Zinc,cadmium, mercury and selenium in polar bears (Ursus maritimus) from Central East Greenland

Muscle, liver, and kidney tissues from 38 polar bears (Ursus maritimus) caught in the Scoresby Sound area, Central East Greenland, were analysed for zinc, cadmium, mercury and selenium. In general, cadmium concentrations were low in muscle, liver and kidney tissue, with geometric means (g.m.) of 0.022 (range: <0.015–0.085), 0.841 (range: 0.092–3.29) and 13.1 (range: 1.04–115) g Cd/g wet weight (ww) respectively. This finding can be explained by low cadmium levels in the blubber of ringed seals. The concentration of mercury in muscle tissue was low (g.m. 0.071; range: 0.039–0.193 g Hg/g ww), whereas concentrations in liver and kidney tissue were relatively high (liver: g.m. 7.87; range: 1.35–24.8 g Hg/g ww, and kidney: g.m. 15.2; range: 1.59–66.6 g Hg/g ww). Mercury and cadmium were positively correlated with age in liver and kidney. Zinc was positively correlated with age in kidney, and selenium was correlated with age in liver. Contrary to other marine mammals, polar bears had higher mercury levels in the kidneys than in the liver. In all three tissues polar bears had significantly lower cadmium levels than ringed seals from the same area. Mercury levels were likewise significantly lower in the muscle tissue of polar bears than in ringed seals, whereas levels in the liver and kidney were significantly higher. The previous geographic trend for cadmium and mercury found in Canadian polar bears could be extended to cover East Greenland as well. Hence cadmium levels were higher in Greenland than in Canada, while the opposite was the case for mercury. Greenland polar bears had higher mercury and cadmium contents in livers and kidneys than polar bears from Svalbard. The mercury levels in muscle and liver tissue from polar bears from East Greenland were twice as high as found in bears from western Alaska, but half the levels found in northern Alaska. Cadmium and zinc were partially correlated in kidney tissue, and this was found for mercury and selenium as well. Cadmium and zinc showed molar ratios close to unity with the highest concentrations occurring in kidney tissue, while the levels of zinc exceeded cadmium in muscle and liver tissue by up to several decades. Mercury and selenium showed molar ratios close to unity in liver and kidneys.     

Selenoprotein W accumulates primarily in primate skeletal muscle,heart, brain and tongue

The human selenoprotein W coding region with the selenocysteine codon (TGA) changed to a cysteine codon (TGT) was fused to six histidine codons (at its 3 end), cloned into a prokaryotic expression vector (pTrc99a), and the corresponding mutated selenoprotein W was expressed in bacteria. The protein was purified by Ni-NTA agarose column and reverse phase HPLC. Polyclonal antibodies raised against this protein were used in Western blots to determine tissue distribution of selenoprotein W from rhesus monkeys fed a commercial chow. Selenoprotein W was found in several tissues with highest amounts in skeletal muscle and heart (muscle 6 fold greater than liver) and lowest levels in liver, but selenium concentrations were highest in kidneys (10 fold greater than muscle) and lowest in skeletal muscle. Northern blots using a human selenoprotein W cDNA probe indicated that mRNA levels were highest in monkey skeletal muscle and heart (2-2.5 fold greater than in liver), which is similar to the pattern found with a human multiple tissue Northern blot. However, as in the monkey, selenium concentrations were highest in human kidney and lowest in skeletal muscle and heart. Thus, selenoprotein W protein levels correlated with selenoprotein W mRNA levels but not with tissue selenium concentrations.     

Cadmium, copper and zinc in tissues of deceased copper smelter workers

Workers at a copper and lead smelter in northern Sweden have a multifactorial exposure to a number of heavy metals. The concentrations of cadmium, copper and zinc in liver, lung, kidney and brain tissues have been determined by atomic absorption spectrometry in 32 deceased long-term exposed male lead smelter workers, and compared with those of 10 male controls. Furthermore, copper and zinc levels in hair and nails were determined by energy-dispersive X-ray fluorescence.

