In order to investigate the effect of SO_4~(2-)deposition on the greenhouse gas emissions from freshwater tidal marsh,simulated SO_4~(2-)deposition was carried out in a Cyperus malaccensis freshwater tidal marsh in Minjiang River Estuary.The enclosed static chamber technique was used to determine the environmental factors and the greenhouse gas fluxes (included CH_4,CO_2 and N_2O) in different months and under different SO_4~(2-)application rates.The stepwise regression was performed to determine the influential environmental factors to the greenhouse gas fluxes.The results showed that the environmental factors and the greenhouse gas fluxes in the plots exhibited distinct monthly variations.The additional sulfate concentration significantly promoted the plant density,and rho(SO_4~(2-)) and rho(NH_4~+-N) in pore water.The additional sulfate significantly suppressed the CH_4 flux;the CH_4 flux decreased by 33.8% and 69.9%,respectively,when the SO_4~(2-)application rate (by SO_4~(2-)-S) reached 40 and 120 kg(hm~2·a).The CO_2 flux decreased with increasing SO_4~(2-)while the N_2O flux increased,though the changes were not significant;the CO_2 flux decreased by 5.2% and 11.8%,respectively,while the N_2O flux increased by 98.0% and 103.0%,respectively,due to 40 and 120 kg(hm~2·a) SO_4~(2-)applications.Sediment temperature,and rho(SO_4~(2-)),rho(NH_4~+-N) and rho(NO_x--N) (included NO_3--N and NO_2--N) in pore water were the influential factors to the greenhouse gas fluxes.The overall greenhouse effect from the emissions of the 3 greenhouse gases decreased with the application of 40 and 120 kg(hm~2·a) SO_4~(2-);the reduction was 5.5% and 13.5%,respectively.Our research concluded that the increase in sulfate deposition rate might be conducive to the reduction of the contribution of tidal marsh to the global warming.