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Environmental fate & pathways

Adsorption / desorption

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Description of key information

The Kd values resulting from validated studies range from 3700L/kg (dw) for organic soil to 30000 L/kg (dw) for the calcareous soil. These values indicate high variability depending on the soil type. Key information for the adsorption/desorption are 6000 L/kg (dw) for acidic soil and 30000 L/kg (dw) for calcareous soil, which correspond to Koc values of respectively 18868 and 89286. A geometric mean value of Koc=41044 will be considered for PNECsed derivation. In conclusion, these studies demonstrate a strong affinity of zirconium coumpounds for the solid phase of the soil particle. 

Key value for chemical safety assessment

Koc at 20 °C:
41 044

Additional information

The study of E .Ferrand used the batch equilibrium method by loading 2 different soils: acidic sandy clayey loamy pH 5.5 (soil A) and clayey calcareous soil pH 8.3 (soil B) with zirconium dichloride oxide (ZrOCl2). Kd values for these soil types were respectively 6000 L/kg (dw) for soil A and 30000 L/kg (dw) for soil B, corresponding to Koc values of 18868 and 89286 respectively. These values demonstrate a strong affinity of zirconium for the solid phase of the soil particle.

In parallel to experimental result of E. Ferrand (2005), Kd values reported in the last version of IAEA (Handbook data) are between 3700 and 5000 L/Kg. Differences reported are related to the soil type used. While these data have been already reviewed by expert no more information were available in order to go further in the behaviour of zirconium in the environment.

Therefore, only values of E. Ferrand's thesis were identified as key information.