摘要：This study aimed to elucidate the environment of sulfidic material accumulation and the development of acid sulfate soil by focusing on the kinds of acid sulfate soil in various soil profiles and the characteristics of sediments in the Lower Central Plain of Thailand. The kinds of acid sulfate soil in all the soil profiles were identified, the soils categorized into profile types A-D and the characteristics of sediments in sedimentary columns were described. The developed acid sulfate soils, profile types A and B, were distributed in the deltaic plain in areas occupied by tidal flat to salt swamp in the period of middle-late Holocene. Sulfidic materials were accumulated in this environment in which mangrove and plant roots were the organic material source for sulfidic formation. Non-acid-sulfate soil, profile type C, was distributed in the tidal plain where shallow marine areas and open bay existed in the middle-late Holocene. The lack of an organic material source and base-rich condition was inappropriate for accumulation of sulfidic material here, whereas in young acid sulfate soil, profile type D, sulfidic material was accumulated recently and the soils have continued developing in the present estuary conditions. Acid sulfate soil in each profile type had different degrees of development due to the influence of oxidation.
