Changes in sorption of indaziflam and three transformation products in soil with aging

•The first reported study on the effect of incubation time on sorption of indaziflam and three metabolites•A mollisol and oxisol (2 depths) were extracted sequentially (CaCl2, acetonitrile) to determine sorption.•Total extractable indaziflam and metabolites decreased during the 112-days of incubation.•The use of batch sorption coefficients instead of 'aged' sorption coefficients would over predict potential movement.

To evaluate environmental risks of pesticides in soil, it is necessary to determine aging effects on sorption processes. Few studies have been carried out on their metabolites. The effect of incubation time on sorption of indaziflam and indaziflam-triazinediamine (FDAT), indaziflam-triazine indanone (ITI) and indaziflam-carboxylic acid (ICA) metabolites was determined on a mollisol and two depths of an oxisol. Soils were treated with [14C]-indaziflam and [14C]-metabolites, incubated for 112 days, then sequentially extracted with 0.01 N CaCl2, acetonitrile:water (4:1), and acetonitrile. Apparent sorption coefficients (Kd,app) were calculated based on compound concentrations in solution and sorbed to soil. Decreases in total remaining chemicals were due to mineralization and formation of bound residues. Kd,app values increased in the first two weeks of incubation, then tended to equilibrate. On average, sorption followed ITI > indaziflam ≫ ICA > FDAT. A significant increase in the sorption potentials of compounds and formation of bound residues was observed with the increase of incubation time (especially within the first 14 days), which would decrease the mobility potential of these molecules in the soil and therefore the possible contamination of underground water sources.