Rapid N<sub>2</sub>O Formation from N<sub>2</sub> on Water Droplet Surfaces
Qi Jiang, Deming Xia, Deming Xia, Xiaofan Li, Hong Zhang, Rujing Yin, Huaijun Xie, Hong‐bin Xie, Jie Jiang, Jingwen Chen, Jingwen Chen, Joseph S. Francisco
Abstract
Abstract Nitrogen (N 2 ) has long been considered as stable atmospheric reservoir for N element and has a persistence time of hundreds of years. This study reveals that oxygen (O 2 ) at typical tropospheric concentrations can rapidly activate N 2 , leading to substantial production of nitrous oxide (N 2 O), the third most impactful greenhouse gas, at rates approaching 2.83±0.41 ppmv hour −1 catalyzed by ubiquitous water droplets in experimental systems. Notably, ozone (O 3 ), typically consumed by N 2 O in the stratosphere, can further accelerate N 2 O formation. In contrast, the produced N 2 O concentration is below detection limits in the absence of O 2 /O 3 or water droplets. A novel reduction‐then‐oxidation (RTO) mechanism was proposed to account for the rapid formation of N 2 O on the water droplet surfaces facilitated by the cooperation of water droplets and O 2 /O 3 . Further extrapolation indicates that the RTO pathway contributes several Tg N N 2 O annually, far exceeding the most known sources of N 2 O. These findings have broad implications for tracing atmospheric N 2 O sources, enhancing understanding of climate‐O 2 /O 3 interactions, and paving avenues for developing new methodologies for N 2 O synthesis.