Acid-Volatile Sulfide Oxidation in Coastal Flood Plain Drains:Iron-Sulfur Cycling and Effects on Water Quality

摘要

The effect of acid-volatile sulfide (AVS) oxidation on Fe-S cycling and water quality in coastal flood plain drains from acid-sulfate soil landscapes was examined using natural sediments and synthetic iron monosulfide.Oxidation of AVS occurred rapidly (half-time < 1 h) and produced elemental sulfur (S_8~o(s)) and iron oxyhydroxide (FeOOH_(s)).The initial rapid AVS oxidation process occurred without significant acidification or changes to the aqueous-phase composition.Severe acidification (pH < 4) occurred only once S_8~o(s) began to oxidize to SO_4 (within 2-3 days of the initial AVS oxidation).Our results demonstrate,for the first time with natural sediments,a significant pH-buffered (near-neutral) AVS oxidation step with the trigger to acidification being the oxidation of S_8~o(s).Acidification resulted in the pH-dependent release of large amounts of Al,Mn,Ni,and Zn even though the sediment metal content was low.