Seasonal and spatial variability of sediment oxygen fluxes in the Beobsan intertidal flat of Taean Bay, mid-western Korean Peninsula

Abstract

Core incubation and oxygen microelectrode measurements were performed at two stations in the Beobsan intertidal flat of Taean Bay on the mid-western Korean Peninsula. Total and diffusive fluxes were determined for four different seasons (August and October 2006 and February and May 2007). Diffusive oxygen fluxes ranged from 7.62 to 11.4 mmol m⁻² d⁻¹ at station S1 and 8.85 to 14.3 mmol m⁻² d^-1 at station S2. Total oxygen fluxes varied from 20.2 to 27.6 mmol m⁻² d⁻¹ at station S1 and from 18.7 to 31.7 mmol m⁻² d⁻¹ at station S2. Total oxygen fluxes were 2∶3 times higher than diffusive oxygen fluxes, a result that agrees well with previous studies of the coastal and continental shelf area. The difference between the total and diffusive fluxes is caused by the bio-irrigation activities of macrofauna living in the sediments, which enhance the ventilation of the sediment and introduce oxygenated water to the deeper, anoxic sediment layer. The total oxygen flux at station S1 exhibited small seasonal variation while that at station 2 showed large seasonal variation. Organic carbon contents in the surface sediments correlated well with total oxygen flux, suggesting that the input flux of organic matter is a major factor controlling the seasonal variation in total oxygen flux. Annual benthic aerobic respiration rates were determined to be 8.8 and 9.1 mol C m⁻² yr⁻¹ at stations S1 and S2, respectively; these values are very similar to estimations for Aarhus Bay, Denmark and the southwestern lagoon of New Caledonia.