Greenhouse gas emission from small bog pools in a boreal peatland in Newfoundland, Canada

Akpoguma, Blessing Ivie (2019) Greenhouse gas emission from small bog pools in a boreal peatland in Newfoundland, Canada. Masters thesis, Memorial University of Newfoundland.

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Abstract

Studies on the greenhouse gases (GHG) potential and emissions from peatlands have been studied extensively in recent years due to the increasing atmospheric concentration of GHG and impact on climate change. However, most research estimating GHG emissions and factors regulating these emissions from peatlands are focused on the terrestrial microforms of peatlands. Thus, less is known about the GHG emission potential from peatland pools, which are the aquatic components. I conducted a study in small bog pools during the 2018 growing season to determine the drivers and concentration of CH4 dissolved in pool surface waters using the headspace method. Also, a five-year growing season (2013, 2014, 2015, 2016 and 2018) static floating chamber was used to quantify the variation in GHG flux from pools across the growing seasons. Results showed that pools are supersaturated with CH4 ranging in concentration from 2.32 to 180.98 µmol L-1 , among the highest concentration reported for small inland waters. The super-saturation observed in these pools may have been influenced by several biological, chemical, and physical factors but were best predicted by a relationship with temperature, vegetation, dissolved organic carbon (DOC), and pool surface area. I also found that CO2 flux was significantly different across the years (p < 0.05) in which pools acted as sources during 2013 and 2018 ( [mean] = 23.91 and 7.79 mmol m-2 d -1 respectively) and as sinks in 2014, 2015 and 2016 ( [mean] = -7.41, -8.98 and -9.04 mmol m-2 d -1 respectively). In contrast, pools acted mostly as sources of CH4 to the atmosphere in 2013, 2016 and 2018 and were negligible sinks during 2014 and 2015 ( [mean] = 0.41, 0.00, -0.01, 0.19 and 0.52 mmol m-2 d -1 for years 2013 to 2018 respectively). However, flux of CH4 was not significantly different across the years (P > iv 0.05). Pools acted mostly as negligible sinks of N2O flux, which is typical of ombrotrophic peatlands. N2O flux did not vary among years (p > 0.05). Pool depth was found to be the best predictor of CO2 fluxes, while dissolved organic carbon was found to be the major predictor of CH4 emission. This study shows that the concentration and emission of GHG from bog pools varies depending on climatic conditions and within pool biogeochemistry, therefore bog pools’ GHG emission potential can be influenced in future climate scenarios.

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