Pond hydrology and dissolved carbon dynamics at Polar Bear Pass wetland, Bathurst Island, Nunavut, Canada



A large number of wetlands, lakes and ponds exist in northern Canada, Alaska and Siberia, and the hydrologic and ecological processes in these water bodies are now responding to a changing climate. A large wetland, Polar Bear Pass (PBP), situated in the middle of Bathurst Island is considered to be one of the most important ecological sites in the region. Numerous ponds exist at PBP and are connected to their surrounding watersheds by streams and groundwater inflow, receiving varying amounts of water and nutrients. In 2008 and 2009, the representative hydrology of typical ponds at PBP along with their quantity of dissolved organic and inorganic carbon (DOC and DIC, respectively) was evaluated. Pond DOC and DIC loads and composition differ depending on the presence or absence of one or more hydrologic linkages that a pond has with its catchment. Elevated DOC loads were mostly of terrestrial origin and occurred in ponds receiving meltwater from snowbeds and discharge from hillslope creeks. The seasonal shift in connectivity of a pond to its catchment was critical in controlling DOC loads and concentrations. The frequency and duration of summer precipitation had a strong control on pond hydrologic connectivity and elevated the contribution of terrestrial DOC from wetland to ponds, especially ones that were hydrologically connected. The estimated DOC yields from wet meadow catchments highlight their importance as a source of carbon to pond ecosystems downstream. These wetland areas and ponds are potentially significant pools of carbon and are sensitive to future climate changes in permafrost-dominated environments. Copyright © 2012 John Wiley & Sons, Ltd.