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

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.