permafrost soils rich in organic carbon (OC). The rivers entrain large quantities of these terrigenous materials in their suspended loads, and deliver them to shallow deltas and shelves covered by ice for most of the year. Although the widespread permafrost soils in the Arctic rim have the ability to retain terrestrial OC for many millennia, evidence indicates that one consequence of the global warming trend is rapid permafrost destabilization, and the abrupt release of carbon stored in this vast reservoir to the oceans and atmosphere. In order to establish whether this process is underway, and to evaluate its impact on biogeochemical processes on Arctic shelves, it is important that we examine current and past supply of terrigenous OC to Arctic river systems. We predict that permafrost destabilization will result in the release of old OC. Whether this is in fact the case remains unclear, as does the ultimate fate of this terrestrial OC. We hypothesize that the large scale retreat of permafrost soils will manifest itself in downstream reservoirs as an increased flux of old carbon. We propose to collect sediment cores from small “stranded” lakes in the Mackenzie River Delta, and to evaluate their utility as historical records of past permafrost stability by assessing variations in the age and flux of terrestrial OC. In late summer, we will stage a two-week field program from Inuvik on the Tuktoyaktuk Peninsula . After a preliminary chronology for the cores has been established, we will submit sediment samples for bulk OC radiocarbon analysis at the NOSAMS facility in order to gain a first assessment of potential variations in OC age from the pre-industrial period to the present-day that would indicate changes in soil OC dynamics associated with permafrost stability. Assuming we are successful in establishing robust chronologies and preliminary 14C signatures for these lake sediments, we will then be well positioned to write a compelling proposal to NSF Arctic Natural Sciences to explore these records in detail using molecular 14C techniques, and to compare and contrast records from other drainage basins in the Arctic.
Originally published: January 1, 2005