A new method was designed for direct determination of 15N abundance of NH4+,NO3-and NO2-in soils with mass spectrometry.The principle of this method was based on analysis and quantification of 15N abundance of the N2O produced from NH4+,NO3-and NO2-through transformation reactions catalyzed with their respective specific chemical reagents separately.The measured values of 15N abundance of the N2O tally well with their respective reference values in NH4+,NO3-and NO2-.The method was characterized by quickness,simpleness and freedom from contamination of atmospheric nitrogen.Especially this method has a very low detection limit,and 5 ～ 20 μg N in the sample is adequate for detection.Therefore,it will be of a great help to study on mineralization,nitrification and denitrification of nitrogen in soils.%用化学方法分别将土壤中微量的铵、硝酸盐和亚硝酸盐转化为N2O气体,然后用带自动预浓缩装置的同位素比值质谱仪测定N2O中的15N丰度.N2O中的15N丰度测量值完全符合铵、硝酸盐和亚硝酸盐的15N参考值.方法快速、简单和准确,不受空气氮的污染.特别是方法的检测限很低,每批次样品中只需含5～ 20μg N.它将有助于土壤氮素的矿化作用、硝化作用和反硝化作用的研究.
展开▼
