Ringed Seal Blubber Research Articles

Biotransformation versus Bioaccumulation: Sources of Methyl Sulfone PCB and 4,4‘-DDE Metabolites in the Polar Bear Food Chain

In the polar bear food chain from the Canadian Arctic, methyl sulfone (MeSO2-) PCBs and 4,4‘-DDE were below detection in arctic cod (<0.01 ng/g, lipid wt). Ringed seal blubber contained 3-MeSO2-4,4‘-DDE (0.4 ng/g) and 14 3- and 4-MeSO2-PCB isomer pairs (∑MeSO2-PCB, ca. 13 ng/g) formed by the biotransformation of PCBs not chlorine substituted at the meta−para positions on one ring (m,p-PCBs). Bioaccumulation/formation efficiencies relative to CB153 (BFE-) from cod to seal were 0.001−0.086 for MeSO2-PCBs and 0.004 for 3-MeSO2-4,4‘-DDE. Twelve MeSO2-PCB isomer pairs (∑MeSO2-PCBs, 432 ± 57 ng/g) and 3-MeSO2-4,4‘-DDE (2.0 ± 0.7 ng/g) were identified in polar bear fat; BFE‘ values were 0.03−0.62 and 0.0001 for MeSO2-PCBs and 3-MeSO2-4,4‘-DDE, respectively. Methyl sulfone formation is important but not the major route for m,p-PCB and 4,4‘-DDE biotransformation in polar bear and ringed seal. Fifteen MeSO2-PCB congeners in the bear are likely bioaccumulated from seal relative to the completely bioaccumulated 3-/4-...

Persistent organochlorine compounds in the blubber of ringed seals ( Phoca hispida) from the Belcher Islands, Northwest Territories, Canada

Samples of blubber and morphometric data were obtained in 1991 from a population of ringed seals ( Phoca hispida) located in southeastern Hudson Bay, near the Belcher Islands. Several PCB congeners, DDT and its metabolites, components of technical chlordane, HCH compounds, dieldrin and mirex were detected at concentrations below 150 ng/g lipid in the blubber of these animals. Female seals had lower concentrations of PCB congeners, DDT compounds and chlordane compounds in the blubber than male seals from this region, but there were no sex-specific differences observed for HCH compounds, dieldrin and mirex. Correlations were observed between the age of male seals and their estimated ‘blubber burdens’ (mg) of total PCBs and total DDT. There was evidence that the male seals from the Belcher Islands had higher concentrations and blubber burdens of total PCBs and lower concentrations of total HCHs than male seals sampled in 1989 from a population at Holman Island in the northwest Canadian arctic. Morphometric data indicated that the Holman Island seals were in better condition than the Belcher Islands seals at the time of sampling. Due to the negative correlation observed between contaminant concentrations in ringed seals and the condition of the animals, analysis of blubber burdens in seals may be a preferable method for monitoring spatial and temporal trends in the contamination of ringed seals in the arctic.

Vitamins A1 (Retinol), A2 (3,4-Didehydroretinol) and E (α-Tocopherol) in the Liver and Blubber of Lacustrine and Marine Ringed Seals (Phoca hispida sp.)

Concentrations of vitamins A1 (retinol), A2 (3,4-didehydroretinol) and E (α-tocopherol) in the liver and blubber of ringed seals from Lake Saimaa (Phoca hispida saimensis), Lake Ladoga (P. h. ladogensis), the Baltic Sea (P. h. botnica) and Spitsbergen (P. h. hispida) were determined by high-performance liquid chromatography. The freshwater seals had much lower levels of vitamin A1 but higher levels of vitamin A2 than the marine seals. The concentrations of vitamin E in the livers of the subspecies studied were high compared with earlier reports of seals, but the ranges were large. The livers of the marine seals contained more vitamin E than the livers of the freshwater seals, but the levels in the blubber were uniform in all populations, except in old specimens from the Baltic. The differences between the freshwater and marine seals are suggested to be due mainly to diet. The ratios of A1 to A2 in the liver and blubber and in the fish diet were similar for the marine seals and for the freshwater seals (but differed in the marine and freshwater populations), which suggests no great differences in the absorption, transport and metabolism of the two analogues. Blubber was an important storage site for the vitamins studied, and age-dependent increases were detected, especially for vitamin E. In the 2-month to 2-year-old ringed seals of Lake Saimaa, however, the vitamin E concentration in the blubber was not affected by age.

