Chemical conditions conducive to the release of mobile colloids from Ultisol profiles
- Pacific Northwest Lab., Richland, WA (United States)
- Univ. of Georgia, Athens, GA (United States)
- Univ. of Georgia, Aiken, SC (United States)
The objective of this study was to determine how soil pH (4.3-6.9), low total electrolyte concentration (TEC, 0.4-2.8 mol{sub c} m{sup -3}) and low Na adsorption ratios (SAR, 0.3-1.8 [mol{sub c} m{sup -3}]{sup 0.5}) affected the concentration of mobile colloids released from 13.5-m{sup 3} reconstructed Ultisol profiles. Critical flocculation concentration (CFC, the minimum TEC to induce flocculation of a clay suspension) tests were conducted using the water-dispersible clay fraction of the Ap horizon of these profiles, which is the primary source for the mobile colloids. Surface soil pH, TEC, and SAR levels of the profiles that released high concentrations of colloids fell within the dispersion domain identified by the laboratory CFC tests. The effect of SAR on dispersion appears to be a continuum that approaches zero, and this effect is significantly (P = 0.01) dependent on TEC. This dispersible nature of these soils is in part attributed to their very low TEC, generally < 2 mol{sub c} m{sup -3}, which results from low concentrations of weatherable minerals. The TEC of 10 of the 13 profiles were < 2 mol{sub c} m{sup -3}, the CFC for SAR = 1 (mol{sub c} m{sup -3}){sup 0.5}, indicating that if the pH is not limiting (pH greater than = 6.0), colloidal dispersion will occur. 24 refs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 200399
- Journal Information:
- Soil Science Society of America Journal, Vol. 60, Issue 1; Other Information: PBD: Jan-Feb 1996
- Country of Publication:
- United States
- Language:
- English
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