Ecosystem level methane fluxes from tidal freshwater and brackish marshes of the Mississippi River Delta: Implications for coastal wetland carbon projects

Wetlands
By: , and 

Links

Abstract

Sulfate from seawater inhibits methane production in tidal wetlands, and by extension, salinity has been used as a general predictor of methane emissions. With the need to reduce methane flux uncertainties from tidal wetlands, eddy covariance (EC) techniques provide an integrated methane budget. The goals of this study were to: 1) establish methane emissions from natural, freshwater and brackish wetlands in Louisiana based on EC; and 2) determine if EC estimates conform to a methane-salinity relationship derived from temperate tidal wetlands with chamber sampling. Annual estimates of methane emissions from this study were 62.3 g CH4/m2/yr and 13.8 g CH4/m2/yr for the freshwater and brackish (8–10 psu) sites, respectively. If it is assumed that long-term, annual soil carbon sequestration rates of natural marshes are ~200 g C/m2/yr (7.3 tCO2e/ha/yr), healthy brackish marshes could be expected to act as a net radiative sink, equivalent to less than one-half the soil carbon accumulation rate after subtracting methane emissions (4.1 tCO2e/ha/yr). Carbon sequestration rates would need case-by-case assessment, but the EC methane emissions estimates in this study conformed well to an existing salinity-methane model that should serve as a basis for establishing emission factors for wetland carbon offset projects.

Study Area

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Ecosystem level methane fluxes from tidal freshwater and brackish marshes of the Mississippi River Delta: Implications for coastal wetland carbon projects
Series title Wetlands
DOI 10.1007/s13157-016-0746-7
Volume 36
Issue 3
Year Published 2016
Language English
Publisher Society of Wetland Scientists
Publisher location McClean, VA
Contributing office(s) Wetland and Aquatic Research Center
Description 13 p.
First page 401
Last page 413
Country United States
State Louisiana
Online Only (Y/N) N
Additional Online Files (Y/N) N