Scales and drivers of seasonal pCO2 dynamics and net ecosystem exchange along the coastal waters of southeastern Arabian Sea

Abstract The impact of seasonal coastal upwelling on the dynamics of dissolved inorganic carbon (DIC) and sea-air fluxes of CO 2 along the coastal waters of Kochi was investigated during 2015, as a part of Ecosystem Modelling Project. The surface water p CO 2 varied from 396 to 630 μatm during the study period. Significant inter-seasonal variations were found in the distribution of physico-chemical variables and surface p CO 2 . An increase of 102.1 μatm of p CO 2 was noticed over a two-decade period with a rate of 5.3 μatm y − 1 . There was an agreement between the fluxes of CO 2 and net ecosystem production (NEP) with respect to the trophic status while NEP was higher than CO 2 fluxes by a factor of 3.9. The annual net ecosystem exchange (NEE) was estimated to be 15.02 mmol C m − 2  d − 1 indicating that the coastal waters of Kochi are highly heterotrophic in nature.