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AMAP Greenland and the Faroe Islands 1997-2001

4 Marine Environment

Citation: Riget, F¹., P. Johansen¹, M. Glasius², K. Vorkamp³, H. Dahlgaard⁴, D. Muir⁵, G. Asmund¹ & E.W. Born⁶: Chapter 4. Marine Environment. In: Riget, F., J. Christensen & P. Johansen (eds). AMAP Greenland and the Faroe Islands 1997-2001. Ministry of Environment, Denmark 
¹ Department of Arctic Environment, National Environmental Research Institute, Frederiksborgvej 399, Box 358, DK-4000 Roskilde, Denmark
² Department of Atmospheric Environment, National Environmental Research Institute, Frederiksborgvej 399, Box 358, DK-4000 Roskilde, Denmark
³ Department of Environmental Chemistry and Microbiology, National Environmental Research Institute, Frederiksborgvej 399, Box 358, DK-4000 Roskilde, Denmark
⁴ Risoe National Laboratory, Radiation Research Department, NUK-204, PO-box 49, DK - 4000 Roskilde, Denmark
⁵ National Water Research Institute, Aquatic Ecosystem Conservation Branch, 867 Lakeshore Road, Burlington ON L7R 4A6 Canada
⁶ Greenland Institute of Natural Resources, PO. Box 570, DK-3900 Nuuk, Greenland

4.1 Introduction

This assessment includes a substantial amount of new heavy metals and OC data in Greenland marine biota, which were collected as part of the following AMAP projects: “Biological core programme”, “Temporal time trend programme”, “Contaminants in Greenland human diet”, “Non-halogenated organic Substances in the Greenland Environment”,”Population structure of west Greenland narwhals”, “Population structure of Atlantic minke whales” and “Effects of Contaminants in the Greenland Sea Polar Bear”. Radionuclides were collected in the projects: “ Radionuclides, remaining phase 2 data, 2001”,”Radionuclides 2000”,”Anthropogenic radionuclides in Greenland and the Faroe Islands” and “Thuleundersøgelse-1997”.

The description of contaminant levels, spatial trends and short-term temporal trends focuses on the heavy metals Cd and Hg (Se) and on the organochlorines ΣPCB, ΣDDT, ΣHCH, HCB and ΣCHL. Appendices A and B shows descriptive statistic of the new available data of heavy metals and organochlorines, respectively. Stable isotopes have been analysed in order to facilitate the interpretation of levels and trends. The radionuclides focus on ¹³⁷Cs, ⁹⁹Tc, ⁹⁰Sr and ^239,240Pu in components of the marine environment and one section deals with plutonium in Bylot Sound in the Thule area because of a nuclear accident here in 1968. Furthermore, one section deals with Pb contamination of seabirds from hunting with lead shot. One section summarizes the use of contaminant signatures beside other signatures (genetic, stable isotopes, fatty acids) to deduce population structure of minke whales and narwhals in Greenland waters.

4.2 Stable isotopes

Stable-nitrogen and stable-carbon isotope ratios were measured in muscle of ringed seal (Phoca hispida) and black guillemot (Cepphus grylle) (see Table 4.2.1) according to Hobson et al. (1997) at the laboratory of Prairie and Northern Wildlife Research Center, US. Stable isotopes data can be informative about feeding preferences and trophic level (Hobson & Welch, 1995). The reason is that the abundance of •¹⁵(¹⁵N/¹⁴N) in the tissues of consumers is typically enriched over that in their prey owing to the preferential excretion of the lighter ¹⁴N during protein transamination and deamination (Hobson & Welch ibid). Different feeding preferences among populations or between years may lead to different levels of bio-accumulating contaminants. Therefore information about stable isotopes is useful when interpretation contaminant levels.


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Ringed Seal

An analysis of covariance (factor: location combined with sampling year, covariate: age allowing different linear relationships between isotopes ( ¹⁵N and ¹³C ) and age among samples) revealed a complicated relationship between both ¹⁵N and ³C and age. In some samples, the relationship between isotopes values and age was negative while in others the relationship was positive. Because of this uncertainty of age dependency, the pairwise test of LSMEAN (least square mean) values was performed to test of differences in mean ¹⁵N and ¹³C among samples. The LSMEAN are estimated age adjusted values (SAS 1999-2001). The results of the statistical comparisons are shown in Table 4.2.2.

Table 4.2.2.
Results of pair-wise comparisons (age adjusted values) between samples for ¹⁵N and ¹³C in ringed seal muscle. Samples are written in decreasing concentrations order and samples underlined were not significant different at the 5% level. Ava = Avanersuaq, Itt = Ittoqqortoormiit, Qeq = Qeqertarsuaq.

Both ¹⁵N and ¹³C values showed significant spatial and temporal differences. The ringed seals from Avanersuaq had higher ¹⁵N that those from the other areas
(especially in 1998) which indicate that these seals had fed at a relatively higher trophic level. One explanation may be the relatively high age (mean 9.2 years) of the seals from Avanersuaq in 1998. The ringed seals from Ittoqqortoormiit had lower ¹³C values compared to those from the other areas. Carbon isotopes ratios can reflect input of dietary resources from inshore versus offshore areas (Hobson et al. 1997), and therefore indicate that the Ittoqqortoormiit seals had been relatively more offshore. In both Avanersuaq and Ittoqqortoormiit significant differences in ¹⁵ N values were seen between sampling years. This was also the case of ¹³C values in Avanersuaq and Qeqertarsuaq. These results have to be taken into account when evaluating spatial and temporal trends of heavy metals and OC levels.

Black guillemot

Analysis of variance was performed in order to test differences in mean ¹⁵N and ¹³C values among samples. The test was performed for juvenile and adult birds separately. Tukey’s post hoc test was used to detect which samples differed from each other (Table 4.2.3).

Table 4.2.3.
Results of Tukey’s post hoc test between samples for ¹⁵N and ¹³C in black guillemot muscle. Samples are written in order of decreasing concentrations and samples underlined were not significantly different at the 5% level. Itt = Ittoqqortoormiit, Qeq = Qeqertarsuaq.

¹⁵N values showed significant differences between 1999 and 2000 in black guillemot from Qeqertarsuaq indicating that the 1999 birds to have been feeding at a relatively higher trophic level. The ¹³C values were significantly different in all cases with the lowest values in Ittoqqortoormiit as were the case with ringed seal.

4.3 Heavy metals

In AMAP phase I, heavy metals were determined in marine sediment, blue mussels (Mytilus edulis), shorthorn sculpin (Myoxocephalus quadricornis), polar cod (Boreogadus saida), glaucous gull (Larus hyperboreus), Icelandic gull (Larus glaucoides) and ringed seals at four locations in Greenland (Riget et al. 2000e). In general, lead levels were found to be low, whereas levels of cadmium, mercury and selenium in Greenland marine biota were high. Cadmium and mercury concentrations increase in higher trophic levels whereas this is not the case for lead and selenium (Dietz et. al. 1996). There was a tendency of higher mercury concentrations in east Greenland, whereas the highest cadmium concentrations were found in central west Greenland (Riget et al. ibid).

4.3.1 Levels and spatial trends

4.3.1.1 Arsenic in marine sediments

The surface layer of Greenland sediments has been analyzed for arsenic. The background was that very high concentrations of arsenic had been found in some surface sediment from the Pechora Sea (Loring et al. 1995). At a station close to Guba Chernaya the concentration of arsenic was 308 mg/kg. The concentrations decreased seawards from this station to background values of less than 20 mg/kg. Although arsenic data were not available for the other circumpolar sediments, the Pechora Sea Arsenic concentrations were considerably higher than those reported (6 mg/kg) for the Gulf of St. Lawrence sediments. The data indicated that arsenic is enriched in the core samples either by natural and/or anthropogenic processes in the surface and near surface layers. The arsenic correlates with the plutonium derived from nuclear weapons under water tests performed at Guba Chernaya. In a Norwegian AMAP study Maage et al. (unpubl.) found high arsenic concentrations at some locations in the Barents Sea near Svalbard far from nuclear weapon test sites. Concentrations between 50 and 80 mg/kg were regularly found just south of Svalbard. Maage et al. found a mean value of 22 (± 22) mg/kg. Interestingly, looking at the As/Li ratio (mean 0.59 ± 0.42), three of the stations closest to the south tip of Novaya Semlya showed relatively high values with two stations showing higher As/Li-ratios than 1.5. This suggests that a relatively large area around the Noveya Zemlya have elevated As sediment values. The other parts of the Barents Sea as such do not seem to have elevated arsenic in sediments even though high absolute values also were seen along King Carls Land east of Svalbard.

