Subarctic catchments underlain by permafrost sequester a major stock of frozen organic carbon (C), which may be mobilized as the Arctic warms. Warming can impact C export from thawing soils by altering the depth and timing of runoff related to changing storm and fire regimes and altered soil thaw depths. We investigated C export in a first order headwater stream (West Twin Creek) and its receiving third order river (Beaver Creek) in interior Alaska using discrete sampling of dissolved organic and inorganic C (DOC and DIC) and 15-min collection of specific conductance (SC), fluorescent dissolved organic matter (fDOM) and water discharge (Q). Storm SC-Q relationships displayed negative slopes, indicating solute limitation and limited influence of seasonal soil thaw on storm runoff chemistry. Concurrently, fDOM-Q displayed positive slopes that decreased over the summer, indicating flushing of a limited fDOM pool. Baseflow DIC increased over the season concurrent with soil thaw, with higher DIC at the larger scale indicating greater influence of deeper, mineral-rich flow paths. Storm and seasonal trends were generally similar at both scales. The biggest difference was in fDOM, which displayed higher concentrations and slower depletion in the first order stream. Improved process understanding from this study can be used to better predict carbon export and cycling by stream networks as northern forests and arctic regions continue to warm.

中文翻译：

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多年冻土下嵌套亚北极流域碳输出的风暴规模和季节性动态

永久冻土之下的亚北极集水区隔离了大量的冷冻有机碳 (C)，随着北极变暖，这些有机碳可能会被动员起来。变暖可以通过改变与变化的风暴和火灾状况以及改变的土壤解冻深度相关的径流深度和时间来影响解冻土壤中的碳输出。我们使用溶解的有机和无机 C（DOC 和 DIC）的离散采样和 15 分钟的特定电导收集，研究了阿拉斯加内陆的一级源水流（West Twin Creek）及其接收的三级河流（Beaver Creek）中的 C 输出(SC)、荧光溶解有机物 (fDOM) 和排水量 (Q)。风暴 SC-Q 关系显示负斜率，表明季节性土壤解冻对风暴径流化学的影响有限和溶质限制。同时，fDOM-Q 显示出在夏季下降的正斜率，表明有限的 fDOM 池被冲刷。基流 DIC 在整个季节与土壤解冻同时增加，较大尺度上的较高 ​​DIC 表明更深、富含矿物质的流动路径的影响更大。风暴和季节性趋势在两个尺度上大体相似。最大的区别在于 fDOM，它在一级流中显示出更高的浓度和更慢的消耗。随着北部森林和北极地区继续变暖，这项研究对过程的理解得到改善，可用于更好地预测河流网络的碳输出和循环。富含矿物质的流动路径。风暴和季节性趋势在两个尺度上大体相似。最大的区别在于 fDOM，它在一级流中显示出更高的浓度和更慢的消耗。随着北部森林和北极地区继续变暖，这项研究对过程的理解得到改善，可用于更好地预测河流网络的碳输出和循环。富含矿物质的流动路径。风暴和季节性趋势在两个尺度上大体相似。最大的区别在于 fDOM，它在一级流中显示出更高的浓度和更慢的消耗。随着北部森林和北极地区继续变暖，这项研究对过程的理解得到改善，可用于更好地预测河流网络的碳输出和循环。