Environ. Sci. Technol. 1996, 30, 3266-3274
Polychlorinated Naphthalenes in Sediment and Biota from the Gdan˜sk Basin, Baltic Sea JERZY FALANDYSZ* AND LIDIA STRANDBERG Department of Environmental Chemistry & Ecotoxicology, University of Gdan ˜ sk, ul. Sobieskiego 18, PL 80-952 Gdan ˜ sk, Poland
PER-ANDERS BERGQVIST, STEN ERIK KULP, BO STRANDBERG, AND CHRISTOFFER RAPPE Institute of Environmental Chemistry, University of Umea˚, S-901 87 Umea˚, Sweden
To identify potential sources and accumulation features concentrations, profiles, and patterns of polychlorinated naphthalene (PCN) residues were determined in sediment, mussel, crab, plankton, and fishes from the Gdan˜sk Basin, Baltic Sea. Different marine organisms of the lower food web clearly bioaccumulate many PCN congeners. Depending on the matrix type, PCNs substituted with four or five chlorines dominate. Due to the characteristic profile and pattern of PCN congener groups found in subsurface plankton, mussel, and surface sediments, deposition from the atmosphere is postulated to be the main source of these pollutants. Nineteen of 22 tetra-, all 14 penta-, 9 of 10 hexa-, and both hepta-CNs could be quantified in the samples. The patterns of tetra-, penta-, and hexa-CNs varied largely between the samples or groups of the samples as well as when compared to the technical PCNs formulation Halowax 1014. This implies different absorption/retention rates and/or marked, structure-dependent metabolism of some PCN congeners by marine species.
Introduction Polychlorinated naphthalenes (PCNs) represent a group of 75 compounds that are relatively well soluble in lipids and organic solvents and have physical and chemical properties such as melting point, volatility, water solubility, octanolwater partition coefficients (KOW), bioconcentration factors (BCF), adsorption coefficients in sediments (KOC), and Henry’s law constant (H), which favor their environmental persistency and bioaccumulation (1-7). These chemicals are ubiquitous pollutants; hovewer, knowledge on environmental fate, distribution, and accumulation in the biota of many PCN congeners found in the technical formulations is very limited (4). * Author to whom correspondence should be addressed; Fax: +4858-410357; telephone: +48-58-415271, ext 272.
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Polychlorinated naphthalenes are primairly industrial chemicals (1, 8) and were introduced into a common practice at the beginning of this century; however, their sources in the environment are related also to the byproducts of human activities due to combustion and chlorination processes (9-24). Halowax is a trade name of a technical PCN product manufactured in the United States, and at least France, Germany, Italy, and Great Britain also had their own PCN formulations (25-27). The synthesis of PCNs on a technical scale was voluntary ceased in United States in 1977, while some volumes were produced in western Europe until the mid 1980s (4). Learning from the lesson with polychlorinated biphenyls (PCBs), it seems possible that PCNs potentially were synthesized in technical scale also in some other countries (for example, it was until recently rather unknown that Poland had its two own technical PCB formulationssChlorofen, which is similar in appearance and composition to Aroclor 1262 (28), and Tarnol, which is similar to Aroclor 1254). There are only rough estimates of the world (United States and western Europe) production volume of PCNs. This volume is assessed to be around 10% of the total production of PCBs (29), which is around 1 500 000 t for the United States, western Europe, Japan and Australia, including also the former USRR and Czechoslovakia (30, 31), while virtually nothing is known on the type and quantity of PCNs potentially manufactured in other coutries. 