The sediment samples from Greenland were collected in the period 1985 to 1994. The top 1cm was analysed for total arsenic by NERI. Loring & Asmund (1996) have previously reported results for several other trace elements in these samples. Analytical results for arsenic and mercury are shown in Table 4.3.1. The average and standard deviation of the arsenic concentrations were 7.87 mg/kg and 5.68 mg/kg. This is much lower than reported by Maage et al. (unpubl.) for the Barents Sea, and comparable to the Gulf of St. Lawrence. The highest concentration found was 24.6 mg/kg. The conclusion is that Greenland marine sediments are not enriched in arsenic as reported for large areas of the Barents Sea.

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4.3.1.2 CD

Invertebrates

Cd concentrations have been determined in blue mussels (Mytilus edulis), Iceland scallop (Chlamys islandica) and queen crab (Chionoetes opilo) (Appendix A). Cd in blue mussels from Qeqertarsuaq ranged from 0.55 to 2.27 mg/kg ww increasing with length of the mussels as previously reported by Riget et al. (1996). Cd levels in blue mussels from Qeqertarsuaq are relative high compared to other locations in Greenland, however, it confirms the relative high Cd levels previously reported here in marine biota (Riget et al. 2000e). The concentration of 2.04 mg/kg ww found in Iceland scallop was lower than previously found in this species (Dietz et al. 1996). The Cd concentration in queen crab muscle was low (0.04 mg/kg ww), whereas it was high (5.1 mg/kg ww) in crab hepatopancreas.

Marine fish

Cd concentrations have been determined in shorthorn sculpin, Atlantic cod (Gadus morhua), Atlantic salmon (Salmo salar), Greenland halibut (Reinhardtius hippoglossoides) and capelin (Mallotus villosus). In muscle, Cd concentrations in all species were low (below 0.003 mg/kg ww). In liver, Cd concentrations ranged from 0.05 mg/kg ww in Atlantic cod to 1.40 mg/kg in shorthorn sculpin. These values are in the range observed in 21 different marine fish species from Greenland (Riget et al. 1997). Cd concentrations in sculpin liver from Qeqertarsuaq were higher in both 1999 and 2000 than in sculpin from Ittoqqortoormiit. However, these differences were not significant at the 5% level (t-test on logarithmic transformed data, 1999: p=0.34, 2000-male: p=0.25, 2000-female: p=0.07).

Seabirds

Cd concentrations have been determined in black guillemot (Cepphus grylle) liver and kidney from Qeqertarsuaq in 1999 and 2000 (only liver) and in black guillemot egg from Ittoqqortoormiit in 2000. In liver Cd concentrations ranged from 1.85 mg/kg ww in adults 1999 to 3.72 mg/kg ww in adults 2000. In kidney, Cd concentrations were higher than in liver (15-22 mg/kg ww). These values were within the range observed previously in that species (Dietz et al. 1996). In 1999, Cd concentrations in juvenile were surprisingly higher than in adults; usually the trend is opposite (Nielsen & Dietz 1989). In eggs, Cd concentrations were low (0.001 mg/kg ww). Cd concentrations in black guillemot liver from Greenland were similar to those observed in the Faroe Islands, Canada and the Barents Sea (AMAP 1998).

Marine mammals

Cd concentrations have been determined in ringed seal (Phoca hispida), narwhal (Monodon monoceros), beluga (Delphinapterus leucas), minke whale (Balaenoptera acutorostrata) and polar bear (Ursus maritimus) (Appendix A).

Cd concentrations in ringed seal liver were available from Qeqertarsuaq and Ittoqqortoormiit in 1999 and 2000, and from Avanersuaq 1998. In blubber, Cd concentrations were determined in seal blubber from Qeqertarsuaq in 2000. Cd concentrations in liver ranged from 8.22 mg/kg ww in seals from Qeqertarsuaq in 2000 to 16.8 mg/kg ww in seals from Qeqertarsuaq in 1999. Cd concentrations in seal blubber was low (0.011 mg/kg ww). These values are within the range observed previously in ringed seals (Dietz et al. 1996). Cd concentrations in ringed seals increase with age (Diet et al. 1998). Therefore, seals has been divided into age groups (0, 1-3, 4-6 and above 6 years old) before testing for differences in mean Cd concentrations between Qeqertarsuaq and Ittoqqortoormiit in 1999 and 2000. Cd concentrations were higher for all age groups and both years in seals from Qeqertarsuaq than in seals from Ittoqqortoormiit. However, no significant (at 5% level) differences were found (t-test on logarithmic transformed data, t-test only performed if n>1). The Cd concentrations in seals from Avanersuaq 1998 were similar to those from Ittoqqortoormiit, however, the relative high average age of Avanersuaq seals should be noted. In general, Cd concentrations in ringed seals from west and east Greenland are similar to seals from the Canadian Eastern Arctic but higher than in Alaska and Svalbard.

Data of Cd concentrations in narwhals are available from Avanarsuaq, Balgoni Island (Melville Bay), Uummannaq, Kitsissuarsuit (Disko Bay) and Saqqaq (see also chapter 4.7.1).

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Figure 4.3.1.
Relationship between Cd concentrations (mg/kg ww) and growth layer (age). Lines represent LOWESS smoother (from Riget et al. 2002)

Cd concentrations in muscle, liver and kidney tissue increase during the first 3 to 4 years of the narwhals life, after which a relatively constant Cd level is observed (a tendency of a slightly decrease can be seen) (Figure 4.3.1). In all tissues (muscle, liver and kidney) the Cd concentrations were significantly higher in females than in males (Riget et al. 2002). A consistent difference between Avanersuaq and Uummannaq was not found in any of the tissues (Figure 4.3.2). In muscle there was significant difference between the samples in 1993 and 1984 from Avanersuaq (Riget et al. 2002). However, the sample in 1985 was not different from the two others. In the sample from Uummannaq 1993, Cd concentrations, especially in females, were higher than in the other samples. Therefore, the year-to-year variation exceeded the geographical differences. In general, the Cd levels in the Greenland narwhals were within the range found in Arctic Canada (Wagemann et al. 1983, 1996).

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Figure 4.3.2.
Mean (mg/kg ww) ± standard error of Cd concentrations in narwhals by area, year and sex (from Riget et al. 2002).

Cd concentrations in blubber of beluga were low (<0.005 mg/kg ww).

Cd concentrations in muscle, liver, kidney and baleen of minke whales from the North Atlantic and European Arctic were determined as a part of a multidisciplinary study of population structure of minke whales. Minke whales from west and east Greenland, Jan Mayen, North Sea, Vestfjorden/Lofoten, west Svalbard and the Barent Sea) were included (Born et al. submitted). Only few statistically significant differences among the above mentioned locations were found, however, there were a tendency of Cd concentrations in tissues of Greenland whales to be higher than in whales from the other locations (Born et al. submitted).

Cd concentrations in muscle, liver and kidney of polar bears (Ursus maritimus) from Ittoqqortoormiit in 1999 and 2000 have been determined (Appendix A). Cd concentrations in muscle were low (below 0.03 mg/kg ww). In liver, Cd concentrations ranged from 0.73 to 1.82 mg/kg ww) and in kidney from 20.1 to 36.7 mg/kg ww. The Cd levels in all tissues were in the range observed previously (Dietz et al. 2000a). Dietz et al. (ibid) compared Cd levels in polar bears from Avanersuaq with bears from Ittoqqortoormiit and found significantly higher concentrations in liver tissue from Avanersuaq, while no significant difference was found in kidney. Based on age normalised Cd concentrations, a trend could be seen of increasing Cd concentrations in polar bear liver from west Canada to east Canada and west Greenland and then lower Cd levels in east Greenland and Svalbard bears (Dietz et al. 2000a).

4.3.1.3 Hg and Se

In this chapter most focus is given to Hg levels. However, in most cases involving determination of Hg in biota, Se levels are also determined. In most Arctic samples, Se is present in a substantial surplus compared to Hg on a molar basis. However, in tissues of marine mammals from Greenland with high Hg concentrations (above approx. 10 nmol/g), a 1:1 molar ratio was found (Dietz et al. 2000b). Se is regarded as an antagonist to Hg and probably Se plays an important role with detoxification of Hg by formation of mercuric selenide complexes (Björkman et al. 1995, Wagemann et al. 1998).

Invertebrates

Hg and Se concentrations have been determined in the species blue mussel, Iceland scallop, queen crab and deep sea shrimp (Pandalus borealis) (Appendix A). Hg concentrations ranged from 0.011 mg/kg ww in blue mussels (4-5cm) to 0.096 mg/kg in queen crab. Se concentrations in muscle tissue ranged from 0.13 mg/kg ww in Iceland scallop to 0.60 mg/kg ww in queen crab. These values were within the range observed previously in invertebrates from Greenland (Dietz et al. 1996).

