Isotopic tracers and chronometers of Earth surface processes (Arctic/subarctic realm)

这项研究遵循促进有关地球系统科学问题的国际倡议的两个相辅相成的轨道：i)气候和海洋的动态，ii)气候变化对土地侵蚀、地球化学循环和海平面的影响，重点是北半球高纬度地区。第一个轨道旨在预测全球变暖下加拿大北极的未来，重点关注：1)海冰的命运及其对沉积体系的影响；2)大陆冰的衰变和径流；3)它们对大西洋经向翻转环流和全球海平面的影响。将重建过去“温暖”时期的气候条件、过去和现在间冰期的上新世和热最佳时期以及向这种气候最佳时期过渡的时期，并用它们来确定边界条件的变化，并用于测试当前气候模型再现这类过去概要的能力。对地质档案，特别是深海沉积物进行稳定的、放射性的和放射性成因的同位素分析是计划开展的研究的主要工具。它们提供了获得地质时间和大量古环境参数的途径，从而获得了从百万年到现在的时间尺度上的地球系统的“前陆源修改”状态。在规划阶段，通过国际原子能机构关于“评估人类活动对大型河流系统水量和水质的影响的同位素工具”的项目，为利用上述某些同位素示踪剂监测现代环境所作的补充努力构成了第二个研究轨道。在这里，重点将放在麦肯齐河、圣劳伦斯河、环哈德逊湾河和哈德逊海峡河，用于示踪校准和记录正在进行的人类与自然驱动的过程，这些过程对土壤侵蚀、径流、沉积物和从陆地到海洋的化学通量产生影响。因此，该方案有基本的和与社会相关的目标，并将允许在对北方发展和/或在当前人为压力下评估土壤和水资源具有重要意义的领域培训多达20名研究生或博士后科学家。

The research follows two complementary tracks contributing to international initiatives about Earth system science issues: i) the dynamics of climate and ocean, and ii) the impact of climatic changes on land erosion, geochemical cycles and sea-levels, with focus on high Northern Hemisphere latitudes. The first track aims at predicting the future of the Canadian Arctic under a warmer globe with attention paid to i) the fate of sea-ice and its impact on sedimentary regimes, ii) continental ice decay and runoff, iii) their impact on the Atlantic Meridional Overturning Circulation and on global sea-levels. Conditions during past "warm" intervals, the Pliocene and thermal optima of the past- and present interglacial stages, and transition intervals towards such climatic optima, will be reconstructed and used to identify changes in boundary conditions and for testing current climate model abilities to reproduce such past-synopses. Stable, radioactive and radiogenic isotope analysis of geological archives, in particular of deep-sea sediments, constitute primary tools for the planned studies. They provide access to geological time and a large array of paleo-environmental parameters, thus to "pre antropogenically-modified" states of the Earth system, at time scale varying from million years to the present. Complementary efforts towards using some of the above isotopic tracers for the monitoring of modern environments constitute the second research track, through a project of the International Atomic Energy Agency on "Isotopic tools to assess anthropogenic impacts on water quantity and quality on large river systems", at planning stage. Here, the focus will be on the Mackenzie, St. Lawrence, circum-Hudson Bay and Hudson Strait rivers, both for tracer-calibration purposes and the documenting of on-going anthropogenically- vs naturally-driven processes with impact on soil erosion, runoff, sediment and chemical fluxes from the land to the ocean. This program has thus basics and socially relevant objectives and will permit the training of up to 20 graduate or post-doctoral scientists in domains of importance for the development of the North and/or the assessment of soil and water resources under the present anthropogenic pressure.