ABSTRACT: Quantifying the impacts of arctic warming and permafrost degradation on the organic carbon (OC) budget of the Hudson Bay using river and ocean sediment DOC and lignin biomarkers.

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Abstract

With increased warming in the Arctic, there is the potential for vast amounts of soil organic carbon (SOC) to enter the system and ultimately change the input of terrigenous and petrogenic carbon entering coastal seas. By understanding changes occurring within the carbon cycle we can begin to assess the potential feedbacks that may arise as global temperatures increase. The Hudson Bay region, located mostly below the Arctic Circle, is important tomonitor due to its temperature gradients which influence vegetation, freeze/thaw cycles and ultimately the hydrology and inputs of carbon into the Hudson Bay carbon cycle. Permafrost degradation is therefore an important process that will affect terrigenous sources to the Bay. Thus, we are collecting samples and data to quantify the effect of arctic warming on riverine inputs, hydrology and the organic carbon (OC) budget of Hudson Bay. Samples were collected during the CCGS Amundsen Expedition, which departed from Quebec City on July 2nd of this year. During a four-week period, freshwater samples were collected from 15 major rivers of the Hudson Bay and a permafrost core and soil samples were extracted at a nearby location by helicopter. Water samples were collected for salinity, O18 and trace metals and a submersible pump with attached fi lter plate was used to filter 20 litres through a GF/F filter to collect the particulates and dissolved organic carbon (DOC). Permafrost coring sites were located from the helicopter by identifying thermokarst features such as pingos, frost heaves and specifi c vegetation to optimize success rate for locating permafrost prior to landing. A permafrost corer was used to extract a core and soil samples were also collected along with a profile and site assessment at each site. SOC and particulate organic carbon (POC) stored in permafrost have the potential of being very old and theircontribution to Hudson Bay organic matter is therefore traceable through radiocarbon measurements. These samples were collected to characterize potential sources of carbon according to their d13C and 14C signaturesin biomarkers such as kerogen and lignin phenols. The data will not only identify the apparent 14C ages of OC entering the Hudson Bay carbon cycle but will also create baseline signatures which will be helpful in determiningfuture permafrost inputs into the OC budget. Presently, the analytical process has just begun and samples have been sent away for isotopic analysis.

Bibliography of Canadian Geomorphology