Acid-volatile sulfide oxidation in coastal flood plain drains: iron-sulfur cycling and effects on water quality.
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 < or = 1 h) and produced elemental sulfur (S8(0)(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 S8(0)(s) began to oxidize to SO4 (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 S8(0)(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.
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
D001315:Australia; D019015:Geologic Sediments / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008670:Metals / Q000032:analysis* / Q000737:chemistry; D010084:Oxidation-Reduction; D012995:Solubility; D013440:Sulfides / Q000737:chemistry*; D013455:Sulfur / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis*
D008670:Metals; D013440:Sulfides; D014874:Water Pollutants, Chemical; D013455:Sulfur