Particulate dominance of organic carbon mobilization from thaw slumps on the Peel Plateau, NT: Quantification and implications for stream systems and permafrost carbon release
Particulate dominance of organic carbon mobilization from thaw slumps on the Peel Plateau, NT: Quantification and implications for stream systems and permafrost carbon release
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DOI：
10.1088/1748-9326/abac36
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发表时间：
2020-10
影响因子：
6.7
通讯作者：
S. Shakil;S. Tank;S. Kokelj;J. Vonk;S. Zolkos
中科院分区：
文献类型：
--
作者：
S. Shakil;S. Tank;S. Kokelj;J. Vonk;S. Zolkos
气候变化正在增加热岩溶作用的频率和强度，并加速将陆地有机物质从以前被隔离的来源输送到水生系统，在那里它会受到进一步的生物化学变化。加拿大西部皮尔高原冰川条件下的富冰和冰缘地形的快速气候变化正在加速融化驱动的质量损耗，其形式是后退性融化滑塌，融化的永久冻土的面积、体积和厚度迅速增加。尽管下游的沉积和地球化学通量的大扰动，很少有研究已经检查的通量和组成的颗粒有机碳（POC）在溪流和河流的永久冻土融化的结果。在这里，我们表明，总有机碳，氮，磷动员流从融化滑塌皮尔高原的数量级增加几乎完全是由于POC和相关的颗粒氮和磷的释放。从颗粒有机物的碱提取荧光推断，块状动员的POC在组成上不同于其溶解的对应物，似乎含有相对较大量的降解有机物。因此，滑塌动员的POC是潜在的比POC存在于非滑塌受影响的流网络更易受干扰。此外，从解冻滑塌动员的POC的很大一部分将被限制在谷底的原生沉积物存储，其中净积累目前超过净侵蚀，导致世纪到千年的规模封存热岩溶动员的POC。这项研究强调了迫切需要更好地了解沉积级联，动员，并在受滑塌影响的河流水库，POC的生物降解性和颗粒营养物质的循环在沉积级联框架内的基线评估。明确纳入POC动态到我们的土地-水碳动员的认识，面对冻土融化是至关重要的了解区域碳循环和河流生态系统的热岩溶的影响。
Climate change is increasing the frequency and intensity of thermokarst, and accelerating the delivery of terrestrial organic material from previously sequestered sources to aquatic systems, where it is subject to further biochemical alteration. Rapid climate change in the glacially conditioned ice-rich and ice-marginal terrain of the Peel Plateau, western Canada, is accelerating thaw-driven mass wasting in the form of retrogressive thaw slumps, which are rapidly increasing in area, volume and thickness of permafrost thawed. Despite major perturbation of downstream sedimentary and geochemical fluxes, few studies have examined changes in flux and composition of particulate organic carbon (POC) in streams and rivers as a result of permafrost thaw. Here we show that the orders of magnitude increase in total organic carbon, nitrogen, and phosphorus mobilized to streams from thaw slumps on the Peel Plateau is almost entirely due to POC and associated particulate nitrogen and phosphorus release. Slump-mobilized POC is compositionally distinct from its dissolved counterpart and appears to contain relatively greater amounts of degraded organic matter, as inferred from base-extracted fluorescence of particulate organic matter. Thus, slump-mobilized POC is potentially more recalcitrant than POC present in non-slump affected stream networks. Furthermore a substantial portion of POC mobilized from thaw slumps will be constrained within primary sediment stores in valley bottoms, where net accumulation is currently exceeding net erosion, resulting in century to millennial scale sequestration of thermokarst-mobilized POC. This study highlights the pressing need for better knowledge of sedimentary cascades, mobilization, and storage reservoirs in slump-affected streams, and baseline assessments of the biodegradability of POC and cycling of particulate nutrients within a sedimentary cascade framework. Explicit incorporation of POC dynamics into our understanding of land-water carbon mobilization in the face of permafrost thaw is critical for understanding implications of thermokarst for regional carbon cycling and fluvial ecosystems.