水稻土厌氧氨氧化活性测定的同位素示踪法方法探讨

Determination of anammox activity in paddy soils with isotope-tracing technique

自然生态系统中的厌氧氨氧化过程是新发现的氮循环途径,已有研究表明水稻土能产生厌氧氨氧化作用,然而目前还鲜有关于水稻土厌氧氨氧化活性测定方法的报道。15N示踪法是定量厌氧氨氧化活性的新方法,根据厌氧氨氧化和反硝化过程原理的不同,该方法可以同时测定厌氧氨氧化和反硝化产生的氮气。本文详细介绍了一种利用稳定同位素标记配对法,通过预培养消耗底物硝酸根后,对反应体系进行三种处理:1)仅加15N-NH4+的阴性对照;2)加15N-NH4+和14N-NO3-的阳性对照;3)仅加15N-NO3-。厌氧培养后分别对三种处理产生的氮气采用稳定同位素质谱仪进行测定,通过数据分析获得厌氧氨氧化活性。本研究建立了水稻土厌氧氨氧化活性测定方法,能较为真实的反应原位条件下水稻土的厌氧氨氧化活性。

Anaerobic oxidation of ammonium （Anammox） is a newly discovered pathway of nitrogen cycling in natural ecosystems. Recently, it has been found that paddy soils can release N by anaerobic ammonia oxidation, however, few studies on determination in paddy soils of anaerobic ammonia oxidation activity have been published. Based on different mechanisms, isotopic-tracing technique was a new method which can quantitative analysis gaseous nitrogen produced both by denitrification and anammox simultaneously. In this study, we conducted an isotope-tracing technique for determination of anammox in paddy soils. After substrate consumption of nitrate and nitrite, three treatments including 1） 15N-NH4＋only as negative control, 2） 15N-NH4＋ and 14N-NO3- as positive control, and 3） 15N-NO3-only, were incubated under anaerobic condition.The gaseous N2 was detected with isotope mass spectrometer for separation of 28N2, 29N2 and 30N2. Then the rates of anammox activities were calculated. The established method may provide reliability of anammox activity in paddy soils in situ.