Abstract
Sedimentary sulfur mainly of FeS2 (pyrite) was oxidized to sulfate with 30% H2O2 and the concentration of sulfate was determined by the turbidimetric method.
Treatment procedures were as follows.
1) Wet sediment (approximately 0.3g) was washed twice with distilled water followed by centrifugation (3, 000rpm, 15mins), and dried at 80°C.
2) The dry sample (0.1g) was reacted with 10ml 30% H2O2 for 30mins at room temperature and then for 2mins at 90-100°C.
3) When oxidation reaction ceased (usually after 15hrs), 50ml distilled water was added and the sample filtered through a 0.45μm membrane filter to separate extract from residue. Filtrate was rinsed and brought to 100ml volume with distilled water for the turbidimetric method.
The content of sedimentary sulfur determined by this method was much higher in the marine and brackish water sediments than in the freshwater sediments. The vertical variation in sulfur content was in good agreement with the succession of diatom assemblages. As a sulfur analysis indicative of paleoenvironmental changes, this method is considered useful for its simplicity and for the small amount of sample used.
