盐分对辽河口湿地土壤DOC及CO2生成的影响

Effects of salinity on DOC concentration and CO_2 production of wetland soil in Liaohe estuarine

以辽河口区芦苇湿地不同深度(0~10、10~20、20~30和30~40 cm)土壤为研究对象,利用盐溶液淋洗土壤至不同的盐分梯度(CK、2.5、5、10 m S·cm-1),采用室内恒温培养法,探讨盐分条件对DOC浓度变化及土壤呼吸释放CO_2的影响。结果表明,56 d培养期间,盐分处理对表层(0~10 cm)土壤DOC浓度的影响不显著,对下层(10~20、20~30和30~40 cm)土壤的DOC浓度的影响显著,盐度升高降低了下层土壤DOC浓度;盐分处理对各层土壤CO_2生成速率无显著影响。不同盐分条件下,DOC浓度及CO_2生成速率在土壤深度间均差异明显,表层DOC浓度及CO_2生成速率明显高于下层。该结果为河口湿地碳循环响应水盐环境变化研究提供理论依据。

To identify the effect of salinity on dissolved organic carbon （DOC） concentration and the rate of carbon dioxide （CO2） production of soil, we collected soils from reed wetland in Liaohe estuary at different depths （0-10, 10-20, 20-30 and 30-40 cm）. After washed to different salinity levels （CK, 2.5, 5, 10 mS·cm-1） with synthesized saline solution, soil samples were incubated for 56 days at 28 ℃. The results showed that salt treatment had no significant effect on the DOC concentration in the topsoil layer （0-10 cm） during the 56d incubation period, but significantly affected the DOC concentrations in the subsoil layers （10-20, 20-30 and 30-40 cm）, and elevated salinity decreased the DOC concentration. However, salt treatment had no significant effect on the rate of CO2 production in any soil layers. The DOC concentration and CO2 production rate were significantly different among different soil layers, and the mean values were significantly higher in the topsoil layer than in the subsoil layers. The results provide a basis for understanding the response of carbon cycles to salt changes in estuary wetlands.