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

目的和目的我的长期研究目标是通过研究气候、植被和第四纪历史之间的一系列相互作用来解释永久冻土地形对融化的敏感性以及它在干扰后恢复的潜力。我的目标是促进我的研究成果在其他领域的直接应用，例如与基础设施设计和维护、碳循环、污染物动员方面的专家合作，以及与能够促进主动适应自己社区环境变化的当地知识持有者合作。在接下来的五年里，我建议描述哈德逊湾周围均衡隆起的景观中的永久冻土热条件和动态，特别是在哈德逊平原生态区，那里拥有具有全球意义的永久冻土湿地和一系列现有的和计划中的基础设施(例如丘吉尔铁路、道路、几个社区)，但那里的永久冻土条件知之甚少，研究很少。我的研究集中在三个主题上：1.哈德逊平原地区一系列均衡抬升的景观中，第四纪历史与多年冻土条件之间的联系。我们将研究多年冻土和地面冰的堆积与植被演替的关系，重点是楔形冰的分布、活动和生长速度。这将改进加拿大最新的地面冰雪地图中使用的模型，该地图包含了该地区尚未解决的重要误差。2.控制地形对不同永冻土退化机制和相关景观演变路径的脆弱性。在低地，我们将阐明池塘和湖泊扩张率的控制、早期稳定和排水后永久冻土恢复。在山坡上，我们将调查地面温度变暖、相关岩土性质的变化，以及哈德逊湾支流沿岸蒂雷尔海沉积物最近大规模浪费增加之间的关系。3.多年冻土退化模式对生物地球化学循环的影响。我们将研究冻土退化过程(例如，0°C附近未冻水含量的增加、活动层加深和融化下沉、热侵蚀)对融化有机物分解产生的温室气体排放的影响，以及对汞向水体的甲基化和潜在动员的影响。预期影响该项目将增进对加拿大北部这一关键和研究不足地区的景观规模的多年冻土动态的了解，阐明对森林-冻土带过渡地带附近低地的多年冻土堆积和退化的控制，并增进对新出现的永久冻土地貌中的大规模浪费的了解。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、水文状况以及社区和基础设施风险的后果提供重要基础。

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.