1-Chloronaphthalene is a liquid at room temperature (1, 8) and is used as an organic solvent and additive in industrial chemical processes. 1-Chloronaphthalene was utilized in Xylamitssa popular wood (and other purpose) preservative widely applied in the past in Poland and also containing technical pentachlorophenol together with the waste products of chlorophenols distillation and other substances (32). Technical PCN formulations are manufactured by the chlorination of molten naphthalene in the presence of iron(III) or antimony(V) chloride (1, 8). Both electrophilic and nucleophilic substitution as well as radical attacks occur predominantly in the R- (peri-; 1, 4, 5, and 8) positions on the naphthalene skeleton (33, 34). Nakano et al. (18) and Wiedmann and Ballschmiter (20) listed all 75 PCN congeners. The predominant PCN congeners found in the equivalent mixture of Halowax 1000, 1001, 1013, 1014, 1031, 1051, and 1099 (Equi-Halowax) are such individuals as PCNs 1, 5/7, 23/24, 33/34/37, 38/40, 52/60, 61, 57, 62, 53, 59, 71/72, 69, and 74 (22). Among the tetra-, penta-, and hexa-CNs in Halowax 1014, PCNs 38, 33, 46, 59, 62, 58, 57, 61, and 65 (18-20, 23) predominate. Such PCN congeners as 39, 54, 55, and 70 were not found in Halowax 1014 (23). On the other hand, as much as 74 of 75 possible PCN congeners are formed in various proportions throughout the radical reactions in the flame (22, 23), a process dependent on kinetic, thermodynamic, and steric effects (17). In products such as fly ash and flue gas, formed in municipal solid waste incinerators (MSWI), PCNs 39, 54, 60, 51, 52, and 66/67 (22, 23) predominate. During tap water chlorination, mono- and di-CNs are formed (11), and nothing is known on the possibility of formation of higher chlorinated PCN congeners.
S0013-936X(96)00057-0 CCC: $12.00
1996 American Chemical Society
FIGURE 1. Sampling locations of plankton (P), sediment (S), and organisms (F) in the Gdan˜sk Basin.
Polychlorinated naphthalenes were identified in the past in various biological samples, as reviewed by some authors (4); however, the analytical methods used were not specific enough to enable quantification of individual congeners. In more recent papers (21, 35) many PCN congeners were quantified in the environmental and technical samples; however, their structure was not shown. Some accurately defined PCN isomers were quantified recently in human adipose tissue in Canada (36), in cod liver and guillemot egg from the Baltic Sea (37), in cod liver from the coastal area of southern Norway (38), in a rice oil causing Yusho poisoning, in adipose tissue of Yusho victim, and in technical PCB formulation of Kanechlor 400 (24). Studies on environmental sources, concentrations, distribution, fate, and effects of PCNs using congenerspecific and highly sensitive analytical methods, which are generally lacking, are required since these xenobiotics are wide spread in nature and many of them pose a high toxic potential (39, 40). Recently, nearly all theoretically possible isomers of tetra-, penta-, hexa-, and hepta-CN could be identified and quantified in tissues of white-tailed sea eaglessa top bird of prey in northern Europe (6)sin harbor porpoise from the Baltic Sea, and in black cormorants breeding at the coast of the Gulf of Gdan ˜ sk, Baltic Sea (7, 41).
