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 language | English (US) |
|---|---|
| Pages (from-to) | 31-40 |
| Number of pages | 10 |
| Journal | Fertilizer Research |
| Volume | 40 |
| Issue number | 1 |
| DOIs | |
| State | Published - Feb 1995 |
| Externally published | Yes |
Keywords
- cadmium
- ion activity products
- isotherm
- phosphate
- soil pollution
- solubility diagram
ASJC Scopus subject areas
- General Environmental Science
- Agronomy and Crop Science
- Soil Science
- General Earth and Planetary Sciences