The key to quantifying chemical weathering intensity: clay stable isotope fractionation factors

化学风化是岩石与天然沃茨接触后溶解的过程。这种溶解过程为植物提供营养，为沃茨提供溶质（你可能会在一瓶矿泉水的标签上找到这种溶质），并通过河流和地下沃茨将营养物质输送到海洋。这些营养物质被藻类和微小的浮游生物用来生长，包括由碳酸钙制成的海洋动物的外壳的生长。大陆上矿物溶解和海洋中生物碳酸钙形成的这一耦合过程在调节全球碳循环方面发挥着关键作用，将碳从大气转移到碳酸盐岩储层，此时贝壳作为沉积物被掩埋。地质学家认为，这一系列简单的反应在调节碳循环和地球历史上的气候方面发挥了关键作用。岩石不只是简单地溶解在雨水中，它们慢慢地分解，通过形成新的矿物质（通常是粘土），它们逐步转化为溶质。粘土是一种非常常见的矿物，存在于我们周围的土壤和岩石中。我们寻求使用新的化学方法来了解粘土如何对化学风化过程起重要作用，利用最新的技术进步，使我们能够非常精确地测量粘土形成中关键元素镁，硅和锂的同位素比率。一种元素的不同同位素，由于原子核中有额外的中子，所以它们的质量差别很小。地球化学家可以测量这些同位素数量的微小差异，并从这些差异中推断出粘土是如何形成的关键点。重要的是，当粘土在自然界中结晶时，这些同位素会发生分馏，但人们对此知之甚少。为了提高我们的理解，我们试图在实验室中制造人造粘土，在那里我们可以仔细控制所有的形成条件，并观察同位素的行为。随着我们对同位素在实验室中的行为的详细了解，我们将把这些知识应用于自然世界，在那里我们将更好地了解化学风化，以及碳循环，从而气候在地球历史上的表现。

Chemical weathering is the process by which rocks dissolve in contact with natural waters. This process of dissolution supplies nutrients to plants, solutes to waters (of the kind you might find on the label of a bottle of mineral water) and delivers nutrients to the oceans via rivers and groundwaters. These nutrients are used by algae and microscopic plankton to grow, including the growth of shells of marine fauna which are made from calcium carbonate. This coupled process of mineral dissolution on the continents and biogenic calcium carbonate formation in the oceans plays a key role in regulating the global carbon cycle, transferring carbon from the atmosphere to the carbonate rock reservoir, when shells become buried as sediments. Geologists think that this simple series of reactions has played a pivotal role in regulating the carbon cycle and hence climate over Earth's history.Critical to this series of processes are clays. Rocks don't simply just dissolve in rainwater, they break down slowly, and their transformation into solutes happens in a stepwise manner via the formation of new minerals, frequently clays. Clays are a very common mineral and present in soils and rocks in the world all around us. We seek to use novel chemical methods to understand how clays are important to the processes of chemical weathering, exploiting recent technological advances that allow us to measure very precisely isotope ratios of the key elements in clay formation, magnesium, silicon and lithium. Different isotopes of an element, have very small differences their mass because of additional neutrons in their nuclei. Geochemists can measure small differences in the amount of these isotopes and from these differences infer key points about how the clays are being made. Importantly these isotopes are fractionated when clays crystallise in the natural world, but this is poorly understood. To improve our understanding, we seek to make artificial clays in the laboratory, where we can control all the conditions of formation carefully, and observe how the isotopes behave. With our detailed understanding of how the isotopes behave in the laboratory, we will then apply this knowledge to the natural world, where we will gain a much better understanding of chemical weathering, and how the carbon cycle, and hence climate has behaved over Earth history.