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Environmental fate & pathways

Adsorption / desorption

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Kp for solid particulate matter and water (Kpsusp): 110000 l/kg (log value: 5.04) (European Commission – Joint Research Centre, Institute for Health and Consumer Protection, European Chemicals Bureau (ECB). 2008. European Union Risk Assessment Report Zinc metal, Volume 42. Final report. (S.J. Munn et al. eds.) 812 pp)
Kp for water and sediment (Kpsed); 73000l/kg ( log value:4.86) (European Commission – Joint Research Centre, Institute for Health and Consumer Protection, European Chemicals Bureau (ECB). 2008. European Union Risk Assessment Report Zinc metal, Volume 42. Final report. (S.J. Munn et al. eds.) 812 pp)
Kd for marine waters is 6010 l/kg (log value: 3.78)
Kd for solids-water in soil is 158.5 l/kg (log value: 2.2)

Key value for chemical safety assessment

Additional information

For metals, adsorption/desorption translates in the distribution of the metals between the different fractions of the environmental compartment, e.g. the water (dissolved fraction, fraction bound to suspended matter), soil (fraction bound or complexed to the soil particles, fraction in the soil pore water,...).This distribution between the different compartments is translated in the partition coefficients between these different fractions. Study records on partition coefficients are given in IUCLID section 5.6.

Partition coefficients for zinc in freshwater has been reviewed in the RAR (European Commission – Joint Research Centre, Institute for Health and Consumer Protection, Risk Assessment Report Zinc metal, Final report, 2008).

Based on the extensive experimental evidence, a partition coefficient for the distribution between solid particulate matter and water (Kpsusp) of 5.04 (log value) has been defined for EU waters and used throughout the RAR.

The Kp for the distribution between sediment and water (Kpsed) was estimated in the RAR from that for particulate matter, as follows: Kpsed= Kpsusp/ 1.5, based on the average difference in concentrations of zinc and other metals in both media. For zinc this results in a Kpsedof 73,000 l/kg (European Commission – Joint Research Centre, Institute for Health and Consumer Protection, Risk Assessment Report Zinc metal, Final report, 2008)

The marine Kd was derived based on data from several marine waters. the geomean value for zinc in seawater is 6010 l/kg

For soil, a solids-water partitioning coefficient of 158.5 l/kg (log value 2.2) was determined experimentally on 11 American soils. This value was used in the RA Zinc.