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United States Department of Agriculture

Agricultural Research Service

Title: Impacts of Iron and Aluminum Ions on Soubility of Phosphates Associated with Natural Organic Matter

Authors
item He, Zhongqi
item T, Ohno - UNIV OF MAINE
item M.S., Erich - UNIV OF MAINE
item Honeycutt, Charles

Submitted to: Annual Goldschmidt Conference
Publication Type: Abstract Only
Publication Acceptance Date: April 10, 2005
Publication Date: May 15, 2005
Citation: He, Z., T, O., M.S., E., Honeycutt, C.W. 2005. Impacts of iron and aluminum ions on soubility of phosphates associated with natural organic matter. Annual Goldschmidt Conference. May 20-25, 2005. Moscow, ID. Geochimica et Cosmochimica Acta. Vol 69 (Supplement I); page A543

Technical Abstract: The interactions among metal ions and phosphates in natural organic matter were investigated. IHSS Elliott Soil humic and fulvic acid standard, Waskish peat humic and fulvic acid reference, phytate and orthophosphate (all in 0.322 mM P) were separately incubated with control, AlCl3 or FeCl3 (3.22 mM) at pH 5.0 and 22oC for 20 h. These mixtures were then equally divided into two aliquots. After 20-h incubation at 37oC with 3-Phytase or water, soluble inorganic P in these mixtures was determined. Less than 1% of phytate P was detected in the absence of the enzyme. About 24% of P in Elliott humic and fulvic acid, or 5% of Waskish humic and fulvic acid P was molybdenum reactive P. Enzymatic hydrolysis released 75% of phytate P, 17% of additional P associated with Elliott humic and fulvic acid, and 2% of additional P associated with Waskish humic and fulvic acid. Ferric ions precipitated 80% of soluble inorganic orthophosphate. Aluminum ions precipitated only 17% of soluble inorganic orthophosphate. Inclusion of metal additives lowered the detectable P in Elliott humic acid to 17%. Both metal ions totally inhibited the enzymatic release of phytate P. In contrast, the inhibitory influence of metal additives on enzymatic release of humic- or fulvic-associated P was not significant. These results suggest that these two metals may have preferential interactions with other functional groups to phosphoesters in humic and fulvic acids.

Last Modified: 8/1/2014
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