Chemical and microbiological parameters were combined to characterize vertical and horizontal distribution of sediments in Kagoshima Bay. Sediments from four contrasting environmental settings were analyzed to determine their texture, total organic matter (IL), acid volatile sulfide (AVS), free sulfide and sulfate-reducing bacteria (SRB) during the summer and autumn of 2004. Sediments taken at the inner and central areas contained significant silt and clay contents, while the outer area had sand and gravel as the main components. IL concentrations were ranged from 2.1% to 13% and higher IL contents were observed at the stations located in central area and station near Amori River (inner area). AVS were ranged from 0.01 to 0.9 mg/g of sediment (dry weight) and showed significant difference between sites. Free sulfide were observed only in the stations belong to the inner area, with the range from 0.01 to 0.2 mg/g of sediment (dry weight). SRB were ranged from 1.7×10² to 5.0×10⁵ cell/g of sediment (dry weight). The results give a clear picture of the horizontal and vertical characterization of the sediments and also make clear the differences at four stations belong to the inner, central and outer areas. It also showed that, coupled with chemical indicators, sulfate-reducing bacteria can be used as a useful indicator to evaluate the sediment condition of Kagoshima Bay.

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