Collaborative Research: Terrestrial Denitrification and Environmental Change

合作研究：陆地反硝化与环境变化

• 批准号: 1655784
• 负责人: Cynthia Nevison
• 金额: $ 13.55万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-08-01 至 2021-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1655784&HistoricalAwards=false
• 关键词: Collaborative; Research; Terrestrial; Denitrification; Environmental

Nitrogen is a vital plant nutrient, and its availability often limits tree growth. The microbial process of denitrification removes available nitrogen from ecosystems and produces a range of nitrogen gases, including nitrous oxide, a potent greenhouse gas. Earth system models often fail to capture the magnitude or global distribution of these nitrogen gas losses. Denitrification occurs under low-oxygen conditions, and measurements are complicated by both analytical challenges and tremendous spatial and temporal variation. This project will apply a suite of measurement approaches to test hypotheses about the way that several environmental factors regulate denitrification, and it will improve the representation of denitrification in an important earth system model. This research has important implications for policies regulating nitrogen as an air and water pollutant, and improvements to the earth system model support international science and policy programs for predicting future environmental change.This project will advance understanding of the environmental regulation of denitrification in both field studies at the Hubbard Brook Experimental Forest in New Hampshire and as represented by the Community Land Model (CLM-CN). At Hubbard Brook, the project will test the role of several environmental factors hypothesized to regulate denitrification, including soil oxygen levels, soil depth, rainfall variability, soil warming, and soil acidification. The project will deploy measurement approaches that include soil core-based fluxes of nitrogen gases, continuous soil oxygen sensors, chamber-based gas fluxes, and nitrate stable isotopes. Together these measurements will provide a comprehensive assessment of denitrification and its environmental drivers, and will enable this project to improve representation of plant-microbe competition and carbon-nitrogen-oxygen biogeochemistry in the Community Land Model. The project will also train two graduate students and one postdoctoral associate, and it will offer hands-on biogeochemistry boot camps for diverse groups of graduate students on the advanced techniques used for measuring greenhouse gas emissions and related ecosystem processes.

氮是一种重要的植物营养素，其可用性常常限制树木的生长。微生物反硝化过程会从生态系统中去除可用的氮，并产生一系列氮气，包括一氧化二氮（一种强效温室气体）。地球系统模型通常无法捕捉这些氮气损失的程度或全球分布。反硝化发生在低氧条件下，分析挑战和巨大的时空变化使测量变得复杂。该项目将应用一套测量方法来测试有关几种环境因素调节反硝化作用方式的假设，并将改善反硝化作用在重要地球系统模型中的表示。这项研究对调节氮作为空气和水污染物的政策具有重要意义，并且地球系统模型的改进支持预测未来环境变化的国际科学和政策计划。该项目将在这两个领域研究中增进对反硝化环境调节的理解位于新罕布什尔州的哈伯德布鲁克实验森林，以社区土地模型 (CLM-CN) 为代表。在哈伯德布鲁克，该项目将测试几个假设的调节反硝化的环境因素的作用，包括土壤氧水平、土壤深度、降雨变化、土壤变暖和土壤酸化。该项目将部署测量方法，包括基于土壤核心的氮气通量、连续土壤氧传感器、基于室的气体通量和硝酸盐稳定同位素。这些测量结果将对反硝化及其环境驱动因素进行全面评估，并使该项目能够改善社区土地模型中植物-微生物竞争和碳-氮-氧生物地球化学的代表性。该项目还将培训两名研究生和一名博士后助理，并将为不同群体的研究生提供用于测量温室气体排放和相关生态系统过程的先进技术的生物地球化学实践训练营。