HR: 0800h
AN: H31B-1311    [Abstracts]
TI: Kinetics of Cadmium Release and Aqueous Transport in Fertilizer Amended Agricultural Soils
AU: * Fish, W
EM: fishw@cecs.pdx.edu
AF: Portland State University, Environmental Sciences and Resources P.O. Box 751 , Portland, OR 97207-0751 United States
AU: Mukome, F
EM: mukomef@pdx.edu
AF: Portland State University, Environmental Sciences and Resources P.O. Box 751 , Portland, OR 97207-0751 United States
AB: Agricultural applications of phosphate fertilizers lead to the release of toxic metals present at low but significant levels in the parent minerals of the fertilizers. Of special concern are the comparatively high levels of Cd in rock phosphate resources and the potential for Cd to be released form fertilizers and taken up by crops or to accumulate in soils. The soil-fertilizer-water system is complex and dynamic and generally must be assumed to be far from at thermodynamic equilibrium conditions. A kinetic model is needed to analyze and understand the behavior of Cd in fertilzer-amended agricultural soils. Our experiments focus on the kinetics of release of Cd from fertilizer and the rates of transfer to the mobile water phase or to soil surfaces. Our data show that Cd release rise rapidly with 24 h of contact with soil moisture, but then peak out and generally decline within 150 h to rates only 20-50% of the peak release rate. The release rates then continue at relative constant values for over 1600 h (exact mass release rates depend strongly on the initial Cd in the fertilizer sample). Release rates are not well correlated with the total mass loss of the fertilizer matrix but do appear to be influenced by the high concs of phosphate. Preliminary calculations suggest an important role for phosphate mineral solubility in regulating the release rates.
DE: 0402 Agricultural systems
DE: 0409 Bioavailability: chemical speciation and complexation
DE: 0461 Metals
DE: 1865 Soils (0486)
SC: Hydrology [H]
MN: Fall Meeting 2005