Examination of dinitrogen (N₂) fixation in the Eastern Tropical South Pacific oxygen deficient zone has raised questions about the range of diazotrophs in the deep sea and their quantitative importance as a source of new nitrogen globally. However, technical considerations in the deployment of stable isotopes in quantifying N₂ fixation rates have complicated interpretation of this research. Here, we report the findings of a comprehensive survey of N₂ fixation within, above and below the Eastern Tropical South Pacific oxygen deficient zone. N₂ fixation rates were measured using a robust ¹⁵N tracer method (bubble removal) that accounts for the slow dissolution of N₂ gas and calculated using a conservative approach. N₂ fixation was only detected in a subset of samples (8 of 125 replicated measurements) collected within suboxic waters (< 20 μmol O₂ kg⁻¹) or at the oxycline. Most of these detectable rates were measured at nearshore stations, or where surface productivity was high. These findings support the hypothesis that low oxygen/high organic carbon conditions favor non-cyanobacterial diazotrophs. Nevertheless, this study indicates that N₂ fixation is neither widespread nor quantitatively important throughout this region.

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试图解决东部热带南太平洋缺氧地区固氮的程度和程度的不同问题

在东部热带南太平洋缺氧区中对二氮（N ₂）固定的研究引起了人们对深海重氮菌的范围及其作为全球新氮源的定量重要性的疑问。但是，在稳定同位素的布署中量化N ₂固定率的技术考虑因素使这项研究变得复杂。在这里，我们报告了对东部热带南太平洋缺氧区域内，上方和下方的N ₂固着性进行全面调查的结果。使用稳健的¹⁵ N示踪剂方法（去除气泡）测量N ₂固定率，这说明了N ₂的缓慢溶解气体，并使用保守的方法进行计算。Ñ ₂固定仅在低氧水域（<20内收集的样本的子集（125 8的复制的测量）检测 μ摩尔Ò ₂ kg的^-1）或在oxycline。这些可检出率中的大多数是在近海站或地表生产率高的地方测得的。这些发现支持以下假设：低氧/高有机碳条件有利于非蓝细菌重氮菌。然而，这项研究表明，在整个区域中，N ₂固定既不广泛也不在定量上很重要。