Oxidation rate of sulfide in sea water, A preliminary study

Previous results have indicated that sea-water spray can constitute only a minor source of airborne sulfate. The principal origin of this sulfate must be from organic materials and volcanic activity. It has been speculated that sea water may release hydrogen sulfide produced in the bottom sediments. After hurricane Donna in September 1960, measurements of sulfur and oxygen in the Florida Bay area of the Everglades National Park yielded puzzling results. Experiments were then initiated to determine the rate of oxidation of dissolved hydrogen sulfide by dissolved oxygen in sea water by adding hydrogen sulfide solution to normal sea water. Changes in sulfide concentration were monitored with an Ag/Ag2S electrode; the pH;. was also monitored. Whatever the reaction mechanism, the sulfide appeared to decrease with a rate constant of about 2×10−1/μM min at about 25°C, calculated as a second-order reaction. In sea water having a constant oxygen content of 170 μM (3.8 ml/l) the half-life for hydrogen sulfide would be about 20 minutes. It is therefore unlikely that hydrogen sulfide can ‘survive’ long enough to penetrate from the bottom of the sea to the atmosphere except in very shallow areas.