Department Seminar: Jenny Bowen

Title: Climate and land disturbance impacts on molecular-level reactivity & global freshwater carbon

Abstract: The distribution of carbon in natural reservoirs on Earth is rapidly changing as humans burn fossil fuels and disturb land ecosystems.  These activities have been shown to rapidly release carbon that has been stored in soils for decades to millennia (aged carbon) to the atmosphere, where it can exacerbate climate change.  Yet, less is known about how freshwater carbon fluxes to the atmosphere and the ocean will change with these human-caused disturbances, or the molecular-level reactions that are driving these responses.  In this talk, I will share my findings on the molecular-level, mechanistic controls that drive the oxidation of aged organic carbon to carbon dioxide in freshwaters neighboring two ecosystems being disturbed by human activity: arctic permafrost and tropical peatlands.  Using the mechanistic controls identified, I estimate that oxidation of aged permafrost carbon to carbon dioxide in arctic freshwaters will increase net ecosystem carbon loss from thawing permafrost soils by ~10%.  I also estimate that the oxidation of aged peat carbon in Southeast Asian freshwaters following widespread deforestation has decreased regional organic carbon exports to the ocean by ~30%.  Together, these findings improve our ability to predict the effects of climate and land disturbance on marine carbon budgets and the carbon climate feedback.