天然水体中铵态和硝态氮δ^(15)N的测定  

Determination of δ^(15)N of ammonium and nitrate in nature waters

作　　者：曾明[1] 余龙飞[1] 张逸[1] 王章玮[1] 

机构地区：[1]中国科学院生态环境研究中心,北京100085

出　　处：《环境化学》2013年第8期1486-1490,共5页Environmental Chemistry

基　　金：中国科学院知识创新方向性项目(K2CX2-YW-GJ01);中国科学院国际合作项目(GJHZ1205);国家重大基础研究(973计划)项目(2005CB422206)资助

摘　　要：介绍了一种天然水体中铵态和硝态氮δ15N的测定方法,包括3个步骤:(1)离子交换法富集水中铵态和硝态氮;(2)蒸馏法进一步提纯铵态和硝态氮;(3)阳离子树脂萃取由转化和蒸馏得到的铵态氮,并将树脂干燥后送入元素分析仪串联质谱(EA-IRMS)测定δ15N.用这种方法处理NH4Cl和KNO3配制的人工模拟水样和野外采集的天然水样,发现δ15N-NH4+和δ15N-NO3-测定的准确性高、重复性好,人工模拟水样δ15N-NH4+的测定值和标准值相差0.560‰,δ15N-NO3-的测定值和标准值相差0.341‰,所有水样重复间的标准偏差在0.008‰—0.384‰之间.测定方法需要的水样体积较少,水样处理速度较快,离子交换后水样中的铵态和硝态氮可长期保存,适合野外天然水体δ15N测定.This paper introduces a method for δ15N determination of ammonium and nitrate in nature waters.It includes three steps： firstly,ion exchange in used to absorb ammonium and nitrate;secondly,the stripped solution distilled to purify ammonium and nitrate;finally the ammonium in the H3BO3 extracted with cation exchange resins and sent to the EA-IRMS for analysis.Simulated water samples with standard NH4Cl and KNO3 and nature waters were treated by this method.Which shows good accuracy and reproducibility.The determined values of δ15N-NH4 and δ15N-NO3 of the simulated water are less by 0.560‰ and 0.314‰ than the standard values,while the standard deviation of all samples is between 0.008‰—0.384‰.Moreover,less volume of water is needed in this method,and the manipulation is fast.Ion exchange provides great convenience for storage and transportation of water samples,which make it also appropriate for field experiments.

关 键 词：天然水体 铵态氮 硝态氮 δ15N 

分 类 号：X832[环境科学与工程—环境工程]