title: Sulfate reduction in sulfuric material after re-flooding: Effectiveness of organic carbon addition and pH increase depends on soil properties.
abstract: Sulfuric material is formed upon oxidation of sulfidic material; it is extremely acidic, and therefore, an environmental hazard. One option for increasing pH of sulfuric material may be stimulation of bacterial sulfate reduction. We investigated the effects of organic carbon addition and pH increase on sulfate reduction after re-flooding in ten sulfuric materials with four treatments: control, pH increase to 5.5 (+pH), organic carbon addition with 2% w/w finely ground wheat straw (+C), and organic carbon addition and pH increase (+C+pH). After 36 weeks, in five of the ten soils, only treatment +C+pH significantly increased the concentration of reduced inorganic sulfur (RIS) compared to the control and increased the soil pore water pH compared to treatment+pH. In four other soils, pH increase or/and organic carbon addition had no significant effect on RIS concentration compared to the control. The RIS concentration in treatment +C+pH as percentage of the control was negatively correlated with soil clay content and initial nitrate concentration. The results suggest that organic carbon addition and pH increase can stimulate sulfate reduction after re-flooding, but the effectiveness of this treatment depends on soil properties.
authors.affiliation: School of Agriculture, Food and Wine, The University of Adelaide, Adelaide, SA 5005, Australia.
authors.forename: Chaolei
authors.initials: C
authors.lastname: Yuan
authors.affiliation: Acid Sulfate Soils Centre, The University of Adelaide, Adelaide, SA 5005, Australia; CSIRO Land and Water, Private Bag No. 2, Glen Osmond, SA 5064, Australia.
authors.forename: Rob
authors.initials: R
authors.lastname: Fitzpatrick
authors.affiliation: Acid Sulfate Soils Centre, The University of Adelaide, Adelaide, SA 5005, Australia; CSIRO Land and Water, Private Bag No. 2, Glen Osmond, SA 5064, Australia.
authors.forename: Luke M
authors.initials: LM
authors.lastname: Mosley
authors.affiliation: School of Agriculture, Food and Wine, The University of Adelaide, Adelaide, SA 5005, Australia. Electronic address: petra.marschner@adelaide.edu.au.
authors.forename: Petra
authors.initials: P
authors.lastname: Marschner
mesh_terms: D002244:Carbon / Q000737:chemistry*; D052918:Environmental Restoration and Remediation / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D010084:Oxidation-Reduction; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000737:chemistry*; D013431:Sulfates / Q000737:chemistry*; D013457:Sulfur Compounds / Q000737:chemistry*; D014867:Water / Q000032:analysis*
chemical_list: D012987:Soil; D012989:Soil Pollutants; D013431:Sulfates; D013457:Sulfur Compounds; D014867:Water; D002244:Carbon
keywords: Acid sulfate soils; Organic carbon addition; Soil properties; Sulfate reduction; Sulfuric material; pH Increase