Spatial and temporal variability of nitrous oxide emissions from a large subtropical Reservoir in Eastern China

Carbonaceous greenhouse gases (i.e., CO₂, CH₄ ) have often reported to be emitted from the surfaces of reservoirs, while other non-carbonaceous greenhouse gases are not available to many reservoirs. In this study, the spatiotemporal variability of N₂O emissions from Xin’anjiang Reservoir was investigated at the different regions over a 13-month period using the method of the static floating chambers combined with gas chromatography. Results showed that the average N₂O emission flux was the highest in the downstream river (220.24±153.68 μg m⁻²·s⁻¹), followed by the upstream river (49.85±48.55 μg m⁻²·s⁻¹). The reservoir’s main body had the lowest flux (26.61-39.07 μg m⁻²·s⁻¹). Seasonal variability indicated that the average N₂O emission fluxes before the dam reached their maximum in March, which was likely influenced by the disappearance of thermal stratification then, caused a short N₂O flux peak at the water-air interface. A thorough investigation should be carried out at the different reservoir regions for a long-term basis to discover the spatiotemporal variability in N₂O emission flux in a hydroelectric reservoir system, which could avoid the error of estimating the N₂O emissions incorrectly.