EESS Winter Seminar Series - Kristie Boering, Professor, Chemistry & Earth and Planetary Science, University of California, Berkeley
EESS Winter Seminar Series - Kristie Boering, Professor, Chemistry & Earth and Planetary Science, University of California, Berkeley, "Top-down and bottom-up: the isotopic composition of atmospheric nitrous oxide since 1940", Abstract: Increases in atmospheric N2O since the industrial revolution are of concern given its importance as both a greenhouse gas and a precursor of nitrogen oxides that play an important role in the balance of ozone in the stratosphere. However, the magnitude and geographic distribution of nitrous oxide sources, and how they have changed over time, is uncertain. A key unknown is the influence of the stratospheric circulation, which brings air depleted in nitrous oxide to the surface. In this talk, measurements of the nitrogen and oxygen isotopic composition of atmospheric N2O will be presented which demonstrate that temporal and spatial variations are detectable and aid in partitioning atmospheric variations in N2O into its various sources and sinks and confirm that the rise in atmospheric nitrous oxide levels is largely the result of an increased reliance on nitrogen-based fertilizers. Complementary field-scale and laboratory microbial measurements will also be presented, with a view towards better coordinating "top down" vs "bottom up" approaches to quantifying and monitoring N2O sources.