Chemical behavior of Cd in rice rhizosphere

Q. LIN, Y. X. CHEN, H. M. CHEN, Y. L. YU, Y. M. LUO, Ming Hung WONG

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Abstract

Chemical behavior of Cd in rice rhizosphere as affected or not by Pb was investigated. The NH4OAc extractable Cd in the rhizosphere was distinctly lower than that in bulk soil. The depletion of Cd in the rhizosphere could not be simply attributed to Cd uptake by rice. The observed phenomena could be attributed to the decreasing pH in the rhizosphere and the complexing capabilities of soluble exudates for Cd. Extractable Cd increased in both the rhizosphere and bulk soil after the addition of Pb, which might be caused by the replacement of Pb for Cd. The extractable Cd in the non-rhizosphere varied with the distance from the root surface, especially within 0-1 mm, which was greatly affected by the combined effects of mass flow, activation and fixation, and had the lowest extractable Cd. Pb addition affected the distribution of extractable Cd in the non-rhizosphere, implying that the affinity of Pb for organic matter was greater than that of Cd. The difference of Cd species between rhizosphere and bulk soil demonstrated that the transformation of exchangeable Cd (EXC-Cd) to OM-Cd (bound to organic matter) and FMO-Cd (bound to iron and manganese oxide) occurred in the rice rhizosphere due to the exudations from the rice root, the activity of microorganisms on the root surface and the activation of Fe and Mn oxides. The interaction between Pb and Cd resulted in the content of EXC-Cd being higher in the presence of Pb, whereas the OM-Cd content was lower in the presence of Pb. Copyright © 2002 Elsevier Science Ltd. All rights reserved.

Original languageEnglish
Pages (from-to)755-761
JournalChemosphere
Volume50
Issue number6
DOIs
Publication statusPublished - Feb 2003

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Rhizosphere
rhizosphere
rice
Soils
Biological materials
Chemical activation
Manganese oxide
Soil
Iron oxides
Microorganisms
Oxides
organic matter
exudation
soil
manganese oxide
Exudates and Transudates
chemical
Oryza
iron oxide
fixation

Citation

Lin, Q., Chen, Y. X., Chen, H. M., Yu, Y. L., Luo, Y. M, & Wong, M. H. (2003). Chemical behavior of Cd in rice rhizosphere. Chemosphere, 50(6), 755-761. doi: 10.1016/S0045-6535(02)00216-3

Keywords

  • Rice rhizosphere
  • Cd
  • Pb