HR: 1330h
AN: B33B-06    [Abstracts]
TI: Effect Of Soil Properties On The Geochemical Speciation Of Arsenic In Contaminated Soils: A Greenhouse Study
AU: * Sharma, S
EM: Saurabh.Sharma@utsa.edu
AF: Environmental Geochemistry Laboratory, Department of Earth and Environmental Sciences, University of Texas at San Antonio, 6900 North Loop 1604 West, San Antonio, TX 78249 United States
AU: Sarkar, D
EM: Dibyendu.Sarkar@utsa.edu
AF: Environmental Geochemistry Laboratory, Department of Earth and Environmental Sciences, University of Texas at San Antonio, 6900 North Loop 1604 West, San Antonio, TX 78249 United States
AU: Datta, R
EM: Rupali.Datta@utsa.edu
AF: Environmental Geochemistry Laboratory, Department of Earth and Environmental Sciences, University of Texas at San Antonio, 6900 North Loop 1604 West, San Antonio, TX 78249 United States
AB: Land-applied arsenical pesticides have contributed elevated soil arsenic (As) levels. Many baseline risk assessments As-contaminated sites assume that all As present in the soil is bioavailable, thereby potentially overestimating the actual health risk. However, risk from As exposure is associated only with those forms of As that are potentially extractable by the human gastrointestinal juices. It has been demonstrated that As may exist in several geochemical forms depending on soil chemical properties, which may or may not be bioavailable. The current study aims at addressing the issue of soil variability on As bioavailability as a function of soil physico-chemical properties in a greenhouse setting involving dynamic interactions between soil, water and plants. Four different soils were chosen based on their potential differences with respect to As reactivity: Immokalee, an acid sand with low extractable Fe/Al, having minimal arsenic retention capacity; Millhopper, an acid sandy loam with high extractable Fe/Al oxides; Pahokee Muck soil with 85% soil organic matter (SOM) as well as high Fe/Al content; and Orelia soil with high clay and Fe/Al content. Soils were amended with sodium arsenate (675 and 1500 mg/Kg). Rice (Oryza sativa) was used as the test crop. A sequential extraction scheme was employed to identify the geochemical forms of As in soils (soluble, exchangeable, organic, Fe/Al-bound, Ca/Mg-bound, residual) immediately after spiking; after 3 mo; and after 6 mo of equilibration time. Concentrations of these As forms were correlated with the in-vitro bioavailable As fractions to identify those As fractions that are most likely to be bioavailable. Results from this study showed that there was little to no plant growth in the contaminated soils. Sequential extractions of the soil indicated that arsenic is strongly adsorbed onto soil amorphous iron/aluminum oxides, and the degree of arsenic retention is a direct function of equilibration time.
DE: 0400 Biogeosciences
SC: Biogeosciences [B]
MN: 2005 Joint Assembly