作者：Shi, W., Yan, Z., Sun, Q., Wu, W., Liang, X., Wang, S., Fan, H., Yin, H., Li, S. & Tian, H.

Inland waters are significant sources of atmospheric nitrous oxide (N2O), and their emissions are expected to rise rapidly due to human activities. However, current estimates remain highly uncertain, partly because sparse field measurements and existing models fail to capture fine-scale variations in N2O emissions, especially due to the interactions between fluid dynamics and biogeochemical drivers. This study developed an N2O module in the Environmental Fluid Dynamics Code (EFDC), a comprehensive numerical model capable of simulating hydrodynamics and water quality in different inland aquatic systems, by incorporating key nitrogen (N) processes that influence N2O production and emissions. The developed model was applied to a typical mountainous reservoir in China, and reliably reproduced the temporal and spatial variations in N2O concentrations and fluxes. Seasonal patterns of N2O fluxes were primarily driven by temperature, stratification, and nutrient availability, with autumn exhibiting the peak values. In contrast, spatial variations were mainly regulated by fluid dynamics and nutrient availability, with the highest N2O fluxes observed in the main part of the reservoir. Furthermore, the whole-reservoir N2O budget indicated that sediments were the primary source of N2O, which is mainly produced via denitrification under low dissolved oxygen conditions, underscoring the importance of understanding the sedimentary N cycle. Overall, our model enables the quantification of significant spatiotemporal variations in N2O emissions from inland waters and unravels the underlying mechanisms, thereby enhancing our mechanistic understanding of N2O dynamics and improving the quantification accuracy of N2O emissions at broader scales.

内陆水体是大气氧化亚氮（N₂O）的重要排放源，且在人类活动影响下其排放量预计将快速上升。然而，当前估算仍存在高度不确定性，部分原因在于稀疏的野外观测与现有模型难以捕捉N₂O排放的精细尺度变化，尤其是水动力学与生物地球化学驱动因子交互作用所致的变化。本研究在环境流体动力学模型（Environmental Fluid Dynamics Code, EFDC）——一个可模拟不同内陆水体水动力与水质的综合数值模型中开发了N₂O模块，纳入了影响N₂O生成与排放的关键氮循环过程。所建模型应用于中国一座典型山区水库，可靠地再现了N₂O浓度与通量的时空变化。N₂O通量的季节格局主要受温度、分层与营养盐可得性驱动，秋季出现峰值；相比之下，空间变化主要由水动力与营养盐可得性调控，最高N₂O通量出现在库区主库段。全库N₂O收支进一步表明，沉积物是N₂O的首要来源，其主要经由低溶解氧条件下的反硝化作用产生,凸显了理解沉积物氮循环的重要性。总体而言，本模型能够定量刻画内陆水体N₂O排放的显著时空变异并揭示其内在机制，从而深化对N₂O动态的机理认识，并提升更大尺度上N₂O排放量化的精度。

（来源：Water Resources Research 2026 Issue 5  DOI: 10.1029/2025wr 041544）