Permafrost aggradation and degradation in relation to disturbance in isostatically uplifted landscapes of the Hudson Bay region

与哈德逊湾地区均衡隆起景观扰动相关的永久冻土退化和加剧

• 批准号: RGPIN-2022-05077
• 负责人: RoyLeveillee, Pascale
• 金额: $ 2.99万
• 依托单位: Université Laval
• 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=753601
• 关键词: Permafrost; aggradation; degradation; relation; disturbance

Purpose and objectives My long-term research goal is to explain the susceptibility of permafrost terrain to thaw as well as its potential for post-disturbance recovery by examining a suite of interactions between climate, vegetation, and Quaternary history. I aim to facilitate direct application of my research results in other fields via collaborations with, for instance, experts in infrastructure design and maintenance, carbon cycling, contaminant mobilisation, and with local knowledge holders who can facilitate proactive adaptation to environmental change in their own communities. In the next five years, I propose to characterize permafrost thermal conditions and dynamics in isostatically uplifted landscapes surrounding the Hudson Bay, particularly in the Hudson Plains ecoregion, which hosts a permafrost wetland of global significance and a range of existing and planned infrastructure (e.g. Churchill Railway, roads, several communities) yet where permafrost conditions are poorly understood and largely understudied. My proposed research focuses on three themes: 1. Links between Quaternary history and permafrost conditions in a sequence of isostatically uplifted, emerged landscapes in the Hudson Plains region. We will investigate the aggradation of permafrost and ground ice in relation to post-emergence vegetation succession, with a focus on wedge ice distribution, activity, and growth rates. This will improve the model used in the latest Ground Ice Map of Canada, which includes important unresolved inaccuracies in this region. 2. Controls on terrain vulnerability to different mechanisms of permafrost degradation and associated landscape evolution pathways. In lowlands, we will elucidate controls on pond and lake expansion rates, early stabilisation, and post-drainage permafrost recovery. On hillslopes, we will investigate relations between the warming of ground temperatures, associated changes in geotechnical properties, and recent increases in mass wasting in Tyrell Sea deposits along Hudson Bay tributaries. 3. Implications of permafrost degradation patterns for biogeochemical cycling. We will investigate the impacts of permafrost degradation processes (e.g. increases in unfrozen water content near 0°C, active layer deepening and thaw subsidence, thermoerosion) on the emission of greenhouse gases from decomposing thawed organics, and on the methylation and potential mobilisation mercury towards water bodies. Anticipated impacts This project will improve understanding of landscape-scale permafrost dynamics in this crucial and understudied region of the Canadian North, elucidate controls on permafrost aggradation and degradation in lowlands near the forest-tundra transition, and advance understanding of mass-wasting in emerged permafrost landscapes. This research will provide crucial foundations to predict consequences of landscape change on ecosystems, biogeochemical feedbacks, hydrological regimes, and risks to communities and infrastructure.

目的和目标我的长期研究目标是解释的敏感性永久冻土地带解冻以及其潜在的干扰后恢复通过检查一套气候，植被和第四纪历史之间的相互作用。我的目标是通过与基础设施设计和维护，碳循环，污染物动员方面的专家以及能够促进积极适应自己社区环境变化的当地知识持有者合作，促进我的研究成果在其他领域的直接应用。在接下来的五年里，我建议在均衡抬升景观周围的哈德逊湾，特别是在哈德逊平原生态区，它拥有一个永久冻土湿地的全球意义和一系列现有的和计划中的基础设施（如丘吉尔铁路，道路，几个社区），但永久冻土条件知之甚少，在很大程度上研究不足的特点冻土热条件和动态。我的研究主要集中在三个方面：1。在哈德逊平原地区一系列均衡上升的景观中，第四纪历史与永久冻土条件之间的联系。我们将调查永久冻土和地面冰的沉积与后出现的植被演替，重点是楔形冰的分布，活动和增长率。这将改进最新的加拿大地冰图中使用的模型，其中包括该地区重要的未解决的不准确之处。2.不同机制的冻土退化和相关景观演变路径对地形脆弱性的控制。在低地，我们将阐明控制池塘和湖泊的扩张速度，早期稳定，排水后永久冻土恢复。在山坡上，我们将调查地面温度的变暖，相关的岩土性质的变化，以及最近增加的质量浪费在沿着哈德逊湾支流的Tyrell海沉积物之间的关系。3.永久冻土退化模式对地球化学循环的影响。我们将调查永久冻土退化过程（例如，0°C附近未冻水含量的增加，活动层加深和解冻沉降，热侵蚀）对分解解冻有机物排放温室气体的影响，以及对甲基化和潜在的移动汞对水体的影响。该项目将提高对加拿大北部这一关键和未充分研究的地区的大规模永久冻土动态的理解，阐明对森林-苔原过渡附近低地永久冻土沉积和退化的控制，并促进对出现的永久冻土景观中质量浪费的理解。这项研究将为预测景观变化对生态系统、生物地球化学反馈、水文制度以及对社区和基础设施的风险的后果提供重要基础。