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English summary
Setting of study and sample collection
NERI conducted a marine environmental study at Thule Air Base (TAB) during14 - 24 August 2002. The setting of this study was the transition of the Dundas area from military to civilian status and in this connection to provide sufficient information about the area so that its future use could be evaluated. On the same background and parallel to the marine environmental study, the consultant company Niras Greenland a/s conducted an investigation of two waste dumps on the Dundas peninsula.
We took 486 samples from 118 stations from the area north of the Dundas peninsula, North Star Bay at the military base, the sea adjacent to the old waste dumps in the southern part of the base, southwestern Bylot Sound and at Qaanaaq (Figure 1-4). The areas in Bylot Sound and at Qaanaaq are considered reference sites. In this report contaminant levels in the Thule region are compared and comparisons are also made with levels in other parts of Greenland and in European waters. Samples were collected of shorthorn sculpin, brown seaweed, clam, Greenland cockle, sea urchin, whelks and sediments. 112 samples were analyzed for 8 metals and 51 samples for PCBs, organic pesticides and polyaromatic hydrocarbons (PAHs)(Appendices 4-15). Two liver samples of shorthorn sculpin sampled in the TAB area were analysed for dioxins, coplanar polychlorinated biphenyls (coplanar PCBs) and brominated flame retardants (Appendix 19). An overview on source, use and toxicology of the contaminants analyzed is compiled in Appendix 18. The whelks were examined for imposex, i.e. female whelks with masculine sexual characteristics (Appendix 17). Finally, 28 samples of whelks, mussels, sculpins and sediments were analysed for organotin (Appendix 16). The present marine environmental study is compared with a similar study from 1984.Environmental impact at TAB in 2002 compared to 1984
Compared to the 1984 study, only PCB concentrations in clams were higher than in 1984. PCB concentrations in sediments from the TAB in 2002 area appear not to be different from the 1984 levels.
It is possible to compare five metals in brown seaweed and mussels between the two years. The concentrations in brown seaweed in 2002 were similar to concentrations in 1984 for lead, zinc and cadmium, and lower for copper. Concentrations in mussels in 2002 were unchanged for mercury, cadmium and lead, even though lead concentrations in 2002 were in the high end of the 1984 range.Contaminant levels at TAB compared to reference sites
Significantly elevated concentrations were found at TAB compared to the reference areas in the following organisms or sediments of the following contaminants. Comparisons have been made with the local reference sites (local background) and with other Greenland reference sites (regional background), where there are no local sources of contaminants.
- - Sculpin liver: PCB (6-30 times above local background level). PCB is also elevated compared to other reference areas in Greenland.
- - Greenland cockle: Chromium, copper and lead (2-6 times above local background level).
- - Clam: PCB (2-10 times above local background level).
- - Sea urchin: Copper and lead (2 times above local background level).
- - Brown seaweed: Copper, lead and zinc (2-5 times above local
background level). Zinc is the only metal with concentrations
above other Greenland reference areas.
- - Sediment: Mercury, arsenic, copper, lead, PCB, HCH and PAH (2-
10 times above local background level). PCB is the only contaminant
with concentrations above other Greenland reference areas.
Sources in the TAB area
In the environmental study in 2002 samples from four TAB areas have been collected and analyzed (Figs. 3a, b): TAB 1 (dump North of the Thule mountain), North Star Bay (south of the Thule mountain and north of the pier), TAB 31 and TAB 37 (dumps to the south of North Star Bay). Based on concentrations of contaminants in organisms and sediments North Star Bay appears to be the most polluted area. The fjord at TAB 1 and TAB 31 are less contaminated, and the fjord at TAB 37 is the least polluted area.
- - In North Star Bay elevated concentrations of metals are found in sediments and brown seaweed, and elevated concentrations of almost all POPs are found in sculpin liver and in sediments. Elevated concentrations of di- and tributyltin in whelks and clams were found only in North Star Bay, where also the highest frequency of imposex in whelk was found.
- The pollutants most likely originate from the effluent pipe, and from the river that enters the head of the bay. Pollutants can also seep from the SV dump situated in the northern part of the bay. Organotin is likely to come from the pier and ships painting. Imposex in whelk is most likely due to organotin concentrations, which the whelk species are thought to be relatively sensitive to.
- - In the area outside of TAB 1 elevated concentrations of metals and
some POPs are found in sediments. Elevated concentrations of PCB are found in sculpin liver, clams and sediments. The second highest frequency of imposex in whelk was found in this area.
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Most contaminants in the area probably seep from the TAB 1 dump. Organotin released from dump and maybe the pier area is probably the reason for the evolved imposex in whelk.
- - In the TAB 31 area higher concentrations of some metals are found in sea urchin and brown seaweed, and the highest concentrations of PCB in organisms and sediments are found in this area. PCB probably seeps from dumped products containing PCB.
- - In the TAB 37 area elevated concentrations of lead and zinc are found in brown seaweed, and higher concentrations of PCB are found in sculpin liver, clam and sediments. These contaminants are likely to seep from the TAB 37 dump.
Overall assessment
PCBs appears to be the most important pollution problem at TAB, because the PCBs show elevated concentrations of 2-30 times both locally and regionally. Concentrations of PCB in sculpin livers are comparable to levels found in fish livers from coastal European areas. The PCB concentrations exceed maximum residue limits for human consumption (100 ng/g wet weight) and a guideline value for assessment of hazards to fish eating wildlife (160 ng/g wet weight). The EU recommended weekly tolerable intake value is reached with a consumption of 100 g or less of sculpin liver from the TAB area. Normally, shorthorn sculpin is not a species used for human consumption, but the fish can be part of sculpin soup. Sculpin is a relatively stationary fish species compared to fish used for human consumption. Therefore, high concentrations in fish used for consumption can not be expected. Sea mammals, like seals, are on a higher level in the food chain than sculpin, but elevated PCB concentrations at TAB are not likely to affect the concentrations in seals, because their feeding areas are large and because they feed on a variety of species.
The study shows that there are several contaminant sources at TAB causing the elevated concentrations of a few contaminants in the marine environment. But the study also shows that the impact is local and limited to an area of 5-10 kilometres from TAB. TAB is therefore not considered to be a major source to the existing level of contaminants found in Wolstenholme Fjord, Bylot Sound and the Thule region as a whole.
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