氮源对甲烷氧化混合菌群甲烷氧化和氧化亚氮排放的影响

Nitrogen source is an important factor affecting the methane oxidation efficiency of methanotrophs, but its influence on the formation rule of N₂O during the methane oxidation process is still not clear. In this study, taking the mixed methanotroph community as the test object, experiments on the effects of nitrogen source types and nitrogen source concentrations on the methane oxidation efficiency and nitrous oxide formation rule of the mixed methanotroph community were carried out, and the N₂O formation pathway during the methane oxidation process of the mixed methanotroph community was studied by using the acetylene inhibition method. The results showed that: compared with NH₄⁺-N and NO₂⁻-N, when using NO₃⁻-N as the nitrogen source, the mixed methanotroph community had a higher methane oxidation efficiency, which could reach 90%, and at the same time, the generated N₂O concentration was relatively low, about 1.0 mg/m³. Different concentrations of NO₃⁻-N had little influence on the methane oxidation ability and N₂O generation of the mixed methanotroph community. High concentration of NH₄⁺-N would reduce the methane oxidation efficiency of the mixed methanotroph community and promote the generation of N₂O. When the NH₄⁺-N concentration increased from 10 mg/L to 50 mg/L, the methane oxidation efficiency decreased from 92.0% to 78.9%, while the N₂O concentration increased from 5.1 mg/m³ to 17.8 mg/m³. The nitrous oxide production mechanism experiment showed that: the N₂O generated by the mixed methanotroph community in the early stage of cultivation was mainly due to non-biological effects, with a contribution of about 79%, and in the later stage of cultivation, it was mainly due to the denitrification of nitrifying bacteria, with a contribution of about 61%.

氮源是影响甲烷氧化菌甲烷氧化效率的重要因素,但其对甲烷氧化过程N_2O的生成规律的影响尚不明晰。本研究以甲烷氧化菌混合菌群为供试对象,开展了氮源类型和氮源浓度对甲烷氧化混合菌群甲烷氧化效率和氧化亚氮生成规律的影响试验,并采用乙炔抑制法研究了甲烷氧化混合菌群氧化甲烷过程的N_2O生成途径。结果表明:与NH_4~+-N和NO_2--N相比,以NO_3~--N为氮源,甲烷氧化混合菌群具有较高的甲烷氧化效率,可达90%,同时生成的N_2O浓度较低,约为1.0 mg/m~3。不同浓度的NO_3~--N对甲烷氧化混合菌群的甲烷氧化能力和N_2O生成影响不大。高浓度NH_4~+-N会降低甲烷氧化混合菌群的甲烷氧化效率且促进N_2O生成,NH_4~+-N浓度从10 mg/L提高到50 mg/L时,甲烷氧化效率由92.0%降低为78.9%,而N_2O浓度由5.1 mg/m~3升高为17.8 mg/m~3。氧化亚氮产生机制试验表明:甲烷氧化混合菌群在培养初期生成的N_2O以非生物作用为主,其贡献约为79%,培养后期以硝化细菌反硝化作用为主,贡献约为61%。