Reduced Inorganic Sulfur Speciation in Drain Sediments from Acid Sulfate Soil Landscapes

摘要

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 muM),consistent with FeS_((S)) precipitation in the presence of high concentrations of Fe~(2+) (generally >2 mM).Acid-volatile sulfide (AVS),with concentrations up to 1019 mumol 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 approx 4000 mumol 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 H_2S oxidation pathways.Overall,RIS speciation in ASS-associated drain sediments is unique and is largely regulated by abundant reactive Fe.