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- Title
Evaluation of Soil Surface Charge Using the Back-Titration Technique.
- Authors
Ge, Ying; Hendershot, William
- Abstract
Variable surface charge (Q[sub v]) is one of the most important soil properties controlling ion adsorption on the soil solid phase. In this study, the back-titration technique was used to determine the Q[sub v] of soils with a wide range of properties. The procedure defines the Q[sub v] as the OH consumption by surface reactions corrected for dissolution of the solid phase and other solution reactions (e.g., metal hydrolysis). The Q[sub v], varying from 0 to 80 cmol[sub c] kg[sup -1], was dependent on the pH of the soil suspension and thc amount of soil organic matter. We used the non-ideal competitive adsorption (NICA)-Donnan model to simulate the surface charge, assuming a bimodal distribution of H[sup +] affinity on the soil solid phase. With the charge data and Microsoft Excel, the NICA-Donnan model parameters were optimized. The model provided an excellent fit to the experimental data. When the pH was below 8, the surface charge was dominantly distributed to the Type 1 sites; the Type 2 sites started to contribute to the total surface charge at pH > 8. Multiple linear regressions showed that the charge maxima (Q[sub max]) of the two sites were related to soil cationexchange capacity (CEC) and organic C (Org. C); these significant statistical relationships may be used to estimate the surface charge of soils using values of commonly measured soil parameters.
- Subjects
SOIL chemistry; ADSORPTION (Chemistry); VOLUMETRIC analysis; SOLIDS; IONS; SOLUTION (Chemistry)
- Publication
Soil Science Society of America Journal, 2004, Vol 68, Issue 1, p82
- ISSN
0361-5995
- Publication type
Article
- DOI
10.2136/sssaj2004.0082