title: Fate and bioavailability of arsenic in organo-arsenical pesticide-applied soils. Part-I: incubation study.
abstract: A laboratory incubation study was conducted to estimate geochemical speciation and in vitro bioavailability of arsenic as a function of soil properties. Two chemically-variant soil types were chosen, based on their potential differences with respect to arsenic reactivity: an acid sand with minimal arsenic retention capacity and a sandy loam with relatively high concentration of amorphous Fe/Al-oxides, considered a sink for arsenic. The soils were amended with dimethylarsenic acid (DMA) at three rates: 45, 225, and 450 mg/kg. A sequential extraction scheme was employed to identify the geochemical forms of arsenic in soils, which were correlated with the "in vitro" bioavailable fractions of arsenic to identify the most bioavailable species. Arsenic bioavailability and speciation studies were done at 0 time (immediately after spiking the soils with pesticide) and after four-months incubation. Results show that soil properties greatly impact geochemical speciation and bioavailability of DMA; soils with high concentrations of amorphous Fe/Al oxides retain more arsenic, thereby rendering them less bioavailable. Results also indicate that the use of organic arsenicals as pesticides in mineral soils may not be a safe practice from the viewpoint of human health risk.
authors.affiliation: Department of Earth and Environmental Science, University of Texas at San Antonio, 6900 N Loop 1604 W San Antonio, TX 78249-0663, United States. dsarkar@utsa.edu
authors.forename: Dibyendu
authors.initials: D
authors.lastname: Sarkar
authors.forename: Rupali
authors.initials: R
authors.lastname: Datta
authors.forename: Saurabh
authors.initials: S
authors.lastname: Sharma
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry; D001152:Arsenicals / Q000032:analysis / Q000378:metabolism*; D001682:Biological Availability; D002101:Cacodylic Acid / Q000032:analysis / Q000378:metabolism; D004784:Environmental Monitoring; D005290:Ferric Compounds / Q000737:chemistry; D010575:Pesticides / Q000032:analysis / Q000378:metabolism*; D018570:Risk Assessment; D012987:Soil / Q000032:analysis*; D012989:Soil Pollutants / Q000378:metabolism* / Q000633:toxicity; D013997:Time Factors
chemical_list: D001152:Arsenicals; D005290:Ferric Compounds; D010575:Pesticides; D012987:Soil; D012989:Soil Pollutants; C000499:ferric oxide; D002101:Cacodylic Acid; D000537:Aluminum Oxide