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Combined application of the natural abundance stable isotope and 15N tracing methods to quantify denitrification in agricultural soils in field studies

结合应用自然丰度稳定同位素和 15N 示踪方法在现场研究中量化农业土壤反硝化作用

基本信息

批准号：
266533143
负责人：
Dr. Dominika Lewicka-Szczebak, Ph.D.
金额：
--
依托单位：
Kompetenzzentrum Stabile Isotope
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2014
资助国家：
德国
起止时间：
2013-12-31 至 2020-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/266533143?language=en
关键词：
Combined application natural abundance stable

项目摘要

Quantifying denitrification in arable soils is crucial in predicting the microbial consumption of nitrogen fertilizers and the associated nitrous oxide (N2O) emissions, but still challenging due to difficulties in direct measurements of dinitrogen (N2) emissions and due to possible co-existence of numerous microbial N-transformations. Isotopomer analyses of emitted N2O (d15N, d18O and SP=Site Preference of 15N within the linear N2O molecule) may help to distinguish production pathways and to quantify N2O reduction to N2. However, such interpretations are often ambiguous because: (i) the majority of basic knowledge about isotopic fractionation factors originate from laboratory experiments and (ii) systematic studies on method transfer into field conditions are still lacking. This proposal aims at combining laboratory and field studies to obtain information on the possible transferability of the methods developed under laboratory conditions to the field scale. The general aim is to develop a method for in situ quantification of the entire denitrification process in agricultural soils. The finally developed method will be solely based on the natural abundance stable isotope approach, i.e., combined isotopomer analyses of N2O and isotopic analyses of soil N-compounds. To precisely determine the isotopic fractionation factors associated with denitrification and possible accompanying processes valid for field conditions, detailed microcosm experiments under controlled conditions and 15N-tracing as a reference method are proposed. The fractionation factors associated with N2O reduction will be validated for field conditions through direct determination of the product ratio (N2O/(N2+N2O) of denitrification from 15N tracing results obtained parallel to N2O isotopomer analyses. Moreover, a 15N-tracer model will be used to estimate the extent of the possibly co-occurring N-transformation processes (nitrification, ammonification, immobilisation and ammonia oxidation) and their impact on isotopic values of emitted N2O. Natural abundance studies of soil N-compounds carried out in parallel, will aim to determine the isotopic fractionation characteristic for these processes. Additionally, the analysis of natural abundance isotopic signatures of soil nitrite will be conducted for the first time in order to better assess the process dynamics of this crucial compound in N-cycling. As an ultimate result of this project, a complex isotopic model will be developed, which should provide a method to quantify the whole denitrification process in agricultural soils under field conditions. In perspective, this model can be combined with the process-based modelling of N2O emissions to help in better estimation of the N2O reduction contribution.

定量反硝化作用在耕地土壤中是至关重要的，在预测微生物的氮肥消耗和相关的一氧化二氮（N2 O）的排放量，但仍然具有挑战性，由于直接测量的二氮（N2）排放量的困难，并由于可能共存的许多微生物的N-转换。同位素分析排放的N2 O（d15 N，d18 O和SP=网站偏好的15 N内的线性N2 O分子）可能有助于区分生产途径和量化N2 O还原为N2。然而，这样的解释往往是模棱两可的，因为：（i）大多数的基础知识，同位素分馏因素来自实验室实验和（ii）系统的研究方法转移到现场条件仍然缺乏。该提案旨在将实验室研究与实地研究相结合，以获得关于在实验室条件下开发的方法是否可推广到实地规模的信息。总的目的是开发一种方法，在农业土壤中的整个反硝化过程的原位定量。最终开发的方法将完全基于天然丰度稳定同位素方法，即，结合N2 O同位素分析和土壤氮化合物同位素分析。为了精确地确定同位素分馏因素与反硝化和可能伴随的过程有效的现场条件下，详细的微观实验控制条件下和15 N示踪作为参考方法提出。将通过直接测定反硝化的产物比（N2 O/（N2+ N2 O）），从15 N示踪结果平行于N2 O同位素分析，验证与N2 O还原相关的分馏因子。此外，15 N示踪剂模型将用于估计可能共同发生的N-转化过程（硝化，氨化，固定和氨氧化）的程度及其对排放的N2 O的同位素值的影响。同时进行的土壤氮化合物的自然丰度研究旨在确定这些过程的同位素分馏特征。此外，将首次对土壤亚硝酸盐的天然丰度同位素特征进行分析，以更好地评估这一关键化合物在氮循环中的过程动态。作为该项目的最终成果，将开发一个复杂的同位素模型，该模型将提供一种方法，以量化在实地条件下农业土壤中的整个脱氮过程。从长远来看，该模型可以与基于过程的N2 O排放量建模相结合，以帮助更好地估计N2 O减排的贡献。