Persistent organochlorine compounds in the blubber of ringed seals (Phoca hispida) from the Belcher Islands, Northwest Territories, Canada

Persistent organochlorine compounds in the blubber of ringed seals (Phoca hispida) from the Belcher Islands, Northwest Territories, Canada

Geographical variation of persistent organochlorine concentrations in blubber of ringed seal ( Phoca hispida) from the Canadian Arctic: Univariate and multivariate approaches

Geographical variation of organochlorine (OC) concentrations in ringed seal ( Phoca hispida) in the Canadian Arctic was studied using univariate and multivariate statistical techniques. The dataset consisted of 80 individual OC components (58 PCB congeners plus DDT- and chlordane (CHL)-related compounds, toxaphene, hexachlorocyclohexanes (HCH), chlorobenzenes (CBz), and dieldrin) determined in 221 ringed seal blubber samples from 13 locations throughout the Canadian Arctic from the period 1983 to 1989. Mean concentrations of the major OC groups in ringed seal blubber (ΣPCBs, ΣDDT, ΣCHL and toxaphene), adjusted for the age and sex of the seals, showed few significant geographical differences. Principal components analysis was used to examine geographical trends. Significant differences in mean factor scores for three of four principal components were found between sampling locations. Locations in the western and high Arctic could be distinguished from those in Hudson Bay by highest scores along principal component two which was associated principally with CBz. PCB congeners with six or more chlorine substitutions declined with increasing north latitude, whereas more volatile OCs (CBz, HCH, less chlorinated PCBs) increased in the proportion of total OCs with latitude. Proportions of less chlorinated PCBs also decreased with increasing longitude, whereas slopes of regressions for more highly chlorinated PCBs increased significantly. The results were generally consistent with the ‘cold condensation’ hypothesis of increasing proportions of more volatile OCs with increasing latitude and distance from sources.

Very long chain polyunsaturated fatty acids in the blubber of ringed seals (Phoca hispida sp.) from Lake Saimaa, Lake Ladoga, the Baltic Sea, and Spitsbergen.

Blubbers of four ringed seal subspecies from Lake Saimaa, Lake Ladoga, the Baltic Sea, and Spitsbergen were analyzed for very long chain polyunsaturated fatty acids (VLCPUFA; > C22) using gas-liquid chromatography and gas chromatography/mass spectrometry. The VLCPUFA of the blubber oils were mainly n-3 polyunsaturated fatty acids--23:5n-3, 24:3n-3, 24:4n-3, 24:5n-3, 24:6n-3, 26:5n-3, 26:6n-3, and 28:7n-3. The largest VLCPUFA components in all populations were 24:5n-3 (0.1-0.2 wt% of total fatty acids) and 24:6n-3 (0.1%), but 24:4n-3 (0.1%) was also prominent in the Baltic specimens. The blubber oils of the freshwater species contained considerably more 24:4n-6 and 24:5n-6 than the blubbers of the marine species. The differences among the VLCPUFA in these subspecies appear to be mainly due to different dietary VLCPUFA.

Zinc, cadmium, mercury and selenium in polar bears (Ursus maritimus) from Central East Greenland

Muscle, liver, and kidney tissues from 38 polar bears (Ursus maritimus) caught in the Scoresby Sound area, Central East Greenland, were analysed for zinc, cadmium, mercury and selenium. In general, cadmium concentrations were low in muscle, liver and kidney tissue, with geometric means (g.m.) of 0.022 (range: <0.015–0.085), 0.841 (range: 0.092–3.29) and 13.1 (range: 1.04–115) μg Cd/g wet weight (ww) respectively. This finding can be explained by low cadmium levels in the blubber of ringed seals. The concentration of mercury in muscle tissue was low (g.m. 0.071; range: 0.039–0.193 μg Hg/g ww), whereas concentrations in liver and kidney tissue were relatively high (liver: g.m. 7.87; range: 1.35–24.8 μg Hg/g ww, and kidney: g.m. 15.2; range: 1.59–66.6 μg Hg/g ww). Mercury and cadmium were positively correlated with age in liver and kidney. Zinc was positively correlated with age in kidney, and selenium was correlated with age in liver. Contrary to other marine mammals, polar bears had higher mercury levels in the kidneys than in the liver. In all three tissues polar bears had significantly lower cadmium levels than ringed seals from the same area. Mercury levels were likewise significantly lower in the muscle tissue of polar bears than in ringed seals, whereas levels in the liver and kidney were significantly higher. The previous geographic trend for cadmium and mercury found in Canadian polar bears could be extended to cover East Greenland as well. Hence cadmium levels were higher in Greenland than in Canada, while the opposite was the case for mercury. Greenland polar bears had higher mercury and cadmium contents in livers and kidneys than polar bears from Svalbard. The mercury levels in muscle and liver tissue from polar bears from East Greenland were twice as high as found in bears from western Alaska, but half the levels found in northern Alaska. Cadmium and zinc were partially correlated in kidney tissue, and this was found for mercury and selenium as well. Cadmium and zinc showed molar ratios close to unity with the highest concentrations occurring in kidney tissue, while the levels of zinc exceeded cadmium in muscle and liver tissue by up to several decades. Mercury and selenium showed molar ratios close to unity in liver and kidneys.

