Abstract: Soil samples (0-10, 10-20, 20-30, 30-40 cm layers) of Phragmites australis wetland in the Liaohe estuary were collected, and the closed incubation-gas chromatography was used to examine the effects of chloride (Cl^-) and sulfate (SO₄^2-) concentrations on soil organic carbon mineralization. The results showed that both the mineralization rate and the cumulative mineralization of soil organic carbon in the surface soil (0-10 cm) were significantly higher than those of the subsoil layers (10-40 cm). During the 20day incubation, mineralization rate showed a decreasing trend with time. In the Cl^- treatment groups, the low concentration of Cl^- (75 mmol·L^-1) promoted mineralization, while the high concentration (450 mmol·L^-1) significantly inhibited the mineralization. In the SO₄^2- treatment, there was no significant effect of ionic concentrations on the mineralization rate for all the soil layers. Our results indicate that Cl^- has a stronger effect than SO₄^2- on organic carbon mineralization for P. australis wetland soil in the Liaohe estuary. The increases of salinity in future may accelerate the loss of soil organic carbon in the wetland of Liaohe estuary.

Key words: microbial characteristics, volcanic mineral spring, hydrochemical characteristics, eco-health implication