GEOC 123 |
| The mobility, fate, bioavailability, and overall biogeochemical cycling of arsenic in soil depend on individual form in which arsenic exists as well as physical and chemical characteristics of the soil. Speciation analysis of arsenic poses a great challenge and is the key to understand the biogeochemistry of arsenic in soils and sediments. The speciation of arsenic in soil may be defined functionally (e.g. bioavailable fraction), operationally, or chemical species-specifically. The extraction of arsenic species from solid matrices generally constitutes a critical step for speciation analysis of arsenic in soils and sediments. Various sequential extraction procedures have been developed to extract operationally defined arsenic species such as water soluble, exchangeable, Fe/Mn oxides associated, organic matter bound, and residual arsenic fractions. Several extractants have been attempted to leach chemically specific arsenic species, mainly arsenite, arsenate, monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA) from solid matrix. Efforts have been made to preserve the integrity of arsenic species during extraction. In this paper, extraction procedures with emphasis on the selection of extractants for chemical-specifically and operationally defined arsenic species will be reviewed and extraction methods for evaluating bioavailable arsenic and spectroscopic technique for directly measuring arsenic species in soils will be briefly discussed. In addition, a few case studies involving arsenic speciation will be presented to demonstrate the importance of arsenic speciation in understanding the fate and transport of arsenic in the environment. |
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Speciation of Arsenic and Other Trace Elements in Soils and Sediments
1:25 PM-5:10 PM, Wednesday, April 9, 2008 Morial Convention Center -- Rm. 211, Oral
Division of Geochemistry |