Organochlorines in the water and biota of Lake Baikal, Siberia

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, respectively. Total polychlorinated biphenyl (CPCB) concentrations 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; seal’s 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

water biota

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’-hexachlorobiphenyl, 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-chlordane

trans-nonachlor

cis-nonachlor Cchlordanes 4,4’-DDE

4,4’-DDD 2,4’-DDT

4,4’-DDT

EDDT IPCB toxaphene

ECD ECD ECD

ECD ECD

ECD

ECD

ECNI-MS

ECNI-MS

ECNI-MS ECNI-MS

ECD

ECD ECD

ECD

ECNI-MS

ECNI-MS

ECNI-MS

ECD ECNI-MS

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

<0.4-4.7 <1.4-3.2 <1.3

<1.1 2.0 f 1.2

2.5 f 1.5

1.9 f 1.1

6.4 <14

1.0 f 1.0 2.3 f 0.9

5.1 f 2.3

8.4 420 f 400

0.040-0.075 0.017-0.024 <0.002 0.021 <0.002 0.028-0.037 0.033-0.041 0.062-0.081 0.082-0.10 0.068-0.089 0.093-0.11 0.034-0.041 0.24 0.74-0.76 0.70-0.89 0.12-0.16 0.1.3-0.17 0.17-0.20 0.52-0.64 0.77-0.97 1.8 2.7-2.8 1.6-2.1

0.056-0.13 0.020-0.021 <0.005-0.001 0.026 <0.002-0.011 0.016-0.035 0.013-0.019 0.040.076 0.037-0.052 0.035-0.071 0.031-0.051 0.0090-0.018 0.14 0.31-0.50 0.094-0.10 0.086-0.15 0.055-0.083 0.029-0.036 0.16-0.27 0.16-0.16 0.61 0.73-1.6 0.93-1.3

0.052-0.075 0 . 2 0 . 2 2 <0.002 0.21 <0.03 <0.01 0.017-0.017 0.14-0.16 0.055-0.056 1.1-1.1 1.3-1.5 0.13-0.14 1.5 43-44 32-39 2.0-2.2 0.037-0.066 BDc 17-21 22-23

24-28 2.2-2.3

62

a Values are as follows: water samples (pg/L) are the mean f standard deviation of seven determinations; pelagic sculpin (C. dybowskii) is the range (mg/kg of lipid) of two measurements of the same pooled sample; omul ( C , autumnalis migratorious) is the range (mg/kg of lipid) of two separate fish (average of two replicated determinations per fish); Baikal seal (P. siberica) is the range (mg/kg of lipid) of duplicate measurements from the same sample. Zchlordanes and IDDT are the average of GC-ECD and GC-ECNI-MS values. ECD and ECNI-MS are GC-electron capture detection and GC-electron capture negative ion-mass spectrometry, respectively. Below detection.

64 ng). Recoveries averaged 81 % for water and 82 % for biological samples (Table 2). Although spike experiments with toxaphene were not done with Lake Baikal water, recoveries were determined on a subsequent trip to the Canadian Arctic using the same method. Yields of toxaphene from two 200-L water samples fortified with 230-300 ng of toxaphene were 92 and 111 7%. All OCs in biological and water samples (dissolved only), with the exception of toxaphene, were corrected for standard recovery. Dissolved HCHs and HCB were corrected using the recovery of y H C H and likewise for DDTs using the 4,4’-DDT recovery. Dissolved 2-3,4-5, and 6-8 chlorinated PCB were adjusted using the recoveries of 2,2’,5-trichlorobiphenyl, 2,2‘,5,6’-tetrachlorobiphenyl, and 2,2’,4,4’,5,5‘- hexachlorobiphenyl, respectively (Table 2). Dissolved chlordane concentrations were corrected using an average of the tri- and tetrachlorobiphenyl recoveries (Table 2).

