Abstract: By using enclosed static chamber-gas chromatograph techniques, this paper measured the methane fluxes of Cyperus malaccensis tidal wetland in Minjiang River estuary. The diurnal variation of the methane fluxes in summer and winter were in the range of 1.29-2.93 mg·m^-2·h^-1 and 0.06-0.22 mg·m^-2·h^-1, respectively. The methane fluxes before flooding, in the process of flooding and ebbing, and after ebbing were 0.11-1.52 mg·m^-2·h^-1,0.10-1.05 mg·m^-2·h^-1, and 0.05-1.70 mg·m^-2·h^-1, and the monthly averaged fluxes were 0.73, 0.47, and 0.72 mg·m^-2·h^-1, respectively. The methane fluxes peaked in September and reached the lowest in March, and were significantly lower in the process of flooding and ebbing than before flooding and after ebbing (P<0.05). The seasonal variation of the methane fluxes was in the order of summer > autumn > spring > winter. Tide was the key factor affecting the diurnal variation of the methane fluxes, while plant growth stage and temperature were the key factors determining the monthly or seasonal variation of the methane fluxes.

Key words: methane, Cyperus malaccensis, tidal wetland, affecting factor, Minjing River estuary, low magnesium stress, low temperature, chlorophyll, photosynthesis, Cucumis sativa.