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

本研究的目标是通过同位素指纹、高塔观测和区域尺度逆模型相结合，增加对美国玉米带一氧化二氮排放源和动态的了解。一氧化二氮是一种长期存在的痕量气体，它会导致气候变暖和平流层臭氧的破坏。农业地区是向大气排放一氧化二氮的主要来源，但这些地区排放的数量和途径存在很大的不确定性。该项目将提供有关一氧化二氮源动态的新知识，这对于设计有效的战略以减少异质农业景观的一氧化二氮排放至关重要。本研究项目的目标是：（1）建立密集的实地活动，以量化农业土壤、自然土壤和典型的玉米带农业排水网络中一氧化二氮（N2 O）排放的代表性同位素特征;（2）使高频、高精度高塔（185米）N2 O同位素观测，将与大气传输模型结合使用，以表征N2 O的同位素组成区域一级的排放量;（3）使用双-示踪剂逆向模拟方法，利用浓度和同位素限制将N2 O排放分为农业土壤的直接排放以及氮浸出和挥发过程产生的间接排放。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准。

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.