Importance and controls of anaerobic ammonium oxidation influenced by riverbed geology
Importance and controls of anaerobic ammonium oxidation influenced by riverbed geology
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DOI：
10.1038/ngeo2684
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发表时间：
2016-05-01
影响因子：
18.3
通讯作者：
Trimmer, M.
中科院分区：
文献类型：
--
作者：
Lansdown, K.;McKew, B. A.;Trimmer, M.
河流是全球过剩生物有效氮的重要汇：它们每年将约40%的陆地N径流转化为生物不可用的N-2气体，并将其返回大气(1)。目前，河流N-2的生产被概念化和模型化为反硝化作用(2-4)。厌氧氨氧化，又称厌氧氨氧化，是海洋环境中重要的N-2产生的另一种途径，但它对河流N-2产生的贡献还不是很清楚(5，6)。在这里，我们使用现场和实验室测量Anammox活性，使用(15)(N)示踪剂和微生物群落的分子分析来评估2013年夏季英国汉普郡Avon流域以粘土、沙子和白垩岩为主的河床中的Anammox。Hzogene编码以酶为中心的厌氧氨氧化代谢，其丰度在不同的地质条件下有所不同。不同地区的厌氧氨氧化速率是相似的，但由于反硝化率的不同，对N-2产量的贡献不同。尽管需要缺氧条件，但厌氧氨氧化很可能与部分硝化作用相耦合，在好氧、可渗透的河床中贡献了高达58%的原位N-2产量。相比之下，反硝化作用在低渗透率的粘土河床河流中占主导地位，在那里Anammox约占N-2气体产量的7%。因此，厌氧氨氧化可能是透水性河流沉积物中氮素流失的一条重要途径。
Rivers are an important global sink for excess bioavailable nitrogen: they convert approximately 40% of terrestrial N runoff per year (similar to 47 Tg) to biologically unavailable N-2 gas and return it to the atmosphere(1). At present, riverine N-2 production is conceptualized and modelled as denitrification(2-4). Anaerobic ammonium oxidation, known as anammox, is an alternative pathway of N-2 production important in marine environments, but its contribution to riverine N-2 production is not well understood(5,6). Here we use in situ and laboratory measurements of anammox activity using (15)(N) tracers and molecular analyses of microbial communities to evaluate anammox in clay-, sand- and chalk-dominated river beds in the Hampshire Avon catchment, UK during summer 2013. Abundance of the hzogene, which encodes anenzymecentral to anammox metabolism, varied across the contrasting geologies. Anammox rates were similar across geologies but contributed different proportions of N-2 production because of variation in denitrification rates. In spite of requiring anoxic conditions, anammox, most likely coupled to partial nitrification, contributed up to 58% of in situ N-2 production in oxic, permeable riverbeds. In contrast, denitrification dominated in low-permeability clay-bed rivers, where anammox contributes roughly 7% to the production of N-2 gas. We conclude that anammox can represent an important nitrogen loss pathway in permeable river sediments.