Climate change is intensifying the Arctic hydrologic cycle, potentially accelerating the release of carbon and nutrients from permafrost landscapes to rivers. However, there are limited riverine flow and solute data of adequate frequency and duration to test how seasonality and catchment landscape characteristics influence production and transport of carbon and nutrients in Arctic river networks. We measured high frequency hydrochemical dynamics at the outlets of three headwater catchments in Arctic Alaska over 3 years. The catchments represent common Arctic landscapes: low‐gradient tundra, low‐gradient and lake‐influenced tundra, and high‐gradient alpine tundra. Using in‐situ spectrophotometers, we measured dissolved organic carbon (DOC) and nitrate (NO₃⁻) concentrations at 15‐min intervals through the flow seasons of 2017, 2018, and 2019. These high‐frequency data allowed us to quantify concentration–discharge (C‐Q) responses during individual storm events across the flow season. Differences in C‐Q responses among catchments indicated strong landscape and seasonal controls on lateral DOC and NO₃⁻ flux. For the two low‐gradient tundra catchments, we observed consistent DOC enrichment (transport‐limitation) and NO₃⁻ dilution (source‐limitation) during flow events. Conversely, we found consistent NO₃⁻ enrichment and DOC dilution in the high‐gradient alpine catchment. Our analysis revealed how high flow events may contribute disproportionately to downstream export in these Arctic streams. Because the duration of the flow season is expected to lengthen and the intensity of Arctic storms are expected to increase, understanding how discharge and solute concentration are coupled is crucial to understanding carbon and nutrient dynamics in rapidly changing permafrost ecosystems.

中文翻译：

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北极地区溶解性有机碳和硝酸盐的浓度-流量关系随地形和季节而变化

气候变化加剧了北极的水文循环，有可能加速多年冻土景观向河流释放碳和养分。但是，河水流量和溶质数据的频率和持续时间有限，无法测试季节性和流域景观特征如何影响北极河网中碳和养分的生产和运输。我们在3年中测量了北极阿拉斯加三个水源流出口的高频水化学动力学。这些集水区代表了常见的北极景观：低梯度冻原，低梯度和湖泊影响的冻原以及高梯度高山冻原。使用原位分光光度计，测量溶解的有机碳（DOC）和硝酸盐（NO ₃ ^-）在2017年，2018年和2019年整个流量季节以15分钟为间隔的浓度。这些高频数据使我们能够量化整个流量季节单个风暴事件期间的浓度-流量（C-Q）响应。在集水区当中的C个-Q响应中的差异指示强横向和侧向上DOC季节性控制和NO ₃ ^-通量。对于两个低梯度苔原集水，我们观察到一致的DOC富集（传输限制）和NO ₃ ^-中的流动事件的稀释（源极-限制）。相反，我们发现一贯NO ₃ ^-高梯度高山流域的富集和DOC稀释。我们的分析表明，高流量事件可能对这些北极溪流的下游出口造成不成比例的贡献。由于预计将延长水流季节的持续时间，并预计将增加北极风暴的强度，因此了解排放量和溶质浓度如何耦合对于了解快速变化的多年冻土生态系统中的碳和养分动态至关重要。