地表水硝酸盐氮同位素测定的前处理过程

Pretreatment process of nitrate nitrogen isotope determination in surface water

为有效识别地表水硝酸盐的污染来源,探讨了硝酸盐氮同位素(δ15N)测定前处理过程的实验步骤和方法。通过对国产717、美国Amberlite IRA402和IRA900强碱性阴离子交换树脂进行NO-3的吸附、洗脱和扩散实验优化研究,分析了树脂高度、吸附流速、洗脱液的浓度和体积、洗脱流速、扩散温度和时间等影响NO-3吸附和洗脱效率的因素。实验结果表明,717、IRA402和IRA900均可以作为吸附NO-3的离子交换树脂,其中IRA402型树脂吸附效果最佳,717型树脂洗脱效果最佳。在过阴离子交换柱之前,通过Al2O3柱吸附水样中的有机物等杂质,可有效提高NO-3的洗脱率。针对九龙江流域地表水样,离子交换柱高度可选择为2.5 cm,吸附流速600~700 m L/h,洗脱液可选择2 mol/L KCl溶液,洗脱流速控制为4~6 m L/h。该实验方法的建立可满足九龙江流域地表水样硝酸盐δ15N测定的前处理要求。

To effectively identify surface water nitrate pollution sources,the experimental steps and methods of the pretreatment process for nitrate δ15N determination were discussed. Experiment optimization research of NO-3adsorption,elution and diffusion were carried through domestic 717,USA Amberlite IRA402 and IRA900 strongly basic anion exchange resin. The effects of height of resin,adsorption velocity,concentration of eluent and volume,elution velocity,diffusion temperature and time,on NO-3adsorption and elution efficiency were analyzed. Results show that 717,IRA402 and IRA900 all can be selected as NO3-N adsorption ion exchange resin. The absorption efficiency of IRA402 is the best,and the elution efficiency of 717 is the best in these three resins. Before anion exchange column adsorption,removal of impurities such as organic matter in water samples through Al2O3 column,which can effectively improve NO-3elution efficiency. 2. 5 cm ion exchange column height,600 ~ 700 m L / h for adsorption velocity,2 mol / L KCl solution for eluent,and 4 ~ 6 m L / h elution velocity were suitable for Jiulong River Watershed surface water samples. The experimental method can meet pretreatment processing requirements of surface water δ15N in Jiulong River Watershed.