资源环境科技发展态势分析平台

Agricultural peatlands are estimated to emit approximately one third of global greenhouse gas (GHG) emissions from croplands, but the temporal dynamics and controls of these emissions are poorly understood, particularly for nitrous oxide (N₂O). We used cavity ring-down spectroscopy and automated chambers in a drained agricultural peatland to measure over 70,000 individual N₂O, methane (CH₄), and carbon dioxide (CO₂) fluxes over 3 years. Our results showed that N₂O fluxes were high, contributing 26% (annual range: 16%–35%) of annual CO₂e emissions. Total N₂O fluxes averaged 26 ± 0.5 kg N₂O-N ha⁻¹ y⁻¹ and exhibited significant inter- and intra-annual variability with a maximum annual flux of 42 ± 1.8 kg N₂O-N ha⁻¹ y⁻¹. Hot moments of N₂O and CH₄ emissions represented 1.1 ± 0.2 and 1.3 ± 0.2% of measurements, respectively, but contributed to 45 ± 1% of mean annual N₂O fluxes and to 140 ± 9% of mean annual CH₄ fluxes. Soil moisture, soil temperature, and bulk soil oxygen (O₂) concentrations were strongly correlated with soil N₂O and CH₄ emissions; soil nitrate () concentrations were also significantly correlated with soil N₂O emissions. These results suggest that IPCC benchmarks underestimate N₂O emissions from these high emitting agricultural peatlands by up to 70%. Scaling to regional agricultural peatlands with similar management suggests these ecosystems could emit up to 1.86 Tg CO₂e y⁻¹ (range: 1.58–2.21 Tg CO₂e y⁻¹). Data suggest that these agricultural peatlands are large sources of GHGs, and that short-term hot moments of N₂O and CH₄ are a significant fraction of total greenhouse budgets.