R/E-24L

Strategic focus area:

Description:

Coastal ecosystems are vulnerable to short term anthropogenic changes such as nutrient loading and longer-term changes such as sea level rise. Together these changes can alter these systems in ways that change the ecosystem services these systems provide. For example, estuaries bury carbon over time which in turn is a major controller for a habitable atmosphere. Carbon can enter estuaries through a number of processes such as photosynthesis, respiration, air-sea exchange, terrestrial runoff, and groundwater input. As it gets buried, it will undergo a series of microbially mediated processes which terminates in the production of methane, a potent greenhouse gas. Methane has been found as gas bubbles in sediments of the Chesapeake Bay and work suggests that a significant amount of it is released to the bottom waters, releasing carbon from the system. One of the main sinks for methane within marine and estuarine sediments is anaerobic oxidation of methane coupled to the reduction of sulfate. Hence the availability of sulfate is a controlling factor for how much methane is oxidized. Sulfate is the second most abundant anion in seawater. I hypothesize here that as sea levels rise due to climate change, saltwater intrusion provides sulfate to these sediments and may counteract the release of methane by enhancing rates of sedimentary anaerobic methane oxidation. To test this hypothesis, I will conduct incubations on sediments with sulfate and temperature amendments, mimicking what might happen with future sea level rise and global climate change. This work will be done in the Patuxent River, a highly eutrophic system. These experiments will provide useful and relevant data to help investigate the impacts of sea level rise and sulfate availability to alter methane cycling.