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首页> 外文期刊>Agriculture, Ecosystems & Environment: An International Journal for Scientific Research on the Relationship of Agriculture and Food Production to the Biosphere >An overview of contemporary advances in the usage of N-15 natural abundance (delta N-15) as a tracer of agro-ecosystem N cycle processes that impact the environment
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An overview of contemporary advances in the usage of N-15 natural abundance (delta N-15) as a tracer of agro-ecosystem N cycle processes that impact the environment

机译：当代概况N-15天然丰富（Delta N-15）作为影响环境影响的农业生态系统N循环过程的示踪剂

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During the past 20 years there have been major advances in the application of N-15 natural abundance (NA) measurements to trace the pathways and magnitudes of N fluxes in the soil-plant-atmosphere continuum. However, estimates are often not quantitative due to the unknown extent of isotopic fractionation during a particular N transformation under study, when other processes compete simultaneously for substrate. Examples are the estimation of N fertilizer use efficiency or the transfer of biologically-fixed N-2 to non-fixing companion species in intercrops or crop sequences. In some cases it has been possible to identify a particular process or source leading to a change in the relative isotopic composition (delta N-15 signature) of a system component, by innovative selection of experimental conditions that isolate the source or process from confounding factors. Nevertheless, there are examples where significant contemporary advances have occurred in the application of NA as a quantitative tracer, such as in the estimation of the symbiotic dependence of a range of N-2 fixing plants. The key is the estimation of isotopic fractionation during N-2 fixation and assimilation, and new knowledge has been obtained on factors contributing to variation, and new approaches devised to obtain more accurate estimates of fractionation. A second example is the innovative application of isotopomer measurements of the potent greenhouse gas N2O that enable presumptive identification of the biological and chemical processes resulting in its production under various agricultural scenarios.
机译：在过去的20年中，在N-15天然丰度（NA）测量的应用中，追踪土壤 - 植物气氛连续核的N个势态的途径和大小的主要进展。然而，由于在研究中的特定N转化期间的同位素分级的未知程度，估计通常不是定量的，当其他过程中的其他过程同时竞争底物时。实施例是估计N肥料使用效率或将生物固定的N-2转移到跨部和作物序列中的非固定伴侣物种。在某些情况下，通过创新的实验条件，可以鉴定导致系统组分的相对同位素组合物（Delta N-15签名）的变化的特定过程或源，该实验条件从混淆因子中分离源或过程。然而，存在在将Na作为定量示踪剂施用中发生显着的当代进步的实例，例如在估计一系列N-2固定植物的共生依赖性中。关键是在N-2固定和同化过程中对同位素分馏的估计，并获得了对变化有助于变化的因素的新知识，并设计了新方法，以获得更准确的分馏估计。第二个例子是有效的温室气体N2O的同位素测量的创新应用，使得能够在各种农业场景下生产的生物和化学过程的推测鉴定。

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