^(15)N标记土壤连续培养过程中扩散法测定无机氮同位素方法改进  

Improvements of the diffusion method to measure inorganic nitrogen isotope of ^(15)N labeled soil

作　　者：孙建飞[1,2] 白娥[1] 戴崴巍[1] 彭勃[1,2] 曲桂芳[1,2] 姜萍[1] 

机构地区：[1]森林与土壤生态国家重点实验室,中国科学院沈阳应用生态研究所,沈阳110016 [2]中国科学院大学资源与环境学院,北京100049

出　　处：《生态学杂志》2014年第9期2574-2580,共7页Chinese Journal of Ecology

基　　金：科技部973项目(2014CB954400);国家自然科学基金项目(31100326)资助

摘　　要：扩散法用于测定土壤浸提液中铵态氮和硝态氮同位素比值已被广泛应用。但是测定15N标记培养的不同生态系统土壤浸提液时,因其同位素丰度高,并且随着培养时间的延长变化较大,目前仍缺少一个系统的方法体系以确定在标记实验中扩散法的同位素分馏效应。本研究对扩散法进行了改进和评估。其中,氨气吸收液改为10μL的KHSO4、培养瓶为500 mL时,培养液体积设为100 mL,使气液比为4∶1,MgO和Devarda合金的量减少至250 mg,在培养温度统一设定为25℃条件下,分别测定了高含氮量和低含氮量的无机氮同位素丰度。结果显示,理论值和实际测量值差别不显著,说明该方法的细节改进有利于大批量测定土壤长期培养过程中铵态氮和硝态氮含量和同位素比值的不断变化。To date, the diffusion method which measures the isotope values of ammonium and nitrate of soil extraction is extensively applied. But we still lack a systematic method to evaluate the isotope discrimination effect in 15N labeled experiments, mainly due to the high 15N abundance and its variation during the incubation period. Here, we presented some efficient improvements of the diffusion method including using 10μL KHSO4 as the ammonia absorption liquid, setting the gas to liquid ratio to 4：1, lowering the use of MgO and Devarda alloy to 250 mg, and selecting 25 ℃ as the incubation temperature. We used this improved method to measure the inorganic nitrogen isotope abundance of solutions with both high and low nitrogen contents. The results indicated that there was no significant difference between theoretical and measured values. Therefore, our improvements are useful to measure ammonium and nitrate isotope ratios of 15N labeled experiments.

关 键 词：15N同位素标记 NO3- NH4+ 扩散法培养 土壤培养 

分 类 号：S151.95[农业科学—土壤学]