Leachate treatment in landfills is a significant N2O source

- N2O emissions from leachate system were intensive, while often ignored.
- The static chamber method was adopted to measure GHG emissions in landfills.
- A first set of GHG emissions from reservoirs and leachate in landfills was collected.
- High N2O EF of 8.9-11.9% was achieved in leachate treatment systems.
- N2O should be included in the inventory of GHG emissions from landfills.

The importance of methane (CH4) emissions from landfills has been extensively documented, while the nitrous oxide (N2O) emissions from landfills are considered negligible. In this study, three landfills were selected to measure CH4 and N2O emissions using the static chamber method. Dongbu (DB) and Dongfu (DF) landfills, both located in Xiamen city, Fujian Province, were classified as sanitary. The former started to receive solid waste from Xiamen city in 2009, and the latter was closed in 2009. Nanjing (NJ) landfill, located in Nanjing county, Fujian Province, was classified as managed. Results showed that for the landfill reservoirs, CH4 emissions were significant, while N2O emissions occurred mainly in operating areas (on average, 16.3 and 19.0 mg N2O m− 2 h− 1 for DB and NJ landfills, respectively) and made a negligible contribution to the total greenhouse gas emissions in term of CO2 equivalent. However, significant N2O emissions were observed in the leachate treatment systems of sanitary landfills and contributed 72.8% and 45.6% of total emissions in term of CO2 equivalent in DB and DF landfills, respectively. The N2O emission factor (EF) of the leachate treatment systems was in the range of 8.9-11.9% of the removed nitrogen. The total N2O emissions from the leachate treatment systems of landfills in Xiamen city were estimated to be as high as 8.55 g N2O-N capita− 1 yr− 1. These results indicated that N2O emissions from leachate treatment systems of sanitary landfills were not negligible and should be included in national and/or local inventories of greenhouse gas emissions.

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