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质-超过大气或土地的总和！土壤有机质主要由碳组成，如果它被生活在土壤中的微生物所利用，它们将“吃掉”这种有机质并呼吸二氧化碳（CO2）。随着气候危机继续改变当地的温度和降水量，我们想了解SOM如何留在地下，而不是作为二氧化碳释放到大气中。一种有助于碳留在土壤中的机制，我们称之为SOM持久性，是SOM颗粒和矿物质之间的正电荷和负电荷，这些电荷来自破碎成小块的岩石。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。在基岩或母质含有大量矿物质的土壤中，这些矿物质可以随着流经土壤的水分、温度和酸的增加而释放。硝酸是一种自然产生的酸，来自生物固氮，豌豆和豆类等植物及其共生细菌可以做到。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，释放出有助于保护SOM的矿物质，从而提高碳的持久性。该项目将研究硝酸对岩石风化的影响，以及它与土壤碳储存的关系，从浅层到深层，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机会，可以通过保护女孩探险队与正在进行的外联工作合作，并将目前的旅行扩大到包括森林生态系统。该项目将为女性、非二元或性别酷儿高中生提供免费教育体验，并且该项目的学生选择不会基于成绩和考试成绩等传统学术基准。相反，学生将根据他们对临界区科学的兴趣和该计划可能改变他们未来的程度来选择。考虑到SOM持久性在C螯合和储存中的矿物相互作用的重要性，了解影响矿物相关有机物（MAOM）形成和持久性的过程是必要的。尽管生物固氮和人为沉积在地球仪的生态系统中引入了大量的氮，但硝酸对风化和随后的MAOM持久性的影响尚未得到研究。这项研究的长期目标是了解氮富集和硝酸风化如何影响MAOM丰度和持续性，跨越气候和主要矿物风化状态。本研究将量化长期土壤氮富集下的MAOM丰度和短期硝酸盐和硝酸输入后的MAOM损失。这些配对的实验将阐明如何MAOM的形成和不稳定的共同发生在增加氮富集和更多和更少的风化玄武岩母材之间。由于深层土壤中储存了大量的土壤碳，本提案的另一个目的是了解SOM保护矿物质协会和不稳定与深度。尽管在了解MAOM和矿物协会的广泛模式方面取得了重大进展，但关键的机械问题仍未得到验证。富氮对MAOM的影响构成了对MAOM形成和持续性以及土壤碳储量的理解的一个重要知识缺口。该提案通过将短期和长期的氮富集与MAOM的精细地球化学驱动因素联系起来，促进了临界区科学的知识。目前迫切需要了解和预测土壤中可以储存多少碳（C）以及这种碳的持续程度。这项工作提供了一个机会，以提高MAOM预测的准确性和陆地碳循环模型在面对全球变化的准确性。通过调查不同土壤氮梯度、温带和热带气候以及低风化和高风化玄武岩母质土壤中的MAOM丰度，这些发现可以应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。