Reduced inorganic sulfur speciation in drain sediments from acid sulfate soil landscapes.
We examined processes regulating reduced inorganic sulfur (RIS) speciation in drain sediments from coastal acid sulfate soil (ASS) landscapes. Pore water sulfide was undetectable or present at low levels (0.6-18.8 microM), consistent with FeS(s) precipitation in the presence of high concentrations of Fe2+ (generally >2 mM). Acid-volatile sulfide (AVS), with concentrations up to 1019 micromol g(-1), comprised a major proportion of RIS. The AVS to pyrite-S ratios were up to 2.6 in sediment profiles containing abundant reactive Fe (up to approximately 4000 micromol g(-1)). Such high AVS:pyrite-S ratios are indicative of inefficient conversion of FeS(s) to pyrite. This may be due to low pore water sulfide levels causing slow rates of pyrite formation via the polysulfide and H2S oxidation pathways. Overall, RIS speciation in ASS-associated drain sediments is unique and is largely regulated by abundant reactive Fe.
Burton
Edward D
ED
Centre for Acid Sulfate Soil Research, School of Environmental Science and Management, Southern Cross University, Military Road, Lismore, NSW 2480, Australia. eburton@scu.edu.au
Bush
Richard T
RT
Sullivan
Leigh A
LA
D011232:Chemical Precipitation; D019015:Geologic Sediments / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000737:chemistry*; D010084:Oxidation-Reduction; D016062:Porosity; D013431:Sulfates / Q000737:chemistry; D013455:Sulfur / Q000737:chemistry*
D013431:Sulfates; D013455:Sulfur; D007501:Iron