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United States Department of Agriculture

Agricultural Research Service

Title: Solvent Extraction Characterization of Bioavailability of Atrazine Residues in Soils

Authors
item Barriuso, Enrique - INRA FRANCE
item Koskinen, William
item Sadowsky, Michael - UNIV OF MINNESOTA

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 27, 2004
Publication Date: September 14, 2004
Citation: Barriuso, E., Koskinen, W.C., Sadowsky, M.J. 2004. Solvent extraction characterization of bioavailability of atrazine residues in soils. Journal of Agricultural and Food Chemistry. 52:6552-6556.

Interpretive Summary: Characterization of pesticide bioavailability, particularly in aged soils, is of continued interest because this information is necessary for environmental risk assessment of pesticides. The objective of this study was to correlate atrazine (a triazine herbicide) residue bioavailability in aged soils, as determined by solvent extraction methods, to atrazine mineralization by an atrazine-degrading bacterium. We identified an extraction procedure using aqueous methanol (a water/alcohol mixture) that can characterize atrazine bioavailability in dissimilar aged soils, which in turn may be useful to determine bioavailability of other compounds in soils, especially other triazine herbicides. Scientists now a relatively easy and inexpensive technique to determine the amounts of one class of pesticides, triazines, available for transport, plant uptake, and microbial degradation, particularly in aged soils, information needed for predicting environmental fate and environmental risk assessment.

Technical Abstract: Characterization of pesticide bioavailability, particularly in aged soils, is of continued interest because this information is necessary for environmental risk assessment. Pesticide bioavailability in aged soils has been characterized by a variety of methods with limited success. The objective of this study was to correlate atrazine residue bioavailability in aged soils, as determined by solvent extraction methods, to atrazine mineralization by an atrazine-degrading bacterium. Webster clay loam and Zimmerman fine sand soils were treated with UL-ring-labeled 14C-atrazine and incubated for up to 8 weeks. At the end of each incubation period, soils were either incubated further, extracted with 0.01 M CaCl2, or extracted with 0.01 M CaCl2/aqueous methanol. Soils were then inoculated with the bacterium Pseudomonas sp. strain ADP, which is capable of rapidly mineralizing the atrazine ring. This allowed for the evaluation of the bioavailability of aged atrazine residues, without the contribution of atrazine desorption from soil. Results of these studies indicated that amounts of atrazine in aged soils extracted by 0.01 M CaCl2 and aqueous methanol were correlated to amounts of atrazine mineralized by Pseudomonas sp. strain ADP. Consequently, 0.01 M CaCl2/methanol extractable atrazine in aged soils can be used to estimate bioavailable residues. This technique may be useful to determine bioavailability of other compounds in soils, especially other triazine herbicides.

Last Modified: 7/31/2014