Organochlorine Insecticides and PCB in the Surficial Sediments of Lake Superior (1973)

J. Great Lakes Res., 1980 Internat. Assoc. Great Lakes Res. 6(2): 113-120

ORGANOCHLORINE INSECTICIDES AND PCB IN THE SURFICIAL SEDIMENTS OF LAKE SUPERIOR (1973)

R. Frank, R. L. Thomas, l H. E. Braun, J. Rasper, and R. Dawson 1 Provincial Pesticide Residue Testing Laboratory Ontario Ministry of Agriculture and Food c/o University of Guelph Guelph, Ontario N1G 2Wl

ABSTRACT. Analysis of 405 Lake Superior surficial sediments (0-3 cm depth) collected in 1973 were to contain low levels of DDE" HEOD, and PCB, but no detectable mirex, heptachlor expoxide, endrzn, endosulfan, or chlordane. P,P -DDE was detected in 50%, HEOD in 9%, and PCB in 44% of the sediment samples at trace or low measurable levels. Mean residues for the whole lake were p,p'-DDE O. 71 ± 1.65 ng/g, HEOD below the detection level of 0.25 ng/g, and PCB 3.3 ± 5. 7 ng/g. p,p'-DDE was more concentrated in depositional basins than in non-depositional zones while PCB levels were similar for the two zones.

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INTRODUCTION Persistent organochlorine insecticides and industrial chemicals have been found as contaminants in water and in plankton (Glooschenko, Strachan, and Sampson 1976; Veith et al. 1977), in fish (Frank et al. 1978; HC 1977; Reinert 1970; Reinke, Uthe, and Jamieson 1972; Veith et al. 1977) and in sediment (Eisenreich, Hollod, and Johnson 1979; Glooschenko et al. 1976; Veith et al. 1977) collected from Lake Superior. Sediments from the other Great Lakes have also been found to contain these same contaminants and in particular sediments from Lake Ontario (Frank et al. 1979a, Holdrinet et al. 1978), Lakes Erie and St. Clair (Frank et al. 1977), Lake Huron and Georgian Bay (Frank et al. 1979.b, and Glooschenko et al. 1976) and Southern Lake Michigan (Leland, Bruce, and Shimp 1973). Eisenreich et al. (1979) reported the highest levels of PCB in the 0.5 cm surface layer of sediments taken from the Lake Superior ecosystem and interpreted this as supportive of aerial transport and deposition. In other Great Lakes, especially Lakes Erie and Ontario, residue data on sediments generated by Frank et al. (1977, 1979a) and Holdrinet et al. (1978) were supportive of river mouth inputs being the primary sources.

All reports reviewed reveal that lake sediments can act as reservoirs of stable organochlorine compounds and in particular DDT and PCB in Lake Superior. The present study was intended to map the concentrations of organochlorine insecticides and PCB in the upper 3 cm of the bottom sediments of Lake Superior. The sampling of sediments in the lake was carried out as part of an ongoing study on the regional sedimentology and geochemistry of the Great Lakes being conducted at the Canada Centre for Inland Waters and described by Thomas and Dell (1978). METHODS AND MATERIALS Collection Samples of Lake Superior sediment were collected using a Shipek bottom sampler on a 14.1 km Universal Transverse Mercater (V.T.M.) grid aligned north east to south west with 10 km north to south U.T.M. spacing in the Duluth arm of the lake and between Isle Royale and Thunder Bay (Figure 1). In all samples the surficial 3 cm of sediment was carefully sub-sampled aboard the Canadian survey ship LIMNOS and freeze-dried for subsequent geochemical analysis. The freeze-dried samples were later sieved to remove pebble sizes greater than 20 mesh and then ground to pass a

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100 mesh sieve to ensure complete homogeneity of the sample. Analysis Procedure Ten grams of sediment were brought to 50% field capacity by adding ca 2 mL of water, and allowed to stand for 12 hr. A hexane: acetone (1: 1 v/v) mixture (250 mL) was used to extract the samples by shaking for 2 hr on a wrist-action shaker. After filtering the extract, an aliquot (100 mL) was mixed with saturated NaCl solution (10 mL) and water (300 mL) and shaken vigorously for 1 min. The hexane phase was passed through a 2-3 cm layer of sodium sulfate and evaporated just to dryness with rotary vacuum (Chiba and Morley 1968). Activated FLORISIL (25 g) was introduced into a 22-mm Ld. chromatography column. After pre-washing with hexane the sample extract was added to the column. The column was eluted successively at the rate of ca 5 mL/min with 200 mL of dichloromethane:hexane (20:80 v/v) and 200 mL of acetonitrile:dichloromethane:hexane (0.35:50: 50 v/v). The eluates were evaporated just to dryness with rotary vacuum and the residue was reconstituted in 5-10 mL of acetone for the first elution and 5-10 mL of hexane for the second (Mills et aZ. 1972). A 10-mm Ld. chromatography column was

