Abstract

Thirty-two grassland sites, distributed over the Netherlands, were sampled to determine 'background" concentrations of dioxins. The sites were chosen on the basis of calculations using a model for a large-scale distribution and deposition of dioxins from especially waste incinerators. Sampling procedure, sample processing and physico chemical analyses are described. Special attention is given to the analytical procedure, the recoveries and the repeatability. 'Background' concentrations from 1.8 to 16.4 ng I-TEQ kg-1 were determined for the layer 0-5 cm below surface level. These concentrations reflect the concentrations to be expected as 'background' concentrations in Dutch soils. It appeared appropriate to predict the concentrations in the soil from the deposition data, not only for 'background' sites but also for sites in the vicinity of waste incinerators. From the viewpoint of policy-making further research was not recommended. Additional studies may be undertaken for scientific reasons, increase in knowledge on the behaviour of dioxins.