单 位：
中国科学院南京土壤研究所土壤与农业可持续发展国家重点实验室
关键词：
太湖地区;膜进样质谱法;15N同位素配对技术;沉积物;反硝化;厌氧氨氧化
摘 要：
为深入了解水体脱氮过程及机理,结合膜进样质谱(MIMS)和15N同位素配对技术(15N IPT)测定太湖地区西部六条河流沉积物的反硝化和厌氧氨氧化潜势,即将15N标记的硝态氮和铵态氮加入到混匀沉积物的上覆水中进行培养,用MIMS直接在线测定培养过程产生的29N2和30N2。结果表明,用MIMS测定29N2和30N2的产生速率是合适的,应用该方法在太湖地区西部研究河流的测定值与已报道的相关研究结果具有可比性。河流沉积物反硝化和总脱氮潜势范围分别为(18.5±2.8)～(133.2±27.1)μmol N·m-2·h-1和(30.0±2.4)～(161.1±30.4)μmol N·m-2·h-1,其中反硝化脱氮贡献率在(61.3±4.5)%～(83.2±2.1)%之间,二者都表现为由研究区域西北部向西南部递减。河流沉积物厌氧氨氧化潜势范围为(10.4±2.3)～(28.0±4.4)μmol N·m-2·h-1,其脱氮贡献率在(16.9±2.1)%～(38.7±4.5)%之间,厌氧氨氧化脱氮贡献率的空间变化趋势与反硝化潜势相反。相关分析显示,沉积物的硝态氮和可溶性有机碳含量是研究区域河流沉积物反硝化和厌氧氨氧化作用的关键影响因子。研究表明,MIMS和15N IPT结合的方法避免了复杂的脱气步骤可能带来的分析误差,同时具有测定直接、所需样品少以及测定速度快等优点,适用于淹水环境反硝化和厌氧氨氧化过程的同时测定,在今后深入开展水体氮循环研究中具有良好的应用前景。研究区域河流沉积物脱氮过程存在显著空间异质性且脱氮过程以反硝化作用为主,但厌氧氨氧化的脱氮作用也不容忽视。
译 名：
Simultaneous Determination of Denitrification and Anaerobic Ammonium Oxidation in River Sediments Using Membrane Inlet Mass Spectrometry
作 者：
ZHAO Yong-qiang;XIA Yong-qiu;LI Bo-lun;YAN Xiao-yuan;State Key Laboratory of Soil and Sustainable Agriculture,Institute of Soil Science,Chinese Academy of Sciences;University of Chinese Academy of Sciences;
关键词：
Taihu Lake region;;membrane inlet mass spectrometry;;15N isotope pairing technique;;sediment;;denitrification;;anammox
摘 要：
We used membrane inlet mass spectrometry(MIMS)and 15N isotope pairing technique(15N IPT)to simultaneously measure denitrification and anammox in river sediments of Taihu Lake region. Homogenized sediment slurries were incubated with 15N-labeled NO-3 and NH+4 amendments to determine the potential rates of denitrification and anammox. Production of 29N2 and 30N2 in slurries was determined using MIMS. Laboratory experiments showed that using MIMS to determinate the production rates of 29N2 and 30N2 was appropriate,and the measured values for river sediments of Taihu Lake region were similar to those reported in other freshwater systems. The potential rates of denitrification and total N removal in the sediments ranged from(18.5±2.8)～(133.2±27.1)μmol N·m-2·h-1 and(30.0±2.4)～(161.1±30.4)μmol N·m-2·h-1,respectively,and were significantly higher in the northwest than in the southwest part of the Taihu Lake region. The contribution of denitrification to the total N2production was(61.3±4.5)%～(83.2±2.1)%. Potential anammox rates varied from(10.4±2.3)～(28.0±4.4)μmol N·m-2·h-1,and N removal by anammox accounted for(16.9±2.1)%～(38.7±4.5)% of the total N2 production. The spatialvariation of the percentages of anammox to total N2 production was opposite to that of potential denitrification. The contents of nitrate and dissolved organic carbon in sediments were probably the main factors controlling denitrification and anammox. This study shows good applicability of MIMS in combination with 15N IPT in simultaneous determination of denitrification and anammox rates in aquatic systems. Advantages of this method include:reduced analytical errors by avoiding complicated gas extraction steps,no need of sample preparation,rapid measurement,and small sample size. Our results indicate that potential rates of N removal in sediments show spatial variation and denitrification is responsible for N removal but anammox should not be ignored.
