CAREER: Taking the hydrochemical pulse of the critical zone in small catchments of the Andes-Amazon

水的旅程--从降水通过土壤和地下水到溪流和河流--决定了这种经济上和环境上必不可少的资源的数量和质量。在其路径上，水参与化学反应，将岩石转化为土壤，释放营养物质，为生态系统提供养料。基本的科学问题仍然是关于水的流动速度有多快，以及它通过分水岭的路线。回答这些问题对于理解地球临界区自然资源的产生和维持至关重要。最近开发的分析技术和理论进步有望从水携带的化学特征中获得新的见解。该项目将开发一个综合的研究和教育计划，通过对秘鲁安第斯-亚马逊地区的五个小流域进行详细的水化学研究来贡献这种洞察力。由于现有的基础设施、互补的正在进行的研究和独特的自然地形坡度，该研究网站提供了一个获得广泛适用的机械理解的难得机会。在Madre de Dios河流域先前工作的基础上，该项目将专注于从陡峭的多山安第斯山脉到低地亚马逊的过渡。山地到洪泛平原的过渡是常见的水文特征，但在现有的观测站中表现得很差。这项研究将确定水化学过程在这一转变过程中如何变化，并将探索观察到的变化的机制。该项目将围绕三个主题展开：(I)水的停留时间；(Ii)岩源溶质的浓度-排放关系；(Iii)植物水源、集水区水文学和岩源养分可获得性之间的关系。将利用新的水文测量和高频水化学测量来探讨这些主题。样本将从降水、溪水、土壤水和地下水中收集，并分析溶质浓度和水同位素比率。水化学研究将通过调查土壤、腐泥岩和基岩中的矿物分布来补充。新的数据将在该地区其他研究的地形、剥蚀率、植物根系和生态系统营养数据集的背景下进行解释。水和土壤样本采集、化学分析和数据解释将成为“关键区域暑期学校”的一部分，该学校构成综合研究和教育计划的核心，并将培训高水平的本科生和初级研究生，他们将在这一跨学科研究领域领导下一代。该项目将通过与景观设计师的合作，以及通过在美国和秘鲁开展更多的外联和教育活动，进一步扩大“关键区域”概念框架的覆盖范围。

Water's journey -- from precipitation through soils and groundwater to streams and rivers -- determines the quantity and quality of this economically and environmentally essential resource. Along its path, water mediates chemical reactions that transform rock into soil and that release nutrients, providing the sustenance for ecosystems. Basic scientific questions remain about how quickly water travels and what route it takes through watersheds. Answering these questions is vital for understanding the generation and maintenance of natural resources in Earth's critical zone. Recently developed analytical techniques and theoretical advances promise new insight from the chemical signatures carried by water. This project will develop an integrated research and education program to contribute such insight through detailed hydrochemical study in five small catchments in the Andes-Amazon of Peru. This study site provides a rare opportunity to gain widely applicable mechanistic understanding because of existing infrastructure, complementary ongoing research, and unique natural topographic gradients. Building on prior work in the Madre de Dios river basin, this project will focus on the transition from the steep, mountainous Andes to the lowland Amazon. Mountain-to-floodplain transitions are common hydrologic features but are poorly represented in existing observatories. The research will identify how hydrochemical processes vary over this transition and will explore mechanisms for observed variations. The project will center around three themes: (i) water residence times; (ii) concentration-discharge relationships of rock-derived solutes; and (iii) relationships between water sources for plants, catchment hydrology, and the availability of rock-derived nutrients. These themes will be explored using new hydrometric and high-frequency hydrochemical measurements. Samples will be collected from precipitation, streamwater, soilwater, and groundwater and analyzed for solute concentrations and water isotope ratios. The hydrochemical studies will be complemented by investigations of mineral distributions in soil, saprolite, and bedrock. New data will be interpreted in the context of topographic, denudation rate, plant root, and ecosystem nutrient datasets from other studies in the region. Water and soil sample collection, chemical analyses, and data interpretation will form part of a "Critical Zone Summer School" that comprises the core of the integrated research and education plan and will train upper-level undergraduate and beginning graduate students who will lead the next generation in this cross-disciplinary research area. This project will further broaden the reach of the "critical zone" conceptual framework through collaboration with landscape architects and through additional outreach and educational activities both in the US and in Peru.