Environ. Sci. Technol., 36 (20), 4253 -4261, 2002. 10.1021/es025660d S0013-936X(02)05660-2 Web Release Date: September 14, 2002 Copyright © 2002 American Chemical Society Solid-State Speciation of Natural and Alum-Amended Poultry Litter Using XANES Spectroscopy D. Peak* Department of Soil Science, University of Saskatchewan, 51 Campus Drive, Saskatoon SK S7N 5A8, Canada J. T. Sims and D. L. Sparks Department of Plant and Soil Sciences, University of Delaware, 149 Townsend Hall, Newark, Delaware 19717-1303 Abstract: While alum amendments have shown to be effective in lowering water-soluble phosphate levels in poultry litter, the mechanism by which this occurs is not fully known. To determine the solid-state speciation of phosphate in litter samples, experiments were conducted with X-ray absorption near edge structure (XANES) spectroscopy. XANES analysis reveals that, in unamended samples, phosphate is present as weakly bound inorganic as well as some organic phosphate, with some dicalcium phosphate-type calcium phosphates also present. When alum is applied in the houses, XANES results suggest that it precipitates out as amorphous Al(OH)3 and then reacts with phosphate via an adsorption mechanism. No evidence was found of aluminum phosphate precipitation in any samples. |