Environ. Sci. Technol. 2002, 36, 2560-2565
Spatial Distribution and Temporal Accumulation of Polychlorinated Dibenzo-p-dioxins, Dibenzofurans, and Biphenyls in the Gulf of Finland P I R J O I S O S A A R I , * , † H A R R I K A N K A A N P A¨ A¨ , ‡ JUKKA MATTILA,§ HANNU KIVIRANTA,† MATTI VERTA,| SIMO SALO,| AND T E R T T U V A R T I A I N E N †,# Department of Environmental Health, National Public Health Institute, P.O. Box 95, FIN-70701 Kuopio, Finland, Finnish Institute of Marine Research, P.O. Box 33, FIN-00931 Helsinki, Finland, Radiation and Nuclear Safety Authority, P.O. Box 14, FIN-00881 Helsinki, Finland, Finnish Environment Institute, P.O. Box 140, FIN-00251 Helsinki, Finland, and University of Kuopio, Department of Environmental Sciences, Finland
Dated sediment cores and surface sediments were analyzed from the Gulf of Finland, a part of the Baltic Sea, to study the sources, levels, distribution, and total amounts of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs). The gulf was found to be severely polluted, with PCDD/F sum concentrations as high as 101 000 ng/kg and 479 ng/kg WHO-TEQ in dry weight. The source of pollution was the former manufacturing and use of a chlorophenol based wood preservative along the Kymijoki River. It was estimated that the impacted sedimentary area stretched a distance of 75 km away out from the coast and that the PCDD/F sum load attributed to the wood preservative source was 1770 kg of PCDD/Fs or 12.4 ((2.8) kg WHOTEQ. The surface sediments contained 24-66% of the maximum concentrations present in the 1960-1970s, showing that the river still acts as a significant PCDD/F source and may contribute to the high levels in fish. Moreover, the reduced PCDD/F and PCB concentrations were partly due to the dilution by increased dry matter deposition. PCBs were uniformly distributed over the gulf, and the PCB load in the polluted area was 2020 kg or 0.14 kg WHOTEQ.
Introduction Sea bottoms form large sinks for polychlorinated dibenzop-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), and other persistent organic pollutants. Those pollutants which were incorporated in the sediments a long time ago are presently covered by more recent deposits. This process called natural burial represents one feasible way of reducing the bioavailability and release of pollutants, * Corresponding author phone: +358 17 201 353; fax: +358 17 201 265; e-mail:
[email protected]. † National Public Health Institute. ‡ Finnish Institute of Marine Research. Present address: University of Western Sydney, Campbelltown Campus, Campbelltown, Locked Bag 1797, Penrith South, NSW 1797, Australia. § Radiation and Nuclear Safety Authority. | Finnish Environment Institute. # University of Kuopio. 2560
9
ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 36, NO. 12, 2002
provided that the recent deposits are much cleaner than the old ones. In cases where natural burial is considered to be an appropriate remediation option, the minimum tools of risk assessment and management should include a survey on the sources and distribution, assessment of the magnitude of pollution, and then investigation of the burial and degradation processes. Several coastal point sources of PCDD/Fs and PCBs have been identified. However, the total pollutant releases are rarely known. Probably the worst case ever reported is the Frierfjord in Norway, where the sediments have become polluted by a PCDD/F amount of 50-100 kg I-TEQ (1). Severe pollution of sediments has also been reported at Newark Bay (NJ), where the total amount of 2,3,7,8-TCDD is 4-8 kg (2). An annual PCDD/F flux of 15 kg has been estimated for the sediments of the Tokyo Bay, Japan (3). Other coastal areas that are notorious for their PCDD/F pollution include the Venice Lagoon in Italy (4) and the harbor of Hamburg in Germany (5). PCB loads as high as several hundred tons have been reported in the Fox River (MI) and in the Hudson River (MI) (6, 7). Great efforts have been expended on dredging projects to remediate PCB contaminated rivers (7, 8) and lakes (9). In Finland, high levels of PCDD/Fs have been analyzed in the sediments of the Kymijoki River, up to 350 000 ng/kg I-TEQ in dry weight (d.w.) (10, 11). It has been estimated that the production and use of a wood preservative, Ky 5, along the Kymijoki River has led to a sedimentary PCDD/F load of 16-21 kg I-TEQ, of which 6-7 kg I-TEQ could have been carried out into the Gulf of Finland, a part of the Baltic Sea (10). The PCDD/F load attributed to another identified point source on the coast of the Gulf of Finland is only about 0.032 kg I-TEQ (12). More thorough investigations on the actual amounts and sources of pollutants into the Baltic Sea are needed, especially as the PCDD/F levels in fish have difficulties in meeting the regulations of the European Union, coming into force in 2002 (13, 14). The purpose of this study was to increase our understanding of PCDD/F and PCB pollution and behavior in marine sediments as an important part of the global pollutant budget and to answer to the questions that have arisen as the need to manage the local pollution case on the Gulf of Finland has evolved.
