SYTTY
SEDIMENTATION, TRANSPORT AND FATE OF ORGANIC POLLUTANTS IN THE GULF OF FINLAND
Project leader: Terttu Vartiainen, National Public Health Institute
(KTL) and University of Kuopio P.O.Box 95, FIN-70701 Kuopio, Finland, tel.
+358-17-201 346, e-mail: Terttu.Vartiainen@ktl.fi
| PUBLICATIONS |
| TIIVISTELMÄ SUOMEKSI |
Researchers:
Pirjo Isosaari, KTL, tel. +358-17-201 353, e-mail: Pirjo.Isosaari@ktl.fi.
Merja Suutari, KTL. Present tel. +358-9-6944 619, e-mail: Merjasuutari@hotmail.com.
Jukka Mattila, Radiation and Nuclear Safety Authority, tel. +358-9-7598
8591
e-mail: Jukka.Mattila@stuk.fi.
Harri Kankaanpää, Finnish Marine Research Institute, tel.
+358-9-6139 4518
e-mail: Harri.Kankaanpaa@fimr.fi.
Markku Korhonen, Finnish Environment Institute, tel. +358-9-4030 0370
e-mail: Markku.Korhonen@vyh.fi.
Hannu Pajunen, Geological Survey of Finland, tel. +358-0205 50 3317
e-mail: Hannu.Pajunen@gsf.fi.
Consortium: Environmental Health Risk of Dioxins
Financing SYTTY organisation: The Ministry of Environment
Funding from SYTTY / Total funding of project (€): 75684
/ 241013
Person-months of work funded by SYTTY / Total person-months of work:
24 / 60
KEY WORDS: dated sediments, PCDDs, PCDFs, organohalogen compounds,
Gulf of Finland
EXTENDED ABSTRACT
1 Introduction
A recent study has shown that the levels of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the sediments of the river Kymijoki are among the highest levels analyzed in the world. Estimations of the pollutant fluxes suggested that the river would still be a notable source of PCDD/Fs into the Gulf of Finland. PCDD/Fs in the river mainly originate from the production of a wood preservative Ky 5 in 1939-1984. In addition to the discharges from the river Kymijoki, sources of PCDD/Fs in the Gulf of Finland may include discharges from the river Neva, surface runoff, atmospheric deposition, natural formation, and unknown sources. Industrial and agricultural areas in the large drainage basin of the gulf also contribute to the load of other organochlorine compounds, such as polychlorinated biphenyls (PCBs; low levels also present in Ky 5) and pesticides.
We have surveyed the pollution history and the present state of pollution in the Gulf of Finland. Levels of PCDD/Fs, PCBs, and organochlorine pesticides were determined from sediment cores to learn about their horizontal and vertical distribution. Levels of extractable organic halogens (EOX) were also analyzed from a sediment core sampled from the Kotka area. In order to study background levels of contaminants and long-term changes in microbial community, a 5.2-m deep sediment core was drilled from a remote lake.
2 Methods
Sediment sampling and dating. Duplicate sediment cores from 21 sampling stations in the Gulf of Finland were taken during two cruises of research vessel Aranda. Sampling stations were in areas with known accumulation of recent sediments but with varying sedimentation rate. During the cruises, a grid of 1 x 1 nautical miles was echosounded at 15 stations, and the data was used to characterize the structure of the seabed. Collected sediment cores were sectioned into 1-5 cm thick subsamples, which were stored frozen, lyophilized, and homogenized before chemical analyses.
Dating of the subsamples was based on the analyses of Cs-137, Pu-239,240 and Pb-210 radionuclides. Activities of Cs-137 ja Pb-210 were determined gammaspectrometrically (a total of 230 analyses), and those of Pu-239,240 were determined by a radiochemical method (63 analyses). The observed activity peak of Cs-137 was used to locate sediment deposits from the year 1986, when the Chernobyl accident took place. The highest Pu-239,240 peak was assumed to correspond to the year 1963, when the fallout from atmospheric nuclear tests was highest. A commonly used CSR model (constant rate of Pb-210 supply) was used for the Pb-210 –based dating.
