温度对猪粪浆N_2O转化的影响

Effect of temperature on N_2O transformation of pig manure slurry

因粪浆处理产生的氧化亚氮(N_2O)是畜牧业温室气体的一个重要来源,试验研究了温度对猪粪粪浆N_2O的产生与消解的影响及代谢底物和可能参与代谢的功能基因丰度变化,旨在探究猪粪浆N_2O转化机制。结果表明:密闭条件下,随着氧的耗竭,粪浆N_2O先累积后消解,3个组的N_2O浓度和产生量都在第3天达到峰值,当温度从15℃升高到35℃时,其峰值从1.70mg/kg升高到4.65mg/kg。试验第10天以后N_2O浓度下降到甚至低于大气本底值。粪浆N_2O的排放速率与硝化和反硝化菌代谢酶基因anzoA、nirK、nirS和nosZ丰度都显著相关(0.62、0.66、0.58和0.49,P<0.01),与niriK与nosZ的比值也显著相关(0.57,P<0.01)。结论:温度升高会加快粪浆N2O生成和还原,提高其排放峰值,但不影响其转化的时间节律。硝化和反硝化菌可能都参与了N_2O的转化,但反硝化代谢酶nirK与nosZ的比值在N_2O排放中起着更关键的作用。

Because nitrous oxide（ N2O） produced by treating animal manure slurry was an important source of agricultural greenhouse gas, the effect of temperature on transformation of N2O from pig manure slurry was investigated under closed conditions. The experimental results showed that under the closed conditions the N2O accumulated at first and then reduced with depletion of oxygen; The N2O concentration and production in the3 groups reached the maximum level all on the 3 rd day,and the peak value increased from 1. 70 mg/kg to4. 65 mg/kg when temperature rose from 15 ℃ to 35 ℃; Ten days later, the N20 concentration decreased to even less than the atmosphere’ s background level. The N20 emission rate significantly correlated to abundances of both nitrifying and denitrifying bacteria’ s metabolic enzyme genes（amoA,nirK,nirS and nosZ）（0.62,0.66,0. 58 and 0. 49, P 〈 0. 01） and also significantly correlated to the nirK-nosZ ratio（ 0. 57, P 〈 0. 01）. It was concluded that the temperature rising could accelerate the N2O production and reduction and raise the N2O emission peak value but could not influence the rhythm of N2O transformation. Both nitrifying and denitrifying bacteria might be involved in the N2O transformation,but the nirK-nosZ ratio of denitrifying metabolic enzymes could play a crucial role in N2O emission.