DIOXIN AND POP-CONTAMINATED SITES • CHALLENGES • SERIES • RESEARCH ARTICLE Levels and homologue proﬁles of PCDD/Fs in sediments along the Swedish coast of the Baltic Sea Kristina L. Sundqvist & Mats Tysklind & Ingemar Cato & Anders Bignert & Karin Wiberg Received: 14 July 2008 / Accepted: 2 February 2009 / Published online: 19 March 2009 # Springer-Verlag 2009 Abstract Background, aim, and scope The primary aim of this study was to explorethe variations in PCDD/F levels and homologue proﬁles of Baltic surface sediments by compre- hensively analyzing polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) in samples from a large number of sites, encompassing not only previously known hotspot areas,butalso sitesnearotherpotential PCDD/F sources, in pristine reference areas (in which there was no industrial activity) and oﬀshore sites. Materials and methods Surface sediment samples (146 in total)were collected at various points along the Swedish coastand oﬀshore areas. In addition, bulk deposition was sampled, monthly, at a singlesite in northern Sweden during 1 year. The concentrations of tetra-through octa- substituted CDD/Fs were determined in both matrices. Results Highly elevated concentrations of PCDD/Fs were found atmany sites in coastalareasand concentrations were also slightly elevatedin someoﬀshoreareas. Homologue proﬁles varied substantially amongst samples from coastal sites,while those from oﬀshore and other pristinesediments wererelatively similar. The oﬀshore sediments showed diﬀerent proﬁles from those observed i the deposition samples. Sediment levels of PCDD/Fs were not generally signiﬁcantly correlated to organic carbon levels,except in some pristine areas. Comparison of data obtained in this and previous studies suggest that both th levelsand proﬁlesare similartoday to thoseobserved 20 yearsago in coastaland oﬀshoreareas.Theonly detected trend is that their levels appear to have decrease slightly in the oﬀshore area of the Bothnian Sea. Discussion The localization ofhotspotareasalong the coast, the lack of consensus between PCDD/F proﬁles of sediments and general background, and their weak corre- lations with organic carbon suggest thatPCDD/Fs in the study area largely originate from local/regional emissions. However, due to complicating factors such assediment dynamics and land upheaval, it is not possible to conclude whether these pollutants derive from recent emissions or from a combination of recent emissions and re-distribution of previous inputs. Conclusions The resultsshow that:elevated levels of PCDD/Fs are present in both coastal and oﬀshore areas of the Baltic Sea, the major hotspots are close to the shore, a there are large variations in proﬁles, indicating that local emissions are (or have been) the major causes of pollution Recommendations and perspectives In order to identify otherhotspotareasand tracesources,comprehensive analysis of PCDD/Fs in surface sediments is needed in all areasof the Baltic Sea thathavenot been previously investigated. The high levelsof PCDD/Fs observed in Environ Sci Pollut Res (2009) 16:396–409 DOI 10.1007/s11356-009-0110-z Responsible Editor: Peter Luthardt Electronic supplementary material The online version of this article (doi:10.1007/s11356-009-0110-z) contains supplementary material, which is available to authorized users. K. L. Sundqvist (*) : M. Tysklind : K. Wiberg Department of Chemistry, Umeå University, 901 87 Umeå, Sweden e-mail: kristina.sundqvist@chem.umu.se I. Cato Division of Geophysic and Marine Geology, Geological Survey of Sweden, Box 670, 751 28 Uppsala, Sweden I. Cato Department of Geosciences, Göteborg University, Box 460, 405 30 Göteborg, Sweden A. Bignert The Swedish Museum of Natural History, Box 50007, 104 05 Stockholm, Sweden