生物固氮速率测定中^(15)N_2同位素示踪剂的引入  

On the introduction of ^(15)N_2 tracer in marine N_2 fixation rate assay

作　　者：陈盛保 张润[1] 陈能汪 赖丽旻 陈敏[1] 郑敏芳[1] 邱雨生[1] Chen Shengbao;Zhang Run;Chen Nengwang;Lai Limin;Chen Min;Zheng Minfang;Qiu Yusheng(College of Ocean and Earth Sciences,Xiamen University,Xiamen 361102,China;College of the Environment and Ecology,Xiamen University,Xiamen 361102,China)

机构地区：[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

出　　处：《海洋学报》2018年第10期42-50,共9页

基　　金：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)

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(^(15)N_2)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^(15)N_2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^(15)N_2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^(15)N_2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^(15)N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^(15)N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。N 2 fixation plays an essential role in marine biogeochemical cycles by supplying new N.Stable isotope tracer(15 N 2)assay has been considered as the best approach for measuring in situ N 2 fixation rate.Introducing 15 N 2 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 15 N 2.It can create 15 N atomic abundance of substrate N 2 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 N 2 fixation rate in aquatic environments.

关 键 词：生物固氮速率 15N2 同位素示踪 

分 类 号：P736.4[天文地球—海洋地质]