Streams are significant emitters of carbon dioxide (CO2) to the atmosphere that are influenced by diel CO2 dynamics. However, we know little about diel CO2 variability within streams, the diel dynamics of CO2 in the air above streams, and the consequences for emission calculations. We studied five pre‐alpine streams by equipping three sites per stream in close proximity (~ 1 km apart) with automatic logging stations that continuously recorded water and air CO2 partial pressures (pCO2) for 2–4 d. All streams and sites showed increased pCO2 at night and decreased pCO2 during the day, however, with fourfold higher diel amplitudes for atmospheric pCO2 compared to the water. Calculating diffusive CO2 fluxes with fixed compared to dynamic measured atmospheric CO2 resulted in negligible to 431% lower estimates. We might thus currently overestimate fluvial CO2 emissions and should include diel water and air CO2 variability to more accurately assess stream CO2 emissions.

中文翻译：

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在未考虑柴油和大气二氧化碳变化的情况下，河流二氧化碳排放量被高估


河流是大气中二氧化碳 (CO2) 的重要排放源，受昼夜二氧化碳动态的影响。然而，我们对溪流内二氧化碳的昼夜变化、溪流上方空气中二氧化碳的昼夜动态以及排放计算的影响知之甚少。我们研究了 5 条高山前溪流，为每条溪流的三个距离很近（相距约 1 公里）的地点配备了自动测井站，连续记录水和空气二氧化碳分压 (pCO2) 2-4 天。然而，所有溪流和地点均显示夜间 pCO2 增加，白天 pCO2 下降，大气 pCO2 的昼夜振幅比水高四倍。与动态测量的大气 CO2 相比，计算固定的 CO2 扩散通量导致估算值低了 431%，可以忽略不计。因此，我们目前可能高估了河流二氧化碳排放量，并且应该包括柴油和空气二氧化碳变化，以更准确地评估河流二氧化碳排放量。