B14A-03
Incomplete Denitrification Causes Rapid Nitrous Oxide Cycling in the Oceanic Oxygen Minimum Zones
Monday, 14 December 2015: 16:30
2002 (Moscone West)
Andrew R Babbin1,2, Bess B Ward2 and Roman Stocker3,4, (1)Massachusetts Institute of Technology, Civil and Environmental Engineering, Cambridge, MA, United States, (2)Princeton University, Geosciences, Princeton, NJ, United States, (3)ETH Zurich, Zurich, Switzerland, (4)Massachusetts Institute of Technology, Cambridge, MA, United States
Abstract:
Nitrous oxide (N2O) is a powerful greenhouse gas and a major cause of stratospheric ozone depletion, yet its sources and sinks remain poorly quantified in the oceans. We used isotope tracers to directly measure N2O reduction rates in the eastern tropical North Pacific. Because of incomplete denitrification, N2O cycling rates are an order of magnitude higher than predicted by current models in suboxic regions, and the spatial distribution suggests strong dependence on both organic carbon and dissolved oxygen concentrations. Furthermore, N2O turnover is 20 times higher than the net atmospheric efflux. The rapid rate of this cycling coupled to an expected expansion of suboxic ocean waters implies future increases in N2O emissions.