Marine fish

Hg and Se concentrations have been determined in shorthorn sculpin, Atlantic cod, Greenland cod, Atlantic salmon, Greenland halibut and capelin. In muscle, Hg concentrations ranged from 0.009 mg/kg ww in capelin to 0.154 mg/kg ww in Greenland halibut. In liver, Hg concentrations ranged from 0.007 mg/kg ww in Atlantic cod to 1.51 mg/kg in Greenland halibut. These values are in the range observed in 21 different marine fish species from Greenland (Riget et al. 1997). Shorthorn sculpin have been sampled in Qeqertarsuaq and Ittoqqortoormiit in both 1999 and 2000. In both years, Hg concentrations was significantly higher in Ittoqqortoormiit than in Qeqertarsuaq (t-test on logarithmic transformed data, separated by sex for year 2000, all cases p<0.01).

Seabirds

Hg and Se have been determined in black guillemot liver and kidney from Qeqertarsuaq in 1999 and 2000 (liver and egg) and in black guillemot eggs from Ittoqqortoormiit in 2000. In liver Hg concentrations ranged from 0.61 mg/kg ww in adults to 1.02 mg/kg ww in juveniles. In kidney, Hg concentrations were 0.54 and 0.51 mg/kg ww in juveniles and adults, respectively. These values were in the higher end of the range observed previously in that species (Dietz et al. 1996). In eggs, Hg and Se concentrations was significantly higher in Ittoqqortoormiit 2000 than in Qeqertarsuaq 1999 (t-test on logarithmic transformed data, Hg: p=0.01 and Se: p=0.008). Hg concentrations in black guillemot liver and eggs from Greenland were similar to those observed in the Faroe Islands, Canada and Franz Josef Land (AMAP 1998).

Hg and Se concentrations in ringed seal liver were available from Qeqertarsuaq and Ittoqqortoormiit in 1999 and 2000 and from Avanersuaq in 1998. In blubber, Hg and Se concentrations were determined in seals from Qeqertarsuaq in 2000. Hg concentrations in liver ranged from 1.78 mg/kg ww in seals from Qeqertarsuaq to 7.13 mg/kg ww in seals from Ittoqqortoormiit. Hg concentrations in seal blubber were very low (<0.005 mg/kg ww). These values are within the range observed previously in ringed seals (Dietz et al. 1996). Hg concentrations in ringed seals increase with age (Diet et al. 1998). Therefore, seals has been divided into age groups (0, 1-3, 4-6 and above 6 years old) before testing for differences in mean Hg concentrations between Qeqertarsuaq and Ittoqqortoormiit in 1999 and 2000. In 1999 no significant (at 5% level) difference in Hg and Se concentrations were found between seals from Qeqertarsuaq and Ittoqqortoormiit, however, for age groups 1-3 and 4-6 years the highest concentrations were found in Ittoqqortoormiit. In 2000, the Hg and Se concentrations were significantly (p<0.01) higher in Ittoqqortoormiit than in Qeqertarsuaq for age group 1-3, which was the only age group allowing statistical testing (t-test on logarithmic transformed data, t-test only performed if n>1). The Hg and Se concentrations in seals from Avanersuaq 1998 were high compared to previously findings in northwest Greenland (Dietz et al. 1996). However, the relative high average age (9.2 years) of Avanersuaq seals and the indication of feeding at a relatively higher trophic level (see chapter 4.2) should be noted. The circumpolar pattern of Hg levels in ringed seal showed the highest levels in Canadian Eastern Arctic, although with high local variability and lower levels in west and east Greenland, Alaska and Svalbard (AMAP unpublished).

Data of Hg and Se concentrations in narwhals are available from Avanarsuaq, Balgoni Island (Melville Bay), Uummannaq, Kitsissuarsuit (Disko Bay) and Saqqaq (see also chapter 4.7.1). Hg and Se concentrations in muscle, liver and kidney tissue showed the same relationship with age as shown in Figure 4.3.1 for Cd. In the first 3 to 4 years of the narwhals life the Hg and Se concentrations increase, after which a relatively constant level is observed. Both Hg and Se concentrations in liver were significantly higher in females than in males, while no sex differences were found in muscle and kidney (Riget et al. 2002). As was the case with Cd, no consistent difference between Avanersuaq and Uummannaq was found in either tissue. The between years variation at one location seem to be larger than the variation between location. In general, the Hg and Se levels in the Greenland narwhals were within the range found in Arctic Canada (Wagemann et al. 1983, 1996).

Hg and Se concentrations in muscle, liver, kidney and baleen (except Se) of minke whales from the North Atlantic and European Arctic were determined as a part of a multidisciplinary study of population structure of minke whales. Minke whales from west and east Greenland, Jan Mayen, West Svalbard, the Barents Sea, Vestfjorden/Lofoten and the North Sea) were included (Born et al. submitted). Irrespective of gender, Hg and Se concentrations in west Greenland whales were consistently low compared to the other areas (Table 4.3.2). Se and Hg concentrations were positively correlated in all tissues (p<0.001). No significant differences were found of the elements or tissues between west and east Greenland whales. The highest Hg and Se concentrations in most tissues were found in whales from the North Sea and Jan Mayen.

Hg and Se concentrations in muscle, liver, kidney and hair (only Hg) of polar bears from Ittoqqortoormiit in 1999 and 2000 have been determined (Appendix A).

Table 4.3.2.
Results of pair-wise comparisons (length adjusted values) between areas for Hg and Se in tissues of female and male minke whales. Areas underlined were not significant different at the 1% level. Abbreviations: WG = west Greenland, CG = central east Greenland, CM = Jan Mayen, EN = North Sea, EC = Vestfjord/Lofoten, ES = Svaldbard, EB = Barents Sea, EAST = CM+ES+EB (redrawn from Born et al. in press).

Hg concentrations in muscle were lower than in liver and kidney. In liver, Hg concentrations ranged from 4.02 to 16.4 mg/kg ww and in kidney from 8.9 to 29.8 mg/kg ww, lowest in subadult bears. Both Hg and Se levels in muscle, liver and kidney were within the range observed previously (Dietz et al. 2000a). Dietz et al. (ibid) compared Hg and Se levels in polar bears from Avanersuaq with bears from Ittoqqortoormiit and found a tendency of higher Hg and Se concentrations in liver tissue from Avanersuaq. Based on age normalised Hg concentrations, a trend could be seen of increasing Hg concentrations in polar bear liver from Svalbard to east Greenland over west Greenland, peaking in bears from south-west Melville Island. Further eastward the Hg concentrations decreased and the lowest concentrations were found in the Chukchi Sea (Dietz et al. 2000a).

4.3.2 Temporal trend

Time series data of heavy metal concentrations in Arctic biota covering the last 20-30 years are scarce. From Greenland, Riget & Dietz (2000f) tried to assess trends of Cd and Hg in Greenland marine biota, however, only few time series were available and with only few “data points”. They concluded that no overall temporal trends in Cd and Hg concentrations were found within the 20-years period. However, Cd concentrations in ringed seals tended to increase in the period late-1970s to mid-1980s and decrease again to the mid-1990s, whereas Hg concentrations tended to increase in the same period. Therefore Riget & Dietz (ibid) interpretated these changes as natural fluctuations caused by shift in feeding behaviour, rather than changes in anthropogenic exposure. During the Greenland AMAP programme biological samples were collected in 1994 and 1999/2000, and in a few cases earlier comparable samples were available. However, data from only two or three years may not give evidence of temporal changes for several reasons, first of all because two or three “data points” are too few. Based on the results obtained during the Greenland AMAP programme phase I, Riget et al. (2000d) evaluated that a time series of 10-17 years with annual data is required to detect a linear trend of 10% per year with a significance of 5% and a power of 80%. Besides the large individual variability in heavy metal levels often observed in biota, a random year-to-year variability must also be expected. The year to year variability occurs because environmental factors such as temperature, production, prey availability etc. differ between years. Despite these difficulties, it has been useful to compare heavy metal levels obtained in 1994 (AMAP phase I) with those obtained in 1999/2000 and in a few cases even earlier results.

Heavy metal data were logarithmic transformed prior to the statistical analysis. Analysis of covariance was performed in cases were the metals increase with length/age of the animals. Otherwise an analysis of variance or t-test was performed. Pairwise t-test of LSMEAN (least square mean values meaning length adjusted values) or Turkey’s post hoc test was performed to test for differences between years. In case where the statistical test showed no significant difference, the power of the test was estimated according to Cohen (1977). The statistical power is defined as the probability to detect a significant difference. In this case a significance level of 5% is used.

4.3.2.1 Cd

Qeqertarsuaq

Table 4.3.3 gives an overview of the results of the statistical comparisons of Cd concentrations in Qeqertarsuaq 1994 and 1999/2000. Few statistically significant differences were found. Cd concentrations in blue mussels (7-8 cm) were significantly higher in 1999 than in 1994. In blue mussel significantly higher Cd concentrations were found in 1994 and 2000 than in 1999 indicating high year-to-year variation. This could also be seen in black guillemot where Cd concentrations were significantly higher in 2000 than in 1999. In ringed seals (1-3 years old), Cd concentrations were higher in 1994 than in 1999 and 2000.


