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ARS Home » Research » Publications at this Location » Publication #116230

Title: REMEDIATION OF HEAVY METAL CONTAMINATED SOILS BY DIAMMONIUM PHOSPHATE TREATMENT

Author
item McGowen, Steven
item BASTA, NICHOLAS

Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 10/13/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Phosphate treatments can reduce metal solubility and transport to safeguard natural resources. This study was conducted to evaluate diammonium phosphate (DAP) as a chemical immobilization treatment and determine mineral solids potentially controlling metal solubility in a contaminated soil. Soil contaminated with Cd, Pb, Zn, and As was collected from a defunct Zn smelter site. DAP treatments of 460, 920,2300, and 20700 mg P/kg, and an untreated check were evaluated using solute transport experiments and chemical equilibrium and transport models. Increasing DAP application decreased heavy metal transport. Application of 2300 mg P/kg was the most effective for immobilizing Cd,Pb, and Zn eluted from the contaminated soil. Model-fitted elution curves showed DAP treatment increased retardation (R) 2-fold for Cd, 3.5-fold for Pb, and 6-fold for Zn. Distribution coefficient (Kd) values also increased with P application from 4.0 to 9.0 L/kg for Cd, from 2.9 to 10.8 L/kg for Pb, and from 2.5 to 17.1 L/kg for Zn. Increased Kd values indicated slower partitioning rates of sorbed metal to mobile metal phases, and a decrease in mobile metal species concentration with increasing DAP treatment. Activity-ratio diagrams suggest DAP decreased solution Cd, Pb, and Zn by forming metal-phosphate compounds with low solubility products.