Quantifying cation exchange: Re-assessing the weathering signature of continental waters

量化阳离子交换：重新评估大陆水域的风化特征

基本信息

批准号：
NE/K000705/2
负责人：
Edward Tipper
金额：
$ 3.19万
依托单位：
University of Cambridge
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2015
资助国家：
英国
起止时间：
2015 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FK000705%2F2
关键词：
Quantifying cation exchange Re assessing

项目摘要

Chemical weathering mediates Earth's carbon cycle and hence global climate over geological time-scales. Ca and Mg from silicate minerals are released to the solute phase during dissolution with carbonic acid. This solute Ca and Mg gets subsequently buried as Ca and Mg carbonates in ocean basins transferring carbon from the atmosphere to the carbonate rock reservoir. This simple reaction has provided the climatic feedback that has maintained Earth's climate equable and inhabitable over the entire history of the Earth. To understand how Earth's climate functions, it is therefore vital to understand silicate weathering and to estimate the flux carbon dioxide associated with modern chemical weathering. Modern day silicate weathering fluxes are estimated from the chemistry of rivers or natural waters. Natural waters contain positively charged elements or cations such as Ca, Mg, Na and K, and it has been understood for decades that the relative and absolute concentrations of these elements depend of the type of rocks that are drained. For example, Ca is mainly derived from the weathering of limestones, whereas Na and K are mainly derived from the weathering of silicate minerals such as feldspar. This distinction is important because only the Ca derived from silicate weathering is important for carbon dioxide consumption. Therefore, the Ca flux from silicate weathering is usually estimated based on Na, which has been thought to a more reliable estimate of silicate weathering. However, chemical weathering is more complex than simple mineral dissolution and a series of other chemical reactions also occur such as cation exchange. This is a process whereby the positively charged cations in solution are attracted to negatively charged mineral surfaces on clays, a process known to buffer groundwaters. One of the key chemical exchanges is Ca for Na, meaning that Na may not provide a true estimate of silicate weathering at all. Recent isotopic data suggests that cation exchange might be more significant that previously thought, which until now has been very hard to fingerprint. One method is to use naturally occurring tracers or isotopes, that allow chemical reactions to be tracked. In this work, it is proposed to examine the naturally occurring isotopes of the elements Li and Mg to examine the role of cation exchange in global budgets. However, to be able to do this successfully, a series of experimental work is proposed to examine the behaviour of the isotopes of Mg and Li during cation exchange. Once we understand how our tracers work we can use them to re-evaluate our understanding of natural waters, and better estimate fluxes of carbon dioxide associated with chemical weathering, with the ultimate aim of better understanding Earth's climate.

化学风化介导地球周期，从而介导地质时间尺度上的全球气候。用碳酸溶解期间，硅酸盐矿物质的Ca和Mg释放到溶质相。此溶质CA和MG随后被埋葬在海盆中的Ca和Mg碳酸盐中，将碳从大气中转移到碳酸盐岩储层中。这种简单的反应提供了气候反馈，在整个地球的整个历史上都保持了地球的气候平等和可居住。为了了解地球的气候功能如何了解硅酸盐风化并估计与现代化学风化相关的通量二氧化碳。现代的硅酸盐风化通量是从河流或天然水的化学反应中估计的。天然水中包含带正电的元素或阳离子，例如Ca，Mg，Na和K，并且几十年来已经理解，这些元素的相对浓度和绝对浓度取决于排水的岩石类型。例如，CA主要源自石灰石的风化，而Na和K主要源自硅酸盐矿物（例如Feldspar）的风化。这种区别很重要，因为只有硅酸盐风化的CA对于二氧化碳消耗很重要。因此，通常基于NA估算硅酸盐风化的CA通量，这被认为是对硅酸盐风化的更可靠的估计。但是，化学风化比简单的矿物溶解更为复杂，并且还会发生一系列其他化学反应，例如阳离子交换。这是一个过程，在该过程中，溶液中带正电荷的阳离子被粘土上带负电荷的矿物表面吸引，这是缓冲地下水的已知过程。关键的化学交换之一是CA的NA，这意味着NA可能根本无法提供硅酸盐风化的真实估计。最近的同位素数据表明，阳离子交换可能比以前认为的更重要，到目前为止，这一直很难指纹。一种方法是使用自然存在的示踪剂或同位素，以跟踪化学反应。在这项工作中，建议检查元素和MG元素的自然同位素，以检查阳离子交换在全球预算中的作用。但是，为了成功地做到这一点，提出了一系列实验性工作，以检查阳离子交换过程中MG和LI的同位素的行为。一旦我们了解了示踪剂的工作方式，我们就可以使用它们来重新评估我们对自然水的理解，并更好地估计与化学风化相关的二氧化碳的通量，以更好地了解地球气候。

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Experimental constraints on Li isotope fractionation during clay formation

DOI：
10.1016/j.gca.2019.02.015
发表时间：
2019-04
期刊：
Geochimica et Cosmochimica Acta
影响因子：
5
作者：
R. Hindshaw;Rebecca Tosca;Thomas L. Goût;I. Farnan;N. Tosca;E. Tipper
通讯作者：
R. Hindshaw;Rebecca Tosca;Thomas L. Goût;I. Farnan;N. Tosca;E. Tipper

Decoupling of dissolved and bedrock neodymium isotopes during sedimentary cycling

沉积循环过程中溶解的和基岩的钕同位素的解耦

DOI：
10.7185/geochemlet.1828
发表时间：
2018
期刊：
Geochemical Perspectives Letters
影响因子：
4.9
作者：
Hindshaw R
通讯作者：
Hindshaw R

Experimental constraints on Mg isotope fractionation during clay formation: Implications for the global biogeochemical cycle of Mg

DOI：
10.1016/j.epsl.2019.115980
发表时间：
2020-02-01
期刊：
EARTH AND PLANETARY SCIENCE LETTERS
影响因子：
5.3
作者：
Hindshaw, Ruth S.;Tosca, Rebecca;Tipper, Edward T.
通讯作者：
Tipper, Edward T.

Clay mineralogy, strontium and neodymium isotope ratios in the sediments of two High Arctic catchments (Svalbard)

DOI：
10.5194/esurf-6-141-2018
发表时间：
2017-09
期刊：
影响因子：
0
作者：
R. Hindshaw;N. Tosca;A. Piotrowski;E. Tipper
通讯作者：
R. Hindshaw;N. Tosca;A. Piotrowski;E. Tipper

Ocean acidification and the Permo-Triassic mass extinction

DOI：
10.1126/science.aaa0193
发表时间：
2015-04-10
期刊：
SCIENCE
影响因子：
56.9
作者：
Clarkson, M. O.;Kasemann, S. A.;Tipper, E. T.
通讯作者：
Tipper, E. T.

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Edward Tipper其他文献

The impact of adsorption–desorption reactions on the chemistry of Himalayan rivers and the quantification of silicate weathering rates

吸附-解吸反应对喜马拉雅河流化学的影响和硅酸盐风化速率的量化

DOI：
发表时间：
2024
期刊：
Earth and Planetary Science Letters
影响因子：
5.3
作者：
Alasdair C. G. Knight;Emily I. Stevenson;Luke Bridgestock;J. Jotautas Baronas;William J. Knapp;B. Adhikari;C. Andermann;Edward Tipper
通讯作者：
Edward Tipper