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.
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
Edward D
ED
Burton
Richard T
RT
Bush
Leigh A
LA
Sullivan
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