College of Life Sciences, Fujian Agriculture and Forest University, Fuzhou, 350002, China.
Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.
Environ Pollut. 2019 Jan;244:127-134. doi: 10.1016/j.envpol.2018.10.050. Epub 2018 Oct 10.
Denitrification is considered as the dominant nitrogen (N) removing pathway, however, anaerobic oxidation of ammonium (anammox) also plays a significant part in N loss in agricultural ecosystems. Large N inputs into agricultural soils may stimulate the growth of anammox bacteria, resulting in high activity and diversity of anammox bacteria and subsequent more N loss. In some specific niches, like oxic-anoxic interface, three processes, nitrification, anammox and denitrification couple with each other, and significant anammox reaction could be observed. Soil parameters like pH, dissolved oxygen, salinity, oxidation-reduction potential (ORP), and substrate concentrations impact the anammox process. Here we summarize the current knowledge on anammox activity and contribution to N loss, abundance and diversity of anammox bacteria, factors affecting anammox, and the relationship between anammox and other N loss pathways in agricultural soils. We propose that more investigations are required for (1) the role of anammox to N loss with different agricultural management strategies; (2) microscale research on the coupling of nitrification-anammox-denitrification, that might be a very complex process but ideal model for further studies responsible for N cycling in terrestrial ecosystems; and (3) new methods to estimate differential contributions of anammox, codenitrification and denitrification in total N loss in agricultural ecosystems. New research will provide much needed information to quantify the contribution of anammox in N loss from soils at landscape, ecosystem and global scales.
反硝化被认为是氮（N）去除的主要途径，然而，氨厌氧氧化（anammox）在农业生态系统中的氮损失中也起着重要作用。大量的氮输入到农业土壤中可能会刺激 anammox 细菌的生长，导致 anammox 细菌的高活性和多样性，以及随后更多的氮损失。在一些特定的小生境中，如好氧-缺氧界面，硝化、anammox 和反硝化三个过程相互耦合，可以观察到显著的 anammox 反应。土壤参数如 pH 值、溶解氧、盐度、氧化还原电位（ORP）和基质浓度都会影响 anammox 过程。在这里，我们总结了当前关于 anammox 活性及其对氮损失的贡献、anammox 细菌的丰度和多样性、影响 anammox 的因素以及 anammox 与农业土壤中其他氮损失途径的关系的知识。我们提出，需要进一步研究（1）anammox 在不同农业管理策略下对氮损失的作用；（2）硝化-反硝化耦合的微观研究，这可能是一个非常复杂的过程，但对于进一步研究陆地生态系统氮循环的理想模型；（3）估计农业生态系统中 anammox、共反硝化和反硝化在总氮损失中差异贡献的新方法。新的研究将提供量化景观、生态系统和全球尺度土壤氮损失中 anammox 贡献所需的信息。
