Direct measurement of anaerobic ammonium oxidation (anammox) and denitrification in intact sediment cores
Direct measurement of anaerobic ammonium oxidation (anammox) and denitrification in intact sediment cores
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DOI：
10.3354/meps326037
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发表时间：
2006-11
影响因子：
2.5
通讯作者：
M. Trimmer;N. Risgaard-Petersen;J. C. Nicholls;P. Engström
中科院分区：
文献类型：
--
作者：
M. Trimmer;N. Risgaard-Petersen;J. C. Nicholls;P. Engström
厌氧氨氧化，即NH4+与NO2-的厌氧氧化反应，重新定义了我们对水生生态系统中氮循环的理解。同位素配对技术(IPT)是量化完整沉积物中反硝化作用的主要工具，但它不能区分厌氧氨氧化和反硝化作用作为氮气的来源，在厌氧氨氧化显著的情况下，可能会导致对真实氮气产量的估计出现较大误差。在以前的研究中，对IPT进行了理论上的修正，并提出了一种解决方案，即在Anammox存在的情况下，使用参数R14，即NO_3-还原区域中的14NO_3-与15NO_3-的比率来校正IPT。我们首先探索以前为估计R14而提出的两种间接技术的局限性。第一，基于Anammox对沉积物泥浆培养中的氮气产生(Ra)的贡献，低估了anammox，并且不能完全纠正IPT。第二种是15N-N气体的产生，是15NO3-浓度的函数，虽然在筛分的沉积物中有效，但在天然完整的沉积物中无效。相比之下，一种新开发的基于N2O的15N标记的直接技术，在天然沉积物中存在显著的厌氨氧化(占生成氮气的48%)的情况下，校正了IPT，甚至可以区分河口沉积物中的厌氨氧化和反硝化作用，但厌氨氧化的贡献率较低(21%)。我们将这些发现与Anammox最小(1%)的沉积物进行了对比。15N-N2O技术使反硝化和厌氧氨氧化可以在沉积物岩芯中使用与原始IPT已建立的技术类似的技术进行量化，重要的是，它表明厌氧氨氧化对氮气产生的影响比以前使用泥浆测量的要大。
Anammox, i.e. the anaerobic oxidation of NH4 + with NO2 - to N2, has redefined our understanding of nitrogen cycling in aquatic ecosystems. The isotope pairing technique (IPT) is the dominant tool for quantifying denitrification in intact sediments, but it cannot distinguish anammox from denitrification as sources of N2 and may, where anammox is significant, lead to large errors in the estimate of true N2 production. In a previous study, the IPT was revised in theory and a solution was proposed whereby the parameter r14, i.e. the ratio of 14 NO3 - to 15 NO3 - in the NO3 - reduction zone is used to correct the IPT in the presence of anammox. We begin by exploring the limitations of the 2 indirect techniques previously proposed for estimating r14. The first, based on the contribution of anammox to N2 production (ra) in sediment slurry incubations, underestimates anammox and cannot fully correct the IPT. The second, derived from the production of 15 N-N2 gas as a function of 15 NO3 - concentration, although valid in sieved sediment, was ineffective in natural intact sediments. In con- trast, a newly developed direct technique based on the 15 N-labelling of N2O, corrects the IPT in the presence of significant anammox (48% of N2 formation) in natural sediment and can even distinguish between anammox and denitrification in estuarine sediment with a lower anammox contribution (21%). We contrast these findings with sediments where anammox is minimal (<1%). The 15 N-N2O technique allows denitrification and anammox to be quantified in sediment cores using techniques similar to those already established with the original IPT and, importantly, shows that the contribu- tion of anammox to N2 production is greater than previously measured using slurries.