PHOTOINDUCED OXIDATION OF H2S SPECIES - A SINK FOR SULFIDE IN SEAWATER

Photokinetic studies demonstrate that sulfide is consumed in seawater upon light exposure. The half-life (t(1/2)) of sulfide (10 mu M) added to Biscayne Bay water and Gulf Stream water are 49(+/-15) and 147(+/- 10) min, respectively. Both UV and visible radiation were shown to acc elerate the photodecomposition of sulfide. However, due to a higher am ount of radiation in the visible range reaching the sea surface, we pr edict that this portion of the light spectrum will be most important i n inducing photoreaction of sufide in seawater. This as yet unaccounte d sink of sulfide in seawater could be responsible for the sulfide day time low and nighttime high concentration values observed by several i nvestigators. This finding further unbalances the sulfide budget and r einforces the need for systematic research on the role of photochemica l processes on sulfur species in seawater.