ISO-THERM: Isotopic testing of Earth's weathering thermostat

ISO-THERM：地球风化恒温器的同位素测试

• 批准号: NE/T011440/1
• 负责人: David Wilson
• 金额: $ 85.15万
• 依托单位: University College London
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FT011440%2F1
• 关键词: ISO; THERM; Isotopic; testing; Earth

Weathering is a chemical reaction which dissolves rocks in rainwater and over long timescales removes carbon dioxide (CO2) from the atmosphere. Both theories and experiments predict that rocks will dissolve faster with warmer temperatures, potentially making chemical weathering the key process that has stabilised Earth's climate over millions of years. Conceptually, if atmospheric CO2 levels increase, the greenhouse effect would lead to warmer temperatures and more weathering, thereby removing CO2 and cooling climate. Hence, weathering can provide a climate "thermostat", preventing big swings in climate and maintaining a habitable planet.However, weathering in the real world is more complex than in the laboratory, and evidence for how this climate "thermostat" operates is lacking. We simply do not know how sensitive weathering is to climate, either locally or globally, and therefore we do not know how well this thermostat works. Indeed, we do not even know if weathering is the most important control on the earth's climate, as some scientists have proposed alternative controls such as seafloor alteration, biological carbon cycling, and sulphuric acid weathering of limestone. Our poor understanding of weathering represents a major gap in our understanding of the global carbon cycle, and a significant challenge for modelling past and future climate change.To test the weathering "thermostat" on Earth, this project will reconstruct how weathering has changed in the past using a programme of geological detective work. Although there have been interesting clues to date, the evidence has been circumstantial and often unreliable. The problem is that records of past ocean chemistry have indicated weathering changes, but we have not had reliable forensics to tie these changes to the continental regions where the weathering occurred. Fortunately, two discoveries from my previous investigations lead to a way forward in this case. First, the distinct composition of the lead (Pb) atoms in continental rocks provides a geological "fingerprint" that is transferred by chemical weathering via rivers into the ocean. Second, sediments formed in the ocean are witnesses to this "fossil seawater" composition. Therefore, by analysing ocean sediments of different ages, a detailed timeline of weathering changes will be reconstructed, and comparison to those continental Pb fingerprints will reveal the weathering culprits. Measuring another element, lithium (Li), will provide corroborating evidence on the weathering environment, revealing how the weathering was carried out and what controlled it.Together, this new evidence will reveal the controls of climate and mountain uplift on the weathering of different rock types in different regions. Computer modelling will then be used, in combination with evidence of past changes in climate and CO2, to determine the strength of the weathering "thermostat". This result is crucial for addressing the question of how a habitable climate is maintained on Earth. Furthermore, this information will improve climate models, because predicting Earth's future climate evolution in response to anthropogenic carbon emissions relies on an understanding of how, and how quickly, weathering will respond to these changes.

风化是一种化学反应，它将岩石溶解在雨水中，并在很长时间内从大气中去除二氧化碳(CO2)。理论和实验都预测，随着温度的升高，岩石的溶解速度会更快，这可能会使化学风化成为数百万年来稳定地球气候的关键过程。从概念上讲，如果大气二氧化碳水平增加，温室效应将导致气温变暖和更多的风化，从而消除二氧化碳，使气候降温。因此，风化可以提供一个气候“恒温器”，防止气候的大幅波动，并维持一个宜居的星球。然而，现实世界中的风化比实验室中的更复杂，这种气候“恒温器”是如何工作的缺乏证据。我们根本不知道气候变化对气候有多敏感，无论是在当地还是在全球，因此我们不知道这个恒温器工作得有多好。事实上，我们甚至不知道风化是否是对地球气候最重要的控制，因为一些科学家提出了其他控制措施，如海底改造、生物碳循环和石灰岩的硫酸风化。我们对风化的缺乏了解是我们对全球碳循环理解的一大空白，也是模拟过去和未来气候变化的一个重大挑战。为了测试地球上的风化“恒温器”，这个项目将使用一个地质探测工作计划来重建过去风化如何变化。尽管到目前为止已经有了有趣的线索，但证据都是间接的，而且往往不可靠。问题是，过去的海洋化学记录表明了风化变化，但我们还没有可靠的证据来将这些变化与发生风化的大陆地区联系起来。幸运的是，我之前调查中的两项发现为这起案件提供了前进的方向。首先，大陆岩石中铅原子的独特组成提供了一个地质“指纹”，通过河流的化学风化作用转移到海洋中。其次，海洋中形成的沉积物是这种“化石海水”成分的见证。因此，通过分析不同时代的海洋沉积物，将重建详细的风化变化时间线，并与大陆铅指纹相比较，将揭示风化的罪魁祸首。另一种元素锂(Li)的测定将为风化环境提供佐证，揭示风化是如何进行的，以及是什么控制了风化。同时，这一新的证据将揭示气候和山脉隆起对不同地区不同类型岩石的风化的控制。然后，将使用计算机模拟，结合过去气候和二氧化碳变化的证据，来确定风化“恒温器”的强度。这一结果对于解决如何在地球上维持宜居气候的问题至关重要。此外，这些信息将改进气候模型，因为预测地球未来应对人为碳排放的气候演变取决于对风化作用如何以及以多快的速度对这些变化做出反应的理解。

项目成果

Cold-water corals as archives of seawater Zn and Cu isotopes

• DOI: 10.1016/j.chemgeo.2021.120304
• 发表时间: 2021-05
• 期刊: Chemical Geology
• 影响因子: 3.9
• 作者: S. Little;David J. Wilson;M. Rehkämper;J. Adkins;L. Robinson;T. Flierdt

The influence of river-derived particles on estuarine and marine elemental cycles: evidence from lithium isotopes

• DOI: 10.1016/j.gca.2023.08.015
• 发表时间: 2023-08
• 期刊: Geochimica et Cosmochimica Acta
• 影响因子: 5
• 作者: Chun-Yao Liu;David J. Wilson;E. Hathorne;Antao Xu;Philip A. E. Pogge von Strandmann

Behaviour of Sr, Ca, and Mg isotopes under variable hydrological conditions in high-relief large river systems

• DOI: 10.1016/j.gca.2023.01.003
• 发表时间: 2023-02
• 期刊: Geochimica et Cosmochimica Acta
• 影响因子: 5
• 作者: Bei Chen;Si‐Liang Li;Philip A. E. Pogge von Strandmann;David J. Wilson;J. Zhong;Tingting Ma;Jian Sun-Jian

Calcium isotopes tracing secondary mineral formation in the high-relief Yalong River Basin, Southeast Tibetan Plateau.

钙同位素追踪青藏高原东南部高地貌雅砻江盆地次生矿物形成。

• DOI: 10.1016/j.scitotenv.2022.154315
• 发表时间: 2022
• 期刊: The Science of the total environment
• 作者: Chen BB

Controls on Lithium Incorporation and Isotopic Fractionation in Large Benthic Foraminifera

• DOI: 10.3390/min13010127
• 发表时间: 2023-01-01
• 期刊: MINERALS
• 影响因子: 2.5
• 作者: Charrieau, Laurie M.;Rollion-Bard, Claire;Bijma, Jelle
• 通讯作者: Bijma, Jelle