Salt marshes play an important role in global and regional carbon cycling. Restoration and conservation of salt marshes have a great potential for carbon sequestration. We measured greenhouse gas (GHG) emissions (CO2, CH4, N2O) biweekly for two growing seasons across a nitrogen-loading gradient of four Spartina salt marshes in Waquoit Bay, Massachusetts, USA. We also measured GHG emissions in a tidally restricted wetland and a restored wetland. The GHG flux measurements were made in situ with a state-of-the-art mobile gas measurement system using the cavity ring down technology that consists of a CO2/CH4 analyzer and an N2O/CO analyzer.
Results/Conclusions
We observed strong seasonal variations in greenhouse gas emissions. We found that the studied salt marsh was a significant carbon sink when all GHG fluxes were combined. The restored coastal wetland decreased CH4 fluxes compared with the tidally restricted freshwater marsh. We conclude that restoration or conservation of the coastal blue carbon sink has a significant social benefit for carbon credit.