Permafrost regions, characterised by extensive belowground excess ice, are highly vulnerable to rapid thaw, particularly in areas such as the Yedoma domain. This region is known to freeze-lock a globally significant stock of soil nitrogen (N). However, the fate of this N upon permafrost thaw remains largely unknown. In this study, we assess the impact of climate warming on the size and dynamics of the soil N pool in (sub-)Arctic ecosystems, drawing upon recently published data and literature. Our findings suggest that climate warming and increased thaw depths will result in an expansion of the reactive soil N pool due to the larger volume of (seasonally) thawed soil. Dissolved organic N emerges as the predominant N form for rapid cycling within (sub-)Arctic ecosystems. The fate of newly thawed N from permafrost is primarily influenced by plant uptake, microbial immobilisation, changes in decomposition rates due to improved N availability, as well as lateral flow. The Yedoma domain contains substantial N pools, and the partial but increasing thaw of this previously frozen N has the potential to amplify climate feedbacks through additional nitrous oxide (N₂O) emissions. Our ballpark estimate indicates that the Yedoma domain may contribute approximately 6% of the global annual rate of N₂O emissions from soils under natural vegetation. However, the released soil N could also mitigate climate feedbacks by promoting enhanced vegetation carbon uptake. The likelihood and rate of N₂O production are highest in permafrost thaw sites with intermediate moisture content and disturbed vegetation, but accurately predicting future landscape and hydrology changes in the Yedoma domain remains challenging. Nevertheless, it is evident that the permafrost-climate feedback will be significantly influenced by the quantity and mobilisation state of this unconsidered N pool.

中文翻译：

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耶多玛永久冻土区潜在的氮动员

永久冻土地区的特点是大量地下过量冰，极易受到快速融化的影响，特别是在耶多马地区等地区。众所周知，该地区冻结了全球重要的土壤氮 (N) 储量。然而，永久冻土融化后氮的命运仍然很大程度上未知。在这项研究中，我们利用最近发表的数据和文献，评估了气候变暖对（亚）北极生态系统中土壤氮库的规模和动态的影响。我们的研究结果表明，由于（季节性）解冻土壤体积较大，气候变暖和解冻深度增加将导致活性土壤氮库的扩大。溶解有机氮成为（亚）北极生态系统内快速循环的主要氮形式。永久冻土中新解冻的氮的命运主要受到植物吸收、微生物固定、由于氮利用率提高而导致的分解率变化以及侧流的影响。耶多马域含有大量的氮库，先前冻结的氮的部分但不断增加的解冻有可能通过额外的一氧化二氮 (N ₂ O) 排放来放大气候反馈。我们的粗略估计表明，耶多马地区的 N ₂ O 排放量可能占全球自然植被下土壤年排放量的约 6%。然而，释放的土壤氮还可以通过促进增强植被碳吸收来减轻气候反馈。在含水量中等且植被受到干扰的永久冻土解冻地点，N ₂ O 产生的可能性和速率最高，但准确预测耶多马地区未来的景观和水文变化仍然具有挑战性。然而，很明显，永久冻土-气候反馈将受到这个未考虑的氮库的数量和动员状态的显着影响。