Cr localization and speciation in roots of chromate fed Helianthus annuus L. seedlings using synchrotron techniques

Int J Phytoremediation. 2014;16(7-12):1073-86. doi: 10.1080/15226514.2013.810584.

Abstract

In order to gain knowledge on the potential use of Helianthus annuus L. for the remediation of Cr(VI) polluted waters, hydroponics experiments were set up to determine Cr uptake and tolerance in different Cr(VI)-sulfate conditions, and Cr biotransformations. Results indicated that Cr(VI) promoted seed germination, and plant tolerance was higher at younger plant stages. Cr uptake was dependent on sulfate concentrations. The highest Cr levels in roots and shoots (13,700 and 2,500 mg kg(-1) dry weight (DW), respectively) were obtained in 1 mM sulfate. The lowest Cr uptake in roots (10,600 mg kg(-1) DW) was observed in seedlings treated with no sulfate. In shoots, Cr concentration was of 1,500 mg kg(-1)DW for the 1 mM sulfate treatment, indicating a different level of interaction between chromate and sulfate in both tissues. For the first time, using micro X-ray florescence (muXRF), we demonstrated Cr reaches the root stele and is located in the walls of xylem vessels. Bulk and micro X-ray Absorption Near-Edge Structure (muXANES) results showed that Cr in the roots is mostly in the form of Cr(III) phosphate (80%), with the remainder complexed to organic acids. Our results suggest this plant species may serve for Cr(VI) rhizofiltration purposes.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Biodegradation, Environmental
  • Biological Transport
  • Chromates / toxicity*
  • Chromium / analysis
  • Chromium / metabolism*
  • Chromium / toxicity
  • Germination / drug effects
  • Helianthus / drug effects
  • Helianthus / growth & development
  • Helianthus / metabolism*
  • Hydroponics
  • Plant Leaves / drug effects
  • Plant Leaves / growth & development
  • Plant Leaves / metabolism
  • Plant Roots / drug effects
  • Plant Roots / growth & development
  • Plant Roots / metabolism
  • Plant Shoots / drug effects
  • Plant Shoots / growth & development
  • Plant Shoots / metabolism
  • Seedlings / drug effects
  • Seedlings / growth & development
  • Seedlings / metabolism
  • Seeds / drug effects
  • Seeds / growth & development
  • Seeds / metabolism
  • Spectrometry, X-Ray Emission
  • Sulfates / pharmacology
  • Synchrotrons
  • Water / chemistry
  • Water Pollutants / analysis
  • Water Pollutants / metabolism*
  • Water Pollutants / toxicity
  • Xylem / drug effects
  • Xylem / growth & development
  • Xylem / metabolism

Substances

  • Chromates
  • Sulfates
  • Water Pollutants
  • Water
  • Chromium