Quantification of Greenhouse Gas Emissions from the Predisposal Stage of Municipal Solid Waste Management

Municipal solid waste (MSW) disposal represents one of the largest sources of anthropogenic greenhouse gas (GHG) emissions. However, the biogenic GHG emissions in the predisposal stage of MSW management (i.e., the time from waste being dropped off in community or household garbage bins to being transported to disposal sites) are excluded from the IPCC inventory methodology and rarely discussed in academic literature. Herein, we quantify the effluxes of carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O) from garbage bins in five communities along the urban-rural gradient in Beijing in four seasons. We find that the annual average CO₂, CH₄, and N₂O effluxes in the predisposal stage were (1.6 ± 0.9)10³, 0.049 ± 0.016, and 0.94 ± 0.54 mg kg^-1h^-1 (dry matter basis) and had significant seasonal differences (24- to 159-fold) that were strongly correlated with temperature. According to our estimate, the N₂O emission in the MSW predisposal stage amounts to 20% of that in the disposal stage in Beijing, making the predisposal stage a nontrivial source of waste-induced N₂O emissions. Furthermore, the CO₂ and CH₄ emissions in the MSW predisposal account for 5% (maximum 10% in summer) of the total carbon contents in a Beijing's household food waste stream, which has significance in the assessment of MSW-related renewable energy potential and urban carbon cycles.