Arctic tundra wetlands may be an important source of dissolved organic carbon (DOC) in Arctic rivers and the Arctic Ocean under global warming. We investigated stable water isotopes and DOC concentrations in wetlands, tributaries, and the mainstream at the lower reaches of the Indigirka River in northeastern Siberia during the summers of 2010−2014 to assess the complex hydrology and role of wetlands as sources of riverine DOC. The wetlands had higher values of δ18O and DOC concentrations than the tributaries and mainstream of the Indigirka River, suggesting that the wetlands can be a source of DOC for the river mainstream through the tributaries during summer. Couplings of temporal variations in δ18O and DOC in one tributary showed that mainstream water flowed into the tributary during relatively high river level periods in summer, whereas high-DOC water in the downstream wetlands could be discharged to both tributary and mainstream at lower river levels. Therefore, since the water level of the Indigirka River gradually decreases after the snowmelt season, the DOC contribution of the downstream wetland water to the river mainstream potentially increases from late summer to autumn with a decrease in the river level.

中文翻译：

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苔原湿地水文稳定水同位素评估作为西伯利亚东北部英迪吉尔卡河低地北极河流溶解有机碳的潜在来源

北极苔原湿地可能是全球变暖下北极河流和北冰洋中溶解有机碳（DOC）的重要来源。我们调查了 2010-2014 年夏季西伯利亚东北部因迪吉尔卡河下游湿地、支流和干流中的稳定水同位素和 DOC 浓度，以评估湿地作为河流 DOC 来源的复杂水文和作用。湿地的δ18O和DOC浓度值高于Indigirka河的支流和干流，表明湿地可以成为夏季通过支流的干流DOC的来源。一条支流δ18O和DOC随时间变化的耦合表明，夏季干流水位在较高河位时流入支流，而下游湿地中的高 DOC 水可以排放到较低河流水位的支流和干流。因此，由于Indigirka河水位在融雪季节后逐渐下降，下游湿地水对河流干流的DOC贡献从夏末到秋季可能随着河水位的下降而增加。