Effect of Sulfate on Selenium Uptake and Chemical Speciation in Convolvulus arvensis L.

Gustavo Cruz-Jímenez; Jose R. Peralta-Videa; Guadalupe de la Rosa; George Meitzner; Jason G. Parsons; Jorge L. Gardea-Torresdey

doi:10.1071/EN05028

RESEARCH ARTICLE

Effect of Sulfate on Selenium Uptake and Chemical Speciation in Convolvulus arvensis L.

Gustavo Cruz-Jímenez ^A ^B , Jose R. Peralta-Videa ^C , Guadalupe de la Rosa ^A ^B , George Meitzner ^C , Jason G. Parsons ^C and Jorge L. Gardea-Torresdey ^A ^C ^D

+ Author Affiliations

- Author Affiliations

^A Environmental Science and Engineering, University of Texas at El Paso, El Paso, TX 79968, USA.

^B Facultad de Química, Universidad de Guanajuato, Col. Noria Alta S/N, Guanajuato 36050, México.

^C Chemistry Department, University of Texas at El Paso, El Paso, TX 79968, USA.

^D Corresponding author. Email: jgardea@utep.edu

Environmental Chemistry 2(2) 100-107 https://doi.org/10.1071/EN05028
Submitted: 3 May 2005 Accepted: 17 May 2005 Published: 24 June 2005

Environmental Context. Selenium (Se) is one of the most serious problems confronted in agricultural soils derived from Se-containing rocks. This metalloid, an essential nutrient for animals and humans, may be toxic at relatively low concentrations. Se removal from soil and water using plants is a promising alternative to traditional chemical or electrochemical techniques. However, very few plant species are able to accumulate Se at high concentrations. Since Se and sulfur (S) have similar chemical properties, sulfate (SO₄²⁻) in the plant growth media may interfere in the process of Se uptake by plants. Thus, plant species able to uptake more Se than S when both elements are present are desired for Se phytoremediation purposes.

Abstract. Hydroponic experiments were performed to study several aspects of Se uptake by C. arvensis plants. Ten day old seedlings were exposed for eight days to different combinations of selenate (SeO₄²⁻), sulfate (SO₄²⁻), and selenite (SeO₃²⁻). The results showed that in C. arvensis, SO₄²⁻ had a negative effect (P < 0.05) on SeO₄²⁻ uptake. However, a positive interaction produced a significant increase in SO₄²⁻ uptake when SeO₄²⁻ was at high concentration in the media. X-ray absorption spectroscopy studies showed that C. arvensis plants converted more than 70% of the supplied SeO₃²⁻ into organoselenium compounds. However, only approximately 50% of the supplied SeO₄²⁻ was converted into organoselenium species while the residual 50% remained in the inorganic form. Analysis using LC-XANES fittings confirmed that the S metabolic pathway was affected by the presence of Se. The main Se compounds that resembled those Se species identified in C. arvensis were Se-cystine, Se-cysteine, SeO₃²⁻, and SeO₄²⁻, whereas for S the main compounds were cysteine, cystine, oxidized glutathione, reduced glutathione, and SO₄²⁻. The results of these studies indicated that C. arvensis could be considered as a possible option for the restoration of soil moderately contaminated with selenium even in the presence of sulfate.

Keywords. : biogeochemistry — phytoremediation — selenium — speciation (nonmetals) — sulfur

Acknowledgements

The authors acknowledge financial support from the NIH (Grant S06GM8012–33), the Stanford Synchrotron Radiation Laboratories/Department of Energy (SSRL/DOE) funded Gateway Program, and the University of Texas at El Paso’s Center for Environmental Resource Management (CERM). The authors also acknowledge the Historically Black Colleges and Universities/Minority Institutions (HBCU/MI) Environmental Technology Consortium, which is funded by the DOE. Portions of this research were carried out at the SSRL, a national user facility operated by Stanford University on behalf of the DOE, Office of Basic Energy Sciences. The SSRL Structural Molecular Biology Program is supported by the DOE, Office of Biological and Environmental Research, and by the National Institutes of Health, National Center for Research Resources, Biomedical Technology Program. Portion of this research was also developed at the Center for Advanced Microstructures and Devices (CAMD), Louisiana State University. J.L.G.-T. acknowledges the Dudley family for the Endowed Research Professorship in Chemistry. G.d.l.R. and G.C.-J. acknowledge CONACyT (Consejo Nacional de Ciencia y Tecnología, México, grant 131996) and the Universidad de Guanajuato.

References

Effect of Sulfate on Selenium Uptake and Chemical Speciation in Convolvulus arvensis L.

Acknowledgements

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