GREENHOUSE GASES (CO2, CH4 AND N2O) FLUXES FROM THE SOUTHEASTERN ARABIAN SEA SHELF

Coastal Upwelling regions have been identified as sites of enhanced greenhouse gas (GHG) emission to the atmosphere. The coastal upwelling area of north-western Indian Ocean is one of the most biological productive regions of the world’s ocean but its GHGs emissions have not been well quantified. In order to budget the climate relevant GHGs (CO₂, CH₄ and N₂O) from southeastern Arabian Sea (SEAS), monthly observations in the shelf waters of Cochin (10°N), SEAS were carried out during January-December 2012. The study reveled that SEAS behaved as a perennial source of CO₂, CH₄ and N₂O. The dynamics and fluxes of CO₂ and N₂O are mostly governed by the biogeochemical processes associated with upwelling, while the dynamics of CH₄ are controlled by the sediment processes and the discharges from nearby wetlands/estuaries. The surface saturation reached up to 312% and 2652% respectively for CO₂ and N₂O and their concentrations increased exponentially in the subsurface waters when O₂ levels fall below 25µM during the peak upwelling. On an annual scale their fluxes ranged between -0.9 - 76 mmol m^-2 d^-1 for CO₂, 0.29 - 467 µmol m^-2 d^-1 for N₂O and 0.7 - 227 µmol m^-2 d^-1 for CH_4.