Concentrations of polychlorinated dibenzo- p-dioxins, dibenzofurans and non- ortho substituted biphenyls in polar bear milk from Svalbard (Norway)

Polychlorinated dibenzo- p-dioxins (PCDD), dibenzofurans (PCDF) and non- ortho substituted biphenyls (PCB, CB) were determined in 6 polar bear milk samples from Svalbard (Norway). For these compounds, no data for polar bears have been reported before from this region. Most of the PCDD/PCDF congeners were found at detectable levels. Concentrations expressed as 2,3,7,8-TCDD equivalents (Nordic model) were in the order of 1–3 pg/g −1 fat (0.2–1.6 pg ml −1 milk) which is comparable with ringed and harp seal blubber from the same region. On whole milk basis, concentrations were similar to those found in human milk. An estimation of the daily uptake via milk showed that the intake is lower for polar bears compared to humans. As in human milk, relatively high levels of OCDD were found in some polar bear milk samples. The PCDD/PCDF congener pattern in the milk was different to that found in polar bear fat from the Canadian Arctic. Non- ortho substituted PCB levels in polar bear milk were similar to those found in polar bear fat from the Canadian North. However, CB 77 or 169 dominated in the milk while CB 126 was the most abundant congener in fat. PCDD/PCDF levels expressed as 2,3,7,8-TE were highly correlated with the fat content of the milk. No correlation between CB and PCDD/PCDF concentrations was found. Some data indicate that PCDD/PCDF concentrations in polar bear milk decrease with increasing time after delivery.

Identification of polychlorocamphenes (PCCs) in the polar bear ( Ursus maritimus) food chain

Fifteen congeners of polychlorocamphenes (PCCs) were identified in polar bear fat and ringed seal blubber using HRGC/ECNI-MS techniques. Several of these compounds coeluted with chlordane and PCB congeners, but could be identified by analysis of the ECNI spectra of the chromatographic peaks and by comparison of their retention times with components in a technical toxaphene mixture and authentic standards. ECNI spectra of pure PCC congeners are also presented. Three nonachlorobomene compounds not in toxaphene were also detected. One of these was at higher levels relative to total PCCs in polar bear than in ringed seal. The pattern of PCC congener distribution in polar bear and ringed seal was more complicated than previously described in arctic mammals and fish. In particular, the octachlorobornane (T2) and nonachlorobomane (T12), which dominate in arctic amphipods, burbot, narwhal and beluga, were only 8–11% of total PCCs in ringed seal and polar bear. Levels of PCCs were 1.0 mg/kg in polar bear and 0.25 mg/kg in ringed seal. The bioaccumulation potential of PCCs in polar bear is similar to that of HCH and DDE, but much less than that of PCBs and oxychlordane. Analysis of polar bear tissues may provide a useful measure of the geographical distribution of PCCs in the arctic environment.

Mono-ortho and non-ortho substituted PCBs in Arctic ringed seal (Phoca hispida) from the Svalbard area: Analysis and determination of their toxic threat

To determine the 2,3,7,8-tetrachloro-dibenzo-p-dioxin (2,3,7,8-TCDD) toxic equivalent (TEQ) of the PCBs in ringed seal, we analysed liver, blubber and kidney for non-ortho and mono-ortho substituted CBs as well as the total PCB and total DDE concentration. The blubber samples were compared with ringed seal blubber samples from another study 1,2, in which total PCB and PCDD/PCDF concentrations were measured, and the TEQ values for the PCBs in our samples were 11 times higher than the TEQ values for the PCDDs/PCDFs in the other seal samples. Comparing the 3 different seal matrices, we found no significant difference in PCB pattern; the absolute concentrations expressed per unit lipid weight were for the females in the following order : blubber ≈ liver > kidney. We found another order for the males: blubber > liver > kidney. Among the different seals, there was a good PCB-sex correlation indicating that the results of different studies, without specific background information, must be compared with great caution.

