Effect of wastewater discharge on greenhouse gas fluxes from mangrove soils

The effects of wastewater on atmospheric fluxes of three greenhouse gases, nitrous oxide (N₂O), methane (CH₄) and carbon dioxide (CO₂) 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 N₂O and CO₂ were obtained from SP. High N₂O 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 CO₂ fluxes were as low as the control irrigated with tap water. Results of soil analyses indicated that the high N₂O emissions from mangrove soils receiving SP and S treatments were attributed to the denitrification and nitrification processes, respectively. The highest CH₄ flux was recorded in LS treatment (186.14-762.40 μmol m^-2 h^-1), which also had the highest CO₂ flux. The fluxes measured during the non-irrigation period were lower than those measured 4 h after irrigation. © 2010 Elsevier Ltd.