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Environmental fate & pathways

Adsorption / desorption

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Description of key information

The information requirement on Koc is waived since arsenic acid is an inorganic compound of arsenic. Partitioning coefficients Kp are determined according to values originating from a RIVM report.

Key value for chemical safety assessment

Additional information

In the case of inorganic substances the use of Kow and Koc to estimate the partitioning between media is not applicable. The sorption of arsenic is considered to be controlled by arsenic oxidation state and depend on prevailing environmental conditions such as metal oxides (iron, aluminium), clay, organic matter. Therefore, the adsorption/desorption between the aqueous phase and the relevant compartments (suspended matter, sediment and soil) need to be described by partitioning coefficients (Kpcomp). Such partitioning coefficients have been identified in a RIVM Report and are proposed to be used for the purpose of the chemical safety assessment of the registered substance.

RIVM Report:

Crommentuijn T, Polder M. and Van de Plassche, E 1997. Maximum permissible concentrations and negligible concentrations for metals, taking background concentrations into account. RIVM, Report 601501001.

Other adsorption coefficient indicated as dimensionless:
- log Kp (solids-water in soil) ,2.28
- log Kp (solids-water in sediment) ,3.82
- log Kp (solids-water in suspended matter) ,4.0