Measuring N2 and N2O fluxes and related processes at high sensitivity and resolution in the field using advanced stable isotopic tools as a basis for model evaluation

使用先进的稳定同位素工具作为模型评估的基础，在现场以高灵敏度和分辨率测量 N2 和 N2O 通量及相关过程

• 批准号: 290270200
• 负责人: Privatdozent Dr. Reinhard Well
• 金额: --
• 依托单位: Institut für Agrarklimaschutz
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/290270200?language=en
• 关键词: Measuring; N2; N2O; fluxes; related

Field scale denitrification data suitable to validate N2 fluxes in denitrification models are cur-rently missing due to previous methodical limitations and the extreme spatio-temporal hetero-geneity of denitrification. Until now, it was thus not possible to evaluate accuracy of models to predict denitrification at the field scale. Therefore, it is necessary to obtain activity data at this scale to better understand denitrification control and as a basis to support the evaluation and upscaling of modelling concepts developed in phase I of our research unit. We will use new and improved stable isotope approaches to provide denitrification data sets comprising as much detail on activity and regulation as possible as a basis to evaluate existing and new de-nitrification models that are applied and/or developed by DASIM subprojects (P7, P8, PC). During phase I our current work focussed on establishing lab and field methods and included controlled lab incubations. For the current application of phase II we will focus at the field scale and propose to work on the following tasks: Tasks 1 and 2 will complete work that was fore-seen for phase I and include determination of (Task 1) the minimum averaging soil volume for N2 and N2O fluxes from arable soils, and (Task 2) the anaerobic soil volume fraction of DASIM soils. Tasks 3 to 5 will cover preparatory work for subsequent field flux studies, including fur-ther development and field-scale testing of the 15N gas flux method (Task 3), establishing a field measurement system (Task 4), and calibrating the isotopocule mapping approach to iden-tify fungal denitrification based on natural abundance isotopic signatures of N2O (Task 5). Task 6 will include field experiments to quantify N2 and N2O fluxes, contributing processes and control factors in cropped soils to elucidate field-scale denitrification dynamics and as a basis for calibration and validation of existing as well as new models developed by DASIM partners. Finally, Task 7 is foreseen to use the data obtained from Task 6 to evaluate selected existing biogeochemical models. The work program will be realised in collaboration with five partners supplying support in field infrastructure and experimentation, modelling of diffusive gas fluxes, continuous in situ measurement of soil nitrate, stable isotope analysis and evaluation of bio-geochemical models.

由于以往方法的局限性和反硝化作用的极端时空异质性，目前缺少适合于验证反硝化模型中N2通量的田间尺度反硝化数据。因此，到目前为止，还无法评估模型的准确性，以预测在现场规模的反硝化作用。因此，有必要获得在这个规模的活动数据，以更好地了解反硝化控制，并作为一个基础，以支持我们的研究单位的第一阶段开发的建模概念的评价和升级。我们将使用新的和改进的稳定同位素方法提供反硝化数据集，包括尽可能详细的活动和监管作为基础，以评估DASIM子项目（P7，P8，PC）应用和/或开发的现有和新的反硝化模型。在第一阶段，我们目前的工作重点是建立实验室和现场方法，包括受控的实验室孵育。对于第二阶段的当前应用，我们将专注于现场规模，并建议开展以下任务：任务1和2将完成第一阶段预见的工作，包括确定（任务1）可耕地土壤中N2和N2 O通量的最小平均土壤体积，以及（任务2）DASIM土壤的厌氧土壤体积分数。任务3至5将涵盖后续现场通量研究的准备工作，包括15 N气体通量方法的进一步开发和现场规模测试（任务3），建立现场测量系统（任务4），以及校准同位素作图方法，以基于N2 O的天然丰度同位素特征来验证真菌反硝化作用（任务5）。任务6将包括实地实验，以量化N2和N2 O通量，作物土壤中的贡献过程和控制因素，以阐明实地规模的反硝化动力学，并作为DASIM合作伙伴开发的现有和新模型的校准和验证的基础。最后，预计任务7将使用任务6获得的数据来评估选定的现有生物地球化学模型。该工作计划将与五个合作伙伴合作实现，这些合作伙伴在实地基础设施和实验，扩散气体通量建模，土壤硝酸盐连续原位测量，稳定同位素分析和生物地球化学模型评估方面提供支持。