Water Resources Research Act Program

Details for Project ID 2019AK016B

Statistical Approach to Photochemical Reactivity of Sub-Arctic Permafrost Natural Organic Matter and its Implications of Surface Water Biogeochemistry

Institute: Alaska
Year Established: 2019 Start Date: 2019-05-15 End Date: 2019-12-30
Total Federal Funds: $15,000 Total Non-Federal Funds: $30,000

Principal Investigators: Kristin R. Gagne

Abstract: Permafrost is earthly material that has been frozen for two consecutive years. As temperatures increase permafrost is at an amplified susceptibility to thaw releasing natural organic matter (NOM). NOM is a complex, carbon-rich heterogeneous mixture whose composition depends on inputs from the environment, ie plant decay and microbial activity. Permafrost contains approximately 7 times more carbon than permafrost-free soils and waters at 750-950 Gt (Romanovsky 2007). Interior Alaska has yedoma permafrost formed in late pleistocene era, which has an increased potential to produce CH4 and CO2 upon thaw and microbial degradation. This is due to yedoma permafrost being known for its high concentrations of sequestered organic carbon, ranging from 2-20% (Abrams 2015, Dutta 2006). For example, Goldstream Lake has recorded an annual CH4 emission of 25 g/m2yr and an annual CO2 emission of 1600 g/m2yr, which is 6-fold higher than other lakes (SepulvedaJauregi 2015). Not only will the permafrost carbon reservoir increase CH4 and CO2 in the atmosphere, but it will also release as dissolved organic carbon into surface waters affecting the water chemistry of the area. The mobilized carbon pool upon thaw is poorly understood for both its chemical composition and reactivity. This study will assess permafrost NOM and its influence on surface waters and water quality. Two questions will be investigated, assessing the 1) composition and reactivity of permafrost NOM, and 2) the influence of permafrost on water quality in a boreal residential watershed. Preliminary results indicate permafrost NOM has a different photochemical reactivity than surface water NOM and cannot be lumped into one homogeneous chemical composition. Additionally, at the end of year one of seasonal sampling we observed a potential permafrost marker by fluorescence. Two additional years of sampling has been obtained but unfortunately, this data set has not been dissected to determine other potential permafrost markers. It is the goal of this project to statistically dissect and interpret over 200 samples from surface waters in a yedoma permafrost underlain residential watershed, for which the 6-fold CH4 and CO2 emissions are recorded. In order to conclude on permafrost influence upon the surface water through its fate and reactivity the determination of permafrost NOM composition is a priority in a warming climate in sub-Arctic. Using statistics to back conclusions is important for any research but especially for this project as it will allow for a better understanding of how permafrost NOM will impact the global carbon cycle specifically in surface water chemistry, through trace metal analysis and optical properties.