Revisiting process-based simulations of soil nitrite dynamics: Tighter cycling between nitrite and nitrate than considered previously
Revisiting process-based simulations of soil nitrite dynamics: Tighter cycling between nitrite and nitrate than considered previously
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DOI：
10.1016/j.soilbio.2023.108958
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发表时间：
2023-01
影响因子：
9.7
通讯作者：
Jinsen Zheng;K. Fujii;K. Koba;W. Wanek;Christoph Müller;A. Jansen-Willems;Y. Nakajima;Rota Wagai;Alberto Canarini
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文献类型：
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作者：
Jinsen Zheng;K. Fujii;K. Koba;W. Wanek;Christoph Müller;A. Jansen-Willems;Y. Nakajima;Rota Wagai;Alberto Canarini
亚硝酸盐是许多对环境有害的化合物（例如硝酸盐、一氧化二氮和亚硝酸）的重要前体。然而，其在土壤环境中的动态尚未完全了解。 NtraceNitrite 工具已成功分析 15N 跟踪数据。在这里，基于标记亚硝酸盐、硝酸盐或铵池的15N示踪实验（在有氧条件下），我们开发了一个扩展模型（NO2Trace），其特点是添加了耦合的硝酸盐还原和亚硝酸盐再氧化以及将硝酸盐池分离为两个子池。与 NtraceNitrite 工具相比，通过优化 5 个附加参数，NO2Trace 能够实现更好的数据拟合。这些附加特征可能为陆地生态系统中硝化作用产生的硝酸盐的同位素组成提供合适的解释。我们的结果有两个重要意义：(i) 违反了用于估计总硝酸盐通量的经典同位素池稀释技术（即无示踪剂回流）的关键假设，导致相当大的低估（测试数据集中为 22-99%）； （ii）再氧化可以主导硝酸盐还原产生的亚硝酸盐的消耗（〜75％），表明该过程作为防止气态氮损失（通过亚硝酸盐还原）的氮保留机制的目标的潜力。扩展模型的附加特征显示土壤亚硝酸盐和硝酸盐之间的循环比之前考虑的更紧密，并提供了对土壤亚硝酸盐转化的更全面的描述。这项研究还强调，需要做更多的工作来开发能够分离特定过程和途径的硝酸盐和亚硝酸盐池的方法。
Nitrite is an important precursor of many environmentally hazardous compounds (e.g., nitrate, nitrous oxide, and nitrous acid). However, its dynamics in the soil environment are not yet fully understood. TheNtraceNitritetool has been successful in analyzing15N tracing data. Here, based on a15N tracing experiment (under aerobic condition) where either the nitrite, the nitrate, or the ammonium pool was labelled, we developed an extended model (NO2Trace), which was featured by the addition of coupled nitrate reduction and nitrite re-oxidation and the separation of the nitrate pool in two sub-pools. With 5 additional parameters optimized,NO2Tracewas able to achieve a superior fit to the data, as compared to theNtraceNitritetool. The additional features might offer a suitable explanation for the isotopic composition of nitrate produced via nitrification in terrestrial ecosystems. Our results carry two important implications: (i) a key assumption of the classical isotope pool dilution technique (i.e., no reflux of tracer) for estimating gross nitrate fluxes is violated, leading to considerable underestimations (22–99% in the datasets tested); (ii) re-oxidation can dominate the consumption (∼75%) of nitrite derived from nitrate reduction, indicating the potential of this process as a target for nitrogen retention mechanism against gaseous nitrogen losses (through nitrite reduction). The additional features of the extended model show a tighter cycle between soil nitrite and nitrate than considered previously and provide a more comprehensive description of soil nitrite transformations. This study also highlights that more work is needed to develop methods capable of separating process- and pathways-specific nitrate and nitrite pools.