prepared containing glass wool, 1 cm sand, 7.5 cm coconut charcoal, and 1 cm sand. The column was pre-washed with 1:3 acetone: ether. The first eluate from the clean-up [dichloromethane:hexane (20:80 v/v) fraction] was added and the column eluted first with 180 mL of acetone: ether (1:3 v/v) and then with 80 mL benzene to give two fractions. Each fraction was evaporated just to dryness with rotary vacuum and reconstituted for determination (Berg, Diosady, and Rees 1972; Holdrinet 1974). Micro-Tek Model MT 220 and Tracor 550 gas chromatographs equipped with Ni 6 3 electron capture detectors were used. These instruments had 1.8 M columns with Ld. of 3.2 mm. Columns were packed with 1.5% OV-17/2.0% OV-2l0 on 100-120 mesh Gas Chrom Q. Columns were preconditioned for 72 hrs at 240°C and 30 mL nitrogen per minute. Operating parameters were: Nitrogen carrier gas at 60 mL/min Injector temperature 220° C Column temperature 180° C Detector temperature 300°C PCB levels were estimated against an Aroclor 1254 standard by summing peaks 7, 8, and 10 according to the Reynolds numbering system (1971). The majority of sample traces resembled an Aroclor 1254 trace most closely.

INSECTICIDES AND PCB IN LAKE SUPERIOR SEDIMENTS Recovery measurements were undertaken using samples fortified at 20 and at 100 ng/g and extracted 2 days, 1 week, and 2 weeks after fortification. The following recovery percentages were obtained (mean of 9 determinations): p,p'-DDE, 91.0; PCB (ArocIor 1254), 89.0; HEOD, 87.5. RESULTS The surficial sediment distribution in Lake Superior has been described by Thomas and Dell (1978) in which the lake was demarcated into nondepositional zones and basins of active sediment accumulation (Figure 2). Analyses of the surficial sediment revealed the presence of only DDE, HEOD, and PCB. p,p'-DDE Only p,p'-DDE of the DDT analogous group (DDT, TDE, and DDE) was positively identified; others, if present, were below the detection limit of 0.25 ng/g. Although p,p'-DDE could not be detected in 50% of samples, it was present at unconfirmed trace levels (0.25 to 0.50 ng/g) in 16% of samples and at measurable levels (>0.5 ng/g) in 34% of samples. The highest reading of 23 ng/g in one sample was three times higher than the next highest residue at 7.1 ng/g. Along with the highest reading (23 ng/g) were traces (0.25 to 0.50 ng/g) of p,p'-DDT and p,p'-TDE, however, in the second highest and lower readings, residues of these components, if present, were below the limits of detection «0.25 ng/g). A mean residue of 0.71 ± 1.65 ng/g DDE was calculated for the whole lake assuming trace levels as being equivalent to 0.4 ng/g and non-detectable levels as being equivalent to 0.1 ng/g (Table 1). A mean residue of 1.71 ng/g was found in those samples where DDE could be measured. Concentrations of p,p'-DDE were found to be approximately two to seven times higher in the depositional basins than in the non-depositional zones. The highest mean concentrations occurred in the Thunder Bay trough, the Duluth sub-basin, and in proximity to Thunder Bay (Table 2). The distribution of p,p'-DDE in the sediments of Lake Superior is shown in Figure 3. This distribution illustrates the generally low levels occurring in the lake. However, three regions of higher concentrations can be observed occurring in the Duluth sub-basin, Thunder Bay basin and trough, and south of the mouth of the Nipigon River. These

