Long‐term carbon storage and hydrological control of CO 2 exchange in tundra ponds in the Hudson Bay Lowland

• Published in: Hydrological Processes
• Main Authors: Macrae, M. L., Bello, R. L., Molot, L. A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2004
• Subjects: Hudson; Hudson Bay; Churchill; Tundra
• Online Access: http://dx.doi.org/10.1002/hyp.1461; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fhyp.1461; https://onlinelibrary.wiley.com/doi/pdf/10.1002/hyp.1461

Abstract Carbon dioxide fluxes and water balance were examined in 43 tundra ponds in the northern portion of the Hudson Bay Lowland near Churchill, Manitoba. Most of the ponds were hydrologically disconnected from their catchments during dry periods throughout the post‐melt season. However, episodic reconnection occurred following large precipitation events where depression storage was exceeded. Significant shifts in pond chemistry were observed following precipitation events, with the degree of CO 2 saturation increasing during these periods. Pond CO 2 concentrations rapidly fell to pre‐event levels following events, suggesting that hydrological connectivity can affect the magnitude and direction of CO 2 gas fluxes in tundra ponds. Atmospheric CO 2 invaded ponds with highly organic sediments for most of the summer, suggesting that terrestrially derived inorganic carbon was insufficient to meet the demands of algal net production. In contrast, ponds with highly mineral sediments continued to evade CO 2 during the summer. In a subset of 11 ponds, long‐term rates of carbon accumulation in sediment ranged from 0·6 to 2·2 mol C m −2 year −1 . Very strong correlations existed between average sediment accumulation rates and pond perimeters and basin areas suggesting that peat may be a major source of sediment carbon. Aeolian transport is also a potentially large source of sediment carbon. Copyright © 2004 John Wiley & Sons, Ltd.