DEGRADATION CHARACTERISTICS OF SEDIMENTARY ORGANIC CARBON AT THE URBAN COASTAL TIDAL FLAT IN OSAKA BAY

Abstract

 The objective of this study was to quantify the biodegradability of organic matter in sediments from 13 tidal flats in the coastal area of Osaka Bay. Sediment organic carbon (SOC) ranged from 0.35 to 30.7 mg/g. Refractory organic carbon and labile organic carbon ranged from 0.32–23.2 mg/g (25–91%) and 0.03–9.37 mg/g (9–75%), respectively. Labile organic carbon showed statistically significant correlations with AVS and ORP, no correlation with carbon dioxide emission rate. Multiple regression analysis was used to identify three factors that affect the labile organic carbon: SOC, carbon stable isotope ratios and water content. These results indicate that organic carbon of marine and terrestrial origin is deposited on tidal flats in the urban coastal areas of Osaka Bay, and that organic carbon sequestration in the sediments on the tidal flats.