GEOC 21 |
| Liyun Xie, Claire E. Farnsworth, and Daniel E. Giammar. Environmental Engineering Science Program, Washington University in St. Louis, Campus Box 1180, One Brookings Drive, St. Louis, MO 63130 |
| Lead soil contamination is an environmental concern, especially in Missouri, the nation’s leading lead producing state. Addition of phosphate amendments to lead contaminated soils has been proposed as a remediation method because of the low solubility of lead phosphate solids. Further research is necessary to evaluate the long-term stability of lead phosphates in contaminated soil systems. Synthetic pyromorphite dissolution and precipitation rates were investigated in batch and flow-through reactors for the pH range 2-7. Influent solutions for precipitation experiments were mildly supersaturated with respect to pyromorphite. Dissolution rates determined in flow-through experiments and equilibrium dissolved lead concentrations in batch experiments both increased with decreasing pH. Changes in the structure of the solid phase were investigated by Fourier transform infrared spectroscopy, electron microscopy and x-ray diffraction. Results suggest that the effectiveness of lead immobilization by phosphate addition will depend on the system pH and the nature of the lead-containing solid. |
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Chemistry of Metals in Terrestrial and Aquatic Systems
8:10 AM-11:30 AM, Monday, March 29, 2004 Marriott -- Marquis NE, Oral
Division of Geochemistry |