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apparently are related to areas of urban and/or industrial activity in the absence of any significant agricultural activities. HEOD HEOD was not detected to a limit of 0.25 ngJg in 91 % of Lake Superior sediments. Unconfirmed traces «2.5 ng/g) were suspected in 4.5% of sediments while only 4.5% contained measurable quantities (>2.5 ng/g). With so few samples containing HEOD the whole lake mean residue was below the limits of detection of 0.25 ng/g (Table 1). However, in those sediments where HEOD was measurable a mean residue of 0.78 ng/g was found. No differences were observed between the mean concentrations in basins and non-depositional zones or between individual depositional basins (Table 2). PCB Polychlorinated biphenyls were not detected to a limit of 2.5 ng/g in 56% of sediments. Unconfirmed traces (2.5-5.0 ng/g) were found in 22% of samples and only 22% contained measurable levels of this contaminant. The mean residue for the lake was 3.3 ± 5.7 ng/g based on an assumed level of 4.0 ng/g for traces and 1.0 ng/g non-detectable readings (Table 1). In those sediments where PCB was measurable the mean residue was 8.5 ng/g. No differences were noted for PCB concentrations between depositional basins and nondepositional zones or between individual basins (Table 2). The highest PCB levels occurred in the sediments from the Duluth sub-basin and the Marathon basin. The distribution of PCB in sediment of Lake Superior is shown in Figure 4 which reveals the generally low level of PCB in the sediments. However, some areas of higher concentrations can be observed. These occur in the Duluth basin, in Thunder Bay, and in a general line extending from southwest of the Isle Royale across the lake north of the Keweenaw Peninsula but across the Keweenaw sill and toward the eastern shore. Another area occurs off the mouth of the Nipigon River extending south and southeastwards into the lake. These distributions show similarity to that observed for DDE (Figure 3), and seem to bear some relationship to the areas of known industrial activities in proximity to the lake basin.

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TABLE 1. Concentration of organochlorine contaminants in 405 bottom sediments collected from Lake Superior in 1973. Number of Sediments with Residues Cone. in Dried Sediments (ngjg)2 Number of Samples

Mean

SD

Min

Max

NonDetected

Unconfirmed Traces

Confirmed Readings

Sediments from Whole Lake p,p'.DDE HEOD PCB

405 405 405

0.71 <0.25 3.3

1.65

<0.25 <0.25 <2.5

23 1.9 57

203 367 227

64 19 89

138 19 89

Sediments with Measurable Residues p,p'-DDE HEOD PCB

138 19 89

1.71 0.78 8.5

0.50 0.50 5.1

23 1.9 57

Contaminants l

5.7

2.17 0.33 7.6

lNo measurable or confirmable residues of the following organochlorine compounds were found - aldrin, chlordane, p,p' or o,p'-DDT, endosulfan, endrin, heptachlor, heptachlor epoxide, mirex, p,p'-TDE (trace amounts of TOE and DDT were found in the sediment with the highest residue of DOE). 2 Por purposes of calculating the mean and SO, trace amounts (0.25-0.50 ng/g) of DOE and HEOD were assigned 0.4 ng/l and non-detectable amounts «0.25 ng/g) assigned 0.1 ng/g, and for PCB trace amounts (2.5-5.0 ng/g) were assigned 4.0 ng/g and non-detectable «2.5 ngfg assigned 1.0 ng/g.

INSECTICIDES AND PCB IN LAKE SUPERIOR SEDIMENTS

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DDE,ppb

I I <1 1-3

_>3

FIG. 3. Distribution ofp,p'·DDE in surficial sediments (3 cm) in Lake Superior.

TABLE 2. Concentrations of DDE, HEOD, and PCB in sediments of depositional basins and non-depositional zones in Lake Superior, 1973. Content in Dry Sediments (ng/g)l p,p'-DDE Locations All Basins Non-Depositional Zone Duluth sub-basin Chefswet sub-basin Apostle sub-basin Thunder Bay Trough Isle Royale sub-basin Thunder Bay Marathon Basin Keweenaw Basin Caribou sub-basin Whitefish sub-basin

Number

216 189 27 27

13 17 50 5 6 4 49 18

PCB

HEOD

Mean

SD

Mean

SD

Mean

SD

1.1

1.9 0.6 1.6 0.8 0.7 5.5 0.7 1.3 0.3 0.7 1.0 1.2

0.25 <0.25 <0.25 <0.25 0.25 0.27 0.25 0.26 0.32 <0.25 0.27 0.28

0.18

4.8 3.9 8.6 3.3 5.0 5.5 4.5 5.7 6.4 3.1 3.7 4.4

5.5 2.1 13.7 1.3 2.2 2.9 2.2 3.6 7.3 1.3 1.6 3.0

0.4 1.9 0.7 0.6 2.7 0.8 1.2 0.7 0.8 0.8 0.9

0.19 0.17 0.15 0.13 0.18 0.28 0.16

lFor purposes of calculating the Mean and SD, trace amounts (0.25-0.50 ng/g) of DDE and HEOD were assigned 0.4 ng/g and non-detectable amounts «0.25 ng/g) assigned 0.1 ng/g, and for PCB trace amounts (2.5-5.0 ng/g) were assigned 4.0 ng/g and non-detectable amounts «2.5 ng/g) assigned 1.0 ng/g.

