Significant spatiotemporal pattern of nitrous oxide emission and its influencing factors from a shallow eutropic lake in Inner Mongolia, China

Eutrophic shallow lakes are generally considered as a contributor to the emission of nitrous oxide (N₂O), while regional and global estimates have remained imprecise. This due to a lack of data and insufficient understanding of the multiple contributing factors. This study characterized the spatiotemporal variability in N₂O concentrations and N₂O diffusive fluxes and the contributing factors in Lake Wuliangsuhai, a typical shallow eutrophic and seasonally frozen lake in Inner Mongolia with cold and arid climate. Dissolved N₂O concentrations of the lake exhibited a range of 4.5 to 101.2 nmol/L, displaying significant spatiotemporal variations. The lowest and highest concentrations were measured in summer and winter, respectively. The spatial distribution of N₂O flux was consistent with that of N₂O concentrations. Additionally, the hotspots of N₂O emissions were detected within close to the main inflow of lake. The wide spatial and temporal variation in N₂O emissions indicate the complexity and its relative importance of factors influencing emissions. N₂O emissions in different lake zones and seasons were regulated by diverse factors. Factors influencing the spatial and temporal distribution of N₂O concentrations and fluxes were identified as WT, WD, DO, Chl-a, SD and COD. Interestingly, the same factor demonstrated opposing effects on N₂O emission in various seasons or zones. This research improves our understanding of N₂O emissions in shallow eutrophic lakes in cold and arid areas.