Materials and Methods Collection of Samples. Surface sediment, subsurface plankton, mollusk, crustacean, lamprey, and 10 species of fishes were collected from the area of the Gdan ˜ sk Basin in 1992. The sampling locations are shown in Figure 1. The common and latin names of organisms examined together with the total number of the individuals and their lipids content and the results of chemical analysis are given in Table 1. A surface sediment sample (0-10 cm) was taken from the nearshore sedimentation area of the Wisla River (Vistula River) in Kiezmark under Gdan ˜ sk in June 6, 1992. Sediments were air-dried, crushed, and Soxhlet-extracted with toluene for 12 h. For the recovery measurements (internal standard) and extract cleanup, the procedure was the same as is given below for the biotic material. A subsurface plankton sample (218 g wet wt) was taken in the central area of the Gdan ˜ sk Deep during the research cruise of R/V Oceania in September 1992. That sample consisted of several species of phyto- and zooplankton, and the dominating genera were such as Chaetoceros, Coscinodiscus,
Nodularia, Anabaena, Prosocentrum, Aphanisomenon, Copapoditi, Nauplii, Bosnina, Keratella, and Cladocera. Mussels (350 specimens, ca. 1.5-4 cm long) were taken by grab sampler, while crab and fishes, except for stickleback, were netted using a bottom trap situated several meters out from the harbor of the port of Gdynia. Adult sticklebacks of both sexes were collected using a hand net directly from the harbor in Oksywie (ca. 2 km north of the site where all other fishes were collected). In the case of lamprey, herring, eelpout, and round goby, adult specimens with body length between 16 and 26 cm were selected. For other specimens, the individuals were small in size, i.e., flounders, lesser sand eel, and sand eel were ca. 13 cm in body length; for perch, it was between 10 and 17 cm; for pikeperch, it was ca. 15 cm; and for cod, it was ca. 20 cm. All animals were deep frozen (-20 °C) directly after capture and kept in such condition in clean polyethylene bags until chemical analysis. Pooled samples, containing from 3 to 30 whole fishes or soft tissue of 350 individual mussels, were subjected to chemical analysis. Chemical Analyses. The analytical method used for the determination of chloronaphthalenes is a part of a multiresidue procedure performed in parallel analysis of many organochlorines and polynuclear aromatic hydrocarbons (PAH) (42). After homogenization of the sample (77-378 g) with anhydrous sodium sulfate, which was baked at 550 °C for 2 days, a powdered mixture was packed into a wide bore open glass column, spiked with an internal standard ([13C12]-3,3′,4,4′,5-pentachlorobiphenyl; PCB 126), extracted with a 500 mL mixture of acetone and n-hexane (2.5:1) and 500 mL of n-hexane and diethyl ether (9:1) to obtain a fat extract. Bulk lipid removal was performed by means of the polyethylene film dialysis method (43, 44). After dissolving the extracted lipids in cyclopentane, dialysis through the polymeric mebrane was accomplished by changing the dialyzate after 24, 48, and 72 h. The three dialyzate fractions, containing normally between 1 and 10% of the original lipids, depending on sample size and matrix type, were combined and concentrated to a few milliliters using a rotary evaporator. The extract was split into two parts, of which 90% was used for analysis of PCNs and some other planar compounds not described here, while 10% was used for the analysis of organochlorine pesticides and the bulk of PCBs. The remaining fat was removed on a combined silica column packed as follows from the bottom: glass wool, potasium silicate (10 mL), a layer