Effects of Sea Level Rise on Production and Emission of CH4 and CO2 in Estuarine Tidal Marshes:Mechanism and Complexity
Sea-Level Rise(SLR)directly changes the hydrology and salinity of estuarine tidal wetlands and is one of the primary drivers of global change that significantly impacts ecosystem processes.Herein,various methodologies and experimental facilities(marsh organs,weirs,and flow-through mesocosms)for manipulating SLR are systematically reviewed.This study provides a comprehensive summary of the effects and mechanisms associated with SLR regarding the fluxes and production rates of CH4 and CO2,and the pathways and rates of soil organic carbon mineralization from the perspectives of SLR-saltwater intrusion and inundation increase.Saltwater intrusion due to SLR notably decreases CH4 production rates and fluxes.It induces a shift in the pathways of soil organic carbon mineralization,transitioning from CH4 production to microbial SO42-reduction in tidal freshwater marshes.The main mechanism reducing saltwater intrusion-induced CH4 flux is the increased presence of the electron acceptor SO42-,which hinders soil CH4 production.The impact of SLR through saltwater intrusion on CO2 emissions in tidal freshwater marshes exhibits distinct uncertainty.Owing to the inherent challenges in experimentally manipulating SLR in situ,few reports concerning the effects of SLR-related inundation on CH4 and CO2 fluxes and production rates exist.However,some studies have suggested that an increase in inundation height leads to a reduction in CO2 emissions.Additionally,this study consolidates information surrounding electron acceptors and microbial mechanisms associated with SLR that influence the pathways and rates of soil organic carbon mineralization in coastal tidal wetlands.Finally,this study outlines the specific domains that warrant further exploration in future research on the impact of SLR on the production and emission of carbon greenhouse gases in estuarine tidal marshes.
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