Sediment oxygen consumption and hydrogen sulfide release in hypoxic areas of Gamak Bay, Korea

Abstract

This study investigated sediment oxygen consumption rates and geochemical characteristics using chamber experiments and geochemical analyses in the hypoxic area of Gamak Bay, Korea. The organic carbon contents of surface sediments in Gamak Bay were higher in the northern inner bay area, and dropped off toward the southern outer bay. The vertical profiles of calcium carbonate content in piston core sediments indicated that hypoxia has frequently occurred during the past century in the northern inner bay. Sediment chamber experiments were conducted in February, May, August, and November 2010 and 2011 in the hypoxic area of the bay. In the sediment incubation experiments at site C3 in the northern inner bay and site C17 in the southern outer bay, the sediment oxygen consumption rate ranged from 3.98-12.43 mmol m-2 d-1 and 3.28-8.18 mmol m-2 d-1, respectively. When the oxygen was completely depleted, hydrogen sulfide was released at 1.38 and 1.3 mmol m-2 d-1 at sites C3 and C17, respectively.