Results and Discussion

OCs in Lake Baikal Water. HCHs were detected in all water samples from Lake Baikal (Table 3). These compounds, while banned in the United States and Canada (except for limited -y-HCH use), are still actively used in Asia, primarily as technical HCH (3). Concentrations of a- and y H C H were remarkably similar to those found in Lake Huron by McConnell (ref 30; Table 4). HCB, a fungicide and industrial byproduct, was found at concentrations from 16 to 27 pg/L and like the HCHs was within the range of the upper Great Lakes (Lakes Superior and Huron; Table 4). Cis- and trans-chlordane occurred at levels below the range in Lakes Superior and Huron found by Stevens and Nielson (ref 31; trans-chlordane = 18-63 pg/L and cis-chlordane = 18-72 pg/L in these lakes; Table 4) but much higher than in the Canadian Arctic (ref 8), where the sum of cis- and trans-chlordane = 3.9 pg/L. Reports of nonachlors in large lakes are scarce, but Kawano et al. (32) does report a trans-nonachlor

Table 4. Organochlorines in Lake Baikal Water Compared to Those in Upper Great Lakes (Superior and Huron).

Lake Baikal upper Great compd (PP/L) Lakes (pg/L) ref

HCB a-HCH 7-HCH heptachlor trans-chlordane cis-chlordane

ZPCBb 4,4’-DDE

20 f 3.7 1100 f 81 240 f 29 5.4 f 1.2 17 f 10 13 f 5.0 10.3 i 3.7 560 f 180

18-73 1300 f 300 420 f 110 14-36 18-63 18-72 18-45 550 f 370

31 30 30 31

31b 31b 31

370

a These values are the sumof both dissolved and particulatephases. 4,4’-DDE and trans- and cis-chlordane from Lake Baikal are the average of GC-ECNI-MS and GC-ECD results. bRange of the detected values. c Dissolved (filtrate) portion only.

concentration of 1.4 pg/L (n = 2) in the North Pacific compared to 6.9 pg/L in Lake Baikal (Table 3; average of GC-ECNI-MS and GC-ECD). Cis-nonachlor (0.72 f 0.55 pg/L; Table 3) was a factor of 10 lower than trans- nonachlor.

The most prevalent DDT compound found was 4,4’- DDT with a total concentration (dissolved + particulate) ranging from 15 to 64 pg/L (average of GC-ECD and GC- ECNI-MS; Table 3). GC-ECNI-MS results for DDT were all lower than those obtained by GC-ECD, which is especially evident for 4,4’-DDE (17 and 3.6 pg/L by GC- ECD and GC-ECNI-MS, respectively; Table 3). 4,4’- DDE may have been overestimated in water samples using GC-ECD, since it was necessary to correct for the contribution of PCB-85 in the sample using the PCB-85/110 ratio in the standard (Aroclor 1254). On the basis of the averaged GC-ECD and GC-ECNI-MS results, concentrations of DDTs in Lake Baikal (Table 3) ranked as

The northern basins (sites 1 and 2; Figure 1) had lower CDDT levels than the southern basin. For instance, 4,4’-

follows: 4,4’-DDT > 2,4’-DDT > 4,4’-DDD > 4,4’-DDE.

Environ. Sci. Technol., Vol. 28, No. 1. 1994 33

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 southern ba.sin, again suggesting a local source of PCBs (30). Overall, the dissolved CPCB concentrations in Lake Baikal were very similar to those measured by Baker and Eisenreich (ref 37; Table 4) in Lake Superior, although the PCB profile is somewhat changed (Figure 2). PCBs in Lake Superior were more dominated by lower chlorinated congeners than Lake Baikal, although congeners 110 and 118 + 149 were also prevalent (38). The difference in PCB patterns may arise from local PCB sources in addition to the long-range atmospheric transport, a difference in partitioning be- havior between dissolved and other phases, and/or the usage of PCB mixtures umlike those used in North America. Further work is needed to clarify this situation.

