Summary
Purposes of the baseline study
The environmental baseline study was performed by NERI during 1998-2001 around the Nalunaq gold mine site, Nanortalik district, South Greenland. The purposes of the study were to determine the background level of contaminants, the accumulation rates and structure of marine sediments, the diversity and biomass of the benthic macrofauna and the abundance and composition of local snow crab populations.
Contaminants in organisms
A total of 872 samples were collected of shorthorn sculpin, Arctic char, blue mussel, brown seaweed, the lichen Cetraria nivalis, snow crab, sea urchin and marine sediments. 140 samples of organisms were analysed for content of arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), mercury (Hg), lead (Pb) and zinc (Zn). Samples were collected prior to the official mine start in 2004. There-fore, highly elevated concentrations was not expected in the Saqqaa and Kirkespir area compared to reference areas in the local Uunartoq Fjord or elsewhere in Greenland. Yet, mining activities took place during the sampling period which could increase concentrations in e.g. the Kirkespir Valley.
Metal concentrations in organisms from the Saqqaa area were, compared to those from the local reference area, elevated only in shorthorn sculpin liver (2-3 times of Cd, Hg and Pb) and in Cetraria nivalis (4-5 times of As, Co and Cr). Slightly elevated levels of Pb and Cr were seen in snow crab muscle and blue mussel.
Marine sediments
Sediment accumulation rates were measured at 10 stations in Saqqaa Fjord using the lead-210 dating technique. The mean accumulation rate was 1089 g/m2 year.
The Saqqaa Fjord could, from the physical and chemical composition of the sediments, be divided in three areas defined by a) the proximity to the Kirkespir river (large amount of sand), b) the deep middle part of the fjord (mainly fine-grained material), and c) the proximity to the Amitsoq island (large amount of coarse material).
Benthic macrofauna
During 2001 the benthic macrofauna was studied in the Saqqaa and Uunartoq fjords. The faunal composition of major taxonomic groups was typical for high latitude boreal fjords and most abundant by biomass were polycaete worms, molluscs and sea urchins. Biodiversity values did not differ markedly between stations, although there was a tendency towards higher diversity in Saqqaa Fjord compared to Uunartoq Fjord.
The sensitivity of the present fauna to an increase in sedimentation rate due to tailings disposal, is not known. If sedimentation rates exceed about 10 cm per year (c. 100 kg/m2 year), burial and extinction of the fauna is a possibility, whereas lower sedimentation rates can either change species composition or even increase number of species and individuals.
Snow crabs
During spring and autumn 2001 snow crabs were caught in Saqqaa and Uunartoq fjords. The populations in these two fjords should be approximately in the middle of their 8-10 years cycle according to Canadian studies of carapace hardness of adult males. The average carapace width during spring was not different from that found in West Greenland populations. During autumn the average carapace width of Saqqaa crabs was reduced by more than 10% compared to the width during spring. The catch per effort (CPUE) during autumn was low compared to CPUE found at the research fishery in the area autumn 1998; during spring 2001 CPUE was comparable to the autumn 1998 catch. The experimental commercial crab fishery in 2001 (96 tonnes) in the Saqqaa and Uunartoq fjords could have an effect on both CPUE and carapace width found autumn 2001. Yet, in West Greenland areas with more than 10 years of commercial fishery such a reduction seems not to have been taken place. A seasonal crab migration could also be a possible explanation.
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