Levels of Polybrominated Diphenyl Ether Flame Retardants in Sediment Cores from Western Europe BART N. ZEGERS, † WILMA E. LEWIS, †,§ KEES BOOIJ, † RIENK H. SMITTENBERG, † WIM BOER, † JACOB DE BOER, ‡ AND JAN P. BOON* ,† Royal Netherlands Institute for Sea Research (NIOZ), P.O. Box 59, 1790 AB Den Burg, Texel, The Netherlands, and Netherlands Institute for Fisheries Research (RIVO), P.O. Box 68, 1970 AB IJmuiden, The Netherlands The levels of 14brominated diphenyl ether (BDE)-congeners in sediment cores from three locations in Western Europe have been determined by GC/MS (negative chemical ionization mode). Sediments from the Drammenfjord (Norway), the western Wadden Sea (The Netherlands), and the freshwater Lake Woserin (Mecklenburg-Vorpommern, Germany) showed a time-dependent pattern in the distribution of BDEs since the beginning of the industrial production of polybrominated diphenyl ether (PBDE) formulations. Two out of three commercially available PBDE formulations could be distinguished. Starting from the beginning of the 1970s, the penta-mix formulation is clearly present, but the deca-mix formulation is only present since the late 1970s. The octa-mix formulation appeared to be still absent in these sediments, as its marker- congener, BDE183, was never detected. In the cores from the western Wadden Sea and Lake Woserin, all TOC- normalized concentrations of the penta-BDE-derived congeners were leveling off in the most recent sediment layers representing 1995 and 1997, whereas those in the Drammenfjord were still increasing in 1999. The levels of BDE209, however, decreased in the most recent layer of all three cores. In Lake Woserin, the concentrations of BDE209 were much less elevated above those of the tri- to hexa-BDEs than in the other the two areas. This might be due to the absence of a significant PBDE input from sources other than the atmosphere to this rural lake. The absence of all PBDE congeners in the older layers of the three sediment cores, as well as in several 100-150- My-old layers from an extremely organic-rich marine sediment from the Kimmeridge clay formation in Dorset (UK), indicated the absence of natural production of the BDE congeners analyzed. Introduction Brominated flame retardantsare added to manyplasticsand printed circuit boards used in electronic household equip- ment, and in textile and polyurethane foam in furniture and cars, for safety reasons. Among the brominated flame retardants (BFRs), there are three commercial formulations that contain the diphenyl ether skeleton. In order of increasingoverallbromination,these formulationsare named the penta-mix, octa-mix, and deca-mix. The global market demands in 1999 were 54 800 t for the deca-mix, 8500 t for the penta-mix, and 3825 t for octa-mix (1). Polybrominated diphenyl ethers (PBDEs) are very hy- drophobic (log Kow 5-10) and resistant to environmental degradation processes. The congeners are numbered ac- cording to the IUPAC nomenclature used for PCBs (Figure 1). The aqueous solubility and vapor pressure of BDE congeners decreases with increasingdegree ofbromination, whereashydrophobicityincreases(2-4).The concentrations of the tetrabrominated BDE47, and the pentabrominated BDE99, and BDE 100 in guillemot (Uria algae) eggs from Stora Karlso ¨ in the central part of the Baltic Proper were measured between 1969 and 1997: the levels of BDE47 . BDE99 > BDE100. The lipid-normalized levels of all three congeners showed a sharp increase from 1973 to 1985 with an about equally rapid decrease from 1987 to 1997 (5). The temporal trends of the occurrence of pollutants in the environment can also be derived from undisturbed and well-dated sediments in seas or lakes. The only example of this approach that is reported in the peer-reviewed literature refers to a sediment core from the Bornholm deep in the Baltic Sea (6).At that time,onlythe congenersBDE47,BDE99, and an unknown penta-BDE congener (probably BDE100) were reported,which showed continuousincreasesfrom 1972 to 1987. Thispresent studyfocused on the determination ofa wider range ofindividualBDE-congeners in a number ofsediment cores from three different locations in northwestern Europe. The main aim of this study was to investigate whether the distribution of PBDEs reflected the scale of their industrial production, or whether there were any indications of the occurrence of naturally produced BDE congeners, by in- vestigating older layers of the same sediment cores as well as in ancient organic-rich sediments. The results of three cores with sediment deposited within the last 100 years and an ancient marine sediment core from the Kimmeridge clay formation on the south coast of England are discussed in this paper. Experimental Section Sample Collection. Dram m enfjord Core. The Drammenfjord is a branch of the Oslofjord in Norway. The sediment was collected in October 1999 with a Rheineck box corer at the position 59°38′ N and 10°26′ E from the R/V Pelagia , in a water depth of 100 m. A subcore was taken with a liner of 70-mm diameter which was sliced into sections of 0.5 cm. Wadden Sea Core. The “Vlieter” was the main gully between the Wadden Sea and the former Zuiderzee before the latter was shut off from the Wadden Sea by the construction ofa dike between the provincesofNorth Holland *Correspondingauthorphone: (+31) 222 369 466; fax: (+31) 222 319 674; e-mail boon@nioz.nl. † Royal Netherlands Institute for Sea Research. § Present address: TNO-MEP, Department for Ecological Risk Studies, P.O. Box 57, 1780 AB Den Helder, The Netherlands. ‡ Netherlands Institute for Fisheries Research. FIGURE 1. General structure of PBDEs; C12OBr xH(10-x). The positions 2-6 and 2′-6′ may contain either bromine or hydrogen atoms. In theory, 209 different molecules are possible. Environ. Sci. Technol. 2003, 37, 3803-3807 10.1021/es034226o CCC: $25.00  2003 American Chemical Society VOL. 37, NO. 17, 2003 / ENVIRONMENTAL SCIENCE & TECHNOLOGY 9 3803 Published on Web 08/06/2003