The biogeochemical response of High Arctic surface waters to changing permafrost and hydrology

这项研究旨在研究水文过程(如降水和土壤水分)和多年冻土扰动(如活动层剥离)的时空变化对北极高地流域活跃层生物地球化学过程和下游河流水质，特别是营养物质和有机质的控制作用。这一综合研究计划将提供所需的基线知识，以开发预测北极高地河流对预计气候变化的水质反应的方法。 我的研究是因为多年冻土地区的气候变化可能会对水文和永久冻土稳定性产生广泛影响，这些因素加在一起将对陆地生态系统功能、河流水质和下游水生生态系统产生重大影响。最近的研究表明，气候变暖、永久冻土扰动和降水制度的变化可能导致北极河流中营养物质和溶解有机物(DOM)浓度的增加。这些增加主要发生在降雨和集中的地下水源促成径流的季节末期。然而，关于气候与溶质、无机氮(N)和DOM的河流输送之间的关系，仍然存在相互矛盾的描述。这些冲突的部分原因是永冻土和地质底质的性质不同，以及普遍缺乏对控制流域中溶质生产和储存的生物地球化学过程以及控制径流中溶质迁移和输出的水文过程的时空变异性的了解。这项研究通过以下几方面的研究来解决这一认识鸿沟：(1)地下水流的来源和质量，以及(2)土壤的物理和地貌特征以及(3)降雨对活跃层中生物地球化学过程的控制的小规模野外和实验室实验。 正是这项研究的综合性，以及流域尺度地貌和季节性水文控制对溶质迁移的调查与特定地点研究的明确联系，考察了地下水流动的关键物理控制和活动层中营养物质和DOM循环的生物地球化学控制，使这项研究具有新颖性和高度相关性。这项工作将有助于从特定地点的知识转移到集水范围，了解气候变化对永久冻土流域水质的影响。这项研究将产生量化数据，这些数据对于制定政策和管理北极高地水资源至关重要，以确保健康的生态系统和保护北极社区的水安全，这些社区已经受到可察觉的区域气候变化的影响。 高素质人员(HQP)将在邦蒂角北极分水岭观测站(CBAWO)接受培训，这是一个在加拿大北极地区独一无二的合作和综合分水岭研究站。拟议的研究计划将为八个总部基地提供项目管理经验，以及广泛的领域和分析技能。学生毕业时将掌握评估北极流域和生态系统对气候变化和人类影响的脆弱性所需的高级知识。我的研究项目毕业生获得的职业生涯表明，HQP获得的知识和技能集受到私营行业和政府的高度重视。总部基地将随时准备为决策和实践的发展做出贡献，这些实践将提高我们在不断变化的气候中管理北极环境和水资源的能力，从而造福于所有加拿大人的健康和经济福祉。

The proposed research investigates the control that spatial and temporal variations in hydrologic processes (such as precipitation and soil moisture) and permafrost disturbances (such as active layer detachments, ALDs) exert on active layer biogeochemical processes and on downstream river water quality, especially nutrients and organic matter, in High Arctic watersheds. This integrated research program will provide baseline knowledge required to develop means of predicting the water quality response of High Arctic rivers to projected climate change. My research is necessitated by the potential for climate change in permafrost regions to have widespread impacts on hydrology and permafrost stability, which combined will significantly impact terrestrial ecosystem function, river water quality and downstream aquatic ecosystems. Recent studies show that warming, permafrost disturbances and changes in precipitation regimes can lead to increases in nutrients and dissolved organic matter (DOM) concentrations in arctic rivers. These increases occur primarily in the late season when rainfall and concentrated subsurface water sources contribute to runoff. However, there are still conflicting accounts of the relationship between climate and the riverine transport of solutes, inorganic nitrogen (N) and DOM. These conflicts are due in part to differences in the nature of the permafrost and geologic substrate, as well as a general lack of understanding of the spatial and temporal variability in the biogeochemical processes controlling solute production and storage in the watershed, and the hydrologic processes controlling solute mobilization and export in runoff. This research addresses this knowledge gap by combining catchment scale studies of (1) the sources and quality of subsurface water flow, with small-scale field and lab experiments investigating the control of (2) the physical and geomorphological characteristics of soils, and (3) rainfall on biogeochemical processes in the active layer. It is the integrated nature of this research, and the explicit linking of investigations of the watershed scale geomorphic and seasonal hydrological controls on solute mobilization, with site-specific studies examining the key physical controls on subsurface water flow and biogeochemical controls on nutrient and DOM cycling in the active layer that makes this research novel and highly relevant. This work will facilitate moving from site-specific knowledge, to a catchment scale understanding of the impact of changing climate on water quality in permafrost watersheds. The research will generate quantitative data that is critical to informing policy and managing High Arctic water resources to ensure healthy ecosystems and protect water security in Arctic communities that are already subject to perceptible regional climate change. Highly qualified personnel (HQP) will be trained at the Cape Bounty Arctic Watershed Observatory (CBAWO), a collaborative and integrated watershed research station that is unique in the Canadian Arctic. The proposed research program will provide eight HQP with a project management experience, and a breadth of field and analytical skills. Students exit the program with the advanced knowledge required to assess the vulnerability of artic watersheds and ecosystems to climate change and human impacts. The careers secured by graduates of my research program demonstrate that the knowledge and skill sets HQP acquire are highly valued by private industry and government. HQP will be poised to contribute to decision-making, and the development of practices that will improve our ability to manage Arctic environments and water resources in a changing climate, and thus benefit the health and economic well being of all Canadians.