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Avanersuaq

Cd concentrations in ringed seals liver were higher for all age groups in 1984/85 than in 1994 and 1998 (Table 4.3.4). However, significant differences were only found for age group 1-3 years where the concentrations in 1984/85 and 1998 were significantly higher than in 1994.

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Ittoqqortoormiit

Table 4.3.5 gives an overview of the results of the statistical comparisons of Cd concentrations in Ittoqqortoormiit 1986, 1994 and 1999/2000. Cd concentrations in ringed seals 1-3 and 4-6 years old were higher in 1996 than in the later years, however this was only significant from 1999 in case of age group 1-3 years and 1994 and 2000 in case of age group 4-6 years.

Table 4.3.5.
Results of statistical tests for difference in mean Cd concentrations in shorthorn sculpin and ringed seal from Itoqqortoormiit. Trend gives the years in the order of decreasing mean concentrations on a logarithmic scale. Years underlined are not significantly different. * denotes significance at 5% level and ** denotes significance at 1% level. The power of the test is given if no significant difference was found (see text).

Samples of polar bears tissues have been collected in 5-7 years since 1983. Figure 4.3.3 and 4.3.4 shows mean Cd concentrations in subadult and adult bears, respectively. In both subadult and adult bears no temporal trend is appearent in any of the tissues. 

Figure 4.3.3.
Mean Cd concentrations (+SD) in tissues of subadult polar bears from Ittoqqortoormiit.

Figure 4.3.4.
Mean Cd concentrations (+SD) in tissues of adult polar bears from Ittoqqortoormiit.

4.3.2.2 Hg

Qeqertarsuaq

Table 4.3.6 gives an overview of the results of the statistical comparisons of Hg concentrations in Qeqertarsuaq 1994 and 1999/2000. In blue mussels, Hg concentrations were higher in 1994 than in 1999 except for size group 7-8 cm. However, only for size group 6-7 cm the difference was significant. In shorthorn sculpin no temporal trend was found and in black guillemot no difference was found between 1999 and 2000. In ringed seals, Hg concentrations were higher in 1994 than in 1999 and 2000, however, this was only significant for age group 1-3 years.

Table 4.3.6  
Results of statistical tests for difference in mean Hg concentrations in marine biota from Qeqertarsuaq. Trend gives the years in the order of decreasing mean concentrations on a logarithmic scale. Years underlined are not significantly different. * denotes significance at 5% level and ** denotes significance at 1% level. The power of the test is given if no significant difference was found (see text).

Avanersuaq

Hg concentrations in ringed seals liver age groups 4-6 and >6 years showed an increasing trend from 1984/85 to 94 and again to 1998, and for both age groups the concentrations in 1984/85 were significantly lower than in 1994 and 1998 (Table 4.3.7). For age group 1-3 years no significant difference was found between 1984/85 and 1994, but the concentrations in 1998 were significantly highest.

Table 4.3.7  
Results of statistical test sfor difference in mean hg concentrations in ringed seals from Avanersuaq. Trend gives the years in the order of decreasing mean concentrations on a logarithmic scale. Years underlined are not significant differently. * denotes significance at 5% level and ** denotes significance at 1% level. The power of the test is given if no significant difference was found (see text).

Ittoqqortoormiit

Table 4.3.8 gives an overview of the results of the statistical comparisons of Hg concentrations in Ittoqqortoormiit 1986, 1994 and 1999/2000. Hg concentrations in ringed seals 0, 1-3 and 4-6 years were highest in 2000, however, this was only significant for age group 1-3 years.

Table 4.3.8 
Results of statistical test for difference in mean hg concentrations in shorthorn sculpin and ringed seal from Ittoqqortoormiit. Trend gives the years in the order of decreasing mean concentrations on a logarithmic scale. Years underlined are not significantly different. * denotes significance at 5% level and ** denotes significance at 1% level. The power of the test is given if no significant difference was found (see text).

Samples of polar bears tissues have been collected in 5-7 years since 1983. Figure 4.3.5 and 4.3.6 shows mean Hg concentrations in subadult and adult bears, respectively. In both subadult and adult bears no temporal trends is appearent in any of the tissues.

Figure 4.3.5.
Mean Hg concentrations (+SD) in tissues of subadult polar bears from Ittoqqortoormiit.  

Figure 4.3.6.
Mean Hg concentrations (+SD) in tissues of adult polar bears from Ittoqqortoormiit.

4.4 Organochlorines

In AMAP phase I, OCs were determined in marine sediments, blue mussels, shorthorn sculpin, polar cod, glaucous gull, Icelandic gull and ringed seals at four locations in Greenland (Cleemann et al. 2000a,c,d). In general, OC concentrations (except ΣHCH) were higher in the marine biota from east Greenland than from west Greenland. OCs bioaccumulate and the highest concentrations were found in species at the highest trophic levels.

4.4.1 Levels and spatial trends

Invertebrates

OC concentrations have been determined in the following invertebrate species: blue mussel, shrimp and snow crab (muscle and liver). In general OC levels in invertebrate were lower than in marine fish, seabirds and marine mammals. The highest levels were found in snow crab liver (eg. PCB-10 41 µg/kg ww) and the lowest in shrimp muscle (eg. ΣPCB-10 0.7 µg/kg ww) (Appendix B). Levels of ΣPCB-10, ΣDDT, ΣHCH and HCB) in soft tissue of blue mussels were comparable to levels reported from other Arctic areas as Canada, Iceland and Russia (Cleemann et al. 2000c).

Fish

Data of OC levels in marine fish are available for Atlantic cod, capelin, Greenland halibut, starry ray (Raja radiata), spottet wollfish and shorthorn sculpin (Appendix B). Fish livers had relatively higher levels of OCs than fish muscle. The highest OC levels were found in Greenland halibut (eg. ΣPCB-10 in muscle and liver were 12 and 493 µg/kg ww, respectively). Greenland halibut is a bottom-feeding predator fish, long-lived and with a relatively high lipid content.

OCs have been determined in shorthorn sculpin liver from Qeqertarsuaq and Ittoqqortoormiit sampled in 1999 and 2000, and also from the Qaqortoq area in 2000. The relatively high PCB levels found in sculpins from Qaqortoq may be due to local contaminant sources (Vorkamp pers. com.). The ΣPCB-10, ΣDDT, ΣCHL,
ΣHCH and HCB concentrations were higher in sculpins from east Greenland (Ittoqqortoormiit) than from west Greenland (Qeqerarsuaq) (Figure 4.4.1), similar to the pattern found during AMAP phase I (Cleemann et al. 2000c).

Seabirds

OC concentrations have been determined in black guillemot, thick-billed murre (Uria lomvia), common eider (Somateria mollissima), king eider (Somateria spectabilis) and kittiwake (Rissa tridactyla) (Appendix B). Both feeding behaviour and wintering areas of Arctic seabirds may explain species differences in OC levels observed. The lowest levels were found in mussel eating birds as common eider and king eider (eg. king eider muscle ΣPCB-10 6.5 µg/kg ww and liver 8.7 µg/kg ww). Somewhat higher OC levels were found in fish-eating birds as black guillemot (eg. liver ΣPCB ranged between 27 and 113 µg/kg ww). The highest OC levels were found in kittiwake (eg muscle ΣPCB-10 98 µg/kg ww.) when only including seabirds sampled in west Greenland. The reason probably is that the kittiwake winters in European and Amarican waters, thereby being more exposed to OCs than eiders, guillemot and murres wintering in the Arctic. Levels of ΣPCB-10 in kittiwake liver were similar to east Baffin Island, Canada but lower than found at Bear Island and in Franz Josef Land (Muir & Johansen unpubl.). However, the OC levels were much higher in opportunistic feeders as glaucous and Icelandic gulls analysed during AMAP phase I (Cleemann et al. 2000d). A similar order of increasing OC levels of eider < kittiwake < glacous gull have been reported from the Barents Sea and partly from Arctic Canada (AMAP 1998).

Figure 4.4.1.
OC concentrations in liver of shorthorn sculpin, black guillemot and ringed seal from west Greenland (Qeqertarsuaq – light grey) and east Greenland (Ittoqqortoormiit – dark grey).

Black guillemot liver and eggs collected in 1999 and 2000 in Qeqertarsuaq (west) and Ittoqqortoormiit (east) were analysed. ΣPCB-10, ΣDDT, ΣCHL, and to lesser extent HCB and HCH levels in birds from east Greenland were higher than in west Greenland (Figure 4.4.1) confirming the spatial trend found previously in glaucous gull (Cleemann et al. 2000d).

Marine mammals

OC levels have been determined in ringed seal, narwhal, beluga and minke whales (Appendix B including data for walrus collected 1978 for comparative reasons).

