盐度变化对闽江河口潮汐湿地土壤CO2和CH4排放通量的影响

he saltwater intrusion of estuarine tidal wetland caused by sea level rise has an important effect on the emission fluxes of carbon dioxide and methane. In view of this, in order to reveal the impact of salt water intrusion on soil carbon-containing greenhouse gas emissions from tidal wetlands in the Minjiang estuary, in this study, the freshwater and brackish wetlands in the Minjiang estuary were treated with soil replacement (freshwater, freshwater → brackish and brackish) , the indexes of pore water (dissolved methane, DOC and DIC) and the emission fluxes of greenhouse gases methane and carbon dioxide were analyzed. Therefore, the response mechanism of soil carbon cycle in the estuarine tidal wetland after saltwater intrusion is clarified, which provides an effective reference for further study of the changes of soil carbon cycle in the estuarine tidal wetland after saltwater intrusion. The results were as follows: (1) When soil was removed from freshwater wetland, carbon dioxide emission flux increased and methane emission flux decreased. (2) When the soil was transplanted from the fresh water wetland to the brackish water wetland, the dissolved CH4 concentration decreased, DIC concentration increased, and DOC concentration increased. (3) The fluxes of carbon dioxide and methane and the concentrations of dissolved methane, DIC and DOC in estuarine freshwater tidal wetlands increased with the increase of air temperature, then decreased gradually and reached the lowest value in winter when air temperature was lower. To sum up, the increase of salinity will increase the carbon dioxide emission flux and decrease the methane emission flux of estuarine wetland, and significantly change the main geochemistry index values of pore water in estuarine wetland, and has the obvious seasonal variation characteristic.