Hydrology and mercury biogeochemistry of the Hudson Bay lowland

关于泥炭地和地表水水质的绝大多数研究都是在小流域进行的，往往具有高度简化的水平衡，这当然适用于对泥炭地在汞的去向和迁移中所起作用的调查。还没有人试图将我们所拥有的关于小型泥炭地汞循环的基于过程的知识扩大到世界上更大范围的泥炭地系统。哈德逊湾低地(HBL)是世界上第二大毗连的泥炭地，总面积约32万平方公里。由于气候变化，HBL所处的地区可能是世界上年平均气温最显著上升的地区。缺乏面向过程的水文和水质数据意味着气候变化对HBL泥炭地的水文和生物地球化学过程以及随后汞循环的变化的潜在重大影响是未知的。鉴于汞循环对北方生态系统和社区的重要性，这是一个重大的知识差距。通过对HBL南部不连续和北部连续永久冻土区的水文学和汞生物地球化学的研究，我希望：1)阐明HBL泥炭地对哈德逊/詹姆斯湾主要支流的水、总汞(THG)和甲基汞(MeHg)收支的贡献；2)从机理上深入了解控制HBL广泛泥炭地中甲基汞的生产和迁移的过程；以及3)将基于景观的泥炭地流域过程模型应用于HBL广泛的泥炭地流域。研究结果将为该地区的土地利用管理和北部社区提供重要指导，因为该地区的资源开采压力越来越大，并为随着气候变化开始影响永久冻土的程度，更北部河流可能发生的水文和生物地球化学变化提供了洞察。

The vast majority of research on peatlands and surface water quality has been done in small catchments, often with highly simplified water balances, and this certainly applies to investigations of the role of peatlands in mercury fate and transport. There have been no attempts to scale up the process-based knowledge that we have about Hg cycling in small peatlands to the larger extensive peatland systems of the world. The Hudson Bay Lowlands (HBL) is the second largest contiguous peatland in the world, with a total area of approximately 320 000 sq km. The HBL is in a region that is likely to be subjected to the most significant increases in annual average temperature due to climate change of anywhere in the world. The absence of process-oriented hydrological and water quality data means that the potentially dramatic impacts of a changing climate on the hydrological and biogeochemical processes of the peatlands of the HBL and the subsequent changes to the mercury cycle are unknown. Given the importance of the mercury cycle to northern ecosystems and communities, this is a significant knowledge gap. By undertaking research on the hydrology and mercury biogeochemistry in both the southern discontinuous and northern continuous permafrost zones of the HBL, I hope to: 1) elucidate the contributions of the HBL peatlands to the budget of water, total mercury (THg) and methylmercury (MeHg) of major tributaries of Hudson/James Bay; 2) gain mechanistic insight into the processes that control MeHg production and transport in the extensive peatlands of the HBL with varying ground ice conditions, and; 3) apply a landscape-based model of peatland-watershed processes to the extensive peatland watersheds of the HBL. Research findings will provide important guidance for land-use management and northern communities in a region that is coming under increasing pressure for resource extraction, and offer insights into the potential hydrological and biogeochemical alterations of the more northern rivers as climate change begins to impact the extent of permafrost.