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Environmental fate & pathways

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Adsorption and desorption

The adsorption and desorption characteristics of 14C-labelled test substance (diflufenzopyr sodium salt) were examined in seven soils (5 US soils and 2 EU soils) by the batch equilibrium method. The adsorption Koc for the loam soil are generally higher than that of soils with higher sand content. However, the desorption Koc values of all soils are considerably greater than the corresponding adsorption Koc values indicating a stronger affinity to soil once adsorbed.

Average Koc value of all US soils for the adsorption based on the linear model is 60, without silt loam the Koc value is reduced to 40. The corresponding average Koc values from the Freundlich model are 68 and 47, respectively. For the EU soils Loamy Sand and Sandy Clay Loam the adsorption Koc values from the Freundlich model and the linear isotherm model are reported to be 30 and 53 and 24 and 41, respectively.

Henry's Law constant

The Henry's Law constant of the test substance (diflufenzopyr sodium salt) was calculated to be 2.11E-013 Pa-m3/mole using HENRYWIN (v3.20) Program (EpiWIN software).