A Novel Semi-Empirical Model for Multi-Scenario Estimations of Nitrous Oxide Emissions from Municipal Solid Waste Landfills

Landfills contain significant amounts of nitrogenous substances and serve as important sources of nitrous oxide (N₂O), with emissions primarily concentrated on the working face. This paper developed a semiempirical model based on the logistic principles to simulate the temporal dynamics of landfill N₂O emissions. Results showed that the model successfully captured the S-shaped N₂O emission pattern observed at a landfill site (<i>R</i>² = 0.54). Both field and laboratory data indicated that the key model parameter <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow><mml:mi>λ</mml:mi></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi>N</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:mi>O</mml:mi></mml:mrow></mml:msub></mml:math>, which represented the rate of N₂O emission potential change with O₂ availability, was strongly correlated with waste nitrogen content, landfill operation practices, and temperature. The model output representative N₂O emission factors for three typical landfill scenarios─waste sorting (WS), business as usual (BAU), and enhanced emission (EE)─with values of 0.51, 5.20, and 10.97 mg N·kg^-1 waste, respectively. Under the BAU scenario, the representative emission factor was used to estimate historical N₂O emissions from Chinese landfills over the past two decades, yielding a total of 12.25 Gg N. In contrast, WS achieved a 90% reduction in N₂O emission by diverting high-nitrogen waste (e.g., food waste), while EE resulted in a 111% increase even exceeding those from composting and incineration. The study demonstrates that that the semiempirical model enables robust estimation of landfill N₂O emissions at both site- and national- scales. This can supplement the current IPCC guidelines on greenhouse gas inventories.