Atmospheric N2O Observations Suggest Shifting Regional Emission Influences in Southern China
Yi Zhong, Tong Xu, Gengchen Wu, Jiangyong Li, Chengliang Zhang, Hao Wang, Xuefeng Shi, Haijun Gong, Jinying Chen, Weiting Chen, Shuo Deng, Boguang WangAbstract
Atmospheric nitrous oxide (N2O) continues to increase globally, yet long-term observations remain limited in regions affected by multiple anthropogenic sources. Here, we report continuous atmospheric N2O measurements conducted at Yuanzu Mountain (Mt. YZ) in southern China during 2018–2021 and evaluate temporal variability and potential regional influences. Background signals were extracted using meteorological screening followed by the robust extraction of baseline signals (REBS) method, with moving average filtering (MAF) and the Thoning curve-fitting (THO) applied to assess method dependence. The REBS-derived mean background N2O concentration was 328.09 ± 3.18 ppb (mean ± SD), lower than contemporaneous values at Mauna Loa and Waliguan; MAF and THO yielded slightly higher estimates but confirmed this lower background feature. Seasonal amplitudes were nearly identical across methods, whereas annual growth rates varied from 0.62 to 1.36 ppb yr–1. All methods showed a pronounced increase from 2018 to 2019, followed by weakened annual increments. Potential Source Contribution Function (PSCF) analysis identified Guangdong, Guangxi, Hunan, Hubei, Jiangxi, Fujian and adjacent coastal areas, and the continental shelf of the northern South China Sea as major potential source regions. Spatial consistency with emission inventories and sectoral statistics suggests that the interannual pattern reflects integrated effects of evolving regional sources and offsets. These findings improve understanding of the drivers of atmospheric N2O variability in southern China and provide observational support for regional greenhouse gas monitoring and mitigation.