Influence of Soil Aging on Sorption and Bioavailability of Simazine

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• 作者：Jussara B. Regitano ; William C. Koskinen ; and Michael J. Sadowsky
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2006
• 出版时间：February 22, 2006
• 年：2006
• 卷：54
• 期：4
• 页码：1373 - 1379
• 全文大小：138K
• 年卷期：v.54,no.4(February 22, 2006)
• ISSN：1520-5118

文摘

Characterization of pesticide bioavailability, particularly in aged soils, is of continued interest becausethis information is necessary for environmental risk assessment. However, pesticide bioavailabilityin aged soils has been characterized by a variety of methods with limited success, due in part tomethodological limitations. The objective of this study was to use solvent extraction methods tocorrelate simazine residue bioavailability in aged soils to simazine mineralization using a simazine-mineralizing bacterium. Soils from Brazil, Hawaii, and the midwestern United States were treatedwith UL-ring-labeled [¹⁴C]simazine and incubated for up to 8 weeks. At the end of each incubationperiod, soils were either incubated further, extracted with 0.01 M CaCl₂, or extracted with aqueousmethanol (80:20 v/v methanol/water). In a parallel experiment, after each incubation period, soilswere inoculated with the bacterium Pseudomonas sp. strain ADP, which is capable of rapidlymineralizing simazine, and ¹⁴CO₂ was determined. The inoculated soil samples were then extractedwith 0.01 N CaCl₂ and with aqueous methanol. This allowed for the evaluation of the bioavailabilityof aged simazine residues, without the contribution of simazine desorption from soil. Results of thesestudies indicated that simazine sorption to soil increased with aging and that amounts of simazine inaged soils extracted by 0.01 M CaCl₂ and aqueous methanol were highly correlated to amounts ofsimazine mineralized by Pseudomonas sp. strain ADP. Consequently, 0.01 M CaCl₂/methanol-extractable simazine in aged soils can be used to estimate bioavailable residues. This techniquemay be useful in determining the bioavailability of other s-triazine compounds in soils.Keywords: Simazine; bioavailability; aged residues; sorption-desorption