扩散法--EA-IRMS测定天然水体铵态氮同位素实验条件研究  

Research on Experimental Conditions of Using Ammonia Diffusion Method to Measure δ^(15)N-NH_4^+ in Natural Waters

作　　者：胡婧[1,2] 刘卫国[1] 

机构地区：[1]中国科学院地球环境研究所,黄土与第四纪地质国家重点实验室,西安710075 [2]中国科学院研究生院,北京100049

出　　处：《矿物岩石地球化学通报》2010年第1期31-37,共7页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：国家自然科学基金资助项目(40673012)

摘　　要：稳定氮同位素是研究氮循环和氮污染源示踪的一个有效手段。然而目前国内对水体中铵态氮同位素测定方法研究较少,限制了水体氮循环和污染机理的深入探讨。本文采用改进的扩散法(EA-IRMS)测定水中铵态氮同位素,探讨了样品制备过程中扩散溶液的体积、浓度和扩散时间对回收率及氮同位素测定值的影响。实验得出最佳扩散条件为:1.50 mg/L氯化铵溶液400 mL扩散14天,回收率大于95%,且不会产生氮同位素分馏。本研究为高精度测定天然水体中铵态氮同位素提供了更可靠的实验条件。Stable nitrogen isotope study is an effective method to study the nitrogen cycling and to identify source of nitrogen pollution.However,the intensive investigations of the nitrogen cycling in natural waters and mechanism of nitrogen pollution are restrained by only a very small number of experimental method studies for measuring nitrogen isotope in natural waters currently.In this paper,an ammonia diffusion method,EA-IRMS,was chosen for measuring ammonium nitrogen isotope in natural waters and three influenced factors,sample volume,concentration and incubation time,were analyzed during diffusion procedure.The optimal diffusion condition,which can give more than 95% recovery rate and no isotopic fractionation,was obtained as 400ml 1.50 mg/L NH4Cl have been incubated for 14 days.This paper provided a more reliable experimental condition to precisely measure ammonia isotopes in natural waters.

关 键 词：铵态氮同位素 扩散法 EA-IRMS 天然水体 

分 类 号：P597[天文地球—地球化学]