Ringed seals are not generally considered to be a highly mobile species although some long migrations have been observed (Kapel et al. 1998). Data of OC in ringed seals are available from Qeqertarsuaq, Avanersuaq and Ittoqqortoormiit. In ringed seal, OC levels increase in tissues in the order kidney < liver < muscle << blubber. In general, OC concentrations are higher in male seals than in females, due to elimination of these lipophilic compounds via lactation. The dominant OCs in ringed seal were ΣPCB, ΣDDT and ΣCHL. The OC levels (except ΣHCH) in ringed seals generally were highest in seals from Ittoqqortoormiit, lowest at Qeqertarsuaq and intermediate at Avanersuaq (Appendix B). The higher OC levels in seals from east Greenland than in seals from west Greenland confirms the previous results of AMAP phase I (Cleemann et al. 2000a). However, in that study no difference in OC levels between seals from Qeqertarsuaq and Avanersuaq were found, while in present study seals from Avanersuaq had higher OC levels than seals from Qeqertarsuaq. ΣPCB and ΣDDT showed a circumpolar trend of higher concentrations in ringed seals from The Yenisey Gulf (Russian Arctic), Svalbard and east Greenland than in west Greenland or the Canadian Arctic (Muir et al. 2000a). ΣHCH levels were higher in the Canadian Arctic than in west Greenland, east Greenland and Svalbard (Muir ibid).

Data of OC levels in narwhal are available from Avanarsuaq, Balgoni Island (Melville Bay), Uummannaq, Kitsissuarsuit (Disko Bay) and Saqqaq (see also chapter 4.5.1). The dominant OC was toxaphene followed by ΣDDT, ΣPCB and HCB. In general, OC concentrations are higher in males than in females, due to elimination of these lipophilic compounds via lactation following the pattern shown in Figure 5.1.1 for total toxaphene. Based on age normalised OC data on a lipid basic (only males), Riget et al. (2002) found no statistically significant differences in ΣPCB, HCB, and ΣHCH among the locations mentioned above, except Saqqaq (analysis of covariance on logarithmic transformed data). ΣDDT showed significantly higher concentrations in narwhals from Balgoni Island, 1993 than all other location except Kitsissuarsuit, 1990 (Riget et al. 2002). Only few OC data of narwhals exist. Beck et al. (1994) cited in Muir et al. (1999) report on levels in 8 males from Lancaster Sound sampled in 1991. PCB appear to be at a little lower or at the same level in the Greenland samples than in the Canadian samples, whereas ΣHCH and ΣDDT appear to be higher.

OC levels in beluga from Saqqaq sampled in 2000 showed similar levels as found in narwhals (Appendix B).

As a part of a multidisciplinary study of population structure of minke whales in the North Atlantic and European Arctic (west and east Greenland, Jan Mayen, West Svalbard, the Barents Sea, Vestfjorden/Lofoten and the North Sea), OC levels were determined in blubber from 42 whales from west Greenland and 4 whales from east Greenland (Hobbs et al. in press). The dominant OC was ΣPCB (female mean 2290 µg/kg ww, sum of 102 congeners) followed by ΣDDT (female mean 650 µg/kg ww). Based on the total data available (155 minke whales), ΣPCB and ΣDDT showed significantly higher levels in males than in females, while no significant differences were observed between sex of ΣHCH, ΣCHL and HCB (Hobbs et al. in press). Concentrations of OC groups as ΣPCB, ΣDDT and ΣCHL generally increased from west to east, while ΣHCH showed the opposite trend. Proportions of OC in minke whales did not reveal any major difference among areas except those whales from Greenland waters and the North Sea differed significantly from those from other areas.

Blubber of 20 polar bears sampled in Ittoqqortoormiit in 1999-2000 were analysed for OCs. ΣPCB and ΣCHL were the major OCs in blubber of polar bear with mean values of 5983 µg/kg ww and 678 µg/kg ww in female bears (Appendix B). ΣDDT were lower, 282 µg/kg ww in female bears.

4.4.2 Temporal trend

Very few data exist to make an assessment of temporal trends of OCs in Greenland biota. In the Greenland AMAP programme biological samples from 1994 and 1999/2000 can be compared. However, data from only two or three years may not give evidence of temporal changes for several reasons, first of all because two or three “data points” are too few. On basis of the results obtained during the Greenland AMAP programme phase I, Riget et al. (2000d) evaluated that a time series of 10-17 years was required to detect a linear trend of 10% per year with a significance of 5% and a power of 80%. Beside the large individual variability in OC levels often observed, a random year to year variability must also be expected. The year to year variability occurs because environmental factors such as temperature, production, prey availability etc. differ between years.

Despite these difficulties, it has been found useful to compare OC levels obtained in 1994 (AMAP phase I) with those obtained in 1999/2000. Three laboratories have been involved (NERI, NWOC, GWOC). Therefore it has been necessary to find groups of OCs, which could be compared. These OC groups were: 
ΣPCB10 = sum of congeners 28, 31, 52, 101, 105, 118, 138, 153, 156, 180 
ΣDDT = sum of p,p-DDE, p,p-DDD, p,p-DDT
ΣHCH = sum of HCH
HCB
ΣCHL = sum of oxychlordane, trans-chlordane, cis-chlordane, cic-nonachlor, trans-nonachlor trans-nonachlor alone

OC data on a lipid basis were logarithmicly transformed prior to the statistical analysis. An analysis of covariance was performed in cases were the compounds increase with length/age of the animals. Otherwise an analysis of variance or t-test was performed. A pairwise t-test of LSMEAN (least square mean values) was performed to test for differences between years. The test was performed for each sex separately if data allowed. In case were the statistical test showed no significant difference, the power of the test was estimated according to Cohen (1977). The statistical power is defined as the probability to detect a significant difference. In this case a significance level of 5% is used.

Qeqertarsuaq

Table 4.4.1 gives an overview of the results of the statistical comparisons of OC concentrations in Qeqertarsuaq 1994 and 1999/2000. In shorthorn sculpin, ΣPCB-10, ΣDDT, ΣHCH and trans-nonachlor showed a significant difference between years (Table 4.4.1 and Figure 4.4.2) with a decrease from 1994 to 1999, and then an increase to 2000). HCH concentrations showed a significant decrease from 1994 to 1999 and 2000. In ringed seal blubber, the temporal changes were more complicated. ΣPCB-10 concentrations showed no significant differences between years (Figure 4.4.2). The ΣDDT concentrations were significantly higher in 1999/2000 than in 1994, whereas ΣHCH and HCB concentrations in males were significant higher in 1994 than in 1999 and 2000. There was no indication of different feeding strategies (see 4.2). OC concentrations in black guillemot liver and ΣCHL in ringed seals were only available for year 1999 and 2000. ΣPCB-10 in males and females and ΣDDT, ΣHCH, HCB and ΣCHL concentrations in female black guillemot were significantly higher in 1999 than in 2000. The birds from 1999 had higher values of stable isotopes (see 4.2) indicating these to had been feeding at a relatively higher trophic level. No significant differences were observed in •ΣCHL in ringed seal blubber between 1999 and 2000.

The OC concentrations in beluga tissues sampled in Saqqaq in 2000 can be compared with samples in Nuussuaq/Disko Bugt from 1989/90 reported by Stern et al. (1994). The comparison can only be indicative because age and sex are unknown for the beluga sampled in 2000. However, the levels of ΣPCB, ΣDDT and ΣCHL appear lower in the recent samples than in the samples from 1989/90.

Table 4.4.1.
Results of statistical tests for difference in mean OC concentrations in marine biota from Qeqertarsuaq. Trend gives the years in the order of decreasing concentrations. Years underlined are not significantly different. * denotes significance at 5% level and ** denotes significance at 1% level. The power of the test is given if no significant difference was found (see text).

Figure 4.4.2.
ΣPCB-10, ΣDDT and ΣHCH concentrations in shorthorn sculpin (length adjusted to male 25 cm and females 28cm) and ringed seals (adjusted to 5 years old) from Qeqertarsuaq sampled in 1994, 1999 and 2000. Males in blue, females in red.

Avanersuaq
Table 4.4.2 gives an overview of the results of the statistical comparisons of OC concentrations in ringed seals from Avanersuaq 1994 and 1998. The only significant differences were observed for ΣHCH and trans-nonachlor in females with the highest concentrations in 1994.

Muir et al. (2000b) compared the OC levels in walrus (Odobenus rosmarus) from Avanersuaq sampled in 1978 and 1988. They found significant (p<0.05) increase for ΣHCH in females but no significantly differences for ΣCBz, ΣDDT, ΣPCB. OC levels in males showed no difference between 1978 and 1988 (Muir et al. ibid). A resampling of the Avanersuaq stock would be useful to examine long-term temporal trends of OCs.

Table 4.4.2.
Results of statistical tests for difference in mean OC concentrations in ringed seal blubber from Avanersuaq. Trend gives the years in the order of decreasing concentrations. Years underlined are not significantly different. * denotes significance at 5% level and ** denotes significance at 1% level.
The power of the test is given if no significant difference was found (see text).

