Abstract: Coastal wetland soils with different salinity in Liaohe estuary were collected and an airtight incubation experiment was conducted to study the characteristics of organic carbon mineralization and its relationship with the salinity. The results showed that the mean values of electric conductibility (EC_1:5) of soil were different among the sampling sites. The cumulative carbon mineralization amounts of top soil (0-10 cm) and subsoil (10-20 cm) were 6.54 g C·kg^-1 and 2.79 g C·kg^-1 for 74d incubation, respectively. According to the first order kinetic, the mean values of mineralization potentials (C₀) were 14.5 g C·kg^-1 for top soil and 3.84 g C·kg^-1 for subsoil, respectively, and the corresponding values of mineralization constants (k) were 0.009 and 0.017 d^-1. The C₀ value of top soil was significantly higher than that of subsoil and they were both significantly different among the sampling sites. There were significant positive relationships between the C₀ values and EC_1:5, soil organic carbon (SOC), total nitrogen (TN), Ca²⁺, Mg²⁺ and Cl^- contents in soil. However, a negative correlation was found between the k values and these properties of the soil. The results of stepwise regression showed that the C₀ value was mainly regulated by the contents of Cl^- and SOC, but the k value was mainly regulated by the SOC content. The results indicated that the soil organic carbon mineralization of the coastal wetland was controlled by a combined effect of soil salinity and organic carbon content.

Key words: environmental factor, subtropical coniferous plantation, extreme high temperature, net ecosystem exchange of carbon dioxide, wavelet analysis.