Investigating climate controls on weathering processes in modern and ancient river systems

本研究项目的总体目标是更好地理解和预测不同时空尺度下化学风化的控制。化学风化反应将元素从大陆地壳转移到河流和海洋。这个过程是通过调节生物地球化学循环来解释为什么地球适合居住的关键。例如，当气候变暖时，化学风化的速度增加，从而加快了海洋碳酸盐降水的速度。碳酸盐沉淀消耗大气中的二氧化碳（CO2），冷却气候，最终降低化学风化速率。这种气候风化反馈使地球能够通过将温度保持在一个紧密而有利的范围内来维持活跃的水循环。化学风化在人类时间尺度上也是一个重要的过程。例如，化学风化影响土壤特性（如肥力）和河流的化学性质，从而控制生态系统和人类社会的可持续性。全球变暖正在迅速改变化学风化反应的背景条件。为了更好地重建过去和预测未来地球表面的条件，迫切需要新的研究来研究气候和风化的相互作用。然而，研究风化是具有挑战性的，因为许多地质环境变量影响这一过程。在接下来的5年里，我的团队将朝着我的总体目标努力，通过以下三个短期目标来研究风化对不同时空尺度上变暖的响应。我们的第一个目标是研究永久冻土覆盖的变化如何影响育空河流域的风化。我们的第二个目标是开发新的古风化代用物，以评估Laramide洪泛平原的土壤对早期古近纪变暖趋势和事件的反应。我们的第三个目标是完善当今海洋锶同位素预算，以研究冰期和间冰期之间风化的变化。这项工作的结果将对决策者产生区域影响，帮助他们改善特定环境（例如育空河流域）的可持续性。这个项目还将提高我们对风化作用的认识，它是气候、海洋成分和生物圈进化的长期驱动因素。这些知识对于开发更强大的地球系统模型来重建过去和预测地球生物地球化学演化的未来至关重要。该研究项目将利用实地和实验室经验、团队合作和多学科合作项目，培养7名理学士、2名理学硕士和3名博士。通过这次培训，HQP将提高他们的软技能，同时获得同位素地球化学和数值方法方面的强大技术知识。该计划将培养多才多艺的环境地球科学家，能够管理加拿大及其他地区的自然资源。

The overarching goal of this research program is to better understand and predict the controls of chemical weathering at different spatiotemporal scales. Chemical weathering reactions transfer elements from the continental crust to rivers and to the ocean. This process is key to explaining why the earth is habitable by regulating biogeochemical cycles. For example, when the climate warms, the rate of chemical weathering increases, thereby accelerating the rate of marine carbonate precipitation. Carbonate precipitation consumes atmospheric carbon dioxide (CO2) and cools the climate, ultimately lowering chemical weathering rates. This climate-weathering feedback has allowed the Earth to maintain an active water cycle by keeping temperature within a tight and favorable range. Chemical weathering is also an important process at human timescales. For example, chemical weathering influences soil proprieties (e.g., fertility) and the chemistry of rivers, thereby controlling the sustainability of ecosystems and human societies. Global warming is rapidly changing the background conditions for chemical weathering reactions. Novel studies are urgently needed to investigate the interactions of climate and weathering to better reconstruct the past and forecast the future conditions on the Earth's surface. However, studying weathering is challenging because many geo-environmental variables influence this process. In the next 5 years, my group will work towards my overarching goal by studying the response of weathering to warming at different spatiotemporal scales as defined by the three following short-term goals. Our first goal will investigate how changes in permafrost cover influence weathering across the Yukon River catchment. Our second goal will develop novel paleo-weathering proxies to assess how soils of Laramide floodplains responded to early Paleogene warming trends and events. Our third goal will refine the marine strontium isotope budget at present-day to investigate the changes in weathering between glacial and interglacial periods. The results from this work will have regional implications for policy makers, helping them to improve the sustainability of specific environments (e.g., Yukon River catchment). This program will also advance our knowledge on the role of weathering as a long-term driver of climate, ocean composition and biosphere evolution. This knowledge is crucial to develop more robust Earth system models to reconstruct the past and predict the future of Earth's biogeochemical evolution. This research program will use field and laboratory experience, team work and collaborative multi-disciplinary projects to train 7 BSc, 2 MSc and 3 PhD. Through this training, HQP will improve their soft skills while gaining strong technical knowledge in isotope geochemistry and numerical methods. This program will educate versatile environmental geoscientists capable of managing natural resources in Canada and beyond.