摘要：Nitrous oxide (N 2 O), an important greenhouse gas, is emitted from landfill reservoirs, especially in the working face, where nitrification and denitrification occur under different O 2 concentrations. In order to explore the effects of O 2 concentration on N 2 O emissions and production pathways, the production of N 2 O from simulated fresh waste landfilling under 0%, 5%, 10%, and 21% (vol/vol) O 2 concentrations were examined, and 15 N isotopes were used as tracers to determine the contributions of nitrification (NF), heterotrophic denitrification (HD), and nitrification-coupled denitrification (NCD) to N 2 O production over a 72-h incubation period. Equal amounts of total nitrogen consumption occurred for all studied O 2 concentration and the simulated waste tended to release more N 2 O under 0% and 21% O 2 . Heterotrophic denitrification was the main source of N 2 O release at the studied oxygen concentrations, contributing 90.51%, 69.04%, 80.75%, and 57.51% of N 2 O under O 2 concentrations of 0%, 5%, 10%, and 21%, respectively. Only denitrification was observed in the simulated fresh waste when the oxygen concentration of the bulk atmosphere was 0%. The nitrate reductase ( nirS )-encoding denitrifiers in the simulated landfill were also studied and significant differences were observed in the richness and diversity of the denitrifying community at different taxonomic levels. It was determined that optimising the O 2 content is a crucial factor in N 2 O production that may allow greenhouse gas emissions and N turnover during landfill aeration to be minimised.
