Biological and chemical determination of contaminant levels in settling particulate matter and sediments - A Swedish river system before, during, andafter dredging of PCB-contaminated lake sediments

A sensitive bioassay, based on EROD induction in cultured chicken embryo li vers, was used together with chemical analysis to determine levels of dioxi n-like contaminants in particulate matter in Eman. Extracts of sediment and settling particulate matter (SPM) collected in the river system before, du ring, and after dredging of a PCB contaminated lake, Lake Jarnsjon, were se parated into three fractions containing a) monoaromatic/aliphatic; b) diaro matic (e.g., PCBs and polychlorinated dibenzodioxins and dibenzofurans); an d c) polyaromatic compounds (e.g., polycyclic aromatic hydrocarbons). The s amples from Lake Jarnsjon contained the highest PCB concentrations and the diaromatic extracts from Lake Jarnsjon samples showed the highest activitie s of EROD-inducing diaromatic compounds. The dioxin-like activity of the di aromatic fraction in sediment collected after the dredging of Jarnsjon had only around 1% of the activity of the pre-dredging sediment, showing that t he remediation was successful in terms of removal of the PCB-contaminated s ediment from the lake. In SPM collected immediately downstream from Jarnsjo n, levels of diaromatic dioxin-like compounds were elevated during the dred ging, and decreased after that. The post-dredging concentrations were howev er higher than in SPM from lakes upstream of Jarnsjon, showing that elevate d levels of dioxin-like diaromatic compounds were still present in the wate r System downstream of Jarnsjon a couple of years after the dredging.