Abstract: In this paper, sulfate reduction rate in salt marshes near the estuary of obsolete Huanghe River was reported. The rates were measured for 2 years (1980—1988) in salt marsh ve getated with two species of Spartina by isotopic label technique. Results indicated that the integrated annual rate is about 77.75mol SO₄^2-·m^-2·yr^-1 in Spartina anglica peat and about 110.3mol SO₄^2-·m^-2·yr^-1 in S. alterniflora peat. Sulfate reduction rates in these experimental fields are probaly higher for three reasons: 1) underground production of Spartina spp. provides a large annual amount of organic substrates over a depth of 20 cm; 2) sulfate is rapidly resuplied to the peat by infiltrating tidal water, so that sulfa te depletion never limits the rate of reduction; 3) sulfate concentration remains below to xic levels. FeS₂ is a main end product of sulfur reduction, while FeSis not. FeS₂ acts as a temporary store of reduced sulfur, changing with seasons in its cocentration. The important role of sulfate reduction in mineralizing organic carbon and the significance of energy flow in salt marsh ecosystem were discussed.

Key words: Sulfate reduction, Salt marsh, Spartina anglica, Spartina alterniflora, Pyrite