Muddying the waters: cation exchange processes as a major control on weathering fluxes.

搅浑水：阳离子交换过程是风化通量的主要控制因素。

基本信息

批准号：
2393952
负责人：
金额：
--
依托单位：
University of Cambridge
依托单位国家：
英国
项目类别：
Studentship
财政年份：
2020
资助国家：
英国
起止时间：
2020 至无数据
项目状态：
未结题

来源：
https://gtr.ukri.org/projects?ref=studentship-2393952
关键词：
Muddying waters cation exchange processes

Muddying waters cation exchange processes

项目摘要

Estimates of carbon consumption by silicate weathering could be wrong by up to 80% because they assume that cations behave in a conservative way during dissolution and transport. One suite of chemical reactions are referred to as cation exchange reactions. They occur rapidly as a chemical equilibrium develops between charged mineral surfaces and a water. One of the most important mineral groups which have charged surfaces are clays. These rapid reactions are well studied in soils and aquifers, but the scientific community working on river chemistry has largely neglected these reactions. Our work shows that once the cation exchange process is taken into account it changes significantly the chemistry of natural waters and the total amount of carbon consumption through chemical weathering, with major implications for climate feedbacks.This project will determine the impact of cation exchange between clay minerals and river waters on estimates of chemical weathering fluxes and thus on the feedback which moderates climate on long timescales. The main objective will be achieved by a combination of laboratory experimental studies, and paired measurements of water chemistries and suspended load depth-profiles on major rivers allowing re-evaluation of silicate chemical weathering fluxes. The student will determine the magnitude of the release of cations from the suspended load exchange pool when rivers enter the ocean and Na replaces Ca, Mg and Sr on exchange sites. This will be done in two ways, firstly with a set of controlled experiments, and secondly in the field setting of the Mackenzie River in the Arctic Circle. The student will sample paired suspended sediment and water across the salinity gradient in the estuary of the Mackenzie River as part of a dedicated expedition. We will trace the effects of cation exchange using a suite of isotope ratio tracers such as Mg, Li and Sr isotope ratios.

硅酸盐风化对碳消耗的估计可能是错误的80％，因为他们认为阳离子在溶解和运输过程中以保守的方式行事。一套化学反应称为阳离子交换反应。当化学平衡在带电的矿物表面和水之间发展时，它们迅速发生。充电表面的最重要的矿物质组之一是粘土。这些快速反应在土壤和含水层中进行了很好的研究，但是从事河流化学的科学界在很大程度上忽略了这些反应。我们的工作表明，一旦考虑到阳离子交换过程，它会显着变化自然水的化学反应以及通过化学风化的碳消耗总量，这对气候反馈产生了重大影响。该项目将确定粘土矿物质和河水之间阳离子交换对化学风化的估算的影响，从而对化学风化的估算值估算，从而调节反馈，从而调节了延长延长延期气候的反馈。主要目标将通过实验室实验研究的组合以及对主要河流上的水化学和悬挂载荷深度构造的配对测量，从而重新评估硅酸盐化学风化通量。当河流进入海洋时，学生将确定从悬挂式负载交换池释放的大小，而NA替代了交换地点上的CA，MG和SR。这将通过两种方式进行，首先是通过一组受控的实验，其次是在北极圆圈的Mackenzie河的田间设置。该学生将在麦肯齐河河口的盐度梯度上采样配对的悬浮沉积物和水，作为专门探险的一部分。我们将使用同位素比率示踪剂（例如Mg，Li和SR同位素比率）追踪阳离子交换的效果。