Analyses of PCDD/Fs, PCBs, pesticides, EOX, and PLFA. For PCDD/F and PCB analyses, portions of 1.5 g of dry sediment were Soxhlet-extracted with toluene. The extracts were purified by eluting them through three columns consisting of sodium sulfate, silica gel, activated carbon, Celite, and aluminum oxide. Sulfur was precipitated from the sediments with copper powder. Quantification of PCDD/Fs and PCBs was achieved by measuring the native compounds and 13C-labeled internal standards by high-resolution gas chromatography-mass spectrometry. The determined compounds included 17 toxic (2,3,7,8-chlorinated) PCDD/F congeners, non-2,3,7,8-chlorinated PCDD/F congeners (as homologue sums), 3 non-ortho PCBs (coplanar PCBs), and 33 mainly mono- and di-ortho PCBs. Toxic equivalence factors (TEFs) defined by WHO were used to calculate toxic equivalents (WHO-TEQs) for both PCDD/Fs and PCBs.
For pesticide analyses, a portion of 1 to 5 g of dry sediment was extracted in an ultrasonic water bath with a mixture of acetone/hexane (1:1, v:v). After the addition internal standards, the samples were purified with sulfuric acid, concentrated, and analyzed using a gas chromatograph equipped with two different columns and electron capture detectors. The analyzed pesticides included hexachlorobenzene, alfa-, beta-, and gamma-hexachlorocyclohexane, trans-nonachlor, alfa-chlordane, p,p’-DDE, -DDD, and -DDT.
Total amount of organohalogen compounds was quantified by measuring the EOX sum parameter (extractable organic halogens). A portion of 1.1-5.0 g of dry sediment was analyzed from the sediment core K19, which was sampled from a large sedimentation area about 20 km away from Kotka. The samples were extracted with cyclohexane-isopropanol, using an ultrasonic bath and a shaker. The supernatant was washed with acidic potassium nitrate to remove inorganic halides, followed by concentration in a rotary evaporator. The concentrated samples were analyzed by an EOX analyzer that utilized combustion at 950 ºC and microcoulometric titration. The number of parallel determinations was 3-7.
The microbial community structure in the sediments was determined by analyzing phospholipid fatty acids (PLFAs). Lipids were extracted from sediments, fractionated in a silica gel column, and the fatty acid composition of phospholipid fraction was determined.
3 Results and Discussion
PCDD/Fs and PCBs. Concentration peaks of PCDD/Fs were typically found in sediment layers that had been deposited between 1970s and mid-1980s. Trends in PCDD/F concentrations followed the production years of Ky 5. Table 1 shows the highest PCDD/F sum concentrations in 5 chronologically and spatially representative sediment cores. The highest sum concentration, 101 000 ng/kg, was analyzed from the sediment core K15, which was sampled from the station closest to Kotka. WHO-TEQ at this depth was almost as high as the guideline value for contaminated soils, 500 ng TEQ/kg. Congener composition of the sample reflected a strong influence of Ky 5, where 1,2,3,4,6,7,8-heptachlorodibenzofuran (1,2,3,4,6,7,8-HpCDF) and octachlorodibenzofuran (OCDF) were the predominating congeners. Samples XV-1 and LL3a defined a less contaminated zone in the vicinity of Kotka. Here the sum concentrations of PCDD/Fs were about 10% of those analyzed at K15. Percentage of Ky 5 indicator congeners declined, while PCB sum concentrations remained nearly the same as in K15. The cleanest samples in terms of PCDD/Fs (sum and WHO-TEQ) and PCBs were found at the mouth of the Gulf of Finland (JML1b) and at Neva Bay (SL2s). Peak concentrations of PCBs and WHO-TEQ did not necessarily coincidence with PCDD/F peaks, but the values in Table 1 are indicative of the level of contamination at each sampling station.
The present PCDD/F levels were <45% of the maximal concentrations at all the above-mentioned sampling stations, except station SL2s, where the concentration had remained unchanged.
