辽河口滨海湿地土壤有机碳矿化及其与盐分的关系

Soil organic carbon mineralization and its relation with salinity in coastal wetland of Liaohe estuary

以辽河口滨海湿地不同盐分土壤为研究对象，采用室内密闭培养法研究了盐分与土壤有机碳矿化的关系。结果表明，不同样点间土壤电导率（EC1：5）差异显著。74d的培养期间，不同盐分土壤表层（0-10cm）和下层（10—20cm）的累积矿化量分别为6．54和2．79gC·kg-1。根据一级动力学拟合结果，相应的有机碳潜在矿化势（C0）和矿化系数（k）分别为14．5、3．84gC·kg-1和0．009、0．017d-1。表层土壤的C0值高于下层土壤，且C0值在不同样点间差异显著。不同盐分土壤C0值与EC1：5、有机碳（SOC）、全氮（TN）、Ca2＋、Mg2＋、Cl-含量之间呈显著正相关，而k值与上述指标呈显著负相关。逐步回归分析表明，供试土壤的C0值更多地受Cl-和SOC的限制，而七值主要受SOC的限制。研究表明，盐分和土壤有机质性质的协同效应对辽河口滨海湿地不同盐分土壤有机碳的矿化具有重要作用。

Coastal wetland soils with different salinity in Liaohe estuary were collected and an air- tight incubation experiment was conducted to study the characteristics of organic carbon minerali- zation and its relationship with the salinity. The results showed that the mean values of electric conductibility （EC1：5 ） 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 （ Co） 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 Co 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 Co values and ECI：~, 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 Co value was mainly regulated by the contents of Cl- and SOC, but the k value was mainly regulated by the SOC con- tent. 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.