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Phosphate treatments can reduce metal dissolution and transport from contaminated soils. However, diammonium phosphate (DAP) has not been extensively tested as a chemical immobilization treatment. This study was conducted to evaluate DAP as a chemical immobilization treatment and to investigate potential solids controlling metal solubility in DAP-amended soils. Soil contaminated with Cd, Pb, Zn, and As was collected from a former smelter site. The DAP treatments of 460, 920, and 2300 mg P kg-1 and an untreated check were evaluated using solute transport experiments. Increasing DAP decreased total metal transported. Application of 2300 mg P kg-1 was the most effective for immobilizing Cd, Pb, and Zn eluted from the contaminated soil. Metal elution curves fitted with a transport model showed that DAP treatment increased retardation (R) 2-fold for Cd, 6-fold for Zn, and 3.5-fold for Pb. Distribution coefficients (Kd) increased with P application from 4.0 to 9.0 L kg-1 for Cd, from 2.9 to 10.8 L kg-1 for Pb, and from 2.5 to 17.1 L kg-1 for Zn. Increased Kd values with additional DAP treatment indicated reduced partitioning of sorbed and/or precipitated metal released to mobile metal phases and a concomitant decrease in the concentration of mobile heavy metal species. Activity-ratio diagrams indicated that DAP decreased solution Cd, Pb, and Zn by forming metal-phosphate precipitates with low solubility products. These results suggest that DAP may have potential for protecting water resources from heavy metal contamination near smelting and mining sites.

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Areas of intensive poultry production are prone to high phosphorus (P) losses due to excessive manure application. Historically, manure application rate has been calculated based on nitrogen (N) needs of the crops and N content of the manure with no attention to the quantity of phosphorus (P) loading. In many instances, a gradual buildup of P in soil has resulted from longterm manure application. Therefore, P input from animal manure via runoff is acknowledged as the primary factor for the eutrophication of surface water bodies. This study was conducted to evaluate (i), the impact of dietary P concentration on the broiler manure P content and the pre-analysis drying methods on the broiler manure nutrient composition with emphasis on phosphorus 2783 ORDER REPRINTS and (ii), to compare the use of Ion Chromatography and the Murphy -Riley method for the determination of inorganic phosphorus in the broiler manure water extract. Four drying methods were used to dry the fresh broiler manure as follows: air drying (AD), freeze drying (FD), oven drying at 658C (OD65), and oven drying at 1058C (OD105). The results were compared with analysis of the fresh broiler manure with no drying (ND). The diet P concentration did not affect the broiler manure total N content. However, a significant decrease in total N occurred at all P levels due to drying when compared with fresh manure analysis. The diet P level had significant effect on total P and water-extractable P. Freeze drying followed by OD105 caused the most reduction in manure total P content. Drying also had a significant effect on the metal nutrient content of the broiler manure. However, the effect was inconsistent.