OCs in the Lake Baikal Pelagic Food Web. KCH levels in Lake Baikal biota are given in Table 3. a-HCH was the predominant HCH at all trophic levels, ranging from 0.021 mg/kg of lipid in fish to 0.20 mg/kg of lipid in the Baikal seal. /3-HCH was detected in all biological samples, but because of poor analytical recovery, these

l6 I I

14 1 dmsalved , 1- Lake Baikal 1 psrticuiate

0 m v) 3

c, 1

Lake S u p e r i o r I I

10 a i

I

E

6

4

2

n

*..- 3 3

m 0 *

PCB congener Figure 2. (a, top) Average percent of total PCB congeners dissolved (filtrate) and particulate (filter-associated) In Lake Balkal water and (b, bottom) dissolved PCBs In Lake Superior (38). PCB congeners are in elution order from a DB-5 caplllary column and numbered according to IUPAC designations. The PCB profile from Lake Superior surface water is the average of five samples collected in 1986, with PCBs isolated using Amberllte XAD-2 from 67 L of lake water and analyzed by GC-ECD.

values are not presented. The CHCH concentrations are generally lower than those measured in other studies, but they are in the range of burbot liver from Lake Winnipeg (ref 39; Table 5), although omul and sculpin are whole- fish homogenates. CHCH in Baikal seal blubber are comparable to those in the Arctic ringed seal (ref 11; Table 5), but would have been higher if P-HCH were included in CHCH.

Five chlordane-related compounds were quantified by GC-ECD and/or GC-ECNI-MS (Table 3). Heptachlor epoxide was also detected, but the results are not given, since the stability of this compound in the sulfuric acid cleanup procedure was suspect. Chlordanes in fish were generally in the range of other studies (Table 5) but lower than in Siskiwit Lake in Lake Superior (41), reflecting higher chlordane levels in the Great Lakes region relative to Lake Baikal (see water discussion). The trans-chlordane to cis-chlordane ratios (TC/CC) changed among trophic levels. This ratio was 1.4 in water and decreased to 0.43, 0.40, and 0.17 in sculpin, omul, and seal blubber, respectively, indicating that cis-chlordane is more recalcitrant than trans-chlordane in this food web. Similar reductions in the TC/CC ratio have been observed in other studies (9, 11). For instance, Muir e t ai. (11) found that trans- chlordane was degraded to nondetectable levels in ringed seal and polar bear fat. Cis-nonachlor was also observed

34 Envlron. Scl. Technol., Vol. 28, No. 1, 1994

Table 6. Comparison of Organochlorine Levels in Lake Baikal Biota to Those in Other Studies.

organism XHCH Xchlordane LDDT XPCB toxaphene location ref

fish walleye pollock 0.19 0.14 0.35 0.41 N. Pacific 40 chum salmon 0.17 0.04 0.08 0.09 salmon 0.35 9.7 19 6.2 Lake Vattern 13 Alpine char 0.24 5.8 10 4.7 (Sweden) 13 lake trout 0.13 0.42 12 5.76 11 Siskiwit Lake 41 whitefish 0.20 0.26 5.8 4.17 7.00 burbot (liver only)b 0.07 0.14 0.62 1.94 0.81 Lake Winnipeg 39

0.04 0.38 1.03 0.87 2.34 Trout Lake 39 bloaterc 0.67 1.64 Lake Michigan 42

1.8 Lake Baikal this study pelagic sculpin 0.021 0.24 1.8 2.8 omul 0.026 0.14 0.61 1.2 1.1 Lake Baikal this study

harbor seal 8.5 76.4 Denmark 43 gray seal 3.86 17.2 Sable Island 44 ringed seald 0.56 0.93 Holman Island 45 ringed seald 0.23 0.37 0.91 0.55 Admirality Inlet 11 ringed seald 0.13 0.22 0.81 0.64 Grise Fiord 11 ringed seald 0.27 0.46 0.71 0.57 Barrow Strait 11

seal

ringed seal 65 75 12 Gulf of Bothnia 13 harp seal 1.7 4.5 1.9 Gulf of St. Lawrence 13 Caspian seal 38 1.9 2.9 Caspian Sea 13 Baikal seal 0.21 1.5 62 26 2.3 Lake Baikal this study

a Concentrations are in mg/kgof lipid. Summed compounds are as in Table 3. Two of many lakessurveyed, those shown were approximately the same latitutde as Lake Baikal (-50’ N). These fish were collected in 1986 and represent a 17-yr data set. d Average of both male and females.

by GC-ECNI-MS at concentrations ranging from 0.014 mg/kg of lipid in the omul to 0.14 mg/kg of lipid in the seal (Table 3).