Ittoqqortoormiit
Table 4.4.3 gives an overview of the results of the statistical comparisons of OC concentrations in Ittoqqortoormiit 1994, 1999 and 2000 (see also Figure 4.4.3).
ΣPCB-10 and ΣHCH concentrations in shorthorn sculpin were significantly lower in 1999/2000 than in 1994. ΣDDT, HCB and trans-nonachlor concentrations showed no significant differences between years. In ringed seal blubber all OC concentrations were lower in 1999/2000 than in 1994. This, however, was only significant for ΣHCH in males.

OC concentrations were determined in 20 polar bears from Ittoqqortoormiit sampled in 1999/2000. Norstrom et al. (1998) analysed OC conceentrations in 18 polar bears sampled in 1990 in Ittoqqortoormiit. The PCB congeners and ΣCHL compounds are not the same in the two studies but they both include the most important ones. In adult males and females levels of ΣPCB and ΣCHL appear to be much lower in 1999/2000 than in 1990 (20-40% of the levels in 1990). No differences were appearent in case of DDE and dieldrin.

Table 4.4.3.
Results of statistical tests for difference in mean OC concentrations in marine biota from Ittoqqortoormiit. Trend gives the years in the order of decreasing concentrations. Years underlined are not significantly different. * denotes significance at 5% level and ** denotes significance at 1% level. The power of the test is given if no significant difference was found (see text).

Figure 4.4.3.
ΣPCB-10, ΣDDT and ΣHCH concentrations in shorthorn sculpin liver and ringed seals blubber (adjusted to 5 years old) from Ittoqqortootmiit from 1994, 1999 and 2000. Black – both sex, blue – males, red – females.

4.5 Radionuclides

Artificial radionuclides have been monitored in the Greenland environment since the 1960’s. The Greenland data have been reviewed in the first Arctic Monitoring and Assessment (AMAP) reports, (Aarkrog et al. 1997; Strand et al.1998). Under the AMAP-II project 1999 – 2002, ¹³⁷Cs, ⁹⁰Sr, ^239,240Pu and ⁹⁹Tc have been monitored in selected components of the Greenland marine environment. Furthermore, results from a study in 1997 in Bylot Sound to investigate the fate of plutonium after the 1968 Thule accident is described in chapter 4.5.2.

4.5.1 Levels of ¹³⁷Cs, ⁹⁹Tc, ⁹⁰Sr, and ^239,240Pu in components of the marine environment

Large seawater samples have been obtained by various means – mostly from ship pumps or with buckets from small boats. Biological samples were all from the NERI sampling, i.e. it is the same samples as used for metal and POP analysis.

Table 4.5.1 gives average radionuclide concentrations observed in surface seawater samples in 1999. These values and similar data from 2000 and 2001 are furthermore shown in Figures 4.5.1-4.5.4.


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Figure 4.5.1
¹³⁷Cs, ⁹⁹Tc and ⁹⁰Sr, mBq L^-1, in surface seawater observed in 1999. 

Figure 4.5.2.
^239,240Pu (µBq L^-1) and salinity (‰) in surface seawater observed in 1999.

Figure 4.5.3.
Tc-99 mBq L^-1, in surface seawater year 2000  

Figure 4.5.4.  
¹³⁷Cs, ⁹⁹Tc and ⁹⁰Sr, mBq L^-1, in surface seawater observed in 2001.

Table 4.5.2 gives average concentrations of ¹³⁷Cs and ⁹⁹Tc in seaweed taken 1999, 2000 and 2001 and Table 4.5.3 gives ¹³⁷Cs concentrations in various edible marine products sampled 1999. The concentrations of several radionuclides in seawater are decreasing in the order northeast Greenland and the coastal East Greenland Current > southwest Greenland > central west Greenland and northwest Greenland >Irmiger Sea ~ Faroe Islands. The same tendency is seen for ¹³⁷Cs and ⁹⁹Tc in seaweed and for e.g. ¹³⁷Cs in seal from east and west Greenland. This is in accordance with long-distance transport patterns from European coastal waters, which are responsible for most of the ⁹⁹Tc and a large fraction of the ¹³⁷Cs (Dahlgaard, 1994, Dahlgaard, 1995).


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Table 4.5.3.
Cs-137 (Bq / kg ww) in various edible products. Except for Sculpin (whole fish), the values are for meat.

There has been some focus on the levels of ⁹⁹Tc in seawater and marine products because the British nuclear fuel reprocessing plant Sellafield increased its discharges from 1994 and onwards. From earlier studies (Aarkrog et al. 1983, Dahlgaard et al. 1986, Aarkrog et al. 1987; Dahlgaard, 1994), the 1994-1995 peak discharge may be expected off North East Greenland from year 2000 and onwards. Seawater data for 2000 actually indicated increased levels of ⁹⁹Tc off NE Greenland (Figure 4.5.3), whereas levels in 2001 seemed to be unchanged. The increased levels in year 2000 samples are probably caused by the increased discharges from Sellafield, but it should be kept in mind that the sampled area is huge and it has not been possible to perform a systematic sampling of the various water masses in the East Greenland Current system. The samples from 1999, 2000 and 2001 are therefore not directly comparable. Shrimp meat samples from southwest Greenland were analysed in 2000, but all results were below detection limits. In normal oxygenated seawater, ⁹⁹Tc appears mainly as anionic pertechnetate with a low affinity to particles and to most marine organisms except brown macroalgae (Fucus, Ascophyllum) and certain crustaceans such as lobster and shrimp.

As a pilot study, liver, kidney and meat from 5 ringed seals caught in Disko Fjord (CW) under NERI’s time-trend programme were analysed for ²¹⁰Po (Table 4.5.4). ²¹⁰Po is a naturally occurring alpha-emitter that appears in the ²³⁸U decay series after ²²⁶Ra, ²²²Rn and ²¹⁰Pb, and it is bioaccumulated in aquatic organisms. The present levels are high compared to average global values of 2.4, 15 and 6 Bq ²¹⁰Po kg^-1 (wet weight) in fish, molluscs and crustaceans, respectively, found in an international study (Aarkrog et al., 1997b). That study concluded that ²¹⁰Po gives rise to a major component of the radiation dose to man from consumption of marine products, but the study did not include marine mammals and doses to Inuits. Consumption of 1 kg of kidney, 1 kg of liver and 4 kg of meat with the present average values would each give a radiation dose around 0.1 mSv. It is thus evident that consumption of fresh seal significantly enhances the natural radiation dose received by Inuits. Canadian caribou holds even higher concentrations in liver and kidney and similar concentrations in meat due to accumulation via lichen (Thomas et al. 1994).


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4.5.2 Plutonium in Bylot Sound - The Thule Accident 1968

On 21 January 1968, a B-52 aircraft from the US Strategic Air Command crashed on the sea ice of Bylot Sound 11 km west of the Thule Air Base in Greenland. The aircraft disintegrated on impact and an explosion and a fire ensued. The 4 nuclear weapons onboard were destroyed and fissionable material - plutonium and uranium - was dispersed. The benthic marine environment in the 180-230 m deep Bylot Sound was then contaminated with ^239,240Pu. The site was revisited August 1997, 29 years after the accident. The following is extracted from Dahlgaard et al. (2001) and Eriksson (2002).

4.5.2.1 Radioactive particles from the Thule accident.

The plutonium was present in an insoluble oxide form and mainly associated to particles with an average size of 2 micrometers (U.S.Air Force, 1970). During the months following the accident a clean up program was performed where most of the debris and the contaminated ice was removed from the area. The total amount of plutonium dispersed in the accident was 6 kg of which 3.5 ± 0.7 kg was found on and in the sea ice. Except for an estimated amount of ~1 TBq (~0.4 kg) remaining in the ice after cleaning, most of this plutonium was recovered and shipped to the US (U.S.Air Force, 1970; Strand et al. 1998), i.e., ~3 kg of plutonium may have entered the environment. This amount may be reduced by an unknown amount attached to aircraft debris (Strand et al., 1998). After the accident, the amount of plutonium in the marine sediments in Bylot Sound have been estimated based on samples taken 1970, 1974, 1979, 1984, 1991 and 1997 (Aarkrog, 1971, Aarkrog, 1977, Aarkrog et al. 1984, Aarkrog et al., 1987, Aarkrog et al. 1994, Strand et al. 1998, Eriksson et al. 1999, Dahlgaard et al. 2001). These inventory estimates have been centred on 1 - 1.6 TBq or approximately 0.5 kg.

