Leachate treatment in landfills is a significant N_2O source

摘要

The importance of methane (CH_4) emissions from landfills has been extensively documented, while the nitrous oxide (N_2O) emissions from landfills are considered negligible. In this study, three landfills were selected to measure CH_4 and N_2O 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, CH_4 emissions were significant, while N2O emissions occurred mainly in operating areas (on average, 16.3 and 19.0 mg N_2O m-2 h-1 for DB and NJ landfills, respectively) and made a negligible contribution to the total greenhouse gas emissions in term of CO_2 equivalent. However, significant N_2O emissions were observed in the leachate treatment systems of sanitary landfills and contributed 72.8% and 45.6% of total emissions in term of CO_2 equivalent in DB and DF landfills, respectively. The N_2O emission factor (EF) of the leachate treatment systems was in the range of 8.9-11.9% of the removed nitrogen. The total N_2O emissions from the leachate treatment systems of landfills in Xiamen city were estimated to be as high as 8.55 g N_2O-N capita-1 yr-1. These results indicated that N_2O 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.