中文摘要：

为了深入开展水体反硝化过程及机理研究,利用HIDEN公司生产的HPR40溶解气体质谱分析仪,通过仪器配置和条件摸索,建立了基于N2：Ar原理直接测定水体反硝化产物溶解N2的分析方法,并总结了采样技术要点.实验结果表明,膜进样质谱仪（MIMS）在长时间（10h）连续测定情况下仍能保持良好的信号稳定性,盐度为0和2%的标样的N2/Ar（物质的量比）变异系数（CV）分别0.53%和0.17%;在最佳实验条件下（恒温槽温度设为18～25℃,磁搅拌气液平衡52h,仪器信号平稳）,15d内绘制了5条校准工作曲线,其斜率的相对标准偏差为3.03%,说明该方法的重复性较好;平行水样的标准偏差小于2μmol·L-1.将N2：Ar法应用于福建省九龙江表层水样的连续观测,可观察到明显的反硝化过程,表明所建立的N2：Ar法在今后各种水体反硝化过程和机理研究中具有良好的应用前景.

英文摘要：

High background concentrations of N2and the spatio-temporal heterogeneity of denitrification make it difficult to measure denitrification rates in aquatic ecosystems.Traditional methods like acetylene inhibition measure denitrification in an indirect way,which is time consuming and insufficiently accurate.The development of membrane inlet mass spectrometry（MIMS） makes it possible to measure denitrification directly and more precisely.In this study,we developed a N2：Ar method to measure the denitrification product（i.e.dissolved N2） using MIMS（HPR-40,from HIDEN Co）.A basic sampling protocol was developed and is discussed in this paper.Laboratory experiments show that the instrument yields high signal stability and precision.The CV of the N2/Ar value during 10h continuous measurements was 0.53% for a standard solution with 0 salinity and 0.17% for the standard with 2% salinity.Five standard calibration curves drawn within 15 days also showed the high reproducibility of the method（relative standard deviation（RSD） of the five slopes of standard calibration curves was 3.03%）.The standard deviation of N2 concentration in triplicate water samples is less than 2 μmol·L-1.The method was applied in the Jiulong River located in Southeast China.Measured data clearly show the denitrification process and its diurnal variation in the water.The present study suggests application of the N2：Ar method in future research concerning the denitrification process and its mechanisms in various aquatic ecosystems.