Analysis of Hypoxia Dynamics Using Pelagic and Benthic Biogeochemical Model: Focus on the Formation and Release of Hydrogen Sulfide

Abstract

A field survey and laboratory analyses of sediment quality in the eastern part of Osaka Bay are carried out to clarify their characteristics and influence on the dynamics of hypoxia. Nitrogen, phosphorus and sulfur cycling in the coastal water and sediment are modeled with a focus on the formation of hydrogen sulfide in hypertrophic sediment and its release to the bottom water. In the calculated results the oxygen consumption in the bottom water by the release of sulfide is much larger than the direct oxygen consumption by the sediment in the northern port of the bay. Without the release of sulfide, the hypoxic water area would be estimated to be limited in and near the port area of the head of the bay. The wide spreading of hypoxia in the eastern part of the bay would be contributed largely by the sulfide release.