Land-water linkages and the biogeochemical effects of permafrost thaw: From pore waters to watersheds and beyond

土地与水的联系以及永久冻土融化的生物地球化学效应：从孔隙水到流域及其他区域

• 批准号: RGPIN-2019-05524
• 负责人: Tank, Suzanne
• 金额: $ 3.13万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=744839
• 关键词: Land; water; linkages; biogeochemical; effects

Climate change is fundamentally altering our planet's Earth systems and social systems alike. Nowhere is this truer than in the north, where permafrost thaw is liberating materials previously locked up in frozen ground for participation in contemporary biogeochemical cycles. Although we understand that this process is substantially increasing the movement of carbon and other biogeochemical constituents from land to reactive freshwater environments, there exists several striking gaps in our understanding of how this change will affect broader biogeochemical cycles. These include a dearth of research exploring the effects of thaw on weathering; an overwhelming focus on dissolved, rather than particulate, species in freshwater studies; poor knowledge of how biogeochemical reactions propagate downstream; and a paucity of studies documenting how region-specific landscape attributes constrain the concentration and reactivity of liberated materials. Given emerging findings that weathering is accelerating in the north, and that particles (via sediment mobilization) often dominate thaw-enabled material transport from land to water, it seems clear that our current understanding of feedbacks between permafrost thaw and contemporary biogeochemical cycles is substantially incomplete. The geographic focus of my NSERC-funded efforts is the Peel Plateau in the western Canadian Arctic, which - because of its positioning at the boundary of the last glacial maximum - hosts thick deposits of late Pleistocene-origin tills that are embedded with substantial ground ice. This renders the Plateau highly susceptible to thaw-driven slumping (thermokarst), similar to glacial margin landscapes worldwide. Over the past 5 years, my group has worked in this region to document the importance of inorganic and particle-associated processes for regulating the biogeochemical response to thaw. Over the coming 5 years, I propose to expand on this foundation via work at watershed, inter-watershed, and inter-regional scales. Specifically, I will assess: (1) How the transport, and processing, of slump-released materials propagate through focal watersheds significantly affected by slumping; (2) how the biogeochemical signature of permafrost thaw varies across gradients of disturbance; and (3) how the magnitude, and fate, of land-water carbon flux differs between regions of variable permafrost composition. This expansion of effort will occur across the Peel Plateau, and in targeted sites elsewhere in the western Canadian Arctic. In addition to critically expanding our understanding of the biogeochemical effects of thaw, this research will provide a cadre of HQP with the logistical, laboratory, analytical, and writing skills necessary to become imminently qualified to tackle emerging issues in the biogeo- and Earth systems sciences. It will also involve northern residents and community organization throughout. I look forward to taking on this research in the western Canadian Arctic.

气候变化正在从根本上改变我们星球的地球系统和社会系统。这一点在北方最为真实，那里的永冻层融化正在释放出以前被锁在冻土中的物质，参与当代的地球化学循环。虽然我们知道这一过程大大增加了碳和其他地球化学成分从陆地到活性淡水环境的运动，但我们对这种变化如何影响更广泛的地球化学循环的理解存在着一些明显的差距。这些包括缺乏研究探索解冻对风化的影响;压倒性的重点溶解，而不是颗粒，淡水研究中的物种;知识贫乏的生态地球化学反应如何传播下游;以及缺乏研究记录区域特定的景观属性如何限制释放的材料的浓度和反应性。考虑到新出现的发现，即北方的风化正在加速，颗粒（通过沉积物动员）通常主导着解冻物质从陆地到水中的运输，很明显，我们目前对永久冻土解冻和当代地球化学循环之间的反馈的理解基本上是不完整的。我的NSERC资助的工作的地理重点是在加拿大北极西部的皮尔高原，其中-因为它的位置在末次冰期最大的边界-主机晚更新世起源冰碛物的厚存款嵌入大量的地面冰。这使得高原极易受到融冰驱动的滑塌（热岩溶）的影响，类似于世界各地的冰川边缘景观。在过去的5年里，我的团队一直在这一地区工作，以记录无机和颗粒相关过程的重要性，以调节解冻的地球化学反应。在未来的5年里，我建议通过流域、流域间和区域间的工作来扩大这一基础。具体而言，我将评估：（1）滑塌释放物质的运输和加工如何通过受滑塌影响显著的焦点流域传播;（2）永久冻土融化的地球化学特征如何在扰动梯度上变化;（3）陆地-水碳通量的大小和命运如何在不同永久冻土成分的地区之间存在差异。这种努力的扩大将发生在整个皮尔高原，并在加拿大西部北极地区的其他目标地点。除了批判性地扩大我们对解冻的地球化学效应的理解外，这项研究还将为HQP提供必要的后勤，实验室，分析和写作技能，以便立即有资格解决地球和地球系统科学中出现的问题。它还将涉及整个北方居民和社区组织。我期待着在加拿大西部的北极地区进行这项研究。