FY 1995

Photoproduction of carbonyl sulfide in south Pacific Ocean waters as a function of irradiation wavelength

Weiss, P.S., S.S. Andrews, J.E. Johnson, and O.C. Zafiriou

Geophys. Res. Lett., 22(3), 215–218 (1995)

Carbonyl sulfide (OCS) photoproduction rates were measured at selected wavelengths of ultraviolet light between 297 and 405 nm in sea water samples from the southern Pacific Ocean. Near-surface and column production rate spectra for natural sunlit waters were calculated using sea-surface sunlight data measured near the austral summer solstice. These plots show that photoproduction rates are at a maximum at 313 nm in tropical waters and at 336 nm in Antarctic waters. Tropical surface and column rates were found to be 68 pM/day and 360 nmol/m/day, respectively, and Antarctic surface and column rates were found to be 101 pM/day and 620 nmol/m/day, respectively. A high degree of variability was observed between photoproduction rates from different ocean regions, with coastal rates being the highest, suggesting that natural environmental variability is an important factor. Photoproduction rates at 297 nm were found to be constant at individual locations with increasing irradiation time. Relative photoproduction rates from this work are compared to previously measured rates from coastal sea water.