Inorganic carbon sequestration and its mechanism of coastal saline-alkali wetlands in Jiaozhou Bay, China

The problem of “missing sink” in the carbon cycle has not been properly explained. To reveal the effects of coastal saline-alkali wetlands on global inorganic carbon sequestration, soil samples with different salinity and alkalinity were collected in Jiaozhou Bay coastal wetlands, and the main work were: split the soil CO2 flux through inactivation treatment; simulate the CO2 absorption process of saline alkali soils; and analyze the mechanism of the above process through stable isotopic labeling. The inorganic carbon sequestration process is common in coastal saline-alkali soil. The increasing salinity and alkalinity of soil can improve its CO2 uptake capacity, and the soil alkalinity showed greater effects on the capacity than soil salinity. The leaching/absorption of atmosphere CO2 and the dissolution/precipitation of carbonate system are confirmed as the two mechanisms of inorganic carbon sequestration. The former mechanism dominates the sequestration process in coastal wetlands. We conclude that the abundant water sources and the high alkalinity of soils contribute to the advantages of carbon sequestration processes in coastal saline-alkali wetlands.