资源环境科技发展态势分析平台

Permafrost thaw in Arctic watersheds threatens to mobilize hitherto sequestered carbon. We examine the radiocarbon activity (F¹⁴C) of dissolved organic carbon (DOC) in the northern Mackenzie River basin. From 2003‐2017, DOC‐F¹⁴C signatures (1.00 ± 0.04; n = 39) tracked atmospheric ¹⁴CO₂, indicating export of “modern” carbon. This trend was interrupted in June 2018 by the widespread release of aged DOC (0.85 ± 0.16, n = 28) measured across three separate catchment areas. Increased nitrate concentrations in June 2018 lead us to attribute this pulse of ¹⁴C‐depleted DOC to mobilization of previously frozen soil organic matter. We propose export through lateral perennial thaw zones occurred at the base of the active layer weakened by preceding warm summer and winter seasons. Although we are not yet able to ascertain the broader significance of this “anomalous” mobilization event, it highlights the potential for rapid and large‐scale release of aged carbon from permafrost.