摘要
硝酸盐氮、氧同位素组成(δ^(15)N、δ^(18)O)被广泛应用于识别水体中硝酸盐的来源及其生化转化过程.离子交换技术作为主要分析方法之一,被大量应用于测定硝酸盐的氮同位素组成,然而在测定氧同位素组成时,由于该方法的样品处理过程复杂繁琐、耗时长(3~5天)等缺点限制了它的广泛应用.通过对原技术路线进行改进:将定量的BaCl_(2)直接加入到野外采集的水样中,消除含氧阴离子(SO_(4)^(2-)和PO_(4)^(3-))对测定NO_(3)^(-)离子δ^(18)O的干扰,然后再通过阴离子交换树脂吸附富集、HCl洗脱NO_(3)^(-)、Ag_(2)O中和,得到用于测试δ^(18)O的AgNO_(3)样品.与原路线相比,改进后方法的优势在于:(1)样品处理步骤由原来的5步缩短到了3步;(2)样品处理时长由3~5天缩短至1~2天;(3)减少了昂贵的化学试剂的用量;(4)减少了同位素的分馏.
The stable nitrogen and oxygen isotopic ratios(δ^(15) N,δ^(18) O)have been used extensively as important tools to identify nitrate sources and understand nitrogen biogeochemical cycle.The ion exchange technique,one of the most widely used analytical methods for nitrogen isotope composition of nitrate,measures oxygen isotope composition of nitrate from a solution can have a complex sample preparation procedure and time-consuming(3~5 days)that have restricted their application in the laboratory.Here we propose an improved method of ion exchange to measure δ^(18) O of NO_(3)^(-),which utilizes BaCl_(2) to remove non-nitrate oxygen-bearing anions(SO_(4)^(2-) and PO_(4)^(3-))in the first step,followed by a collected of water nitrate with an anion exchange column,eluted with HCl,then neutralized with Ag_(2)O to obtain solid AgNO_(3) and analyzed for its δ^(18)O.Comparing with an original ion exchange technique,the benefits of improved method are:(1)the procedure employed to separate nitrate reduced from 5 steps to 3 steps;(2)the time taken to sample preparation dropped from 3~5 days to 1~2 days;(3)reduction of the need for expensive chemical reagents;(4)reduction of oxygen isotopic fractionation.
作者
王波
刘彪
王雪梅
WANG Bo;LIU Biao;WANG Xue-mei(College of Chemistry and Chemical Engineering,Isotopomics in Chemical Biology,Shaanxi Key Laboratory of Chemical Additives for Industry,Shaanxi University of Science&Technology,Xi′an 710021,China)
出处
《陕西科技大学学报》
北大核心
2024年第1期88-94,共7页
Journal of Shaanxi University of Science & Technology
基金
陕西省科技厅自然科学基础研究计划项目(2019JQ-776)
陕西省教育厅专项科研计划项目(19JK0141)。
关键词
氧同位素
硝酸盐
离子交换法
oxygen isotope ratio
nitrate
ion-exchange technique
