Influence of phosphate on cadmium adsorption by soils

L. M. Xiong*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

In batch equilibrium experiments, it was found that orthophosphate increased Cd adsorption and decreased its desorption by three representative soils. Ion activity products in the equilibrium solution indicated that cadmium activity was under saturated with respect to Cd3(PO4) (s) on the Red earth(Typic Hapludult) and the Yellow-brown earth(Typic Hapludalf). With the calcareous Yellow fluvo-aquic soil(Typic Haplaquent), phosphate enhanced Cd adsorption at lower Cd concentration but it decreased the adsorption at high Cd level. Ion activity products and solubility diagrams suggested that at high Cd level Cd3(PO4)2 had formed and the activity of Cd in solution was controlled by this precipitate. This implies that the formation of Cd3(PO4)2 (s) is unable to decrease Cd activity so long as soil adsorption sites are unsaturated by Cd. It is suggested from these results that one could not expect decreasing soil Cd availability by phosphate fertilization unless a simultaneous rise in soil pH also occurs.

Original languageEnglish (US)
Pages (from-to)31-40
Number of pages10
JournalFertilizer Research
Volume40
Issue number1
DOIs
StatePublished - Feb 1995
Externally publishedYes

Keywords

  • cadmium
  • ion activity products
  • isotherm
  • phosphate
  • soil pollution
  • solubility diagram

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Soil Science

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