Hydrology and mercury biogeochemistry of the Hudson Bay lowland

绝大多数关于泥炭地和地表水质量的研究都是在小型集水区进行的，通常采用高度简化的水量平衡，这当然适用于泥炭地在汞归宿和迁移中的作用的调查。目前还没有人尝试将我们对小型泥炭地中汞循环过程的了解扩大到世界上更大的泥炭地系统。哈德逊湾低地（HBL）是世界上第二大连续泥炭地，总面积约为32万平方公里。由于气候变化，HBL所处的区域可能是世界上年平均温度上升最显著的区域。缺乏以过程为导向的水文和水质数据意味着，气候变化对高海拔地区泥炭地的水文和生物地球化学过程的潜在巨大影响以及汞循环的后续变化尚不清楚。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。通过对哈得逊湾南部不连续和北方连续多年冻土区水文和汞地球化学的研究，希望：1）阐明哈得逊湾泥炭地对哈德逊/詹姆斯湾主要支流水、总汞（THg）和甲基汞（MeHg）收支的贡献; 2）从机理上深入了解在具有不同地面冰条件的高冰边界的广阔泥炭地中控制甲基汞生产和运输的过程; 3）将泥炭地-流域过程模型应用于大面积泥炭地流域。研究结果将为该地区的土地使用管理和北方社区提供重要指导，该地区的资源开采压力越来越大，随着气候变化开始影响永久冻土的范围，研究结果将深入了解北方河流的潜在水文和地球化学变化。

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.