Postdoctoral Fellowship: EAR-PF: Linking soil nitrogen enrichment to mineral weathering and associated organic matter persistence

博士后奖学金：EAR-PF：将土壤氮富集与矿物风化和相关有机物持久性联系起来

• 批准号: 2305518
• 负责人: Amelia Fitch
• 金额: $ 18万
• 依托单位: Fitch, Amelia A
• 依托单位国家: 美国
• 项目类别: Fellowship Award
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-05-01 至 2026-04-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2305518&HistoricalAwards=false
• 关键词: Postdoctoral; Fellowship; EAR; PF; Linking

Soils store a huge amount of organic matter - more than the atmosphere or land combined! Soil organic matter is mostly made up of carbon, and if it becomes available to microbes living in the soil, they will “eat” this organic matter and respire carbon dioxide (CO2). As the climate crisis continues to alter local temperatures and precipitation, we want to understand how the SOM will stay in the ground instead of being released to the atmosphere as carbon dioxide. One mechanism that helps carbon stay in the soil, which we call SOM persistence, are positive and negative charges between SOM particles and minerals, which come from rocks broken into tiny pieces. The process of breaking rocks down into minerals that help protect SOM from microbes is called weathering. In soils where the bedrock, or parent material, has a lot of minerals, these minerals can be released with increasing amounts of moisture, temperature, and acids that flow through the soil. Nitric acid is a naturally produced acid from biological nitrogen (N) fixation, which plants like peas and beans with their symbiotic bacteria can do. Across soils that have a lot of N fixing plants, more nitric acid may have helped to weather parent material and release minerals that can help protect SOM, leading to more carbon persistence. This project will investigate the relationship between rock weathering by nitric acid and how it relates to soil C storage from shallow to deep soils, and across ecosystems with low and high weathered parent material. The sites chosen to study the long-term N enrichment gradient in Oregon forests also provide an opportunity to collaborate with ongoing outreach efforts through the Inspiring Girls Expeditions and expand the current trips to include forest ecosystems. This program will be a no-cost educational experience for high school students identifying as women, non-binary, or genderqueer, and selection of students to this program will not be based on traditional academic benchmarks such as grades and test scores. Instead, students will be chosen based on their interest in Critical Zone sciences and the degree to which this program may change their futures.The need to understand the processes that affect mineral-associated organic matter (MAOM) formation and persistence are imperative given the importance of SOM persistence by mineral interactions in C sequestration and storage. Though biological nitrogen (N) fixation and anthropogenic deposition introduce significant quantities of N in ecosystems across the globe, the effects of nitric acid on weathering and subsequent MAOM persistence has not been studied. The long-term goal of this research is to understand how N enrichment and nitric acid weathering affects MAOM abundance and persistence across climates and primary mineral weathering states. This research will quantify both MAOM abundance under long-term soil N-enrichment and MAOM loss after short-term nitrate and nitric acid inputs. These paired experiments will clarify how MAOM formation and destabilization co-occur across increasing N enrichment and between more and less weathered basalt parent material. Because deep soils store a substantial amount of soil C, an additional aim of this proposal is to understand SOM protection by mineral-associations and destabilization with depth. Despite the significant gains in understanding broad patterns of MAOM and mineral associations, key mechanistic questions remain untested. The effects of N enrichment on MAOM constitutes a significant knowledge gap in the understanding of MAOM formation and persistence, and consequently, soil C storage. This proposal advances knowledge in Critical Zone science by linking short and long-term N enrichment with fine-scale geochemical drivers of MAOM. There is an urgent need to understand and predict how much carbon (C) can be stored in soils and the degree to which this carbon persists. This work offers an opportunity to improve the accuracy of MAOM predictions and the accuracy of terrestrial C cycling models in the face of global change. By investigating MAOM abundance in soils across a gradient of soil N, between temperate and tropical climates, and between soils of low and high weathered basalt parent material, these findings can apply to many ecosystems that experience N enrichment.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.

土壤储存了大量的有机物——比大气或土地的总和还要多。土壤有机物主要由碳组成，如果生活在土壤中的微生物能够利用这些有机物，它们就会“吃掉”这些有机物并呼吸碳！随着气候危机继续改变当地的温度和降水，我们希望了解 SOM 如何留在地下，而不是作为二氧化碳释放到大气中，这是一种帮助碳留在土壤中的机制。我们称之为 SOM 持久性，是积极的SOM 颗粒和矿物质之间的负电荷，这些负电荷来自破碎成小块的岩石。在基岩或母质含有大量矿物质的土壤中，将岩石分解成有助于保护 SOM 免受微生物侵害的矿物质的过程称为风化。随着流经土壤的水分、温度和酸的增加，这些矿物质会被释放出来。硝酸是生物固氮 (N) 过程中自然产生的酸，豌豆和豆类等植物及其共生细菌可以做到这一点。 。穿过在有大量固氮植物的土壤中，更多的硝酸可能有助于风化母质并释放有助于保护 SOM 的矿物质，从而导致更多的碳持久性。该项目将研究硝酸导致的岩石风化之间的关系及其如何发生。涉及从浅层到深层的土壤碳储存，以及具有低风化和高风化母质的生态系统。选择研究俄勒冈州森林中长期氮富集梯度的地点也提供了一个通过鼓舞人心的项目与正在进行的外展工作合作的机会。女孩们探险并扩大当前的旅行范围，将森林生态系统纳入该计划，该计划将为女性、非二元性别或性别酷儿的高中生提供免费的教育体验，并且该计划的学生选择将不会基于传统的学术背景。相反，学生将根据他们对关键区域科学的兴趣以及该计划可能改变他们的未来的程度来选择。需要了解影响矿物相关有机物（MAOM）的过程。形成和坚持是必要的尽管生物固氮和人为沉积在全球生态系统中引入了大量的氮，但硝酸对风化和随后的 MAOM 持久性的影响尚未研究。这项研究的长期目标是了解氮富集和硝酸风化如何影响不同气候和初级矿物风化状态下 MAOM 的丰度和持久性。短期硝酸盐和硝酸输入后的 MAOM 损失将阐明 MAOM 的形成和不稳定是如何在氮富集增加以及更多和更少风化玄武岩母质之间同时发生的，因为深层土壤储存了大量的土壤 C，该提案的另一个目的是了解矿物组合对 SOM 的保护以及深度的不稳定作用，尽管在理解 MAOM 和矿物组合的广泛模式方面取得了重大进展，但关键的机制问题仍未得到检验。 MAOM 氮富集的研究构成了理解 MAOM 形成和持久性以及土壤碳储存方面的重大知识差距，该提案通过将短期和长期氮富集与精细地球化学驱动因素联系起来，推进了关键区域科学的知识。 MAOM。迫切需要了解和预测土壤中可以储存多少碳（C）以及这些碳的持续程度，这项工作为提高 MAOM 预测的准确性和陆地碳循环的准确性提供了机会。型号面对全球变化，通过调查不同土壤氮梯度、温带和热带气候之间以及低风化玄武岩和高风化玄武岩母质土壤之间的MAOM丰度，这些发现可以适用于许多经历氮富集的生态系统。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。