Water Resources Research Act Program

Details for Project ID 2018AK140B

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

Institute: Alaska
Year Established: 2018 Start Date: 2018-03-01 End Date: 2019-02-28
Total Federal Funds: $15,000 Total Non-Federal Funds: $30,000

Principal Investigators: Jennifer Guerard, Kristin Gagne

Project Summary: Permafrost is earthly material that has been frozen for two consecutive years. As temperatures increase permafrost is at an increased suseptibility to natural organic matter (NOM) release. Permafrost thaw could have significant ramifications on the global carbon cycle due to the large amount of sequestered NOM that can mobilize. NOM is a complex, carbon-rich heterogeneous mixture whose composition depends on inputs from the environment, e.g., plant decay and microbial activity. Permafrost contains approximately 7 times more carbon than permafrost-free soils and waters, totalling 750-950 Gt globally (Romanovsky 2007). Late pleistocene era yedoma found in portions of interior Alaska (Abrams 2015) contains high organic concentrations ranging from 2-20% organic carbon (Dutta 2006). Lakes underlain by Pleistocene yedoma permafrost also lead to increased methane (CH4) and carbon dioxide (CO2) emissions compared to other lakes in Alaska. For example, Goldstream Lake has recorded an annual CH4 emission of 25 g m-2 yr-1 and an annual CO2 emission of 1600 g m-2 yr-1, which is 6-fold higher than other lakes (Sepulveda-Jauregi 2015). Not only will thawing permafrost lead to increased methane and CO2 in the atmosphere, but it will also release dissolved organic carbon, altering the surface water chemistry of the area. However, the relationship between permafrost thaw and surface water chemistry and reactivity is poorly understood, on both a qualitative and quantitative level. 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 released 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 at the end of year one of seasonal sampling we observed a potential permafrost marker by fluorescence in lakes underlain by yedoma. The determination of permafrost NOM composition is a priority for understanding the fate and reactivity of NOM in a warming climate in the Arctic and sub-Arctic.