The relative contribution of spatial-, sampling- and analytical variation to the PAH and PCB concentrations in Baltic Sea sediments

In the study of the distribution and dynamics of organic pollutants in aquatic environments the sediment have traditionally played an important role. In larger water bodies the properties of a few sediment samples are often extrapolated to large areas and the question how representative these samples are is often left unattended. In this study it was shown that the sediment properties in large accumulation areas can beʹ relatively constant over several km2. However, it is also shown that the sampling procedure introduces significant variation, and that this variation can be reduced by pooling samples prior to chemical analysis. When different accumulation areas are to be compared for concentrations and distribution, it is recommended that several samples are taken at each location and pooled before analysis. This applies also to carbon and content of different lipids classes. Comparisons of chemical profiles also revealed that PAH profiles exhibited significant patchiness in the sediments.