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

该研究遵循两个互补的轨道，为有关地球系统科学问题的国际倡议做出贡献：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，重点是北方高纬度地区。第一轨道的目的是预测加拿大北极地区的未来在一个温暖的地球仪的关注i）海冰的命运及其对沉积制度的影响，ii）大陆冰的衰变和径流，iii）它们对大西洋经向翻转环流和全球海平面的影响。在过去的“温暖”的时间间隔，上新世和热的过去和现在的间冰期阶段的最佳状态，以及向这样的气候最佳状态的过渡时间间隔的条件，将被重建，并用于确定边界条件的变化和测试目前的气候模式的能力，以重现这种过去的天气。对地质档案，特别是深海沉积物进行稳定、放射性和放射性同位素分析，是计划进行的研究的主要工具。它们提供了获取地质时间和大量古环境参数的途径，从而可以在从百万年到现在的时间尺度上了解地球系统的“前人为改变”状态。利用上述同位素示踪剂监测现代环境的补充努力构成了第二个研究方向，即通过国际原子能机构的一个项目，即“利用同位素工具评估人类活动对大型河流系统水量和水质的影响”，该项目正处于规划阶段。在这里，重点将放在麦肯齐，圣劳伦斯，环哈德逊湾和哈德逊海峡河流，无论是示踪剂校准的目的和记录正在进行的土壤侵蚀，径流，沉积物和从陆地到海洋的化学通量的影响与自然驱动的过程。因此，这一方案具有基本的和社会相关的目标，并将允许在对北方发展和/或在目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.