of neutral silica gel, 40% sulfuric acid silica gel (20 mL), and at the top a layer of anhydrous sodium sulfate. The column length was 20 cm, and the diameter was 38 mm. The gravimetric elution of planar organochlorines was done with 200 mL of n-hexane, and 40 µL of tetradecane was added as a keeper before evaporation of the solvent. The extract was then fractionated on HPLC using an activated carbon column (Amoco PX-2; 2-10 µm, dispersed on LiChrospher RP-18; 15-25 µm) (44, 45). Between the carbon column and the precolumn, a filter valve (Valco Instruments Co. Inc., TX) was mounted, enabling backflush of the column. The elution from the HPLC carbon column was performed with 1% methylene chloride in n-hexane for 7.5 min, solvent 1, and then gradient elution up to 10% toluene, solvent 2, for 32.5 min. Fraction one, containing organochlorine pesticides and 2-4 ortho PCBs, is collected during the first 15 min, and fraction two, containing mono-ortho PCBs, is collected between 15 and 40 min. The total volume of the solvents used was 160 mL, and the flow rate was 4 mL/min. PCNs
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0.14
1,2,3,5,7-/1,2,4,6,7P5CN 1,2,4,5,7-P5CN 1,2,4,6,8-P5CN 1,2,3,4,6-P5CN 1,2,3,5,6-P5CN 1,2,3,6,7-P5CN 1,2,4,5,6-P5CN 1,2,4,7,8-P5CN 1,2,3,5,8-/1,2,3,6,8P5CN 1,2,4,5,8-P5CN 1,2,3,4,5-P5CN 1,2,3,7,8-P5CN total penta-CNs
1,2,3,4,6,7-/ 1,2,3,5,6,7-H6CN 1,2,3,4,5,7-/ 1,2,3,5,6,8-H6CN 1,2,3,5,7,8-H6CN 1,2,4,5,6,8-/ 1,2,4,5,7,8-H6CN 1,2,3,4,5,6-H6CN 1,2,3,4,5,8-H6CN total hexa-CNs
1,2,3,4,5,6,7-H7CN 1,2,3,4,5,6,8-H7CN total hepta-CNs total PCNs
52/60
66/67
73 74
63 65
a
0.012 0.012 0.024 6.7
0.0066 0.0033 0.081
0.018 0.0082
0.012
0.033
0.070 0.074 ND 1.1
0.016 0.016 0.032 7.6
0.0093 0.007 0.14
0.019 0.019
0.016
0.072
0.16 0.014 0.0056 1.4
0.037 0.34 0.082 0.030 0.014 0.12 0.15 0.15
0.055 0.055 0.11 110
0.26 0.16 1.4
0.21 0.26
0.19
0.30
4.4 0.61 0.14 34
1.0 6.9 2.2 0.86 0.21 2.3 5.4 3.0
7.4
1.1 7.5 16 7.4 1.1 77
7.0 0.96 11 2.6
5.1 17
0.42 0.41 0.83 320
0.84 0.26 21
8.3 3.0
2.9
5.7
8.9 0.33 0.42 180
8.2 54 11 3.6 0.33 7.3 10 2.2
69
0.52 8.1 5.7 7.4 1.2 120
3.7 1.6 9.2 1.4
42 42
0.017 0.009 0.026 6.3
0.0076 0.013 0.92
0.41 0.066
0.023
0.40
0.13 0.014 0.031 2.6
0.042 0.38 0.042 0.021 0.0054 0.12 0.13 0.14
1.6
0.044 0.43 0.31 0.16 0.015 2.8
0.55 0.020 0.038 0.05
0.64 0.52
1.3 7.3 5.2 3.6 0.32 60
5.6 0.51 7.1 1.1 0.16 1.6 1.5 0.59 0.029 16
2.0 0.083 2.1 0.25
3.2 4.0
4.2 0.41 0.12 53
1.6 11 1.6 0.87 0.34 5.6 5.7 2.6
19
0.70 0.063 0.028 10
0.26 2.1 0.50 0.14 0.064 0.74 1.2 0.79
3.7
0.14 0.096 1.9
0.47 0.29
0.30
0.59
0.017 0.023 0.28
0.057 0.042
0.039
0.097
0.21 0.10 0.31 36
0.030 0.017 0.047 120 b
0.003 0.001 0.004 17
0.018 0.022 0.32
0.063 0.034
0.052
0.13
0.57 0.051 0.020 8.0
0.27 1.7 0.34 0.14 0.063 0.74 1.1 0.75
2.3
0.080 0.91 0.64 0.015 0.0039 8.7
1.2 0.034 1.3 0.12
2.2 2.2
0.08 0.07 0.15 29
0.064 0.054 1.5
0.39 0.34
0.21
0.45
1.3 0.10 0.042 15
0.49 4.4 0.26 0.064 0.15 1.0 1.3 1.0
4.5
0.21 1.8 0.84 0.61 0.032 13
1.9 0.096 1.3 0.24
3.5 2.6
0.005 0.0047 0.0097 19
0.029 0.085 1.9
0.45 0.68
0.14
0.52
0.85 0.048 0.032 12
0.44 3.3 0.070 0.039 0.056 0.41 0.59 0.38
5.7
0.12 0.92 0.51 0.39 0.016 5.6
0.58 0.027 0.65 0.10
1.3 0.99
NA, not applicable. c ND, not detected.
0.0045 0.0015 0.006 26
Heptachloronaphthalenes
0.42 0.41 8.6
4.2 1.4
0.96
1.2
Hexachloronaphthalenes
1.2 0.076 0.0086 21
1.6 6.6 0.36 0.15 0.0048 1.8 1.2 0.74
7.4
Pentachloronaphthalenes
0.071 0.64 0.27 0.19 0.018 6.1
0.29 0.022 0.37 0.041
11 17
Tetrachloronaphthalenes 3.2 1.0
Column headings represent sample type, Latin name, volume (g) or number of species, and lipids content (%).
