CONCENTRATIONS AND FLUXES OF DISSOLVED BIOGENIC GASES (DMS, CH4, CO, CO2) IN THE EQUATORIAL PACIFIC DURING THE SAGA-3 EXPERIMENT

The equatorial Pacific Ocean is a source of both sulfur and carbon to the atmosphere. In February and March 1990, as part of the Soviet-Amer ican Gases and Aerosols (SAGA 3) expedition, dimethysulfide (DMS), met hane (CH4), carbon monoxide (CO), and carbon dioxide (CO2) partial pre ssures were determined in both surface seawater and the overlying atmo sphere of the central equatorial Pacific Ocean (15-degrees-N to 10-deg rees-S, 145-degrees-W to 165-degrees-W). The partial pressures were us ed to calculate the net flux of these gases from the ocean to the atmo sphere. The average regional DMS and CO fluxes were similar, 7.1 and 4 .2 mumol/m2/d, respectively. The mixing ratio of CH4 in surface seawat er was close to equilibrium with the overlying atmosphere and hence th e average flux was only 0.39 mumol/m2/d. The flux of CO2 clearly domin ated the air-sea carbon exchange with an average regional flux of 5.4 mmol/m2/d.