Carbonyl sulfide concentrations in the surface waters and above the Pacific Ocean

Abstract

We measured the concentration of carbonyl sulfide (OCS) in the marine atmospheric boundary layer and in the surface layer of the equatorial and northern Pacific Ocean on two oceanographic cruises during May and June of 1982 and during March–May of 1983. Our measurements of the mean concentration of atmospheric OCS are 502 ± 21 parts per trillion (ppt) on the 1982 cruise and 511 ± 19 ppt on the 1983 cruise. We found surface water OCS concentrations to range upward from 0.3 STP nL L −1 to a few cases over 3.0 STP nL L −1 . We estimate the global mean supersaturation ratio of OCS in seawater to range from 1.5 to 3.0, indicating a global source of OCS from the ocean of 0.2 to 0.4 Tg yr −1 . We have made laboratory measurements of the dimensionless Henry's law coefficient of solubility H , the concentration of OCS in air divided by its concentration in 34.90 per mil salinity seawater. We found ln H = 12.722 ± 0.082 − (3,496 ± 24)/ T , with no evidence for nonlinearities in the solubility at ambient atmospheric concentrations of OCS.