Assessing the role of deltaic flood plain wetlands on regulating methane and carbon balance.

ABSTRACT

Present study deals with the role of wetland for regulating greenhouse gases (GHG) particularly methane (CH4) emission and carbon (C) sequestration in mature Ganges deltaic environment. The annual total amount of emission and sequestration in wetlands of varying types was estimated along with the seasonal variation. Result showed that the streams were the highest emitter of CH4 followed by ox-bow lakes in all the seasons whereas the bheries (embanked pisciculture arresting tidal water) consistently exhibited the lowest average emission. The average sequestration of C was the highest in ox-bow lakes followed by marshes and mudflats. The average emission in monsoon season was 43% and 78% higher than the average emission of pre and post-monsoon seasons respectively. The yearly total emission was 8.01 × 103 ton and yearly total sequestration was estimated 908.98 × 103 ton. From the perspective of GHG regulation, the wetlands were found to yearly uptake four times higher carbon dioxide (CO2) than the CO2 equivalent (CO2e) of emitted CH4. After offsetting the fixation cost of emitted CH4, the yearly surplus sequestrated C in the wetlands of the entire region was worthy of 68.46 million US dollar (USD). So, wetland plays positive role for reducing greenhouse gas effect and associated temperature rise which is considered to be serious issue. Such result has made a good agreement on the debated issue of wetland CH4 emission and C sequestration and will encourage restoring wetland for even mediating GHG issue.