PW03 Plant Toxicology and Soil Interactions
Exhibit Hall
8:00 AM - Wednesday, 12 November 2003
(PW068) XAS analysis of arsenic compounds in terrestrial plants.
Smith, P.1, 2, Gordon, R.3, Koch, I.1, Reimer, K.1, 2, 1 Environmental Sciences Group, Kingston, ON, Canada2 Department of Biology, Queen's University, Kingston, ON, Canada3 Simon Fraser University, Burnaby, BC, Canada
ABSTRACT- Arsenic (As) is a naturally occurring element which can often be found complexed with sulfide minerals, or released into the environment through anthropogenic activities such as mining, industrial and agricultural processes. Arsenic is perhaps best known for its toxicity; however, arsenic toxicity varies depending on its chemical form. To understand the risks posed by arsenic contaminated soil to human, wildlife, and plant populations, it is important to understand which arsenic compounds are available to organisms, and the mechanisms by which the arsenic is taken up and subsequently transformed by these organisms. Commonly used methods for detecting arsenic compounds such as High Performance Liquid Chromatography - Atomic Absorption Spectrometry (HPLC-AAS) and HPLC - Inductively Coupled Plasma Mass Spectroscopy (HPLC-ICP-MS), involve both physical and chemical manipulation of the sample. This sample manipulation may alter the chemical form of the arsenic being studied. X-ray Absorption Spectroscopy (XAS) provides an alternate means of sample analysis which minimizes sample manipulation. Our research group is interested in assessing the extent to which XAS can be used in the determination of the chemical forms of arsenic in the terrestrial environment, focusing on plants. XAS spectra for standards of biologically important arsenic compounds indicate that this technique can be used to identify between many different compounds and may be valuable in distinguishing between arsenic compounds in the solid state from those in solution. These standard spectra were then used in a novel study to identify arsenic compounds within the roots, stems and leaves of radishes. Preliminary results indicate an arsenic-sulfur compound as the main form of arsenic in whole samples of radish stems and leaves, supporting the recent hypothesis that arsenic is transported throughout plants in this form.
Key words: arsenic compounds, X-ray absorptionspectroscopy, terrestrial plants, model arsenic standards