[en] The net CO₂ flux across the air-sea interface has been determined in December, 1982, in the Caribbean Sea and the tropical North Atlantic Ocean using the pCO₂ and radon-222 methods. The thermodynamic driving force for CO₂ gas transfer has been characterized in terms of the difference between the CO₂ partial pressures, pCO₂, in the surface ocean water and the overlying atmosphere, and the gas exchange coefficient (expressed in terms of the piston velocity) has been estimated on the basis of the vertical distribution of radon-222 gas in the upper 200 meters of water column. The net CO₂ flux across the air-sea interface has been computed using these two quantities. The areas north of the 10⁰N parallel are a CO₂ sink area, where a net CO₂ flux ranging from 0 to about 1 mole CO₂/m² y (from air to sea) has been observed. This compares with the global mean net CO₂ flux of about 0.6 mole CO₂/m² y (from air to sea). On the other hand, the areas south of 10⁰N are a CO₂ source area. The sea-to-air net flux of as high as 3 moles CO₂/m² y has been observed east of the mouth of the Amazon River. Although the equatorial surface water exhibited high pCO₂ values, the gas exchange piston velocity was small particularly in the doldrum, and hence the net CO₂ flux values ranging between 1 and 2 moles CO₂/m² y were observed