Dissolved inorganic carbon and methane in the connected Freshwater Creek, Greiner Lake, and Cambridge Bay system, Victoria Island, Nunavut: Quantifying fluxes and seasonal variations with time-series monitoring

Abstract

Inland waters are important parts of the global carbon cycle and generally emit greenhouse gases to the atmosphere, though there is variation between systems and seasons. Arctic lakes and rivers have unique characteristics like seasonal ice and spring meltwater that influence water biogeochemistry and the movement of greenhouse gases between connected water bodies and across the air-water interface. This study used time-series inorganic carbon and methane monitoring in the connected Greiner Lake, Freshwater Creek, and Cambridge Bay system to quantify greenhouse gas fluxes and characterize seasonal variations. A continuum approach was employed to examine the role of lake ice in moving inorganic carbon and methane across the terrestrial-marine interface during breakup. Working across boundaries included critical review of poetic inquiry as an interdisciplinary method to foster systems thinking and explore facets of uncertainty and knowledge-making complementary to western science methods. The annual exports from Freshwater Creek to the downstream coastal ocean were estimated as 3.12 Gg C y-1 and 848 kg C y-1 in the forms of DIC and CH4 respectively. When normalized to watershed size, Freshwater Creek delivered a dissolved inorganic carbon yield comparable to larger Arctic rivers, which is impressive considering it only flows for part of the year. Most of the annual dissolved inorganic carbon and methane exports were achieved within weeks of spring breakup. Similarly, the highest carbon dioxide and methane emission rates from Freshwater Creek occurred during breakup. Considering rivers as parts of continuums is key in anticipating possible responses to climate change. The over-winter accumulation of gases under the ice at Greiner Lake and the configuration of the lake-river-coastal ocean continuum set up a lake-ice pump that moves greenhouse gases across the terrestrial-marine interface as part of an annual cycle that aligns with the six Arctic seasons. The holistic approach extended beyond the continuum of environments, and poetic inquiry was considered as a method that fosters systems thinking. This project makes the case for incorporating poetic inquiry into natural sciences research to think and work across boundaries, position the researcher within the research workflow, and understand and convey complex interconnections and uncertainties.