Environ. Sci. Technol. 1994, 28, 31-37
Organochlorines in the Water and Biota of Lake Baikal, Siberia
John R. Kucklick,'pt Terry F. Bldieman,t~**~ Laura L. McConnell,*lL Michael D. Walls,* and Gennadi P. Ivanovll Marine Science Program and Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, and Limnological Institute, P.O. Box 41 99, Irkutsk 664033, Russia
Organochlorine contaminants were measured in water, fish, and Baikal seal from Lake Baikal, Siberia. Organochlorine levels in water were comparable to those reported from the upper Great Lakes, with the exception of chlordanes, which were a factor of 2 lower. Dissolved toxaphene and CDDT (sum of4,4'-DDE, 4,4'-DDD, 2,4'-DDT, and 4,4'- DDT) averaged 64 f 37 pg/L and 87 f 37 pg/L, respec- tively. Total polychlorinated biphenyl (CPCB) concen- trations in biota ranged from 1.2 to 26 mg/kg of lipid in the omul (an endemic salmonid) and the Baikal seal, respectively. Tetra- and pentachlorobiphenyl congeners accounted for a greater proportion of CPCB in omul and hexa-, hepta-, and octachlorobiphenyl congeners in pelagic sculpins and seal. Toxaphene concentrations in biota ranged from 1.1 to 2.3 mg/kg of lipid in sculpin and seal, respectively. A linear relationship was observed between the log bioconcentration factor and log octanol-water partition coefficient with slopes ranging from 0.47 f 0.08 for the omul to 0.88 f 0.11 for seal (rs = 0.45 and 0.62, respectively).
Introduction It is well-established that organochlorines [OCs; e.g.,
DDTs, toxaphene, chlordanes, hexachlorocyclohexanes (HCHs), and polychlorinated biphenyls (PCBs)] are transported long distances via the atmosphere from their site of application or usage (1-7). As a result, areas with no historical use of OCs, such as the Arctic, have measurable levels of these compounds in water (2,3,8,9). Because OCs are persistent and hydrophobic, they also bioaccumulate to high levels in arctic fish (9-121, seals (11-13), whales (11, 12, 14-17), and people (18, 19).
Most studies of OC contamination in large lakes (such as the Great Lakes) and northern marine ecosystems were conducted mainly in North America or western Europe, with a few from the northern Pacific (20, 21). Few investigations have assessed OC levels in the large lakes of Asia. The objective of this paper is to help fill this gap by presenting OC levels found in water and representatives of the Lake Baikal food chain and to compare these data to those from other areas, primarily North America and the Canadian Arctic. We expected OC concentrations in Lake Baikal water, barring substantial local sources, to be similar to the upper Great Lakes due to a diffuse atmospheric source and similar temperature regimes.
* Address correspondence to this author at his present address: Chesapeake Biological Laboratory, The University of Maryland System, P.O. Box 38, Solomons, MD 20688.
+ Marine Science Program, University of South Carolina. * Department of Chemistry and Biochemistry, University of South Carolina.
#Present address: Environment Canada, Atmospheric Environ- ment Service, ARQP, 4905 Dufferin St., Downsview, Ontario M3H5T4, Canada.
Present address: Agricultural Research Service, United States Department of Agriculture, Beltsville, MD 20705.
11 Limnological Institute.
0013-936X/94/0928-0031$04.50/0 0 1993 American Chemlcal Soclety
Upper Angara R.
Lake Baikal i
100 km Flgure 1. Lake Baikal and water sampling sites (numbers).
Lake Baikal is a rift lake located from approximately 52 to 56O N and 104 to 110" E (central Siberia, Russian Republic) and is 635 km long, with a maximum width of 80 km (Figure 1). The lake is unique in several ways: it is the world's deepest (1640 m in the central basin); the largest by volume; and the oldest (10-20 million years). The pelagic trophic structure in Lake Baikal is fairly well described (e.g. ref 22). Baikal seals (Phoca siberica) occupy the top trophic level (aside from humans) feeding primarily on the endemic whitefish or omul (Corogonus autumnalis migratorious) and planktivorous sculpin (e.g., Comephorus dybowskii). The Lake Baikal pelagic food web is similar to that of the Great Lakes in that there are few trophic links, and it is comparable to that of the Arctic by the presence of a large aquatic mammal (the Baikal seal).
