Page Banner

United States Department of Agriculture

Agricultural Research Service

Research Project: PRACTICES TO PROTECT WATER QUALITY AND CONSERVE SOIL AND WATER RESOURCES IN AGRONOMIC AND HORTICULTURAL SYSTEMS IN THE NORTH CENTRAL US

Location: Soil and Water Management Research

Title: Sorption-desorption of indaziflam and its three metabolites in sandy soils

Authors
item Trigo, Carmen -
item Koskinen, William
item Kookana, Raj -

Submitted to: Journal of Environmental Science and Health
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 13, 2014
Publication Date: N/A

Interpretive Summary: Indaziflam is a relatively new herbicide for which sorption-desorption information is lacking, and nothing is available on its metabolites. Information is needed on the multiple soil and pesticide characteristics known to influence these processes. Sorption, as measured by a batch slurry technique, on four soils was the parent chemical, indaziflam, greater than the three metabolites; triazine indanone metabolite greater than fluoroethyldiaminotriazine metabolite, equal to indaziflam carboxylic acid metabolite. Once bound to the soil, the chemicals were difficult to desorb (exhibited hysteresis). Sorption, when determined at mositure content typical of what is found in the field, was similar to the batch values. Sorption of indaziflam and its metabolites is affected by soil properties and depends on the chemical structure. The metabolites being more polar than the parent compound, showed lower sorption, and are potentially more moble and can be transported offsite. However, using batch slurry sorption characteristics only would over-predict potential offsite transport if desorption hysteresis is not taken into account Regulartory agenices for the first time have data that can help predict the potential offsite transport of the principle metabolites of the herbicide indaziflam.

Technical Abstract: Indaziflam is a relatively new herbicide for which sorption-desorption information is lacking, and nothing is available on its metabolites. Information is needed on the multiple soil and pesticide characteristics known to influence these processes. Freundlich sorption isotherm slopes were < 1, therefore Kd values were calculated from the Freundlich coefficients at a concentration of 1 ng mL-1. For four soils, the order of sorption was indaziflam (Kd = 4.9, Koc = 362) > triazine indanone metabolite (Kd = 1.9, Koc = 147) > fluoroethyldiaminotriazine (Kd = 0.32, Koc = 25) = indaziflam carboxylic acid (Kd = 0.28, Koc = 27) metabolite. Desorption was hysteretic for all chemicals. Sorption Kd values of indaziflam and fluoroethyldiaminotriazine determined at low water contents using the unsaturated transient flow method were similar to the batch values. Sorption of indaziflam and its metabolites is affected by soil properties and depends on the chemical structure. The metabolites being more polar than the parent compound, showed lower sorption. Desorption was hysteretic for the four chemicals. Unsaturated transient flow Kd’s were lower than batch Kd’s for indaziflam but similar for fluoroethyldiaminotriazine. Batch Kd’s would over-predict potential offsite transport if desorption hysteresis is not taken into account.

Last Modified: 10/1/2014
Footer Content Back to Top of Page