[First Hit]

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Datta, Rupali1, Dibyendu Sarkar1
(1) University of Texas at San Antonio, San Antonio, TX

ABSTRACT: Effect of Previous HitSoilNext Hit-Aging on Geochemical Fate of Arsenic in Pesticide-Contaminated Soils

Excessive use of arsenical pesticides has resulted in elevated levels of arsenic, a group A carcinogen, in agricultural soils. Encroachment of suburban development on agricultural lands has greatly increased the potential for human contact with arsenic. An accurate health risk assessment due to exposure to arsenic-rich soils requires an estimate of bioavailable arsenic. Current protocols assume that all arsenic present in Previous HitsoilNext Hit is bioavailable, due to the expenses and logistic difficulties in conducting "in-vivo" animal studies. Arsenic bioavailability is a function of its geochemical forms, which in turn is dependent on Previous HitsoilNext Hit properties and equilibration time. An incubation study was conducted to identify the relationship between geochemical speciation and “in-vitro” bioavailability of arsenic as a function of Previous HitsoilNext Hit aging. We used two soils, Immokalee, a sand with minimum arsenic retention capacity and Millhopper, a sandy loam with relatively high concentration of Fe/Al-oxides, and hence higher arsenic retention potential. The soils were amended with sodium arsenate at three rates. A sequential extraction scheme was used to identify the various geochemical forms of arsenic, which were correlated with the “in-vitro” bioavailable fractions. Comparative arsenic speciation and bioavailability studies at 0 time (immediately after spiking the soils with pesticides), four-month and one-year incubation period were done. Our results indicate significant effect of Previous HitsoilTop properties and equilibration time on arsenic bioavailability. This study will provide realistic starting points in site- and composition-specific health risk assessment associated with exposure to low doses of arsenic in soils.


AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.