@article{ab185767b1e54e60a1c2dde267a94abf,
title = "Isotopic Constraints on Nitrous Oxide Emissions From the US Corn Belt",
abstract = "Agriculture is the dominant source of anthropogenic nitrous oxide (N2O) –a greenhouse gas and a stratospheric ozone depleting substance. The US Corn Belt is a large global N2O source, but there remain large uncertainties regarding its source attribution and biogeochemical pathways. Here, we interpret high frequency stable N2O isotope observations from a very tall tower to improve our understanding of regional source attribution. We detected significant seasonal variability in δ15Nbulk (6.47–7.33‰) and the isotope site preference (δ15NSP = δ15Nα–δ15Nβ, 18.22–25.19‰) indicating a predominance of denitrification during the growing period but of nitrification during the snowmelt period. Isotope mixing models and atmospheric inversions both indicate that indirect emissions contribute substantially (>35%) to total N2O emissions. Despite the relatively large uncertainties, the upper bound of bottom-up indirect emission estimates are at the lower bound of the isotopic constraint, implying significant discrepancies that require further investigation.",
keywords = "Corn Belt, direct emissions, indirect emissions, isotopes, nitrous oxide, regional budget",
author = "Griffis, {T. J.} and Z. Yu and Baker, {J. M.} and Millet, {D. B.}",
note = "This work was supported by grants from the US National Science Foundation (projects 2110241 and 2110430). We thank Alex Frie and Ke Xiao for their technical assistance with the transport models used in this study. The University of Minnesota Supercomputing Institute ( https://www.msi.umn.edu/ ) provided computational support for the atmospheric transport modeling. Calibration of NO isotopes was realized as part of a Transnational Access project supported by the European Commission under the Horizon 2020\u2014Research and Innovation Framework Programme, H2020\u2010INFRAIA\u20102020\u20101, ATMO\u2010ACCESS Grant Agreement number: 101008004. We thank Dr. Joachim Mohn, Empa, Laboratory for Air Pollution/Environmental Technology, D\u00FCbendorf, Switzerland, for providing calibration materials, advice, and comments on an early draft of this manuscript. 2 This work was supported by grants from the US National Science Foundation (projects 2110241 and 2110430). We thank Alex Frie and Ke Xiao for their technical assistance with the transport models used in this study. The University of Minnesota Supercomputing Institute (https://www.msi.umn.edu/) provided computational support for the atmospheric transport modeling. Calibration of N2O isotopes was realized as part of a Transnational Access project supported by the European Commission under the Horizon 2020\u2014Research and Innovation Framework Programme, H2020-INFRAIA-2020-1, ATMO-ACCESS Grant Agreement number: 101008004. We thank Dr. Joachim Mohn, Empa, Laboratory for Air Pollution/Environmental Technology, D\u00FCbendorf, Switzerland, for providing calibration materials, advice, and comments on an early draft of this manuscript.",
year = "2024",
month = nov,
day = "16",
doi = "10.1029/2024GL109623",
language = "English (US)",
volume = "51",
journal = "Geophysical Research Letters",
issn = "0094-8276",
publisher = "John Wiley & Sons, Ltd.",
number = "21",
}