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This article in JEQ

  1. Vol. 31 No. 6, p. 2104-2110
     
    Received: Sept 10, 2001
    Published: Nov, 2002


    * Corresponding author(s): nterry@nature.berkeley.edu
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doi:10.2134/jeq2002.2104

Evaluation of the Macroalga, Muskgrass, for the Phytoremediation of Selenium-Contaminated Agricultural Drainage Water by Microcosms

  1. Z.-Q. Lina,
  2. M. de Souzaa,
  3. I. J. Pickeringb and
  4. N. Terry *a
  1. a Dep. of Plant and Microbial Biology, University of California, 111 Koshland Hall, Berkeley, CA 94720-3102
    b Stanford Synchrotron Radiation Laboratory, Stanford Linear Accelerator Center, MS 69, 2575 Sand Hill Road, Menlo Park, CA 94025-7015

Abstract

Previous field studies suggested that the macroalga, muskgrass (Chara canescens Desv. & Lois), plays an important role in the removal of selenium (Se) from agricultural drainage water. This study evaluated the efficiency of Se removal from drainage water by muskgrass-vegetated wetland microcosms, and determined the extent to which muskgrass removed Se through phytoextraction and biovolatilization. Six flow-through wetland microcosms were continuously supplied with drainage water containing an average Se concentration of 22 μg L−1 over a 24-d experimental period. The Se mass input and outflow and the rate of Se volatilization were monitored daily for each microcosm. Three microcosms containing muskgrass reduced the daily mass Se input in the inflow drainage water by 72.1%; this compared with a reduction of 50.6% of the mass Se input for three unvegetated control microcosms. Selenium accumulated in muskgrass tissues accounted for 1.9% of the total mass Se input in the microcosm, followed by 0.5% via biological volatilization. The low rates of Se volatilization from selenate-supplied muskgrass, which were 10-fold less than from selenite, were probably due to a major rate limitation in the reduction of selenate to organic forms of Se in muskgrass. This conclusion was derived from X-ray absorption spectroscopy speciation analysis, which showed that muskgrass treated with selenite contained 91% of the total Se in organic forms (selenoethers and diselenides), compared with 47% in muskgrass treated with selenate.

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Copyright © 2002. American Society of Agronomy, Crop Science Society of America, Soil Science SocietyPublished in J. Environ. Qual.31:2104–2110.

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