THE OXIDATION OF H2S IN FRAMVAREN FJORD

The oxidation of H2S with 02 was measured in Framvaren Fjord at 25-degrees-C. The measurements were made on mixtures of surface waters and waters collected from below the anoxic interface (20 m). Measurements were also made on deep waters after a rapid equilibration with air. Oxidation rates varied according to the concentration of Fe(II) and Mn(II) in the solutions, in agreement with earlier studies. For waters collected at the particle maximum (22 m) t1/2 = 20 min for poisoned and unpoisoned samples. The inter-mediates SO3(2-) and S2O3(2-) were followed along with the disappearance of H2S during the course of oxidation. The formation of the intermediates was modeled with the overall rates of oxidation of H2S (k1) and SO3(2-) (k2) and the formation of S2O3(2-) (k3). The values were all larger than found for seawater. These results indicate that Fe(II) and Mn(II) also affect the oxidation of SO3(2-) and the formation of S2O3(2-) in anoxic waters. The deep waters contained concentrations of H2S as high as 6,000-mu-M. Low levels of SO3(2-) and S2O3(2-) were found near the anoxic interface. Quite variable levels (1-35-mu-M) of what is thought to be S2O3(2-) were found in the deep waters. No SO3(2-) was detected below the interface.