Re-evaluation of concentration levels of polychlorinated dibenzo-p-dioxins and dibenzofurans in Arctic seal from Spitzbergen

Levels of polychlorinated dibenzo-p-dioxins (PCDD), dibenzofurans (PCDF) and pesticides in ringed seal blubber have been reported in Chemosphere 17 , 1291 (1988). Additional informations about sex, age and exact area which had gone lost by accident, have now been regained. They made a re-evaluation of the data necessary since the animals were caught much closer to the settlement at Ny Ålesund than assumed earlier. No influence of this local source on the determined concentrations was found when they were compared with the levels in Arctic seals which have been published in the meantime.

Polychlorinated dibenzo- p-dioxins and dibenzofurans in marine mammals in the Canadian North

Polychlorinated dibenzo- p-dioxins (PCDDs) and dibenzofurans (PCDFs) were determined in pooled samples of ringed seal ( Phoca hispida) blubber, beluga ( Delphinapterus leucas) blubber and polar bear ( Ursus maritimus) liver and fat from several areas throughout the Canadian north and compared to mean PCB and HCB levels in the same samples. All seal samples, and all but one polar bear sample, had detectable 2,3,7,8-TCDD at concentrations ranging from 2 to 37 ng/kg, but TCDD was not found in beluga blubber (<2 ng/kg). All seal samples and one of three beluga samples contained 2,3,7,8-TCDF at levels of 2 to 7 ng/kg, but TCDF was not found in any bear sample. TCDF must therefore be cleared rapidly by polar bears. No other PCDF congeners were found at detection limits of 4 to 8 ng/kg. OCDD concentrations in seal blubber and polar bear samples ranged from not detected (<8 ng/kg) to 43 ng/kg. No apparent biomagnification of TCDD, OCDD or TCDF occurred from seal to bear fat, similar to previous findings for DDT, and unlike ΣPCBs and HCB which biomagnified 6- to 17-fold. Highest concentrations of 2,3,7,8-TCDD and OCDD in seals and bears were found in the central Canadian Arctic Archipelago, and lowest were found in Hudson Bay, the reverse of PCB concentration distribution. The reason for higher levels of TCDD and OCDD in the Arctic than in the sub-Arctic is suggested to be trans-polar movement of aerosols with combustion-related origins in Eurasia. Levels of 2,3,7,8-TCDF were more evenly distributed throughout the North, and were positively correlated with PCB, but not with HCB or 2,3,7,8-TCDD levels in seals.

Organochlorine contaminants in arctic marine food chains: accumulation of specific polychlorinated biphenyls and chlordane-related compounds

Polychlorinated biphenyl congeners (S-PCB) and chlordane-related compounds (S-CHLOR) as well as DDT, hexachlorocyclohexane, toxaphene, and chlorobenzenes were determined in pooled arctic cod (Boreogadus saida) muscle and polar bear (Ursus maritimus) fat and in the blubber and liver of 59 ringed seals (Phoca hispida) from the east-central Canadian Arctic. S-PCB concentrations ranged from 0.0037 mg/kg (wet wt) in cod muscle to 0.68 mg/kg in male seal blubber and 4.50 mg/kg in bear fat. Tri- and tetrachloro PCB homologues were the dominant PCBs in fish, while pentachloro/hexachloro and hexachloro/heptachloro congeners predominated in ringed seal blubber and polar bear fat, respectively. Chlordane compounds detected in seal blubber were oxychlordane, cis- and trans-nonachlor, and cis-chlordane as well as nine minor components of technical chlordane, including nonachlor-III (a nonachlor isomer). Toxaphene and HCH isomers were the major organochlorines in cod muscle with mean concentrations of 0.018 and 0.010 mg/kg, respectively. S-CHLOR/S-PCB ratios ranged from 0.6 in fish muscle and bear fat to 0.7-0.9 in seal blubber, much higher than observed in more southerly marine environments, suggesting a proportionally greater input of chlordane into the Arctic.