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ARS Home » Midwest Area » St. Paul, Minnesota » Soil and Water Management Research » Research » Publications at this Location » Publication #304281
Title: Changes in sorption of indaziflam and three transformation products in soil with aging

Author
item ALONSO, DIEGO - University Of Maringa
item OLIVEIRA, RUBEM - University Of Maringa
item HALL, KATHLEEN - University Of Minnesota
item Koskinen, William
item CONSTANTIN, JAMIL - University Of Maringa

Submitted to: Geoderma
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/8/2014
Publication Date: 2/1/2015
Citation: Alonso, D.G., Oliveira, R.S., Hall, K.E., Koskinen, W.C., Constantin, J. 2015. Changes in sorption of indaziflam and three transformation products in soil with aging. Geoderma. 239-240:250-256.

Interpretive Summary: To evaluate environmental risks of pesticides in soil it is necessary to study the effect of contact time in soil on sorption processes. This has been reported for a number of pesticides, however few studies have been carried out on the metabolites arising from the degradation of these chemicals. This study determined the effect of incubation time on sorption of indaziflam and its metabolites indaziflam-triazinediamine (FDAT), indaziflam-triazine indanone (ITI) and indaziflam-carboxylic acid (ICA) in a Minnesota mollisol soil and two depths of a Brazilian oxisol soil treated with [C14]-indaziflam and [C14]-metabolites and incubated for 112 days. After selected times during the 112 day incubation, the concentration of the compound in solution and sorbed to the soil were determined, and apparent sorption coefficients (Kd,app) calculated. The chemicals slowly degraded during the incubation, and there was an increase in binding, i.e. aged Kd,app values, during the first two weeks of incubation, after which, apparent sorption coefficients tended to equilibrate. Indaziflam showed higher concentrations of bound residues than its metabolites, which reduces its bioavailability. Indaziflam also presented much higher sorption than FDAT for both BRA soil depths analyzed. In MN soil sorption followed, ITI >indaziflam >>ICA >FDAT, on average. While there were no changes in the potential mobility classification of these compounds with aging, predicted depth of leaching would decrease. These data will facilitate regulators' determination of potential offsite mivement of these chemicals.

Technical Abstract: To evaluate environmental risks of pesticides in soil it is necessary to study the effect of contact time on sorption-desorption processes. This has been reported for a number of pesticides, however few studies have been carried out on the metabolites arising from the degradation of these chemicals. This study determined the effect of incubation time on sorption of indaziflam and its metabolites indaziflam-triazinediamine (FDAT), indaziflam-triazine indanone (ITI) and indaziflam-carboxylic acid (ICA). A Minnesota (MN) mollisol and two depths of a Brazilian (BRA) oxisol were treated with [C14]-indaziflam and [C14]-metabolites and incubated for 112 days. The herbicide and its metabolites were extracted sequentially with the aqueous solution 0.01 N CaCl2, acetonitrile:water solution (4:1), and acetonitrile. The concentration of the compound in solution and sorbed to the soil were determined, and apparent sorption coefficients (Kd,app) calculated. Mineralization and the formation of bound residues were also quantified. The increase in aged Kd,app values was more pronounced in the first two weeks of incubation, after which, apparent sorption coefficients tended to equilibrate. Mineralization of metabolites was higher than that of its parent compound during the study period. Indaziflam showed higher concentrations of bound residues than its metabolites, which reduces its bioavailability. Indaziflam also presented much higher sorption than FDAT for both BRA soil depths analyzed. In MN soil sorption followed, ITI >indaziflam >>ICA >FDAT, on average. While there were no changes in the potential mobility classification of these compounds with aging, predicted depth of leaching would decrease.