On the use of the partitioning approach to derive Environmental Quality Standards (EQS) for persistent organic pollutants (POPs) in sediments: A review of existing data
Résumé
A review of experimental data has been performed to study the relationships between the
concentration in water, pore water and sediments for different families of organic
contaminants. The objective was to determine whether it is possible to set EQS for
sediments from EQS defined for surface waters in the Daughter Directive of the European
Parliament (COM (2006) 397). The analysis of experimental data showed that even though in
some specific cases there is a coupling between water column and sediments, this coupling
is rather the exception. Therefore it is not recommendable to use water column data to
assess the chemical quality status of sediments and it is necessary to measure in both
media. At the moment EQS have been defined for the water column and will assess only the
compliance with good chemical status of surface waters. Since the sediment toxicity depends
on the dissolved pore water concentration, the EQS developed for water could be applied to
pore water (interstitial water); hence, there would be no need of developing another set of EQS.
The partitioning approach has been proposed as a solution to calculate sediment EQS from
water EQS, but the partitioning coefficient strongly depends on sediment characteristics and
its use introduces an important uncertainty in the definition of sediment EQS. Therefore, the
direct measurement of pore water concentration is regarded as a better option.