Abstract
Muscle, liver, and kidney tissue from 456 ringed seals (Phoca hispida) from eight areas in Greenland were analysed for cadmium, mercury, zinc and selenium. In general, cadmium concentrations were high in liver and kidney tissue, with geometric means of 7.79 and 33.5 μg/g (all data on wet weight basis), respectively. Muscle levels were considerably lower, at 0.067 μg/g. The concentration of mercury was relatively high in liver tissue with a geometric mean of 2.59 μg/g. Muscle and kidney mercury levels were somewhat lower, with geometric means of 0.210 and 0.956 μg/g, respectively.Cadmium and mercury levels were strongly dependent upon age and sampling area, as well as the interaction combinations, indicating that the accumulation of cadmium and mercury varies with age and area. Mercury accumulated in all three tissues throughout life, whereas cadmium in liver and kidneys peaked in the age group 5-10 years old where after it dropped significantly.Cadmium levels showed a tendency towards higher concentrations in the northern municipalities, which may be due to the higher cadmium levels in certain prey items in the northern areas. Mercury levels were higher in seals from East Greenland compared to West Greenland. Variations in feeding habits probably explain some of the differences in levels of cadmium and mercury in ringed seals from different geographical areas.Cadmium concentrations were correlated (both pairwise and partial) in the three organs. This was true for mercury as well, whereas only half of the combinations were significant for zinc and selenium. Cadmium was strongly correlated to mercury in all three tissues and zinc only in liver and kidneys. Mercury was only correlated to selenium in liver and not to zinc.High concentrations of cadmium were found in the bile from 58 ringed seals, and were about 10-fold higher than in muscle. The concentration of mercury in bile was relatively low, being only one third of the muscle level. The bile levels reflect that substantial amounts of especially cadmium are circulated through the bile. However, it is uncertain whether these amounts are actually excreted or reabsorbed in the intestine (enterohepatic circulation).
Highlights
Ringed seals (Phoca hispida) have been the most numerous and most commonly hunted marine mammal species by the Inuit population in Greenland and other Arctic areas for centuries (Reeves et al this volume, Teilmann and Kapel this volume)
Cadmium and mercury data in ringed seal from the municipalities sampled are presented for the following age groups: one year, 2-4 years, 5-10 years old and> 15 years, in order to elucidate geographical differences (Tables 1 and 2)
Data from the remaining age groups and all the data for zinc and selenium are presented without geographical subdivision, as the sample size is too small to allow meaningful comparisons
Summary
Ringed seals (Phoca hispida) have been the most numerous and most commonly hunted marine mammal species by the Inuit population in Greenland and other Arctic areas for centuries (Reeves et al this volume, Teilmann and Kapel this volume). Ringed seals are abundant throughout the year in most of Greenland's coastal waters. During recent years there has been an increasing interest in documenting and understanding food chain accumulation and geographical and temporal trends of contaminants levels. Some of these issues have recently been elucidated for the Greenland and the Arctic marine ecosystems (e.g. Dietz et al 1996, 1997, in press b). Baseline data on seals from Greenland waters are included in a review of the marine ecosystem (Dietz et al 1996). A much more detailed presentation and data analysis is provided
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