Johansen, P., Riget, F., Asmund, G., Josefson, A.B. & Hansen, J.L.S. 2006. Technical Report from NERI No. 605. 102 pp.
At Maarmorilik in the municipality of Uummannaq lead and zinc ore was mined from 1973 to 1990 by the mining company Greenex A/S. The ore was primarily found in the mountain called “Black Angel”. It was mined at an altitude of about 600 metres above sea level and transported in cable cars across the fjord Affarlikassaa to a processing plant in Maarmorilik. Here a lead and a zinc concentrate were produced and loaded on ships, which transported the concentrates to smelters in Europe.
There were a number of sources of pollution while mining took place. Ore crushing and transport of concentrate created dust that was dispersed in the environment. Waste rock dumps with low contents of lead and zinc were also a dust source, but they also polluted the fjords with lead and zinc. The most important pollutant source, however, were the mine tailings that were discharged into and settled in Affarlikassaa. Here a waste rock dump also was placed, when the mine closed.
Environmental studies have been conducted at the mine since 1972 by monitoring lead and zinc in seawater, sediments and biota in the fjords at Maarmorilik. Studies of the benthic fauna also have been carried out. This report presents the results of environmental studies conducted in 2005 and assesses the state of the environment in the area. The results are compared with data collected from 1972 to 2002.
The lead and zinc dispersal with dust around Maarmorilik has been monitored by use of the lichen Cetraria nivalis. This species is used to monitor dust dispersal, as the only take-up of water, nutrients and pollutants is from the surface of the lichen.
The lead and zinc concentration in lichens after one year of transplantation to locations at Maarmorilik has been used as a measure of metal dispersal as dust. From this study we have found elevated lead levels in lichens in the areas around Affarlikassaa and Qaamarujuk, whereas the area affected by zinc is smaller. There is no clear time trend in the lead and zinc levels in lichens from the area in the period 1997 to 2005, although there is a tendency that the lead concentration has decreased in Outer Qaamarujuk and the area to the west of here.
The pollution of seawater has changed drastically since mine closure, after which only small amounts of lead are released from settled tailings and waste rock in the fiord Affarlikassaa. Zinc is still released, but clearly less than when mining took place. In the bottom water of the fiord, the lead concentration was about 1,000 times and the zinc concentration about 10 times lower in 2002 than in 1988-89. Metal concentrations in surface waters of Affarlikassaa and Qaamarujuk have also declined significantly, and in 2002 and 2005 we did not find elevated lead and zinc concentrations here.
Brown algae in the tidal zone take up metals from the surrounding water and may be used to monitor seawater pollution. Over the monitoring period, where comparable data exists (1982-2005), both the lead and zinc concentration has decreased significantly, especially after mine closure and lead levels have decreased more than zinc levels. In the outer, western and the inner part of Perlerfiup Kangerlua the lead concentration now is close to the baseline level.
Also blue mussels from the tidal zone take up metals from seawater, algae and particles. As they are stationary they may be used to monitor metal pollution. In blue mussels sampled in 2005 lead levels above background are found in Affarlikassaa, Qaamarujuk and Perlerfiup Kangerlua. In previous years the lead concentration in blue mussels was so high, that local people were advised not to collect and eat blue mussels from these fjords. But as the studies in 2005 showed that the lead contamination of the blue mussels in the fjords had declined significantly, we now recommend diminishing the area with restrictions to Affarlikassaa, Qaamarujuk and the area just west of here. The lead and zinc concentrations in blue mussels have been declining over a number of years, but lead levels only slowly, because the mussels cannot eliminate all the lead taken up originally. Elevated zinc levels are found in a smaller area close to Maarmorilik.
We also measure the pollution by transplanting blue mussels from a clean site to the Maarmorilik region and analyse their lead and zinc content one year or more years later. These studies show that the tidal zone still is affected by lead and zinc pollution 15 years after mine closure, but the impact is steadily declining and is significantly lower than when mining took place. The most recent studies indicate that the impact has declined to 1/10. They also indicate that diffuse sources (probably primarily metals in dust) now are more important than point sources to the pollution of the fjords.
In muscle tissue from spotted wolfish, Greenland cod and shorthorn sculpin caught at Maarmorilik in 2005 the lead concentration is low. Liver tissue from spotted wolffish and shorthorn sculpin are analysed to monitor the time trend of the lead pollution. In 2005 we found elevated lead concentrations in the livers of both species. The level is similar to what we have found after mine closure and during the last years of mining, but the concentrations found in 2005 are among the lowest found. However, unexpected high lead concentrations were found in capelin caught at Maarmorilik in 2006. A mean concentration of 0.5 µg/g wet wt was found, thereby exceeding the Danish residue guideline for lead in fish of 0.3 µg/g. It is unclarified, if this “pollution” is real or could be caused by contamination of the fish when the catch was handled. To clarify this, new samples should be collected in 2007.
In prawns from Qaamarujuk the lead concentration is elevated in 2005. The lead concentration is significantly higher in the heads and shells than in meat. In the meat the lead concentration is low compared to Danish residue guidelines. Since 1988 lead levels in prawns have been clearly declining, but most in the beginning of this period.
Lead and zinc concentrations in the sediments of Affarlikassaa have declined after mine closure, but are still much higher than baseline levels. In Qaamarujuk the concentrations increased the first 8 years after mine closure, but have since decreased again. Today in Qaamarujuk the lead concentration is elevated 3-7 times and the zinc concentration 1.2 to 2.3 times. In the fjord area c. 4 km west of Qaamarujuk lead in the sediment is only slightly elevated, while zinc is not.
Tailings deposition from the mine has markedly impacted the benthic fauna in Affarlikassaa and Inner Qaamarujuk. A study conducted in 2005 shows that “the normal” benthic society was not re-established 15 years after tailings discharge ceased. In the primary area for tailings deposition, Affarlikassaa, the state of the benthic society could be described as ”Poor” to ”Bad”. In Inner Qaamarujuk the state was ”Moderate” to ”Poor”. In Outer Qaamarujuk the state was ”Good” to ”High”, while mining took place, as it was in most of the whole area before mining started. It is likely that the impact on the benthic fauna is a result of both physical factors (burial in tailings) and chemical (toxic effect of heavy metals in the sediment).
The environmental studies conducted in 2005 show that pollution sources still exist at Maarmorilik 15 years after mine closure in 1990. We can still see elevated lead and zinc levels in the environment. However, over a number of years lead and zinc levels in seawater and biota have decreased, in particular after the mine closed, and the area affected by pollution with lead and zinc has become smaller and smaller over the years. It is now primarily in Affarlikassaa and Qaamarujuk, an impact can be seen.
Full report in pdf-format (1,199 kB).