Experimental Section Sampling. Seven 180-L high-volume (HV) water
samples were collected from Lake Baikal during June 1991; one each from the northern and central basins while aboard the R. V. G. Yu Verashchagin (Figure 1; sites 1 and 2) and five from the southern basin during day excursions (Figure 1; site 3). Each sample consisted of 10 portions collected in 18-L stainless steel containers, which were rigorously cleaned before use. To avoid contamination, surface grab samples were taken by securing the containers to a line and dropping them from the bow of the ship as it moved slowly forward. Water samples were filtered through a 142-mm Gelman A/E precombusted (450 "C for 24 h) glass fiber filter (GFF) enclosed in a stainless steel high-pressure
Envlron. Scl. Technol., Vol. 28, No. 1, 1994 51
Table 1. Samples Analyzed from Lake Baikal
sa m p 1 e nb % lipid
water 7 pelagic sculpin (Comephorus dybowskii) 35 7.1 omul (Coregomus autumnalis migratorious) 2 7.8 Baikal seal (Phoca siberica) 1 93
a Water samples were 180 L with both a filtrate and filter portion analyzed. 35 sculpins were pooled and analyzed in duplicate; two individual omul and one seal blubber sample were analyzed in duplicate. -
Millipore filter holder by pressurizing the sample vessels using activated carbon-filtered air from a one-quarter H P diaphragm pump. Filtrate was then pushed through a 2 cm X 15 cm glass-enclosed column of Amberlite XAD-2 resin at a flow of 250-350 mL/min to remove OCs. All tubing in this apparatus was Teflon. Amberlite XAD-2 (Mallinckrodt, mesh size 20-50) was precleaned using the method of Capel and Eisenreich (23). After sampling, the columns were capped with glass stoppers, sealed with Teflon tape, wrapped in aluminum foil, and refrigerated. GFFs, l / l80 L, were wrapped in aluminum foil and frozen.
Biological samples were procured from several sources. Two freshly caught omul(22 cm totallength) were collected from the southern basin by a local fisherman and were wrapped in aluminum foil and immediately frozen. A total of 35 (2-10 cm total length) pelagic sculpins, collected from the southern basin in 1990, were provided by G. T. Chandler (University of South Carolina). Frozen Baikal seal blubber (0.5 kg; seals age and sex unknown) was supplied by the Limnological Institute, Irkutsk. The frozen fish and seal blubber were packed on ice in coolers and transported back to the United States, where they were immediately refrozen at -20 C. The samples collected from Lake Baikal are summarized in Table 1.
Extraction and Separation. Analytes were recovered from XAD-2 resin by separate elutions with 150 mL of methanol followed by 150 mL of CHgC12 (DCM). A saturated NaCl solution (50 mL) was added to the methanol fraction followed by liquid/liquid extraction with DCM. The resulting extract was combined with the other DCM fraction and then washed with double-distilled water. Water filters were refluxed for 24 h in DCM. Fish samples were homogenized whole using a stainless steel tissue blender. Sculpins were pooled due to their small size. Individual omul were analyzed separately. Subsamples of about 2 g of fish were taken from the homogenate and mixed with 12 g of NaZS04 and Soxhlet-extracted for 24 h with DCM. Seal blubber (2 g) was refluxed in DCM for 24 h, with one-tenth of the final extract subjected to further cleanup. Extracts were reduced in volume to 5-10 mL by rotary vacuum evaporation followed by solvent exchanged to hexane. Bulk lipids were determined gravimetrically by subsampling the solvent extract, evaporating the hexane at 7OoC, and weighing the residue (Table 1). The extracts were then treated with 1.0 mL of 18 M H2S04 to eliminate lipids with a final cleanup using a neutral alumina technique (24) . A two-fraction silicic acid/neutrd alumina procedure, similar to that of Keller and Bidleman (251, separated PCBs from most other organochlorine pesticides before analysis. Fraction 1 (petroleum ether) contained PCBs, hexachlorobenzene (HCB), and heptachlor. Frac- tion 2 (20% DCM in petroleum ether) included toxaphene, DDTs, chlordanes, and HCHs. 4,4-DDE split between the two fractions (26). Tissue samples were extracted in duplicate, and the results of the analysis were averaged.
Table 2. Quality Control Informationa
a-HCH 3.4 1.4 0.7 92 Y-HCH 1.0 1.3 82 0.7 55 HCB 2.8 0.4 0.1 103 heptachlor 2.6 1.1 0.5 102 trans-chlordane 1.8 0.6 1.0 85 cis-chlordane 2.0 0.4 0.3 82 trans-nonachlor 0.6 0.4 0.2 86 4,4-DDE 1.0 14 0.2 52 4,4-DDD 1.4 1.0 0.4 73 2,4-DDT 0.8 1.7 0.4 90 4,4-DDT 2.4 0.6 71 0.3 86 toxaphene 2of PCB-28 94 PCB-53 93 PCB-153 71 CPCB 206 203 32
LOD is the limit of detection defined as the mean plus three times the standard deviation of the blank. Amounts of each compound spiked are given in the text. GC-ECD based on a 180-L sample. The samples were analyzed by GC-ECD. d The mean of two spike recoveries. e The mean of four samples analyzed by GC- ECD and corrected for preexisting tissue concentrations. f Mean of XAD-2 field blanks analyzed by GC-ECNI-MS.