4,4’-DDE was the dominant DDT group compound in all representatives of the food web ranging from 0.25 mg/ kg of lipid in the omul to 40 mg/kg of lipid in the Baikal seal (Table 3; the average of GC-ECD and GC-ECNI- MS). GC-ECD and GC-ECNI-MS DDT group results agree well, although GC-ECD appears to have slightly overestimated 4,4’-DDE in omul, possibly due to PCB-85 interference in fraction-1. The amount of unconverted 2,4’- and 4,4’-DDT in the sculpin and omul was nearly equal to the metabolite 4,4’-DDE, which is unlike fish from the Great Lakes. For instance, 4,4’-DDE made up 84% of CDDT in Lake Michigan bloater (42) and 74% in Lake Ontario lake trout (331, but it only made up 40 % of CDDT in Lake Baikal fish, indicating that there is more unconverted DDT in Lake Baikal than in the Great Lakes.

Figure 3 shows the PCB congener profile in Lake Baikal biota. The omul retained more tetra- and pentachlorinated congeners and fewer hexa-, hepta-, and octachlorinated congeners relative to the sculpin or the seal. In general, the main congeners retained in both fish and Baikal seal were 101,118 + 149,105 + 132 + 153, and 138 (more so in seal than in fish) as also found in Arctic fauna (11) with CPCB levels in the seal 10-fold higher than in fish. Concentrations of CPCBs in the omul and sculpin were comparable to those in the Lake Michigan bloater (ref 42; Table 5). CPCBs in the Baikal seal were similar in concentration to seals from the western North Atlantic and Sable Island (refs 13 and 43-45; Table 5).

Toxaphene was detected in fish and seal by GC-ECNI- MS generally in the range of other investigations (Table 5) . There was little fish to seal trophic transfer of total toxaphene (omul + sculpin = 1.5 mg/kg of lipid and seal = 2.3 mg/kg of lipid; Table 5). The toxaphene pattern in the seal is more degraded relative to either fish or the toxaphene standard but retains several prominent toxaphene congeners (Figure 4). The labeled peaks in Figure 4 are two toxaphene congeners found to be conserved in

26 , I

I 4

0

-1- - v)

e,

P C B Congener

Figure 3. Average percent of total PCB congeners In the omul, sculpin, and Baikai seal. Bars are the average of duplicate measurements of two individual whole omul, a pooled sample of 35 sculpins, and a slngle Baikal seal blubber sample. Congener numbers are the same as in Figure 2.

Environ. Scl. Technol., Vol. 28, No. 1, lg94 35

2

1 1

1 Water

, I Standard 1

Flgure 4. GC-ECNI-MS chromatograms of toxaphene from the omul, sculpin, seal, and toxaphene standard. The Ions monitored were 373, 375,379,381, 413, and 415. Peaks labeled 1 and 2 are T2 and T12 structurally Identified by Stern et a/. ( 7 6 ~ from narwhal blubber. Peak 3 Is descrlbed In the text.

both burbot liver and narwhal blubber (16,34,39). Peaks 1 and 2 in seal are respectively an octachlorobornane and a nonachlorobornane, as recently isolated and identified from beluga blubber by Stern et al. (16). Peak 3, which is the largest peak in the Baikal seal, is also the dominant peak in ringed seals from the Canadian Arctic and shows an octachlorobornane spectrum (Bidleman and Muir, unpublished).

OCs partition into biota from water mainly based on their solubility in lipid phases, which in a practical sense is represented by the octanol-water partition coefficient (KO,). This relationship is usually described by a linear relationship between the log biota/water partition coefficient or bioconcentration factor (BCF) and log KO, (32, 41, 46). OCs in Lake Baikal fish and seal also exhibited a linear relationship between log KO, and log BCF with r2 ranging from 0.45 for omul to 0.62 for seal (Figure 5). 4,4'-DDE is not included in the regression, since it has a metabolic formation route (41), which is apparent by its deviation from the plot, especially in seal (Figure 4). The slopes of these plots range from 0.47 f 0.08 (A standard deviation) for the omul and approach unity for the seal (0.88 f 0.11).

