Streams and rivers are known to be significant processors and emitters of carbon (C) to the atmosphere. There have been many large-scale estimates of fluvial C emissions, yet many lack quantification of temporal variability. Here, we compared the relative importance of spatial versus seasonal variability of CO\(_2\) and CH\(_4\) concentrations and fluxes, and DOC concentration in 23 streams and rivers spanning seven Strahler stream orders in two regions with contrasting watershed features, geomorphology and climate in boreal Québec. Much of the overall variance in pCO\(_2\), pCH\(_4\) and DOC concentration could be explained by region and site-specific properties rather than season. Region was the main driver of pCO\(_2\), pCH\(_4\), and DOC concentration followed by network-specific variability. pCO\(_2\) had the strongest seasonal patterns, yet season accounted only for 16% of the total variation, whereas intrinsic network and landscape properties accounted for 60%. Seasonality explained even less of the overall variability for pCH\(_4\) (5%) and DOC (6%) once the region and network features were accounted for. Despite significant spatial and temporal variation in pCO\(_2\) and pCH\(_4\) point fluxes were not significantly different between regions and seasons, because of a modulating interplay between concentration and gas exchange at the whole network scale. The declining trend of pCO\(_2\) and pCH\(_4\) with flow distance across all watersheds and seasons (even under ice and snow) suggests a predominance of network degassing independent of season, and together with the relative constancy of fluxes across regions and time further suggests that seasonality may be dampened when considering fluvial emissions at large spatial scales and especially when integrating these emissions at the whole network scale.

众所周知，溪流和河流是大气中碳 (C) 的重要加工者和排放者。已有许多对河流 C 排放的大规模估计，但许多缺乏对时间变化的量化。在这里，我们比较了 CO \(_2\)和 CH \(_4\)浓度和通量的空间与季节性变化的相对重要性，以及跨越两个具有对比流域特征的地区的 7 个 Strahler 流阶的 23 条溪流和河流中的 DOC 浓度, 魁北克北部的地貌和气候。pCO \(_2\)、pCH \(_4\)和 DOC 浓度的大部分整体差异可以通过区域和特定地点的特性而不是季节来解释。地区是 pCO 的主要驱动力\(_2\)、pCH \(_4\)和 DOC 浓度，然后是网络特定的变异性。pCO \(_2\)具有最强的季节性模式，但季节仅占总变异的 16%，而内在网络和景观属性占 60%。一旦考虑了区域和网络特征，季节性对 pCH \(_4\) (5%) 和 DOC (6%)的整体变异性的解释甚至更少。尽管 pCO \(_2\)和 pCH \(_4\)点通量在区域和季节之间存在显着的时空变化，但由于整个网络尺度上浓度和气体交换之间的调节相互作用，因此区域和季节之间没有显着差异。pCO下降趋势\(_2\)和 pCH \(_4\)在所有流域和季节（甚至在冰雪环境下）的流动距离表明网络脱气的优势与季节无关，并且与跨区域和时间的通量的相对恒定性一起进一步表明在考虑大空间尺度的河流排放时，尤其是在整个网络尺度上整合这些排放时，季节性可能会受到抑制。