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了解厌氧条件土壤反硝化气体(N2、N2O和NO)、CO2和CH4排放特征,是认识反硝化过程机制的基础,并有助于制定合理的温室气体减排措施.定量反硝化产物组成,可为氮转化过程模型研发制定正确的关键过程参数选取方法或参数化方案.本研究选取质地相同(砂壤土)的两个水稻土为研究对象,通过添加KNO3和葡萄糖的混合溶液,将培养土壤的初始NO-3和DOC含量分别调节到50 mg·kg-1和300 mg·kg-1,采用氦环境培养-气体及碳氮底物直接同步测定方法,研究完全厌氧条件下土壤N2、N2O、NO、CO2和CH4的排放特征,并获得反硝化气态产物中各组分的比率.结果表明,在整个培养过程中,两个供试土壤的N2、N2O和NO累积排放量分别为6~8、20和15~18 mg·kg-1,这些气体排放量测定结果可回收土壤NO-3变化量的95%~98%,反硝化气态产物以N2O和NO为主,其中3种组分的比率分别为15%~19%(N2)、47%~49%(N2O)和34%~36%(NO);但反硝化气体产物组成的逐日动态均显现为从以NO为主逐渐过渡到以N2O为主,最后才发展到以N2为主.以上结果说明,反硝化气体产物组成是随反硝化进程而变化的,在以气体产物组成比率作为关键参数计算各种反硝化气体产生率或排放率的模型中,很有必要重视这一点.
Knowing the characteristics of denitrifying gas (N2, N2O and NO), CO2 and CH4 emission in anaerobic conditions is the basis of recognizing the mechanism of denitrification process and helping to formulate reasonable greenhouse gas emission reduction measures. The composition of denitrification products, We can develop the right key process parameter selection method or parameterization scheme for the development of nitrogen conversion process model.In this study, we selected two paddy soils with the same texture (sandy loam soil) as the research object, and added the mixed solution of KNO3 and glucose, The initial NO-3 and DOC contents were adjusted to 50 mg · kg-1 and 300 mg · kg-1, respectively. The helium environment-gas and carbon and nitrogen substrate were used to determine the initial concentration of nitrogen, N2O, NO, CO2 and CH4, and the ratio of each component in the denitrified gaseous products was obtained.The results showed that the accumulated emissions of N2, N2O and NO in the two soils were 6 ~ 8, 20, and 15 ~ 18 mg · kg-1, respectively. The results of these gas emission measurements can recover 95% ~ 98% of the NO-3 change in the soil and the denitrification products are dominated by N2O and NO, The ratios are 15% to 19% (N2), 47% to 49% (N2O) and 34% to 36% (NO), respectively; however The daily dynamics of the product composition of nitrification gas appears to gradually shift from mainly NO to N2O and finally to N2.The above results indicate that the composition of denitrification products varies with the denitrification process, It is important to pay attention to this model in the calculation of various denitrification gas generation rates or emission rates using the gas product composition ratio as a key parameter.