Why the Arctic?
The Arctic is warming twice as fast as the rest of the planet. Warmer temperatures at northern latitudes have led to increased sea ice recession, decreased snow and ice cover on land, and increased areas of frozen ground beginning to thaw which is expected to have dramatic impacts on energy development, national security, social and environmental sustainability, and global ecosystem functioning.
Arctic soils contain over twice as much carbon as what can be found in the atmosphere. This is because of environmental conditions (short summers and long, cold, dark winters) that have slowed the decomposition of dead plants and animals--soil organic matter.
As the ground continues to thaw due to warming, this carbon-rich organic matter will suddenly become available to soil microbial communities for decomposition. The process of breaking down this previously frozen material could irreversibly release massive amounts of carbon dioxide and methane, two of the most potent greenhouse gases contributing to global warming, into the atmosphere thereby creating an irreversible positive feedback loop. This is one reason why the Arctic is often referred to as a “tipping point."
However, thawing organic matter may also release important nutrients--mainly nitrogen--into the soil which could promote plant growth and productivity, or carbon intake via increased photosynthesis rates. This would create a negative feedback to the effects of warming, and could help maintain these soils as a 'sink' for atmospheric carbon.
Figuring out which of these processes is more likely to occur, and understanding what controls these processes, is important to ecosystem and global scale models that predict how our climate is going to change in the future. With more detailed data, and therefore more reliable models, scientists can then work with policy makers to make more informed decisions about our energy and environmental future both in the Arctic and around the world.
Where and how does chemistry fit in to all this?
Since nitrogen is limited in these systems, as the organic matter thaws and warms, it's thought that both plant and microbial communities will compete for the organic nitrogen that is released. We still don't understand what controls this competition and how it may impact the larger ecosystem.
How much organic nitrogen can be found in these systems? What forms of organic nitrogen are available to either the plant or microbial communities? Do certain plants, or microbes, prefer certain forms of organic nitrogen over others? How does the chemical composition, plant uptake, or microbial decomposition of this 'pool' change over time, or under warming conditions?
My research uses a combination of high-throughput, highly selective and sensitive techniques to measure organic nitrogen availability in these systems. The goal of my dissertation work is to develop a robust, high-performance mass spectrometry workflow that will characterize and monitor how the pool of soil organic nitrogen varies across the landscape, with soil depth, and under different warming conditions. This data will then be used to help improve the predictive capabilities of ecosystem and climate models developed by the NGEE-Arctic modeling team.