Chelating Ability of Soil Organic Matter1
- Frank L. Himes and
- Stanley A. Barber2
It was discovered that organic matter reacted with divalent metal ions in a manner similar to chelation reactions. Radioactive zinc was used to facilitate the adsorption measurements. Multiple regression was used to develop a prediction equation to determine the amount of zinc adsorbed as influenced by zinc added, pH, and ionic strength of the solution.
Removal of organic matter by oxidation with hydrogen peroxide destroyed the ability of the soil to chelate zinc. Removal of hydrous silicates did not influence the retention of zinc by the soil.
The organic matter was fractionated into the humic and fulvic fractions. Both fractions reacted with zinc in a manner similar to the untreated soil. Methylation of the organic matter was used to determine the functional groups involved in the chelation reaction. Carboxyl groups did not appear to be important.
The stability constant for the zinc soil complex was investigated by two independent methods. For a Maumee sandy loam soil at pH 7 and 2N KCl it was found to be 5.6.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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