An improved method to determine the total inventory of a heterogeneously distributed contamination of marine sediments has been described (Eriksson, 2002). The estimate is based on gamma spectrometric screening of the ²⁴¹Am concentration in 450 one-gram aliquots from 6 sediment cores. The ²⁴¹Am activity is building up as a decay product of ²⁴¹Pu (half-life 14.4 yr.) which is present in weapons plutonium as an impurity. Based on radiochemical determination of the plutonium concentration in 20 of these subsamples, the ²⁴¹Am values are used to estimate the ^239,240Pu concentrations. A Monte Carlo programme then simulates a probable distribution of the activity, and based on that, a total inventory is estimated by integrating across the area to 100 km from the point of impact using a double exponential function. Results centre on a total inventory around 9.5 TBq or 3.5 kg ^239,240Pu, which is 7 times higher than earlier estimates (0.5 kg). The difference is partly explained by the full inclusion of hot particles in the present methodology. It should however be noted, that only 6 sediment cores are included in the present estimate, and that a large uncertainty is connected to the result. Thus the new result can at the present state not be considered as significantly different from the earlier, although it fits better to the estimate above of the missing 3 kg.

Figure 4.5.5.
Thule-1997. Sediment ^239,240Pu concentration (Bq kg^-1 dry) profiles.

4.5.2.2 Plutonium in water and seaweed.

The concentration of ^239,240Pu in Fucus disticus (a brown alga) around Thule and 750 km to the south near Uummannaq was measured. Concentrations in the range 0.15 – 1.14 Bq kg^-1 dry weight were observed. The source of most of this plutonium is global fallout – maybe except the highest value seen in a single sample near the accident site. With the exception of a near-bottom water sample taken at the point of impact, which shows a total concentration of 30 mBq ^239,240Pu m^-3, no clear effect of the accident was seen in any of the water samples. 42% of this elevated level was particulate (McMahon et al. 2000, Dahlgaard et al. 2001) indicating that resuspended sediments containing accident plutonium is an important source. The general level inside, as well as far away from, Bylot Sound was 5 - 10 mBq ^239,240Pu m^-3 unfiltered surface water which may be regarded as global fallout background. The water and brown algae data thus indicate that plutonium from the contaminated sediments is not transported into surface waters in significant quantities.

4.5.2.3 Sediments

A set of plutonium sediment depth profiles are given in Figure 4.5.5 – for contaminated cores from Bylot Sound as well as for assumed background cores taken outside Bylot Sound (ny-3, 1412 and Schades Øer). In all cases, plutonium seems to be well mixed in the upper 3-5 cm sediment layers. It should be noted that the concentration axis in Fig. 4.5.5 is logarithmic. In spite of this, the large variation of observed plutonium concentrations is obvious. This is caused by hot particles (cf. 4.5.2.1).

Plutonium concentrations in surface sediment are shown in Figure 4.5.6. The figure shows that the highest concentrations are centered on the accident site, and it indicates a fairly even distribution in the remaining deep part of Bylot sound, whereas almost fallout background concentrations prevail outside Bylot Sound. The accident site – around location V -with the highest concentrations is situated at water depths of 180 – 230 meters. The two assumed background sites outside Bylot Sound, Ny-3 and 1412, are at depths of 500 and 640 m, respectively. A surface 0-3 cm concentration of 0.12 Bq ^239,240Pu kg^-1 dry was observed 750 km further south. The surface concentrations outside Bylot sound, locations 1412 and ny-3, are an order of magnitude higher. It is not clear whether this is caused by accident plutonium or it is a natural perturbation caused by differences in sedimentological parameters. At other Arctic marine locations such as the waters south of Spitzbergen, similar levels of plutonium have been ascribed to global fallout.

4.5.2.4 Benthic biota

Where possible, plutonium concentrations in biota samples have been compared with concentrations in 0-3 cm surface sediments (Figure 4.5.6) to give a “concentration ratio”, CR, Bq ^239,240Pu kg^-1 dry biota / Bq kg^-1 dry 0-3 cm sediment (Table 4.5.6). It is noted that although the analysed biota is living buried in the sediments or on the sediment surface, the CR values indicate that the bioavailability of the weapons plutonium is low. Most of the observed CR values are in the range 0.01 – 0.1, i.e. plutonium concentrations in benthic biota are in general 1-2 orders of magnitude lower than in surface sediments. Furthermore, a significant part of this plutonium is probably not metabolised but rather associated to particles in the guts and adhering to the surface structure of the animals. Higher transfer rates to benthic biota have been observed in the Irish Sea (Ryan et al. 1999), probably due to differences in physical and chemical forms of plutonium. One single bivalve sample showed a much higher level, which was probably due to a hot particle.

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Figure 4.5.6.
Thule-1997. Plutonium concentrations in surface 0-3 cm layer of sediments, Bq ^239,240Pu kg^-1 dry. Location names in italics, concentrations in bold. The point of impact was on the sea ice at the location marked V2.

4.5.2.5 Isotope ratios

A number of Thule sediment samples from the present 1997 sampling as well as a few stronger ones taken earlier have been analysed for ²⁴⁰Pu/²³⁹Pu atom ratios by HR-ICPMS (Dahlgaard et al. 1999). These samples show ²⁴⁰Pu/²³⁹Pu atom ratios in the range 0.027 - 0.057. The calculated uncertainties on most of the samples are 2 - 10 %. The samples with highest activity – which have all been identified as “hot particles” – show a significant variation in the ²⁴⁰Pu/²³⁹Pu atom ratios, i.e. there is a variation in plutonium isotope ratios in the Thule debris significantly larger than measurement errors. This supports the earlier conclusion (Mitchell et al. 1997) that the Thule plutonium originates from at least two sources of different quality. Plutonium concentrations in the samples used for this work are dominated by the Thule weapons accident. Therefore, the higher ²⁴⁰Pu/²³⁹Pu atom ratio observed in global fallout, approx. 0.18, will not affect the results. Any influence of the higher ²⁴⁰Pu/²³⁹Pu atom ratios in Sellafield discharges, up to around 0.25 is even more unlikely, as the Sellafield contribution to the Arctic Ocean plutonium concentration is supposed to be less than global fallout.

Average isotope ratios, ²⁴⁰Pu / ²³⁹Pu atom ratios and ²³⁸Pu / ^239,240Pu and ²⁴¹Am / ^239,240Pu activity ratios for sediment samples containing more than 20 Bq ^239,240Pu kg^-1, i.e. at least an order of magnitude above the fallout background, are given in Table 4.5.7. The reference date is the sampling date, i.e. 1997. By comparison of the ²⁴¹Am / ^239,240Pu activity ratios for the sediments (Table 4.5.7) with data for the benthic biota samples (Table 4.5.8), it is seen that some of the biota groups seem to have a higher uptake of americium than of plutonium, especially molluscs and brittle stars (Ophiuroids). A higher affinity for americium than for plutonium in some biota groups is not new. Thus IAEA reported higher CF values for Am than for Pu in molluscs (IAEA, 1985).

Table 4.5.7.
Thule-1997.Isotope ratios in sediment samples holding more than 20 Bq ^239,240Pu kg^-1. Reference date: August 1997.


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Conclusions and recommendations

• In the plutonium contaminated Bylot Sound, biological activity has mixed accident plutonium efficiently into the 5-12 cm new sediment resulting in continued high surface sediment concentrations 3 decades after the accident.
  
• Plutonium from the contaminated sediments is not transported into the surface waters in significant quantities. This is deduced from analytical results of surface seawater and brown algae. However, plutonium-bearing sediments seem to be resuspended near the bottom.
  
• A recent Ph.D. thesis indicates that “hot particles” hold considerably more plutonium than previously anticipated and that the Bylot Sound sediments may be accounting for the major part of the un-recovered amount, i.e. around 3 kg.
  
• Transfer of plutonium to benthic biota is low – and lower than observed in the Irish Sea. This is supposed to be caused by the physico-chemical form of the accident plutonium.
  
• A survey of the plutonium contamination in the Bylot Sound should be carried out in 2003 with special attention to be paid to the effect of hot particles and to possible changes in physico-chemical form that may increase bioavailability and mobility. The plutonium contamination in Bylot Sound should be monitored regularelly, e.g. every 5 years. 
  
• A follow-up survey of plutonium levels in the terrestrial environment based on organic surface soil samples from areas where plutonium was detected after the Thule accident is suggested.

4.6 Lead contamination of Greenland seabirds hunted with lead shot

Southwest Greenland waters are important wintering grounds for seabirds, in particular thick-billed murre (Uria lomvia) and common eider (Somateria mollissima), and during winter substantial numbers, about three hundred thousands, of these two species are killed with lead shot in this region of Greenland. The study referred to here was initiated to assess human lead exposure from eating these birds.

Birds killed with lead shot were collected from winter hunting in the Nuuk region (64°N, 51°W), murres in 1998 and common eiders in 2000. Eiders not killed with lead shot were also collected. Each bird was x-rayed and shot pellets were located and counted. Wings, head, tarsus and toes were cut off, the bird was skinned and the viscera were removed. Then each skinned carcass without viscera was boiled according to a recipe often used in Greenland. After boiling, the right pectoral muscle was selected for chemical analysis. If the x-ray photos had shown presence of shot pellets in the muscle, visible pellets were located and removed. We used this procedure to simulate the human lead exposure from eating seabirds in Greenland.