Conclusions

Lake Baikal water, fish, and seal all contained measurable levels of organochlorine contaminants. These findings support other observations (1-7) that OCs are widely dispersed throughout the Northern Hemisphere, most likely through atmospheric transport and deposition. HCH and CPCB concentrations are comparable to the upper Great Lakes (30,38), which implies these two regions are experiencing similar inputs either by atmospheric

10

9

8

7

6

5

4

r2=0 .62 m=0.6810.11 b=2.11+0.71

/; a/ a - H C H

4 , 4 ' - D D E m=O 47f0 0 8

' / 0 5 - ~ a - H C H ri

4 -

rC=0.68 4 , 4 ' - D D E 1 m=0.73&0.07

a - H C H 4

3 4 5 6 7 8

ow log K Flgure 5. Plot of log BCF (water/llpld-based OC concentrations) versus log Kow for the omul, sculpln, and Balkal seal. Filled and unfllled symbols are PCB congeners and the OC pestlcldes, respectively. HCH, heptachlor, and toxaphene Kow's are from ref 47-50; all other Kow's are from ref 5 1.

deposition or local emissions. Chlordanes and related compounds were nearly a factor of 2 lower in Lake Baikal than in the upper Great Lakes, which may experience a more regional influence from historic chlordane usage in the southeastern United States. Unfortunately, there is not enough information available on water column DDT levels in the Great Lakes water for an adequate comparison between these two areas. From the limited information available, there appears to be more unconverted 4,4'-DDT and 2,4'-DDT entering Lake Baikal, most likely from Asian use of DDT. Considerable work is still needed to identify the relative magnitude of atmospheric and riverine OC sources. Lake Baikal's morphometry gives it a small surface area relative to its total volume, consequently only 1 2 % of the lake comes in contact with the atmosphere per year (52). Therefore, the magnitude of gas exchange is likely much lower than, for instance, the Great Lakes. In addition, runoff of snow-scavenged OCs from the moun- tains that completely surround the lake is also likely t~ be important.

OC levels in fish were comparable to those in upper Great Lakes fish (e.g., the Lake Michigan bloater; ref 42) reflecting the similar concentrations in water, although there are substantial differences in individual OCs. The Baikal seal displayed OC levels lower than Arctic seals and more similar to seals from western Europe or the

36 Envlron. Scl. Technol., Vol. 28, No. 1, 1994

Caspian Sea, although more samples are required for a thorough comparison. The omul and the Baikal seal are important food sources for people in the vicinity of Lake Baikal. In the case of seal blubber, CPCB, 4,4'-DDE, and 4,4'-DDT exceed legal limits for fish in both Canada and the United States and toxaphene limits in Canada (53). Therefore, additional measurements of OCs in seal tissues, especially meat, are needed to assess human health risks.

Acknowledgments

The authors wish to thank the University of South Carolina Venture Fund and the United States Man and the Biosphere (MAB) Program for financial assistance. Thanks also to Justin McArdle of Richardson Scientific Co., London, England, for shipping solvents to Irkutsk, Russia; Mikhail Grachev and Olga Margonskaja of the Limnological Institute in Irkutsk; and the captains and crews of the vessels used during our sampling. The thoughtful comments and suggestions of Joel Baker and Clifford Rice are also greatly appreciated. This is contribution No. 989 of the Belle W. Baruch Institute. The opinions, recommendations, and conclusions of this paper do not necessarily represent the policies or views of any of the agencies and institutions supporting the U. S. MAB Program.

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15, 377-393.

24, 342-352.

1988,22, 543-548.

2-59.

1988, 331, 295-301.

349, 665-669.

Received for review February 19, 1993. Revised manuscript received August 17, 1993. Accepted August 30, 1993.'

Abstract published in Aduance ACSAbetracts, October 15,1993.

Envlron. Sci. Technol., Vol. 28, No. 1, 1994 57

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Organochlorines in the water and biota of Lake Baikal, Siberia