69 71/72
64/68
59 49 56
0.45 0.085 0.029 0.031 0.0074 0.056 0.070 0.082
0.074 0.42 1.2 0.53 0.079 6.0
0.014 0.084 2.0 0.74 0.12 5.5
58 61 50 51 54 57 62 53/55
0.69 0.079 0.78 0.18
0.67 0.097 0.096 0.027
0.29
0.46 1.5
0.18 1.5
structure
42 1,3,5,7-T4CN 33/34/37 1,2,4,6-/1,2,4,7-/ 1,2,5,7-T4CN 47 1,4,6,7-T4CN 36/45 1,2,5,6-/1,3,6,8-T4CN 28/43 1,2,3,5-/1,3,5,8-T4CN 27/30/39 1,2,3,4-/1,2,3,7-/ 1,2,6,7-T4CN 32/48 1,2,4,5-/2,3,6,7-T4CN 35 1,2,4,8-T4CN 38/40 1,2,5,8-/1,2,6,8-T4CN 46 1,4,5,8-T4CN 41 1,2,7,8-T4CN total tetra-CNs
PCN no.
ND ND ND 89
0.15 0.060 2.0
0.22 0.93
0.23
0.37
1.9 0.14 0.026 47
2.2 17 0.48 0.17 0.092 2.4 1.8 1.8
19
0.27 3.3 2.6 1.7 0.15 40
4.1 0.17 3.2 0.36
17 7.0
0.0050 0.0025 0.0075 22
0.038 0.098 3.0
0.61 0.79
0.17
1.3
0.73 0.053 0.015 14
0.61 2.8 0.089 0.042 0.058 0.30 0.56 0.37
8.4
0.091 0.69 0.57 0.50 0.045 5.2
0.28 0.031 0.58 0.098
1.6 0.75
0.07 0.05 0.12 260
0.53 0.082 5.7
2.0 0.064
0.65
2.4
9.7 1.3 0.12 160
5.3 47 4.1 0.93 0.46 11 19 13
45
1.2 13 4.5 2.7 0.14 98
14 0.35 15 0.80
28 18
0.004 0.001 0.005 13
0.036 0.034 1.4
0.50 0.29
0.17
0.35
0.26 0.016 0.0061 78
0.35 2.6 0.028 0.018 0.014 0.29 0.31 0.18
3.7
0.045 0.26 0.33 0.19 0.020 39
0.27 0.019 0.3 0.042
1.9 0.47
lesser sand Baltic round crab lamprey flounder stickleback sand eel perch pikeperch elepout cod eel herring goby plankton mussel sediment mixed Mytilus Carcinus Lampetra Platychthis Gasterosteus Amodytes Heperoplus Clupea Perca Stizostedion Zoarces Neogobius Gadus surface species trossulus means fluviatilis flesus aculeatus tobiasus lanceolatus harengus fluviatilis lucioperca viviparus melanostomus morhua (0-10 cm) ca. 220 g 350 3 3 5 30 20 20 3 8 3 3 6 3 b NA 1.83 1.30 1.27 6.27 4.78 2.44 5.48 5.73 9.00 5.96 4.44 3.02 4.78 3.40
Concentrations of Polychlorinated Naphthalenes in Surface Sediment (ng/g Dry Wt), Plankton, Mussel, Crab, Lamprey, and Fishes (ng/g Lipid Wt) from the Gdan˜sk Basin, Baltic Seaa
TABLE 1
together with PCDDs, PCDFs, and non-ortho planar PCBs were reverse eluted in fraction three with 80 mL of toluene (Burdick and Jackson, Muskegon, MI), degassed with argon. The eluate was concentrated and spiked with [13C12]2,2′,4,5,5′-pentachlorobiphenyl (PCB 101) as the recovery standard and evaporated to a final volume of 30 µL with tetradecane added as a keeper. A gas chromatograph (Hewlett Packard 5890 GC) coupled to a mass spectrometer (VG Analytical 11-250 J, Altrincham, United Kingdom) was used for the determination of PCN congeners. Injections were made using splitless mode, and the oven was temperature programmed as follows: initial temperature 180 °C; initial time 2 min; rate 1, 20 °C/min to 200 °C, rate 2, 4 °C/min to final temperature 300 °C and final time 15 min. A Rtx-5 fused silica capillary column (60 m × 0.32 mm i.d.), coated with crossbond 5% diphenyl95% dimethyl polysiloxane with a film thickness of 0.25 µm was employed for the analysis. The ion source was kept at 250 °C and operated under electron ionization (EI) conditions at 70eV, and the MS was tuned in the selected ion monitorng (SIM) mode. For the confirmation/ quantification of PCNs, the two most abundant ions in the chlorine cluster of the molecular ion were monitored at m/z 263.9 and 265.9 for tetra-CNs, m/z 297.9 and 299.9 for penta-CNs, m/z 331.8 and 333.8 for hexa-CNs, and m/z 365.8 and 367.8 for hepta-CNs. Isotopically labeled PCBs 126 (internal standard) and 101 (recovery standard) were used for compensation of possible losses during the enrichment procedure. A procedural blank was performed with every set of the real samples analyzed. The technical mixture Halowax 1014 was used to determine elution order and pattern of PCNs in the sample chromatograms. Appropriate chromatographic data published for Halowax 1014 by Wiedmann and Ballschmiter (20), Nakano et al. (18), Takasuga et al. (22), and