After ashing of the entire pectoral muscle in a porcelain crucible, the ash was dissolved in suprapure nitic acid and analysed by AAS. Table 4.6.1 shows the results from the study. As the frequency distribution of data is very skewed, the “bootstrap method” (Efron & Tibshirani, 1993) using 1000 ’resamples’ was chosen to characterize data. 4 single high lead concentrations (above 1000 µg/g ww) were omitted from data treatment, because it was suspected that a whole pellets or large pellet fractions were not detected and removed before analysis.


Click on the picture to see the html-version of: ‘‘Table 4.6.1‘‘

The lead concentration is significantly higher (a factor of about 8) in eider than in murre, and it is much higher (a factor of 44) in eiders killed with lead shot than in drowned birds. But lead levels in drowned eiders are also elevated (a factor of about 3 above the detection limit), probably because the breast meat is contaminated by lead from being shot at earlier without being killed. In the drowned birds we found from 0 to 3 pellets in the breasts analyzed, and Falk & Merkel (2001) report that 24% of the common eiders in Greenland carry embedded lead shot.

Wingbones from eiders were also analysed, as the lead concentration in bone tissue is considered a good indicator for lead exposure over the lifetime of the individual. The lead level was low, indicating that the eiders only accumulate lead to a small degree and that lead has no toxic effect on the birds.

The mean lead concentration 0.73 µg/g ww. in whole murre breasts is 3 to 4 times higher than we found when we analyzed 0.5-1 gram sub samples from the same birds, 0.22 µg/g ww. (Johansen et al., 2001). The 95% confidence limits of the two means overlap, but a contributing explanation of this difference could be that all non-visible lead fragments will be included when the whole breast is analyzed, whereas only a fraction of these fragments is included in the sub sample.

Table 4.6.2 compares the Greenland data with similar Canadian and with residue guidelines for lead in Denmark (0.3 µg/g ww (Anon., 2002)) and Canada (0.5 µg/g ww (Scheuhammer et al. 1998)). In murres 11-17% of the observations exceed these residue guidelines, whereas in eiders this is the case for more than half of the birds analyzed.


Click on the picture to see the html-version of: ‘‘Table 4.6.2‘‘

FAO/WHO have established a “Provisional Tolerable Weekly Intake” (PTWI) for lead of 25 µg per kg bodyweight for both adults and children. In general lead levels in Greenland biota is very low, and consequently human lead intake from local food items is also estimated to be low, on average only 15 µg per adult per week (Johansen et al. 2000). However, this estimate does not include any significant contribution from shot pellets, and the use of lead shot in Greenland may increase human lead intake considerably.

To illustrate the importance of birds as a dietary lead source we have calculated the lead intake from our analysis of whole breasts. If as an example we consider a meal being 200 gram bird meat, the resulting mean lead intake from such a meal will be 146 µg for murre and 1220 µg for eider. This implies that only one eider meal will result in a lead intake close to the PTWI. For murre the lead intake from one meal will be about 10% of the PTWI.

The actual lead intake from birds hunted with lead shot over longer periods will depend on 1) the amount of bird meat per meal, 2) the frequency of bird meals and 3) the lead concentration in the meals. There are not sufficient data to quantify this, but our calculation in the example illustrates that birds hunted with lead shot are a significant lead source and probably the most important single source. The example also indicates that the lead intake must be expected to exceed the PTWI in a number of cases, as both murre and eider are important in the diet, particular in southwest Greenland during winter.

4.7 Contaminant signatures as reflecting population structure

4.7.1 West Greenland narwhals

Samples of muscle, liver, kidney, blubber and skin tissues of narwhals from West Greenland collected in the period 1983 to1994 have been analysed for heavy metals, organochlorines, stable isotopes and DNA (Figure 4.7.1) to test a hypothesis that different populations of narwhals in the West Greenland area exist. The obtained results of metal concentrations and DNA were included in the existing database, whereas no previous data on organochlorines and stable isotopes in West Greenland narwhals existed. The results of this study are described in Riget et al. (2002).

Metal analysis

In total, Cd, Hg, Se and Zn concentrations in muscle, liver and kidney tissues of app. 150 narwhals were analysed. Cd, Hg, Se concentrations were increasing in the first three to four years of the animals life, where after no dependence on age was observed. Females had significantly higher concentrations than males in case of Cd in all tissues and Hg and Se in liver. No consistence difference in metal levels between narwhals from Avanersuaq and Uummannaq was found. The between year variation at one location seem to be larger than the variation between the two location. The metal levels found were within the range of previous published results on narwhals from Arctic Canada and Avanersuaq, West Greenland.

 
Figure 4.7.1.
Map of sampling localities

Organochlorines

In total, organochlorines in blubber from 101 narwhals were analysed. OC concentrations were dependent on age and differences were found between males and females. Females showed decreasing OC concentration in the first 8 to 10 years, while males showed a slightly increase of ΣPCB, ΣDDT and trans-nonachlor while ΣHCH, HCB, ΣCHL and toxaphene showed a slightly decrease in the first years and then rather independent of age. No or few statistical differences in mean OC concentrations were observed, however, the narwhals from Balgoni Island 1993 and Kitsissuarsuit 1990 showed the consistently highest levels and whales from Avanersuaq 1993 the lowest level. Also the pattern of PCB congeners showed some differences between samples. PCBs seem to be at a little lower or at the same level in the west Greenland samples as in the Canadian samples, whereas ΣHCH and ΣDDT seem to be higher. Total toxaphene was one of the dominanting OCs as previously observed in small Arctic toothed whales.

Stable isotopes

Stable isotope ratios (¹⁵N/¹⁴N expressed as per mille is denoted ¹⁵N and ¹³C/¹²C denoted ð¹³C) in muscle of 150 narwhals were analysed. The ratios showed a decreasing trend in the first year when they live of mother’s milk, hereafter the ratios were relative stable with age. ¹⁵N was found to be significantly higher in samples from Uummannaq 1993 compared to the samples from Avanersuaq 1984 and 1985 indicating some difference in trophic levels of the narwhals. ¹³C were also found to be significant higher in samples from Uummannaq 1993 than from Avanersuaq 1985 but not from Avanersuaq 1984. No correlations were found between stable isotopes ratios and metal and OC concentrations. 

Genetic data

Genetic haplotypes in the skin of 426 narwhals were analysed from the same regions covered by the other analysis. Additionally 99 samples were analysed from Disko Bay, Upernavik, Eastern Canada and east Greenland. In general, the genetic variation was low relative to that found for other cetacean. However, the genetic data gave the strongest evidence for the existence of different populations in the West Greenland area expressed by the frequencies of haplotypes.

The population structure with two West Greenland populations suggested by the genetics study could not be supported by the metal and OC concentrations and stable isotopes.

4.7.2 North Atlantic minke whales

In 1998 samples of tissues of 159 minke whales were collected from: west and east Greenland, Jan Mayen, West Svalbard, the Barents Sea,, Vestfjorden/Lofoten and the North Sea (Figure 4.7.2). Tissues have been analysed for OCs (blubber), elements (muscle, liver, kidney and baleen), stable isotopes (muscle), caesium-137 (muscle), fatty acids (blubber) and genetic studies. The aim of the study was to deduce the population structure of minke whales in the northeast Atlantic and the North Sea. The results of each of the individual studies have been published for OCs (Hobbs et al. in press), element and stable isotopes (Born et al. sumitted, a), caesium-137 (Born et al. submitted, b), fatty acids (Møller et al. submitted) and genetics (Andersen et al. submitted).

Figure 4.7.2.
Map of sampling locations of tissues of minke whales in 1998. Redrawn from Born et al. submitted 

The individual studies revealed somewhat similar population structure of the minke whales in the northeast Atlantic and the North Sea.The difference in OC concentrations suggested that west and east Greenland minke whales constitute one group distint from whales from the other areas. However, the general similarity in mean values and proportions of OC compounds also suggested that the minke whales are quite mobile and may feed in multiple areas (Hobbs et al. in press).

The pattern of elements with relatively long biological half life suggested that minke whales have fidelity to certain summer feeding areas at least for several years and the following stocks was inferred: Greenland, Jan Mayen, a northern stock in the Barents Sea, Svalbard and coastal Norway and the North Sea (Born et al. submitted, a). Caesium-137 concentrations also showed differences among the areas, as the significantly highest levels were found in minke whales from the North Sea and the significantly lowest levels in whales from Svalbard (Born et al. submitted, b).

The fatty acid composition (a total 43 fatty acids) indicate differences between whales from Greenland (west and east), the Northeast Atlantic and the North Sea (Møller et al. submitted).

The genetic study including sequencing of the D-loop in mtDNA and 16 polymorhic nuclear microsatellite markers suggested 4 genetically different sub-populations: a west Greenland, central stock (north of Iceland), northeastern Atlantic and a North Sea sub-population (Andersen et al. submitted). This study also included previous collected samples, in total 306 whales.

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