Identifying Potential Carbon Flux Responses to Shifting Hydroecological and Climactic Regimes in the Peace-Athabasca Delta

• Main Author: Light, Caleb W.
• Format: Text
• Language: unknown
• Published: Scholars Commons @ Laurier 2010
• Subjects: Environmental Indicators and Impact Assessment; Physical and Environmental Geography; Peace-Athabasca Delta; Two Ponds; Lake Athabasca
• Online Access: https://scholars.wlu.ca/etd/961; https://scholars.wlu.ca/context/etd/article/1960/viewcontent/MR64351.PDF

The CO2 flux response of organic carbon stored in lake sediments and littoral peat contained in sensitive, northern wetlands may contribute to accelerating atmospheric CO2 concentrations. Temperature and moisture conditions are important variables that affect the rate and quantity of CO2 released to the atmosphere from organic matter stored in lake sediments and peat. Antecedent hydroecological conditions also influence the direction and magnitude of CO2 fluxes to the atmosphere in a changing environment. To better understand and characterize the role of antecedent conditions on CO2 fluxes, this study combines paleolimnological reconstructions with laboratory incubations of littoral peat and lake sediment from two ponds in the Peace - Athabasca Delta (PAD) in Alberta to (1) investigate the role that past and present hydrological conditions plays on the amount and lability of stored organic carbon to oxidation and respiration potentials and (2) evaluate potential production of CO2 in light of anticipated future hydroecological conditions. Lake sediment geochemical records from a currently closed-drainage site (PAD 1) provide evidence for a three-phase hydrological history spanning the last -600 years, consistent with other independently identified climatic intervals in the PAD. Bulk organic carbon and nitrogen elemental and isotopic analyses of lake sediment organic matter and reconstruction of lake water 8 O from cellulose oxygen isotope analyses reveal periods of hydrological connectivity to Lake Athabasca during the Little Ice Age (LIA) high-stand. Low 513Corg, high C/N and variable but elevated 5180|W values from the beginning of the record to -1600 CE, align with the Medieval Period (MP), when lower water levels characterized the central interior of the PAD and this site would have been a closed-drainage basin. A shift to higher 513Corg, lower and constant C/N and lower 5 0]w values occur during the LIA, suggesting that elevated Lake Athabasca water levels would have been capable of inundating this basin ...