Effect of cropping systems on adsorption of metals by soils: II. Effect of pH
- Iowa State Univ., Ames (United States)
The effect of pH on adsorption of Cd, Cu, Ni, Pb, and Zn by soils under different cropping systems was investigated. Plots of metal adsorption vs. pH (unadjusted) were generated for 24 soils, 12 from each of two long-term cropping systems. Two soils, one from each site, were selected to study the metal adsorption over a range of adjusted pH values. Results showed that differences in metal adsorption were dependent on the initial heavy-metal concentration. Although some of the adsorption behavior of these metals was consistent with that based on meal hydrolysis, other results showed that this mechanism could not explain metal adsorption. Metal distribution coefficients, K{sub d}, decreased sharply with increasing initial metal concentration and followed the sequence: Pb {ge} Cu >> Cd = Ni = Zn. Also, K{sub d} values were related to solution pH. At high solution pH, part of the Pb and Cu adsorption could be explained by adsorption of hydroxocomplexes from hydrolysis reactions of these metals. Plots of K{sub d} vs. initial metal concentration suggested that Cd, Ni, and Zn adsorption could be attributed to ion-exchange reactions.
- OSTI ID:
- 7045532
- Journal Information:
- Soil Science; (United States), Vol. 153:3; ISSN 0038-075X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
METALS
ADSORPTION
SOILS
PH VALUE
SORPTIVE PROPERTIES
AGRICULTURE
CADMIUM
COPPER
CROPS
CULTIVATION TECHNIQUES
HYDROLYSIS
ION EXCHANGE
LEAD
NICKEL
ZINC
CHEMICAL REACTIONS
DECOMPOSITION
ELEMENTS
LYSIS
SOLVOLYSIS
SORPTION
SURFACE PROPERTIES
TRANSITION ELEMENTS
540220* - Environment
Terrestrial- Chemicals Monitoring & Transport- (1990-)