Table 1. Maximal PCDD/F sum concentrations of 5 sediment cores, and PCB concentrations, WHO-TEQs (all in dry weight), and percents of the main Ky 5 congeners at the same depths; maximal DDT sum concentrations.
| Sampling station | K15 | XV1 | LL3a | JML1b | SL2s |
| Distance from | 12 km | 40 km | 56 km | 190 km | 130 km |
| Kotka (direction) | (south) | (south-east) | (south-west) | (west) | (east) |
| PCDD/F maximum | |||||
| Depth, cm | 25-27 | 12-13 | 25-27 | 4-5 | 7-8 |
| Years (CsPu)a | 1968-1971 | 1981-1982b | 1970-1973 | 1972-1978 | 1974-1979 |
| PCDD/F sum, ng/kg | 101000 | 9510 | 9160 | 1430 | 570 |
| PCB sum, ng/kg | 57300 | 37100 | 56700 | 21500 | 19800 |
| WHO-TEQc, ng/kg | 479 | 73 | 64 | 26 | 12 |
| HpCDF+OCDFd | 96% | 91% | 93% | 61% | 58% |
| DDT maximum | |||||
| Depth, cm | 12-13 | 17-18 | 25-27 | 4-5 | 9-10 |
| DDT sume ng/kg | 5410 | 10560 | 29500 | 17090 | 11800 |
Further reports will also address PCDD/F and PCB levels detected in sediments from the beginning of the 20th century, and include an estimate of the total amounts of these contaminants in the sediments of the Gulf of Finland.
Surface sediments of Lake Ahmasjärvi, in central Finland, only contained low levels of industrial background contamination. Sum concentration of PCDD/Fs was 84.3 ng/kg dry weight. However, a low level (2.0 ng/kg) of PCDD/Fs was still detected at the depth of 4.0 m, where the sediments were more than 8000 years old. A characteristic PCDD/F congener profile (distribution) was found in all pre-industrial sediment layers. Recent studies have associated similar congener profiles with natural formation mechanisms of PCDD/Fs.
EOX. The highest EOX concentration in the core from station K19 was 16.6+0.25 mg/kg dry weight. It was analyzed at the depth of 19 cm, representing sediments that had deposited around the year 1970. Elevated EOX concentrations in the 1960s-1980s were probably due to the high discharges of chlorine bleaching effluents into the sea. The most contaminated sediments were covered by cleaner, freshly deposited sediments. However, the surface concentrations were higher than the background levels of around 1-2 mg/kg, which were analyzed at depths below 25 cm. Natural formation of organochlorine compounds probably contributed to the surface concentrations. It must be emphasized that the observed vertical organochlorine profiles are not only influenced by temporal emission of the toxic substances. Geological and sedimentation conditions (i.e. currents, seabed structure etc.) also affect deposition of organic compounds into sediments.
Pesticides. Organochlorine pesticides were analyzed from 9 sediment
cores. Concentrations of p,p’-DDT and its metabolites p,p’-DDE and p,p’-DDD
as well as other pesticides (hexachlorobenzene, alfa-, beta-, and gamma-hexachlorocyclohexane,
trans-nonachlor, and alfa-chlordane) were more uniformly distributed in
sediments than PCDD/Fs (Table 1). Pesticide concentrations were low, and
the highest concentrations were located below the most recently deposited
surface sediments. At sampling station K15, the highest concentrations
were possibly not reached in the analyzed sediment slices, because of the
high sedimentation rate.
In addition to chemical data, this study produced echosounding data
and data on sediment structure from 15 stations, and will be included in
further reports.
PLFAs. The microbial community structure determined by PLFAs was fairly similar from layers 310-320 cm to 110-120 cm below the Lake Ahmasjärvi bottom. In the surface layer of 20-30 cm the proportions of 16:1 acids with different positions in the double bond, 18:1w7, TBSA and br-17 acids were slightly elevated, in addition to iso- and anteiso-branched acids. These acids indicate increases in gram-negative and gram-positive bacteria including actinomyces. However, in the surface differences in PLFAs from deeper sediments were relatively small and it is difficult to estimate to what extend they resulted from the pollution, and differences in lake bottom conditions compared to deeper sediments.
4 Conclusions
Vertical distribution of PCDD/Fs in the sediment cores sampled near
the estuary of the river Kymijoki correlated with the production years
of the wood preservative Ky 5. The sediment layers that were most heavily
contaminated by PCDD/Fs, PCBs and other organohalogen compounds were covered
by cleaner, more recently deposited sediments. Horizontal distribution
of PCDD/Fs and the composition of PCDD/F congeners reflected the historical
and present role of the river Kymijoki as the major source of PCDD/Fs in
the Gulf of Finland.