Soil to Sea: The fate of terrestrial permafrost carbon in aquatic systems

This research focuses on the urgent issue of permafrost thaw in the Arctic and its significant implications for global climate change. Permafrost, a permanently frozen layer on or under the Earth's surface, is thawing rapidly due to increased temperatures in the Arctic, releasing large amounts of carbon that have been stored for thousands of years. This release of carbon could lead to runaway global warming, with potentially devastating consequences for both the environment and society. However, most studies have focused on the gaseous emissions and have neglected the organic carbon that is lost through thaw. This carbon could be buried again in the sediment at the bottom of lakes or the sea, or enter the bacterial food web and end up being consumed, producing CO2, a greenhouse gas, a process known as respiration. Either fate for permafrost organic carbon will have an impact on climate projections for the area, and in other degrading system. My aim is to quantify the loss of organic carbon from permafrost and determine if it is reburied in lake or marine sediment. I will then estimate what has been emitted after respiration to establish the fate of organic carbon lost in permafrost thaw. I have developed a novel Radiocarbon technique known as Ramped Pyroxidation, to analyse bulk organic material to separate sources according to their resistance to breakdown under heat. I then use the radiocarbon age of fractions to attribute them to sources, to identify if permafrost carbon lost in thaw is sequestered in aquatic sediment. I will use the data to build a model to understand the flow and impact of permafrost carbon in aquatic systems, and estimate the proportion of permafrost organic carbon that is respired in the foodweb and released as CO2. By studying the cores of permafrost, lake sediment, and marine sediment, I will track the carbon's journey from the permafrost to the aquatic environment, and ultimately understand its impact on the global carbon cycle. To achieve these goals, the project will involve field expeditions to collect permafrost cores, and lake water and sediment from Toolik Lake Alaska. Project partners will provide marine cores from Prudhoe Bay. As the organic carbon loss from thaw is severely under-studied, it hasn’t been included in climate projection models. This research will highlight the potential for this permafrost carbon pathway to be a major source of emissions if respiration is larger than burial. Overall, this research project addresses a critical gap in our understanding of the impact of permafrost thaw on the global carbon cycle, highlighting the urgency of mitigating the effects of climate change on these sensitive environments.