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PCB,ppb

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FIG. 4. Distribution ofPCB in surficial sediments (3 em) in Lake Superior.

Other Organochlorines No residues of endosulfan, endrin, heptachlor epoxide, or chlordane were detected in the sediments. Eighty of the 405 samples (19.7%) were randomly selected and analyzed for mirex but no residues were detected to a limit of 0.3 ng/g. Many of these samples came from the areas where DDE and PCB were present at measurable levels.

DISCUSSION Glooschenko et al. (1976) sampled sediments in 1974 at locations in close proximity to major rivers, industrial plants, and municipal waters. In this study due to grid dimensions few samples were taken close to shore. Therefore in comparing the two sets of data only five samples were taken by Glooschenko et al. (1976) in deep, off-shore waters compared to 385 of 405 samples collected in this study. When these were compared there was good agreement for DDE and HEOD at all five locations and in four of the five sites where

PCB was reported. The one discrepancy found, occurred between a single reading of 90 ng/g from a mid lake site (Glooschenko et al. 1976), a location surrounded by four stations in this study that averaged 5 ng/g. The highest reported inshore reading was 1.3 ng/g and located off Marathon (Glooschenko et al. 1976). This location was almost 10 km from the nearest site of this study (X-47) making it possible that both residues could be real and reflecting high residues being associated with inshore activities. The PCB residues in sediments reported by Veith et al. 1977) and collected in 1972-73 were of the same order of magnitude herein reported. There workers found a mean residue of 7.0 ± 0.5 ng/g, a similar level to the 3.3 ± 5.7 ng/g reported herein for the whole lake or the 8.5 ± 7.6 ng/g for those samples where PCB was measurable. In samples collected in 1977, Eisenreich et al. (1979) reported PCB residues from 5 to 290 ng/g in the surface 0-0.5 cm and these declined to non-detectable at a depth of 4 cm. These residues were one to two orders of magnitude higher than those reported

INSECTICIDES AND PCB IN LAKE SUPERIOR SEDIMENTS by Veith et al. (1977), Glooschenko et al. (1976), and in this study when only off-shore sites are compared. In view of the findings by Eisenreich et al. (1979) some explanation of the lower values reported here seems necessary. Sample values for PCB by Eisenreich et al. (1979) are for the surface 0.5 cm and involve the sum total of Aroclor 1242 and 1254. These authors emphasized that a rapid decline in PCB values occurred down the sediment profile. In this study we report the value of a homogenized surface 3 cm which will obviously be substantially lower than the value for the surface 0.5 cm. In all our samples the surface oxidized ooze was always examined for disruption and loss. Any perturbation of this zone by the Shipek sampler indicative of loss resulted in the samples being rejected and the taking of a repeat sample. The surface layer represented a watery ooze ranging from about 0.5 to 1.5 cm in thickness of lower density overlying the more dense and compacted light colored clays characteristic of the lake. Some loss of surface ooze may have occurred but is considered unlikely when the care in sampling is taken into account. It should be noted that sampling in the study by Eisenreich et al. (1979) was conducted in 1977 as compared to 1973 for this study. Only Aroclor 1254 was reported in samples collected in 1973 as this fraction predominated. In the sediments reported by Eisenreich et al. (1979) Aroclor 1242 was the predominant fraction. When the residues of the two studies were compared on the basis of Aroclor 1254 residues, good agreement was observed at six of the nine comparable sites in deep water. At the other three sites residues were about one magnitude higher in sediments collected in 1977. This could reflect increased contamination between 1973 and 1977 that could have been deposited in the upper 0.1 cm according to the higher sedimentation rates reported by Kemp, Dell, and Harper (1978) of 0.1 to 2 mm/year. The fact that PCB levels in sediments during 1973 were not significantly different between basins and non-depositional zones supports the suggestion by Eisenreich et al. (1979) that it is derived from aerial transport. The levels ofp,p'-DDE, HEaD, and PCB concentrations in Lake Superior sediments were considerably lower than those measured in other lakes down stream by Frank et al. (1977, 1979a, 1979b). This conforms but may not necessarily be correlated

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with lower residues in fish caught in Lake Superior (Frank et al. 1978, Reinert 1970, Reinke et al. 1972, and HC 1976) as compared to levels found in fish from lakes downstream.

