Assessment of methane and nitrous oxide flux from mangroves along Eastern coast of India

Mangroves are considered to be a minor source of greenhouse gases (CH4 and N2O) in pristine environmental condition. However, estimates of efflux suggest that anthropogenic activities have led to a pronounced increase in greenhouse gas emission. Along the east coast of India, mangroves vary substantially in area, physiography and freshwater input, which ultimately modify the biogeochemical processes operating within this ecosystem. An attempt has here been made to elucidate the existing variation and role of climatic variability on the emission of greenhouse gases from mangroves. The flux estimates of CH4 and N2O have been quantified from Bhitarkanika mangrove accounting for spatial and temporal (seasonal) variation. The annual rates were estimated to be 0.096 × 10 9 g CH4 year−1 and 5.8 × 103g N2O year−1 for the whole mangrove area of the east coast of India. Upscaling these estimates yield an annual emission of 1.95 × 10 12 g CH4 year−1 and 1.1 × 10 11 g N2O year−1 from worldwide mangrove areas. The influence of elevated nutrient inputs through anthropogenic influence enhances the emission of greenhouse gas. The present article shows the need to develop an inventory on greenhouse gas flux from mangrove ecosystem.