Rapid Organic and Reduced Inorganic Sulfur Analysis in Upland and Wetland Soils and Its Indication of Soil Submergence Conditions.

Direct analysis of organic and reduced inorganic sulfur by the multi-element scanning thermal analysis (MESTA) has opened up a convenient option for us to understand soil sulfur, which has not been studied as much as other major essential elements in soils. This report compares the distinct signatures of sulfur between upland and wetland soils. Upland soil sulfur and dominated by amino-acid-like forms whereas wetland soil sulfur has three more forms: the organic sulfur formed by the reactions between soil organic matter and hydrogen sulfide, the metal sulfides and elemental sulfur. All those forms can be differentiated and quantified by MESTA. Metal sulfides and elemental sulfur are easily re-oxidized to sulfate when anaerobic conditions were removed. The organic sulfur formed by hydrogen sulfides, however, could be preserved for some time and thus can serve as an indicator of soil submergence history and the extent of sulfate reduction that had occurred.