Mechanisms of Hydrogen Sulfide Release from Coastal Marine Sediments to the Atmosphere

In two shallow, coastal areas in Denmark the rates of H2Srelease were directly measured by continuously collecting the gas over a known area. Peak emission rates of up to 0.30 and 6.7 mmol H2m-2 h-1 were found with a diurnal average of 0.063 and 1.58 mmol H2SM-2 H-1. The release mainly takes place at night since photosynthetic microorganism efficiently oxidize the sulfide during the day. Only traces of H2Sescape through a stagnant layer of oxic water 10 cm deep. The rate of H2Srelease is compared to the diurnal changes in light, temperature, Eh, pH, O2, and H2Sat the sediment surface and with the rate of sulfate reduction within the sediment.