Landcover and Seasonal Hydrological Processes as Controls on the Flux and Composition of Dissolved Carbon in High Arctic Headwater Catchments
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Authors
Pereira, Cedelle
Date
2024-07-29
Type
thesis
Language
eng
Keyword
Hydrology , Permafrost , Carbon , Climate Change
Alternative Title
Abstract
Climate warming is increasing air temperatures, precipitation events and the occurrences of permafrost thaw and disturbances. These changes have the potential to affect organic matter mineralization and weathering rates. Permafrost thaw can result in the release of previously frozen organic carbon in the form of dissolved organic carbon (DOC), which may be converted into carbon dioxide (CO2) through mineralization. Additionally, the exposure and warming of permafrost soils due to disturbances and thawing can enhance mineral weathering by carbonic acid, a process that converts atmospheric CO2 into dissolved carbonate species. Therefore, this weathering process has the potential to counterbalance the release and mineralization of organic carbon. However, there is limited research on the potential of weathering to consume CO2 in the High Arctic.
To address this knowledge gap, this study examines seasonal carbon fluxes in three headwater catchments at the Cape Bounty Arctic Watershed Observatory (CBAWO), which represent different land cover types: wet sedge, mesic tundra, and permafrost disturbance. The disturbed stream exhibited higher concentrations of dissolved inorganic carbon (DIC), whereas the mesic tundra and wet sedge streams were dominated by dissolved organic carbon (DOC). Despite lower DIC concentrations, the mesic tundra catchment showed significantly higher DIC fluxes compared to the disturbed site, primarily due to its higher and sustained discharge. The optical properties of dissolved organic matter (DOM) indicate that DOM from the disturbed site was fresher compared to the vegetated sites, suggesting that DOM from disturbed sites is likely more structurally labile. Therefore, as the Arctic continues to warm, the balance of the impacts of increasing weathering, and increases in the flux of DOC and their potential feedbacks on atmospheric CO2 will depend on both the extent and nature of disturbances, as well as their net impact on hydrology.
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ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
Attribution-NonCommercial-NoDerivatives 4.0 International