不同盐碱程度土壤氧化亚氮(N2O)排放途径的研究

选取内蒙古河套灌区4种不同盐碱程度土壤(极度盐土、盐土、重度盐土和轻度盐土),通过室内低浓度乙炔抑制技术和纯氧气抑制技术,研究不同盐碱程度土壤中N_2O的排放途径及其贡献率。结果表明:N_2O累积排放量随着土壤盐碱程度的升高而升高,轻度盐土(SA)、重度盐土(SB)、盐土(SC)和极度盐土(SD)的N_2O累积排放量分别为289.71、500.08、951.66、1 750.39μg·kg~(-1);在整个培养实验期间,4种不同盐碱程度土壤的硝化过程和反硝化过程的N_2O排放总贡献率分别为22.51%~35.75%和60.35%~72.46%,其他过程的N_2O排放贡献率为3.90%~5.81%,表明反硝化过程是盐碱土壤中N_2O的主要排放途径。4种不同盐碱程度土壤,不同排放途径N_2O排放贡献率随着土壤盐碱程度(电导率)的升高,硝化过程的N_2O排放贡献率逐渐升高,反硝化过程的N_2O排放贡献率逐渐降低。

Studies on emission pathways of nitrous oxide from different salinization soils

Soil salinization has great effect on the microbial activity and thus N2O emissions. Most studies focused on factors impacting N2O emission including soil moisture, salinity content, soil organic matter, soil temperature and nitrogen application rate, while little information was found about the N2O emission pathways and contribution rates in salinization soils in Northern China. In order to explore the N2O emis-sion pathways and contribution rates, we used the inhibitors of acetylene and pure oxygen in culture experiment to study 4 kinds of different salinization soilsextremely salinization soil(SD), salinization soil(SC), severely salinization soil(SB), slightly salinization soil(SA)] in Hetao irrigation area of Inner Mongolia. The results showed that cumulative N2O emissions increased with the increasement of salinization, whose values were 289.71, 500.08, 951.66, 1 750.39μg·kg-1, respectively. In the period of incubation, the N2O emission contribution rates of ni-trification and denitrification ranged from 22.51%to 35.75%and 60.35%to 72.46%, respectively while the contribution rates of other pro-cesses ranged from 3.90% to 5.81%, which showed that denitrification remained the main process contributing to N2O emissions. At the same time, with the electric conductivity increasing, the contribution rates of nitrification increased,while the contribution rates of denitrifi-cation decreased.