Hao Kong1, Jintai Lin1*, Yuhang Zhang1, Chunjin Li1, Chenghao Xu1, Lu Shen1, Xuejun Liu2, Kun Yang3,4, Hang Su5,6, Wanyun Xu7
1. Laboratory for Climate and Ocean-Atmosphere Studies, Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing 100871, China
2. College of Resources and Environmental Sciences, National Academy of Agriculture Green Development, China Agricultural University, Beijing 100193, China
3. Ministry of Education Key Laboratory for Earth System Modeling, Department of Earth System Science, Tsinghua University, Beijing 100084, China
4. National Tibetan Plateau Data Center, State Key Laboratory of Tibetan Plateau Earth System and Resource Environment, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China
5. Multiphase Chemistry Department, Max Planck Institute for Chemistry, Mainz 55128, Germany.
6. Department of Environmental Engineering, Tsinghua University, Beijing 100084, China
7. State Key Laboratory of Severe Weather & Key Laboratory for Atmospheric Chemistry of CMA, Institute of Atmospheric Composition, Chinese Academy of Meteorological Sciences, Beijing, 100081, China
*Corresponding author. Email: linjt@pku.edu.cn
Nitrogen oxides affect health and climate. Their emissions, in the form of nitric oxide, from inland waters such as lakes are generally considered negligible and are absent in air quality and climate models. Here we find unexpected high emissions of nitric oxide from remote lakes on the Tibetan Plateau, based on satellite observations of tropospheric nitrogen dioxide vertical column densities and subsequent emission inversion at a fine resolution of 5 km. The total emissions from 135 lakes larger than 50 km2 reach 1.9 metric tons N h-1, comparable to anthropogenic emissions in individual megacities worldwide or the Tibet Autonomous Region. On average, the emissions per unit area reach 63.4 μg N m-2 h-1, exceeding those from crop fields. Such strong natural emissions from inland waters have not been reported, to the best of our knowledge. The emissions are derived from microbial processes in association with substantial warming and melting of glacier and permafrost on the plateau, constituting a previously unknown feedback between climate, lake ecology and nitrogen emissions.
We thank Y. Li and R. Xu for information of the TP, and D. Wu for discussion of nitrogen emission mechanisms. Funding: The Second Tibetan Plateau Scientific Expedition and Research Program grant no.2019QZKK0604; The National Natural Science Foundation of China grant no. 42075175
