Collaborative Research: Quantifying controls on weathering of volcanic arc rocks

化学风化作用使岩石变成土壤。在很长一段时间内，它还会降低大气中的二氧化碳含量。了解不同岩石类型的土壤形成速度对可持续农业和林业非常重要。这对于理解数百万年来驱动世界气候变化的因素也很重要。该项目使用三种不同的方法来测量波多黎各各种岩石的风化和土壤生成速率，并将涉及两种使用同位素的新测量方法。这些岩石类型很常见，容易风化，在全球范围内非常重要。它汇集了普渡大学和波多黎各大学马亚圭斯分校的研究人员。这项资助为这两所大学的研究生和本科生带来了新的教育和研究机会，包括波多黎各学生，他们传统上在STEM领域的代表性不足。该项目的目标是测量火山和富含铁的火成岩的化学风化如何依赖于物理侵蚀提供的新鲜矿物。这种关系对于理解地质时期构造过程在控制全球碳循环和气候方面的作用至关重要。确定长期风化速率的主要方法将利用宇宙核素的测量，这是由地球表面附近矿物中的宇宙射线产生的。其中包括一种利用矿物磁铁矿中产生的宇宙成因氯-36的新方法，以及一种利用大气中产生的宇宙成因铍-10并通过雨水沉积到土壤中的新方法。这些长期速率将在具有不同岩石类型和物理侵蚀速率的各种流域中测量。它们将与通过测量溪流中溶解的矿物质而确定的短期速率进行比较，以探索短期过程（如热带气旋驱动的滑坡导致的新鲜岩石暴露）对风化作用的影响程度，这是波多黎各和其他地方的一个重要侵蚀过程。这项工作有望为系统地解决各种岩石类型的化学风化和物理侵蚀提供一些第一批数据，也有助于测试和验证新的、广泛适用的基于宇宙核素的方法。该项目有助于支持和发展普渡大学和波多黎各大学马亚圭斯分校的科学家之间的新研究关系，并为两所机构的学生带来新的教育和研究机会，包括波多黎各学生，他们传统上在STEM中代表性不足。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Chemical weathering turns rock into soil. Over long periods of time it also lowers carbon dioxide in the atmosphere. Knowing how fast soil forms on different rock types is important for sustainable farming and forestry. It is also important for understanding what drives the world’s climate over millions of years. This project uses three different methods to measure weathering and soil production rates on a variety of rocks in Puerto Rico and will involve two new measuring methods using isotopes. These rock types are common, easy to weather, and very important on a global scale. It brings together researchers at Purdue University and the University of Puerto Rico, Mayaguez. This grant brings new education and research opportunities to both graduate and undergraduate students at the two institutions, including Puerto Rican students, who are traditionally under-represented in STEM. The goal of this project is to measure how the chemical weathering of volcanic and iron-rich igneous rocks depends on the supply of fresh minerals by physical erosion. This relationship is critical for understanding the role of tectonic processes for governing the global carbon cycle and climate through geologic time. The primary methods for determining long-term weathering rates will utilize the measurement of cosmogenic nuclides, which are produced by cosmic rays in minerals near Earth’s surface. These include a new method using cosmogenic chlorine-36 produced in the mineral magnetite, as well as an emerging method that uses cosmogenic beryllium-10 produced in the atmosphere and deposited onto the soil by rainwater. These long-term rates will be measured in a variety of watersheds with different rock types and physical erosion rates. They will be compared to short-term rates determined from measurement of dissolved minerals in stream water to explore the degree to which weathering is driven by short-term processes such as the exposure of fresh rock by tropical cyclone-driven landsliding, an important erosional process in Puerto Rico and elsewhere. This work is expected to contribute some of the first data that systematically address chemical weathering and physical erosion for a variety of rock types, and also serves to test and validate new and widely applicable cosmogenic nuclide-based methods. This project helps support and develop a new research relationship between scientists at Purdue University and the University of Puerto Rico, Mayaguez and brings new education and research opportunities to students at the two institutions, including Puerto Rican students, who are traditionally under-represented in STEM.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.