Although marine sediments are known "hotspots" of nitrous oxide (N2O) production and emission, current estimates and future projections of this potent greenhouse gas from coastal areas, especially in response to lower levels of dissolved oxygen and increased nitrogen inputs, are an approximation at best. Scientists from the University of Southern California and Woods Hole Oceanographic Institute plan to improve upon these values by determining N2O dynamics at two coastal sites, Sylt, the German Wadden Sea, and Santa Catalina Island, a California Coastal lagoon. To attain their goal, they will carry out in-situ, high resolution microsensor measurements of N2O, oxygen, nitrate, nitric oxide, hydrogen sulfide, pH, redox potential, and temperature in conjunction with sediment and pore water analyses. Some of the sediment cores to be collected will be subjected to changes in oxygen content and nitrate concentrations in the overlying water to determine changes in nitrogen cycling activity and N2O flux as a function of low oxygen or nitrate addition. Using experimental incubations, the isotopic composition of N2O, nitrate, and ammonia will be measured to provide a quantitative estimate of net isotopic flux and N2O cycling processes. The combined use of microprofiling and multi-isotope approaches will provide not only detailed insight into N2O production and flux at these sites, but also yield data for a recently developed metabolic model to simulate and predict N2O dynamics under varying environmental conditions.
Broader Impacts: The research would strengthen the collaboration with German scientists. The proponents plan to create a webpage to discuss the technologies used in their project, as well as the activities taking place during their field trips. One postdoc and one undergraduate student from the University of Southern California would be supported and trained as part of this project.