Analysis. The gas chromatographic conditions and instruments are given in Patton et al. (27). The internal standards 6-HCH and mirex were added to fraction 1, and HCB and mirex were added to fraction 2 for quantification. The internal standards were chosen after careful pre- screening of the samples for the presence of these compounds in the fractions. A total of 61 PCB congeners were quantified using a congener-specific method utilizing standards of Aroclor 1242,1254, and 1260 and the weight percents given in Capel et ai. (28), with some differences (29). PCB congener 85 interfered with4,4-DDE in fraction 1. Levels of 4,4-DDE were corrected for this interference by subtracting the contribution of PCB 85 using the area ratio of PCB 85/110 in the Aroclor 1254 standard and the area of 110 in the sample. In addition, fraction 2 samples, except water filters, were further analyzed by GC-electron capture negative ion-mass spectrometry (GC-ECNI-MS) in the selected ion monitoring mode (SIM) for chlordanes, DDT plus metabolites, and toxaphene using a similar method and the same instrument described in Patton et al. (27). The SIM ions were as follows: chlordanes, 408, 410; nonachlors, 444, 446; 4,4-DDE and 4,4-DDT, 316, 318; 2,4-DDT, 246, 248; and toxaphene (hepta- to non- achloro components), 373, 375, 379, 381,413, and 415.
Quality Control. Two blanks were performed on XAD-2 columns, lipids cleanup, and filters taken through the entire extraction and cleanup procedure (26). The limit of detection (LOD) was defined as the mean plus 3 standard deviations of blank values (Table 2). Samples exceeding this value were considered above the detection limit and then blank corrected. Spikes were also done using two HV water samples and four omul extracts. Water samples were spiked in the field by adding an acetone solution containing T-HCH, 2,2,5-trichlorobiphenyl, 2,2,5,6-tetrachlorobiphenyl, 2,2,4,4,5,5-hexachlorobi- phenyl, and 4,4-DDT to four (numbers 2, 4, 6, and 8 in a series of 10) of the stainless steel vessels and then processed as above. The amount of each compound added ranged from 191 to 227 ng. Omul were amended with 1.0 mL of a pesticide standard containing a mixture of chlordanes (38-40 ng), HCHs (39-51 ng), and DDTs (40-
32 Environ. Sci. Technol., Vol. 28, No. 1, 1994
Table 3. Concentrations of Organochlorines in Lake Baikal Water and Biological Samples. water biota
compd methodb dissolved particulate pelagic sculpin omul Baikal seal
HCB wHCH Y-HCH CHCH heptachlor trans-chlordane
cis-nonachlor Cchlordanes 4,4-DDE
EDDT IPCB toxaphene
ECD ECD ECD
20 f 3.7 1100 f 81 240 f 29 1340 5.9 f 1.3 17 f 9.3 14 f 13 13 5.7 8.9 f 6.0 9.5 f 4.4 4.3 f 4.0 0.72 f 0.55 40 17 f 7.1 3.6 f 1.5 17 & 7.3 26 12 12 f 4.9 50 f 23 31 f 12 87 560 f 180 64 f 37
DDT ranged from 15 to 31 pg/L in the northern and central (n = 2) and 60 f 4.9 pg/L (n = 3) in the southern basin. This suggests that there may be local inputs of DDT to the southern region of the lake (which is more inhabited and industrialized) either from the Selenga River or atmospheric loadings from Irkutsk (30). There are few reported DDT concentrations from the upper Great Lakes other than those from Stevens and Nielson (ref 31; Table IV). These authors cite 4,4'-DDE in Lake Huron ranging from 18 to 45 pg/L (mean of 24 pg/L); 4,4'-DDT was below detection in all of their Great Lakes samples. Although not from the upper Great Lakes region, Oliver and Niimi (33) report 4,4'-DDE and 4,4'-DDT from Lake Ontario a t 76 f 20 and 19 f 7.2 pg/L, respectively. Therefore, it appears there is less unconverted DDT in the Great Lakes relative to Lake Baikal, which is probably experiencing inputs from regional usage.
Toxaphene is a complex mixture of polychlorinated bornanes (6-10 chlorines) containing over 200 separate components and was found in all water samples by GC- ECNI-MS. This product was one of the most heavily used pesticides in the United States until it was banned in 1982, but its use likely continues in eastern Europe and the former Soviet Union (2,34). Dissolved toxaphene in Lake Baikal water ranged from 35 to 143 pg/L with an average concentration of 64 f 37 pg/L (n = 7; Table 3). The values from Lake Baikal fall within the 32-400 pg/L range from the Arctic Ocean (81' N; ref %), suggesting that the source is from long-range transport rather than local use.
The dominant PCB congeners (dissolved + particulate) were 101,110, and 118 + 149 (Figure 2). The dissolved PCB profile (Figure 2) shows a higher proportion of di- through tetrachlorinated congeners when compared to those associated with particles, which is expected since these compounds are generally more soluble and less particle-active (lower Kow; e.g., ref 35). The amount of CPCBs in the filter and filtrate was extremely variable ranging from no detected PCB congeners to 70% associated with the filter (mean was 35% f 27%; n = 7). This may be partially explained by the presence of colloids, which bind OCs, but pass through the filter (36) or variations in suspended particulate matter. Similar to DDT, there were higher CPCB levels in the southern basin relative to the northern and central basins (other OCs did not show this trend). The CPCB (dissolved + particulate) ranged from 300 to 490 pg/L (n = 2) in the northern and central basins and 1100 f 370 pg/L (n = 5) in the souther...