Effect of wastewater discharge on greenhouse gas fluxes from mangrove soils

摘要

The effects of wastewater on atmospheric fluxes of three greenhouse gases, nitrous oxide (N_2O), methane (CH4) and carbon dioxide (CO_2) from mangrove soils were investigated, and the differences among shrimp pond wastewater (SP), livestock wastewater (LS) and municipal (S) sewage were compared. The gas emissions from mangrove soils were significantly enhanced after wastewater irrigation and the highest emission of N_2O and CO_2 were obtained from SP. High N_2O emission was also found in S treatment, where fluxes varied from 13.42 to 16.78 μmol m~(-2) h~(-1), but the CH4 and CO_2 fluxes were as low as the control irrigated with tap water. Results of soil analyses indicated that the high N_2O emissions from mangrove soils receiving SP and S treatments were attributed to the denitrification and nitrification processes, respectively. The highest CH_4 flux was recorded in LS treatment (186.14-762.40 μmol m~(-2) h~(-1)), which also had the highest CO_2 flux. The fluxes measured during the non-irrigation period were lower than those measured 4 h after irrigation.