Department of Civil, Environmental and Mechanical Engineering, University of Trento, Trento, Italy.
Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA.
Sci Total Environ. 2022 Oct 15;843:156844. doi: 10.1016/j.scitotenv.2022.156844. Epub 2022 Jun 21.
Nitrous oxide (NO) is currently the leading ozone-depleting gas and is also a potent greenhouse gas. Predictions of NO emissions from riverine systems are difficult and mostly accomplished via regression equations based on dissolved inorganic nitrogen (DIN) concentrations or fluxes, although recent studies have shown that hydromorphological characteristics can influence NO emissions in riverine reaches. Here, we propose a predictive model for NO riverine concentrations and emissions at the reach scale. The model is based on Damköhler numbers and captures the primary effects of reach-scale biogeochemical and hydromorphological characteristics in flowing waters. It explains the change in NO emissions from small streams to large rivers under varying conditions including biome, land use, climate, and nutrient availability. The model and observed data show that dimensionless NO concentrations and emission rates have higher variability and mean values for small streams (reach width <10 m) than for larger streams due to high spatial variability of stream hydraulics and morphology.
一氧化二氮（NO）目前是消耗臭氧的主要气体，也是一种强效温室气体。河川系统中一氧化二氮排放量的预测很困难，主要通过基于溶解无机氮（DIN）浓度或通量的回归方程来完成，尽管最近的研究表明水力学形态特征会影响河川断面的一氧化二氮排放。在这里，我们提出了一种在河段尺度上预测河流中一氧化二氮浓度和排放的模型。该模型基于达默勒数，捕捉了流动水中河段尺度生物地球化学和水力学形态特征的主要影响。它解释了在不同条件下，从小溪流到大河流的一氧化二氮排放变化，包括生物群落、土地利用、气候和养分供应。模型和观测数据表明，由于溪流水力学和形态的空间变异性较高，与较大的溪流（河道宽度<10 米）相比，小溪流（河道宽度<10 米）的无量纲一氧化二氮浓度和排放率具有更高的变异性和平均值。
