Keywords:CNS elemental analysis, tidal flat sediments
The ratio of total sulfur (TS) to total organic carbon (TOC) (C/S ratio) and concentration of TS have been used to identify whether sediment deposited under freshwater or brackish water or sea water. For example, Berner & Raiswell (1984) reported that the C/S ratio of marine sediment is 0.5-5 (the average is 2.8±1.5), and freshwater sediment is >10, for sediment containing >1% TOC. Terashima et al. (1983) analyzed sediments of freshwater lakes, brackish water lakes and deep sea at and around Japan. The results showed that C/S ratio of marine sediments and freshwater sediments are >6 and >9, respectively. They also suggested that TS in freshwater sediments is usually low, but that the ratio of Lake Suwa (0.09 %) is similar to those of deposits of Obama (0.07 %) and Suruga (0.09 %) bays. More recently, Sheng et al. (2015) investigated Laizhou Bay in China, where the mean C/S ratios were 55.91 in marine sediment and 35.08 in river sediment, respectively. TS in marine sediment were 0.01-0.09 % and the average is 0.03 %. TS in river sediment were 0.42 %, and were anthropogenically-derived. Since C/S ratio and TS vary considerably from region, it is necessary to construct a determination indicator for the research area. This study reports CNS elemental analysis of tidal flat sediments in Ena Bay , Miura Peninsula, Kanagawa Prefecture, central Japan to establish the criteria for applying Holocene alluvial lowland around Shizuoka Prefecture.