Registration Dossier

Diss Factsheets

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

In batch equilibrium studies, the adsorption of Yb(III) on silica and aluminium was shown to strongly depend on pH. While adsorption at acidic pH values in negligible, Kd values at the pH range of ca. 6.6 to 8 range between 2,300 and 12,000, see section 5.4.1. As batch equilibrium studies were conducted (not only screening studies), no further information regarding adsorption/desorption was deemed as necessary.

Additional information

Due to the low water solubility of the metal components contained in the test substance (zirconium oxide, hafnium and ytterbium doped), a full transformation/dissolution protocol was carried out to study the potential release of these metals to the environment.

After 7 and 28 days (nominal loading of 100 mg/L, pH 8), only ytterbium(III) was found in solution with a maximum concentration of 0.069 µg/L. Zirconium and hafnium were both below the detection limit of 0.07 and 0.02 µg/L, respectively. Therefore, information on ytterbium(III) is relevant for the assessment of environmental fate properties ofzirconium oxide, hafnium and ytterbium dopedand adsorption studies with ytterbium are used in a read-across approach.