Materials and Methods Study Area. The Gulf of Finland is surrounded by Finland, Russia, and Estonia (Figure 1). The gulf has a small waterbody (1100 km3) compared to its large catchment area of 30 000 km2, which makes it vulnerable to anthropogenic pollution. The main rivers discharging into the gulf are the Rivers Neva, Kymijoki, and Narva. Active sedimentation prevails in the gulf with annual sedimentation rates of 2-20 mm/a (average 6 mm/a) (15). Until 1984, a wood preservative Ky 5 (mainly 2,3,4,6tetrachlorophenol) was manufactured in a chemical plant situated next to the Kymijoki River. Despite the discontinuation of the production and use (by 1988) of this chemical, polluted sediment particles still carry manufacturing byproducts, PCDD/Fs, toward the estuary. The river has two branches, and they both transport almost an equal amount of suspended solids. Sediment Sampling and Dating. Duplicate sediment cores were taken during two cruises of the research vessel Aranda (Finnish Institute of Marine Research) in December 1997 and June 1998. Sampling stations were located in areas with a known accumulation of recent sediments but with 10.1021/es0158206 CCC: $22.00
2002 American Chemical Society Published on Web 05/04/2002
FIGURE 1. A map of the sampling area. different sedimentation rates. A grid of 1 × 1 nautical miles was echosounded at the stations, and the data were used to characterize the structure of the seabed and to verify the suitability of the site for sampling. A gravity corer was used to take samples, diameter 8 cm and length about 50 cm. The sediment cores were sectioned onboard into 1-2 cm sections, which were stored frozen until the chemical analyses. Based on the dating results, 11 representative cores were selected for PCDD/F and PCB analyses. In addition to the above-mentioned sediment cores, seven coastal surface sediment samples (C1-C7) and one core (A1) were collected in 1996-1997 using a Limnos-type sampler with a diameter of 11 cm. We also received five surface (0-5 cm) sediment samples which had been collected, using similar sampling methods, from the Russian territorial waters in October 1998. Dating of the subsamples was based on the activities of Cs-137, Pu-239,240, and Pb-210 radionuclides. The activities of Cs-137 and Pb-210 were determined gammaspectrometrically (16), and those of Pu-239,240 were determined by a radiochemical method (17). The observed activity peak of Cs-137 was used to locate sediment deposits from the year 1986, when the accident at the Chernobyl (Ukraine) nuclear plant took place. This method has been shown to be suitable for the estimation of sedimentation rates in the Gulf of Finland (15). The highest Pu-239,240 peak was assumed to correspond to the year 1963, when the fallout from atmospheric nuclear tests was at its highest. A commonly used CSR model (constant rate of Pb-210 supply) was applied for the Pb210-based dating (18). Analyses of PCDD/Fs and PCBs. For the PCDD/F and PCB analyses, 1.5-g samples of lyophilized and homogenized sediment were Soxhlet-extracted with toluene for 20 h. The extracts were fractionated and purified by eluting them through three columns consisting of (1) sodium sulfate and silica gel, (2) activated carbon and Celite, and (3) aluminum oxide. Sulfur was precipitated from the sediments with activated copper powder. The quantification of PCDD/Fs and PCBs from the concentrated samples was achieved by measuring the native compounds and 13C-labeled internal standards by high-resolution gas chromatography-mass spectrometry (19, 20). The determined PCDD/Fs included all the 17 toxic (2,3,7,8-substituted) PCDD/F congeners and non-2,3,7,8-substituted PCDD/F congeners as homologue
sums. The determined PCBs included those with the IUPAC numbers 18, 28, 33, 37, 47, 49, 51, 52, 60, 66, 74, 99, 101, 110, 114, 118, 122, 123, 128, 138, 141, 153, 156, 157, 167, 170, 180, 183, 187, 189, 194, 206, 209, 77, 126, and 169. 2,3,7,8-TCDD toxicity equivalents (TEQs) were calculated according to the recommendations of the World Health Organization (21). Quality Control and Assurance. The participating testing laboratories used accredited methods to analyze the sediment samples. Laboratory contamination was checked, and analytical blanks were routinely carried along with each sample series. In parallel samples, the coefficients of variation (CV) of 2,3,7,8-substituted PCDD/F congeners (present at concentrations >1 ng/kg) were 300 ng/kg) were
