生物固氮速率测定中<sup>15</sup>N<sub>2</sub>同位素示踪剂的引入

陈盛保; 张润; 陈能汪; 赖丽旻; 陈敏; 郑敏芳; 邱雨生

doi:10.3969/j.issn.0253-4193.2018.10.005

生物固氮速率测定中¹⁵N₂同位素示踪剂的引入

doi: 10.3969/j.issn.0253-4193.2018.10.005

1.
厦门大学海洋与地球学院, 福建厦门 361102
2.
厦门大学环境与生态学院, 福建厦门 361102

基金项目: 国家重点基础研究发展计划（2015CB452903）；科技基础资源调查专项子课题（2017FY201403）；国家自然科学基金（41676174）。

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出版历程
- 收稿日期: 2018-04-15
- 修回日期: 2018-06-29

On the introduction of ¹⁵N₂ tracer in marine N₂ fixation rate assay

1.
College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
2.
College of the Environment and Ecology, Xiamen University, Xiamen 361102, China

摘要

摘要: 生物固氮作用是一个重要的海洋新氮来源，在海洋生物地球化学循环中扮演着不可替代的角色。基于稳定同位素（¹⁵N₂）示踪吸收法，是目前直接测定海洋生物固氮速率最有效的手段。其中，高效、洁净地将¹⁵N₂引入海水培养体系，并准确定量培养体系底物的同位素示踪水平，是同位素示踪吸收法准确获取固氮速率的关键。本研究针对¹⁵N₂同位素示踪剂引入这一关键环节进行了探讨，确认改进气泡法是将¹⁵N₂引入海水培养体系的首选操作。在对培养体系造成的较小扰动的情况下，可将培养体系氮气底物的¹⁵N原子丰度提升至10%以上，相对于另一种导入同位素示踪剂的手段——预溶解海水法，改进气泡法将培养瓶中氮气底物的¹⁵N原子丰度提升了近200%。此外，改进气泡法还具有最小化痕量金属沾污、操作简便等优点。将改进气泡法结合与稳定同位素比值质谱测定结合，是准确测定水体生物固氮速率的推荐方法。
- 生物固氮速率 /
- ¹⁵N₂ /
- 同位素示踪
Abstract: N₂ fixation plays an essential role in marine biogeochemical cycles by supplying new N. Stable isotope tracer (¹⁵N₂) assay has been considered as the best approach for measuring in situ N₂ fixation rate. Introducing ¹⁵N₂ in an efficient and clean way, and precisely determining the isotopic enrichment level in the incubation system, is thus fundamental for obtaining true rates. In this study, we show that modified bubble treatment is a recommended practice in introducing ¹⁵N₂. It can create ¹⁵N atomic abundance of substrate N₂ in the incubation bottle higher than 10%. Such enrichment is twice higher when compared with gas pre-dissolution treatment. Moreover, modified bubble treatment is featured by much lowered risk of trace metal contamination and less time/labor consuming. We propose that the modified bubble method coupled to stable isotope mass spectrometry should be widely used in measuring N₂ fixation rate in aquatic environments.
- N₂ fixation rate /
- ¹⁵N₂ /
- isotope tracer assay

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参考文献(13)

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