REFERENCES Berg, O. W., Diosady, P. L., and Rees, G. A. V. 1972. Column chromatographic separation of polychlorinated biphenyls from chlorinated hydrocarbon pesticides, and their subsequent gas chromatographic quantitation in terms of derivatives. Bull. Environ. Contam. Tax 7:338-347. Chiba, M., and Morley, H. V. 1968. Factors influencing extraction of aldrin and dieldrin residues from different soil types.J. Agr. Good Chern. 16:916-922. Eisenreich, S. J., Hollod, G. J., and Johnson, T. C. 1979. Accumulation of polychlorinated biphenyls (PCBs) in surficial Lake Superior sediments. Atmospheric deposition. Environ. Sci. and Technol. 13:569-573. Frank, R., Holdrinet, M., Braun, H. E., Thomas, R. L., Kemp, A. L. W., and Jaquet, J. M. 1977. Organochlorine insecticides and PCBs in sediment of Lake St. Clair (1970 and 1974) and Lake Erie (1971). Sci. Total Environ. 8 :205-227. _ , Holdrinet, M., Braun, H. E., Dodge, D. P., and Spangler, G. R. 1978. Organochlorine insecticide and PCB residues in fish from Canadian waters of Lakes Huron and Superior, 1968-1976.Pestic. Manit. J. 12:60-68. _ , Thomas, R. L., Ho1drinet, M., Kemp, A. L. W., and Braun, H. E. 1979a. Organochlorine insecticides and PCB in surficial sediments (1968) and sediment cores (1976) from Lake Ontario. J. Great Lakes Res. 5:18-27. _ ' Thomas, R. L. Holdrinet, M., Kemp, A. L. W., Braun, H. E., and Dawson, R. 1979b. Organochlorine insecticides and PCB in the sediments of Lake Huron (1969) and Georgian Bay and North Channel (1973). Sci. Total Environ. 13: 101-117. Glooschenko, W. A., Strachan, W. M. J., and Sampson, R. C. J. 1976. Distribution of pesticides and polychlorinated biphenyls in water, sediments and seston of the Upper Great Lakes - 1974. Pestic. Manit. J. 10:61-67. Holdrinet, M. 1974. Determination and confirmation of hexachlorobenzene in fatty samples in the presence of other halogenated hydrocarbon pesticides and PCBs. JA.O.A.C. 57 :580-584. _ , Frank, R. Thomas, R. L., and Heding, L. 1978. Mirex in sediments of Lake Ontario. J. Great Lakes Res. 4:69-74. International Joint Commission, 1976. Report of the Upper Lakes Reference Group to the International Joint Commission. The waters of Lake Huron and Lake Superior, Vol. 1, Summary and Recommendations. Windsor, Ontario. _ , 1977. Report of the Upper Lakes Reference Group

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to the International Joint Commission. The waters of Lake Huron and Lake Superior, Vol. lIB - Lake Huron, Georgian Bay and the North Channel, Windsor, Ontario. Kemp, A. L. W., Dell, C. I., and Harper, N. S. 1978. Sedimentation rates and a sediment budget for Lake Superior. J. Great Lakes Res. 4:276-287. Leland, H. V., Bruce, W. M., and Shimp, N. F. 1973. Chlorinated hydrocarbon insecticides in sediments of Southern Lake Michigan. Environ. Sci. Technol. 7:833840. Mills, A., Bong, A., Kamps, R., and Burke, A. 1972. Elution solvent system for Florisil column cleanup in organochlorine pesticide residue analyses.JA.OA.C. 55:39-43.

Reinert, R. E. 1970. Pesticide concentrations in Great Lakes. Fish. Pestic. Manit. J. 3:233-240. Reinke, J., Uthe, J. F., and Jamieson, D. 1972. Organochlorine pesticide residues in commercially caught fish in Canada (1970). Pestic. Manit. J. 6:43-49. Reynolds, L. N. 1971. Pesticide residue analysis in the presence of polychlorinated biphenyls (PCBs). Residue Rev. 34:27-57. Thomas, R. L., and Dell, C. I. 1978. The Sediments of Lake Superior.J. Great Lakes Res. 4:264-275. Veith, G. D., Kuehl, D. W., Puglish, F. A., Glass, G. R., and Eaton, J. G. 1977. Residues of PCBs and DDT in the western Lake Superior ecosystem. Arch Environ. Can· tamin. Toxicol. 5:487499.