Sediment Oxygen Consumption Rate and Hydrogen Sulfide Release by Dissolved Oxygen Depletion in Hypoxic Area of the Gamak Bay, Korea

Abstract

This study investigated sediment oxygen consumption rates and geochemical characteristics of sediment in hypoxic area of the Gamak Bay based on the chamber experiments and geochemical analyses. The organic carbon contents of surface sediment in the Gamak Bay showed that the inner bay area has higher organic carbon content than those of the outer bay. They toward the outer bay, contents dropped off. The vertical profiles of calcium carbonate (CaCO3) content at piston core sediment assumed that the hypoxia have been frequently occurred during past century in the northern inner bay. The benthic chamber experiments were conducted in February, May, August and November 2010, 2011 in the hypoxic area of the Gamak Bay. In the sediment incubation experiment with chamber at site C3 in the northern inner bay and site C17 in the southern outer bay, the sediment oxygen consumption rate ranged from 3.98 mmol m-2 d-1 to 12.43 mmol m-2 d-1 and 3.28 mmol m-2 d-1to 8.18 mmol m-2 d-1, respectively. When the oxygen was completely depleted, the toxic hydrogen sulfide was released with 1.38 mmol m-2 d-1 and 1.3 mmol m-2 d-1, respectively.t in the Gamak Bay showed that the inner bay area has higher organic carbon content than those of the outer bay. They toward the outer bay, contents dropped off. The vertical profiles of calcium carbonate (CaCO3) content at piston core sediment assumed that the hypoxia have been frequently occurred during past century in the northern inner bay. The benthic chamber experiments were conducted in February, May, August and November 2010, 2011 in the hypoxic area of the Gamak Bay. In the sediment incubation experiment with chamber at site C3 in the northern inner bay and site C17 in the southern outer bay, the sediment oxygen consumption rate ranged from 3.98 mmol m-2 d-1 to 12.43 mmol m-2 d-1 and 3.28 mmol m-2 d-1to 8.18 mmol m-2 d-1, respectively. When the oxygen was completely depleted, the toxic hydrogen sulfide was released with 1.38 mmol m-2 d-1 and 1.3 mmol m-2 d-1, respectively.