Imagawa and Yamashita (23) were used to identify the ellution pattern of tetra- to hexaCNs on the Rtx-5 capillary column chromatograms in this study. In one of the papers (18), the congeners of chloronaphthalene have been characterized but the structures have not in all cases been unquestionably determined. PCNs 66/67, 71, and 73 (synthesized by Dr. Eva Jakobsson, Stockholm University) were native standards used together with the above-mentioned PCBs 101 and 126 for GC/MS quantification based on the peak area, and the results were corrected for recoveries. The hexa- and hepta-CNs were quantified on the basis of the molar response (MR) factors of congeners 66/67, 71, and 73, respectively. Since the standards of individual native mono- through penta-CNs or their 13C12-labeled analogues were not available during the course of analysis, the MR (SIM) factors of hexa-CNs were used to quantify the tetra- and penta-CNs without correction for the differences in the ionization cross-section (Q), which is 33.7, 36.9, and 40.1 × 10-16 cm2 for the tetra-, penta-, and hexa-CNs, respectively (20).
Results and Discussion Polychlorinated naphthalenes were detected in the Wisla River surface sediment and in all biological samples (Table 1). Such species as crab, round goby, mussel, and stickleback showed highest concentrations of the total PCNs between 110 and 320 ng/g, and for other biological samples it was from 6.3 to 89 ng/g lipid weight. The lipid-weight based concentrations of the total PCNs in whole fishes were independent of the lipid contents of fish. Apart from the concentration of the total PCNs, there are also substantial
differences in the profile of congener groups as well as in the patterns of tetra-, penta-, and hexa-CNs between various samples analyzed; however, some similarities also could be observed (Figures 2-4 ). PCNs were quantified recently also in the muscle tissue and/or liver of pike, burbot, cod, and herring from the Swedish waters (35) and in liver of cod from Norway (38). Since only a few PCN congeners were found/measured or reported in fishes in both the above-cited contributions (35, 38), the data gained cannot be compared with the total PCN concentrations quantified in this study and presented in Table 1. Nevertheless, some of the isomers of penta-CN (35) were found in pike from the Swedish lakes (especially Lake Ja¨rnsjo¨n) in much higher concentration than in fishes from the Gulf of Gdan ˜ sk, and the reason is mainly because of a significant point pollution source in the area. Congener Groups Profile. Halowax 1014 is the formulation containing naphthalene (0.3%), and all homologue groups such as mono- (0.4%), di- (0.3%), tri- (2.8%), tetra(18.2%), penta- (46.8%), hexa- (23.0%), hepta- (1.6%), and octa-CN (6.6%) (20). The vacuum-distilled Nibren D130 as well as dark colored non-vacuum-distilled Nibren RN 130 waxes are the German PCN technical mixtures and are similar in chloronaphthalene homologue group composition (%) to Halowax 1014 (46). Unfortunately, a detailed knowledge of PCN congener composition of these two European formulations is lacking. The profile of PCN congener groups in Halowax 1014 is quite different from those found in the sediment sample and most of the organisms examined. There is only a rough similarity between the congener group profile of tetra (16.9%), penta(58.48%), hexa- (23.76%), and hepta-CNs (0.86%) in flounder and Halowax 1014. In this study surface sediment, plankton (mixed phytoand zoo-) and mussel in their profile of PCN congener groups show very high contribution from tetra-CNs (between 68.13 and 82.17%) (Table 1). The knowledge on volatility of individual PCNs is very scare. Tetra-CNs have much higher vapor pressure (estimated value of 3.6 × 10-4 mmHg for PCN 37) than penta- (3.2 × 10-5 mmHg for PCN 52), hexa- (7.1 × 10-6 mmHg for PCN 64), hepta- (2.8 × 10-6 mmHg for PCN 74), and octa-CN (1.0 × 10-6 mmHg; PCN 75) (4). The differences in voltality of different PCN homologue groups can prefer the higher environmental mobility of lower chlorinated congeners. A specific composition (%) of PCN homologue groups in the sediments as well as in the biological matrices like plankton and mussel, with a higher proportion of tetra- and penta- than hexa- and hepta-CNs, seems to support such a hypothesis. This finding can suggest the atmosphere as a main route of transportation, deposition, and source of PCNs to the Gdan ˜ sk Basin. Congener Pattern. Tetrachloronaphthalenes. There are 22 theoretically possible isomers of tetra-CN, of which 19 can be present in the sediment and biota samples (Table 1). Fourteen tetra-CN isomers were not well resolved one from the another during a run on the Rtx-5 60-m long capilary column selected for gas chromatographic separation and formed six peaks on the chromatogram. There are large differences in the pattern of tetra-CNs found in sediments and biological samples when compared to Halowax 1014, and such differences are also observed for various organisms (Figure 2). Nevertheless, there are some similarities in pattern of tetra-CNs for different groups of fishes and between mussels. Depending on the type of the
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FIGURE 2. Pattern of tetrachloronaphthalenes in biological samples, sediment, and Halowax 1014 [data for Halowax were taken from Imagawa et al. (19), and details of the isomers numbering are explained in Table 1].
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FIGURE 3. Pattern of pentachloronaphthalenes in biological samples, sediment, and Halowax 1014 [data for Halowax were taken from Imagawa et al. (19), and details of the isomers numbering are explained in Table 1].
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FIGURE 4. Pattern of hexachloronaphthalenes in biological samples, sediment, and Halowax 1014 [data for Halowax were calculated from Wiedman and Ballschmiter (20), and details of the isomers numbering are explained in Table 1].
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ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 30, NO. 11, 1996
matrix investigated, PCNs 42, 33/34/37, 28/43, 35, and/or 38/40 were the dominating isomers among tetra-CNs. PCN 42 is only a minor (1.2%) constituent among tetra-CNs in the technical Halowax 1014 (19, 23) and Equi-Halowax mixtures, which contain all theoretically possible PCN congener groups (18, 22). Contrary to its low abundance in Halowax formulations, PCN 42, which is a symetrical molecule substituted in two reverse-opposite peri- and two reverse-opposite lateral positions, seems to be very persistent in the environmental conditions and is the most abundant component among tetra-CNs in most of the fishes examined. PCNs 33/34/37 form a single peak on the Rtx-5 chromatogram and occupy altogether 21.7% in Halowax 1014 (19, 23) and 8.5% in Equi-Halowax (18, 22). These three isomers dominate among tetra-CNs in plankton and mussels as well as in nearshore and mainly feeding on plankton fish species such as lesser sand eel, stickleback, and sand eel. PCNs 33/34/37 are very abundant also in sediment, crab, and many other fishessapart from cod and flounder. PCN 28 (with 0.6%) and 43 (with 8.8%) contributed 9.4% to tetra-CNs in Halowax 1014 (19, 23) and 11.4% to the total PCNs in Equi-Halowax (18, 22). Both these isomers occupied from 7.80 to 15.36% (except of 1.38% in lamprey) in fishes, from 7.49 to 14.33% in crab, plankton, and mussel, and only 1.74% in sediment (Figure 2). PCNs 38 and 40 also elute unresolved from the Rtx-5 column and form a single peak on a chromatogram. These two compounds represent, respectively, 36.8 and
