Registration Dossier

Environmental fate & pathways

Endpoint summary

Administrative data

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Additional information

For metals, the transport and distribution over the different environmental compartments 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,...) is described and quantified by the metal partition coefficients between these different fractions. Information on these partition coefficients is given under 5.6.

Partition coefficients for zinc in freshwater have been reviewed in the RAR (ECB 2008). Based on this 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 was 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 Kpsed of 73,000 l/kg. (ECB 2008)

These partition coefficients have been used since then in other legislative processes in the EU (e.g. the water framework directive) and will also be used for REACH.

For the marine water, a partition coefficient water/suspended matter of 6010 l/kg has been derived.

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.