Bioassay-directed fractionation of organic extracts of marine surface sediments from the North and Baltic Sea -: Part I:: Determination and identification of organic pollutants

Goal, Scope and Background. Bioassay-directed fractionation (BDF) has become a valuable technique to investigate and chatacterise environmental samples with regard to toxicity. BDF was used as a tool to determine the ecotoxicological potential for marine sediments from the North Sea, the Baltic Sea, and the Skagerrak (samples taken far away from point sources). In order to look for the substances causing and contributing to the overall toxicity, the identification of priority compounds such as polycyclic aromatic hydrocarbons (PAH), polycylclic chlorinated biphenyls (PCB) and other organochlorines (OC), the quantitative determination of target substances of medium and high polarity, as well as a comprehensive, non-target screening were in the focus of this investigation: In this article the chemical results of the approach are described (Part I). Methods. Sediment extracts were prepared by a sequential extraction of wet material with acetone and n-hexane. The extracts were subjected to a three step fractionation procedure by gel-permeation chromatography (GPC) and high pressure liquid chromatography (HPLC). Several compounds were quantified in the fractions: 16 PAHs, 21 other OCs, alkylphenols, nitroaromatics, synthetic musks, organo phosphorus compounds and brominated substances. Non-target analysis was performed using gas chromatography and mass spectrometry (GC/MS), and led to a long list of identified compounds in the samples. Results and Discussion. Bioassay-directed fractionation was well suited to direct the chemical screening. The lipophilic contaminants PAHs and PCBs are still the predominant substances in the investigated marine sediments. Their concentrations were higher in sediment extracts from the Baltic Sea than in samples originating from the North Sea. Although lower concentration levels were found in North Sea samples, the contamination patterns of the North Sea samples were more complex, compounds. Especially some brominated indoles and phenols were detected in high concentrations in the North Sea sediments only. Generally, there were linear correlations between sediment characteristics, such as the total organic carbon (TOC) content and concentrations of some examined compounds. Compounds of biogenic origin such as brominated phenols and indoles can be assumed to contribute to toxicity in the polar HPLC fractions. Application of sediment quality guidelines demonstrates that the predicted effect levels were exceeded for some samples. Conclusion. For the first time, a wide approach of chemical analysis and biological testing was applied to marine sediments of the North and Baltic Sea. The results of the chemical analyses of several lipophilic and polar target compounds, and a nontarget screening in combination within the bioassay-directed fractionation approach delivered a complex data set about the contamination status of marine sediment samples. Concerning non-polar and some medium polar contaminants, a quite comprehensive description could be achieved, while less comprehensive data were obtained for more polar compounds. Recommendation and Outlook. Toxicological effects were not restricted to industrial sites and harbours, but were found also in open sea areas. Anthropogenic as well as biogenic substances should be considered for marine sediment toxicity in future studies.