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ADSORPTION OF CADMIUM ONTO DIFFERENT FRACTIONS OF BIOSOLID-AMENDED SOILS
Citation:
Hettiarachchi**, G. M. AND J A. Ryan*. ADSORPTION OF CADMIUM ONTO DIFFERENT FRACTIONS OF BIOSOLID-AMENDED SOILS. Presented at Annual Meeting of the American Society of Agronomy, Charlotte, NC, 10/21-25/2001.
Description:
We hypothesized not only organic but also inorganic fraction in biosolids controls the metal availability in soil systems. To test this hypothesis we conducted Cd adsorption experiments on different fractions of biosolids, biosolid amended soils, and unamended soils. Soils were collected from Beltsville, MD. Organic fractions of soils was removed by treating with NaOCl adjusted to pH 8.5. Manganese oxide fraction was removed with 0.01 M NH2OH.HCl + 0.01 M HNO3. Iron and Mn fractions were removed with 0.4 M NH2OH.HCl in 25% HOAc. Cadmium adsorption increased with incresing biosolid rate. Removal of organic carbon reduced Cd adsorption but did not account for the observed differences between biosolid-amended soils and controls, indicating that the increased adsorption associated with biosolids applicaton was not limited to the increased organic carbon due to addition of biosolids. Removal of Mn and/or Fe oxides reduced Cd adsorption in biosolid-amended soils suggesting that the relative contribution of these inorganic fractions on Cd adsorption in biosolid-amended soils is significant. The adsorption of Cd before and after extracting different fractions of controls and biosolid-amended soils will be presented. The extracting solutions removed varying amounts of targeted phase as well as additional components. Therefore, the effects of these extracting solutions on each soil fractions will also be presented.