Collaborative research: Controls of climate and dust on soil chemical erosion and nutrient supply

土壤是地球表面环境的重要组成部分。它们是维持生命的营养物质的仓库，它们为植物和动物提供栖息地，它们通过在全球碳循环中的作用影响地球气候。该项目的主要目标是量化气候和灰尘如何影响土壤化学侵蚀速率和土壤养分含量。 这一点很有意义，因为化学侵蚀加速了地貌的演变，调节了地球的气候，而且灰尘是土壤养分的主要来源。为了调查这些相互关联的现象，该项目将在加州圣哈辛托峰沿沿着两个垂直断面建立一系列研究点，那里近3公里的地形造成了惊人的气候梯度，年平均温度为18摄氏度。 这项工作将支持一个团队的两个早期职业教师（一名女性，都前任期），并将通过PI团队的支持，促进多样性举措，一个人是一个代表性不足的群体（阿拉斯加原住民）的成员，以及通过招聘学生通过校园计划的学生从代表性不足的群体。 外联和教育活动将侧重于与圣地亚哥县教育办公室和威斯康星州大学地质博物馆的专家合作，为中学教师开发资源。尽管长期以来人们期望气候应该强烈影响化学侵蚀速率，但事实证明，量化自然界中的这些影响是困难的，部分原因是这些速率难以测量，部分原因是岩性和灰尘等其他因素会掩盖气候影响。 灰尘对土壤养分供应的影响也是一个持续争论的话题，部分原因是它取决于土壤生产和化学侵蚀的速度，而这些速度很少在灰尘沉积速度相同的地方测量。 拟议的工作将通过结合SJP的化学侵蚀速率、气候、灰尘沉积速率和来源的测量来避免这些问题，SJP跨越了美国单一未冰川化岩性内最大的温度范围。 这将建立在以前的工作，通过应用新的放射性同位素测量基岩，土壤，灰尘和植被。 这些数据将量化化学侵蚀速率对气候的敏感性，并为灰尘对土壤养分供应的影响的时空变化提供新的见解，这在这项工作中将针对的季节性时间尺度上没有很好的约束。 更广泛地说，这项工作有可能消除一个障碍，了解地球的地形，表面化学和灰尘循环如何在空间变化的气候下演变，这是地球山脉的一个共同特征。 最终，这些测量跨越了美国最引人注目的气候梯度之一，应该指导未来的努力，将气候和尘埃明确纳入地球表面地形和化学演变的模型中。该奖项反映了NSF的法定使命，并被认为值得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来支持。

Soils are a critical component of Earth’s surface environment. They are storehouses of nutrients that sustain life, they provide habitats for plants and animals, and they influence Earth’s climate through their role in the global carbon cycle. This project’s main goal is to quantify how climate and dust affect soil chemical erosion rates and soil’s nutrient content. This is of interest because chemical erosion accelerates landscape evolution and modulates Earth’s climate, and because dust is a key source of nutrients to soils. To investigate these linked phenomena, this project will establish a series of study sites along two altitudinal transects at San Jacinto Peak, California, where nearly 3 km of relief creates a striking climate gradient with a range in mean annual temperature of 18 degrees C. This work will support a team of two early career faculty (one female, both pre-tenure), and will promote diversity initiatives through the support of the PI team, one whom is a member of an underrepresented group (Alaska Native), as well as through the recruitment of students via on-campus programs for students from underrepresented groups. Outreach and education activities will focus on developing resources for middle school teachers in collaboration with experts at the San Diego County Office of Education and the University of Wisconsin Geology Museum.Despite longstanding expectations that climate should strongly affect chemical erosion rate, quantifying these effects in nature has proven difficult, partly because these rates are difficult to measure, and partly because other factors like lithology and dust can obscure climatic effects. Dust’s impact on soil nutrient supply is likewise an ongoing topic of contention, partly because it depends on rates of soil production and chemical erosion, which are rarely measured in the same places that dust deposition rates are. The proposed work will avoid these issues by combining measurements of chemical erosion rates, climate, and dust deposition rates and provenance at SJP, which spans the largest range in temperature within a single unglaciated lithology in the United States. This will build on previous work by applying novel radiogenic isotope measurements in bedrock, soil, dust and vegetation. These data will quantify the sensitivity of chemical erosion rates to climate and provide new insights into spatial and temporal variations in dust’s impact on soil nutrient supply, which is not well constrained at the seasonal time scales that will be targeted in this work. More broadly, this work has the potential to remove a barrier to understanding how Earth’s topography, surface chemistry, and the dust cycle evolve under spatially variable climates—a common feature of Earth’s mountain ranges. Ultimately, these measurements across one of the most striking climate gradients in the United States should guide future efforts to include climate and dust explicitly in models of the topographic and chemical evolution of the Earth’s surface.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.