Collaborative Research: Isotopic Fingerprinting of Nitrous Oxide Emissions from the United States Corn Belt

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This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). The goal of this research is to increase the understanding of the sources and dynamics of nitrous oxide emissions from the US Corn Belt through a combination of isotopic fingerprinting, tall tower observations, and regional-scale inverse modeling. Nitrous oxide is a long-lived trace gas that contributes to climate warming and the destruction of stratospheric ozone. Agricultural regions are a major source of nitrous oxide to the atmosphere, but large uncertainties exist in the magnitude and pathways of their emissions from these regions. This project will provide new knowledge about nitrous oxide source dynamics that will be critical to designing effective strategies for mitigating nitrous oxide emissions from heterogeneous agricultural landscapes. The objectives of this research project are to: (1) Establish intensive field campaigns to quantify representative isotopic signatures for nitrous oxide (N2O) emissions from agricultural soils, natural soils, and agricultural drainage networks typical of the Corn Belt; (2) Make high-frequency, high-precision tall tower (185 m) observations of N2O isotopocules that will be used in combination with atmospheric transport modeling to characterize the isotopic composition of N2O emissions at the regional scale; and (3) Use a dual-tracer inverse modeling approach that leverages concentration and isotopic constraints to partition N2O emissions into direct emissions from agricultural soils as well as indirect emissions arising from N leaching and volatilization processes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.