Collaborative Research: Feammox - A new pathway for nitrogen loss from terrestrial ecosystems

氮是微生物、植物和动物的关键营养物质，大量研究旨在了解陆地生态系统中氮的保留和损失的控制。尽管作出了这样的努力，但仍有许多不确定性，特别是关于气态氮的损失。这在人类改变氮循环的背景下尤其令人不安，这极大地增加了氮污染、径流和一氧化二氮（一种重要的辐射温室气体）的排放。该研究将通过量化“Feammox”这一新发现的全球氮循环途径的作用，有助于我们对陆地氮循环的理解。Feammox是氨的厌氧氧化与铁[Fe (III)]的还原相结合。它有可能产生惰性二氮气体以及反应性亚硝酸盐，这些亚硝酸盐随后可以在厌氧条件下还原为气态或有机氮或铵。考虑到陆地环境中氮的潜在气态损失，这一途径可能在全球氮循环中发挥重要作用。拟议的研究将通过(i)确定Feammox是否由土壤微生物介导，如果是，确定负责的生物，（ii）确定含铁和含氮化合物作为Feammox控制的相对重要性，以及（iii）量化Feammox在土壤总氮排放中的作用，将新发现的氮转化途径置于更大的氮循环背景下。加州大学伯克利分校的土壤生物地球化学实验室和内布拉斯加州大学林肯分校的微生物生物地球化学实验室的合作研究将提高对陆地氮循环的机理理解。实地工作将在波多黎各的Luquillo长期生态研究站进行。该研究解决了陆地生态系统中一个以前未量化的途径，该途径不仅对土壤中的养分保留有影响，而且还可能进化出一氧化二氮，一种与全球变化有关的温室气体。本项目将资助一名早期职业女性科学家、两名研究生、一名本科生和一名博士后。在波多黎各收集样品的同时，将为波多黎各高中学生举办讲习班和培训活动。波多黎各和加利福尼亚的科学咖啡馆将为广大公众提供生态和全球变化教育外展的组成部分。

Nitrogen is a key nutrient to microbes, plants and animals, and considerable research has been directed at understanding the controls on it's retention and loss in terrestrial ecosystems. Despite this effort, much uncertainty remains, especially with regard to gaseous nitrogen losses. This is particularly troubling in the context of human modification of the nitrogen cycle, which is dramatically increasing nitrogen pollution, runoff, and the emission of nitrous oxide, a radiatively important greenhouse gas. This research will contribute to our understanding of the terrestrial nitrogen cycle by quantifying the role of "Feammox", a newly discovered pathway in the global nitrogen cycle. Feammox is the anaerobic oxidation of ammonium coupled to ferric iron [Fe (III)] reduction. It has the potential to produce inert dinitrogen gas as well as reactive nitrite, which could subsequently be reduced to gaseous or organic nitrogen, or ammonium under anaerobic conditions. Given the potential gaseous loss of nitrogen from terrestrial environments, this pathway may play a significant role in the global nitrogen cycle. The proposed research will place this newly discovered nitrogen transformation pathway in the context of the larger nitrogen cycle by (i) determining if Feammox is mediated by soil microbes, and if so identify the responsible organisms, (ii) determining the relative importance of iron- and nitrogen-containing compounds as controls on Feammox, and (iii) quantifying the role of Feammox in total nitrogen gas emissions from soils. The collaborative research between a soil biogeochemistry laboratory at the University of California at Berkeley and a microbial biogeochemistry laboratory at the University of Nebraska, Lincoln will improve the mechanistic understanding of terrestrial nitrogen cycling. Field work will take place at the Luquillo Long Term Ecological Research site in Puerto Rico. The research addresses a previously unquantified pathway in terrestrial ecosystems that not only has implications for nutrient retention in soils, but could also evolve nitrous oxide, a greenhouse gas implicated in global change. This project will support for an early career female scientist, two graduate students, one undergraduate student, and one postdoctoral researcher. In concert with sample collection in Puerto Rico workshops and training activities will be held for Puerto Rican high school students. Science cafes in Puerto Rico and California will provide an ecology and global change educational outreach component to the public at large.