Environ. Sci. Technol. 2010, 44, 1968–1973
Arsenic Mobilization in a Seawater Inundated Acid Sulfate Soil S C O T T G . J O H N S T O N , * ,† ANNABELLE F. KEENE,† EDWARD D. BURTON,† RICHARD T. BUSH,† LEIGH A. SULLIVAN,† ANGUS E. MCELNEA,‡ COL R. AHERN,‡ C. DOUGLAS SMITH,‡ BERNARD POWELL,‡ AND ROSALIE K. HOCKING§ Southern Cross GeoScience, Southern Cross University, Lismore, NSW 2480, Australia, Department of Environment and Resource Management, 80 Meiers Road, Indooroopilly, Qld. 4068, Australia, and Monash Centre for Synchrotron Science and School of Chemistry, Monash University, Clayton, Vic. 3800, Australia
Received October 13, 2009. Revised manuscript received January 22, 2010. Accepted February 1, 2010.
Tidal seawater inundation of coastal acid sulfate soils can generate Fe- and SO4-reducing conditions in previously oxicacidic sediments. This creates potential for mobilization of As during the redox transition. We explore the consequences for As by investigating the hydrology, porewater geochemistry, solid-phase speciation, and mineralogical partitioning of As across two tidal fringe toposequences. Seawater inundation induced a tidally controlled redox gradient. Maximum porewater As (∼400 µg/L) occurred in the shallow (