The highest cadmium concentrations among both workers and controls were observed in kidney, followed in order by liver, lung and brain. The levels in kidney, liver and lung were all significantly higher in the workers than in the controls (p < 0.03). Among the workers relatively strong positive correlations (p < 0.03) were observed between cadmium concentrations in liver and lung, liver and kidney, liver and brain, and lung and brain. In the exposed workers a positive correlation was observed between cadmium and zinc concentrations in the kidney (r_s = 0.38; p = 0.034). This is probably mainly due to the protein metallothionein, which is stored in the kidney, binding equimolar amounts of these two metals.

The highest concentrations of copper were found in hair and nails among both workers and controls, followed in order by liver, brain, kidney and lung. The tissue concentrations of copper in brain, lung and kidney were all significantly higher among the smelter workers than in the controls (p ≤ 0.036). Copper levels in lung and age at time of death were positively correlated among the exposed workers (r_s = 0.39; p = 0.029). In the same group, positive correlations between copper and zinc concentrations in kidney (r_s = 0.45; p = 0.009) and nails (r_s = 0.68; p < 0.001) were also observed, reflecting possible biological interactions between these two metals.

Among both workers and controls, the highest zinc concentrations were found in hair, followed in order by nails, liver, kidney, brain and lung. Significantly higher tissue concentrations among the workers as compared with the reference group were noted in kidney, liver and brain (p ≤ 0.033).

Neither copper nor zinc concentrations in hair and nails seemed to provide a useful measure of the trace element status of the smelter workers.     

双峰驼不同生态环境条件下组织中微量元素的分布研究

对砾石和沙质两种不同的荒漠区双峰驼组织中６种微量元素的含量及分布规律进行了研究。结果表明,Ｃｕ、Ｍｎ、Ｆｅ、Ｍｏ的丰度在肝脏最高,Ｓｅ和Ｚｎ则分别在肾脏和肌肉组织中最高。由于砾石荒漠区土壤和牧草中Ｆｅ、Ｃｕ、Ｍｏ含量极显著高于沙质荒漠区（Ｐ〈０．０１）,导致两地双峰驼肝脏和肾脏Ｃｕ含量差异极显著（Ｐ〈０．０１）．同时发现,上述两地区双峰驼组织中Ｍｎ含量显著低于其他反刍动物。     

Trace Element Distribution in Selected Edible Tissues of Zebu (Bos indicus) Cattle Slaughtered at Jimma,SW Ethiopia

The amount of trace elements present in edible bovine tissues is of importance for both animal health and human nutrition. This study presents data on trace element concentrations in semitendinosus and cardiac muscles, livers and kidneys of 60 zebu (Bos indicus) bulls, sampled at Jimma, Ethiopia. From 28 of these bulls, blood samples were also obtained. Deficient levels of copper were found in plasma, livers, kidneys and semitendinosus muscles. Suboptimal selenium concentrations were found in plasma and semitendinosus muscles. Semitendinosus muscles contained high iron concentrations. Trace elements were mainly stored in the liver, except for iron and selenium. Cardiac muscles generally contained higher concentrations of trace elements than semitendinous muscles except for zinc. A strong association was found between liver and kidney concentrations of copper, iron, cobalt and molybdenum. Liver storage was well correlated with storage in semitendinosus muscle for selenium and with cardiac muscle for cobalt and selenium. Plasma concentrations of copper, selenium, cobalt were well related with their respective liver concentrations and for cobalt and selenium, also with cardiac muscle concentrations. The data suggest multiple trace element deficiencies in zebu cattle in South-West Ethiopia, with lowered tissue concentrations as a consequence. Based on the comparison of our data with other literature, trace element concentrations in selected edible tissues of Bos indicus seem quite similar to those in Bos taurus. However, tissue threshold values for deficiency in Bos taurus cattle need to be refined and their applicability for Bos indicus cattle needs to be evaluated.     

Relationship between Selenium Content of Forage,Blood and Organs of Sheep,and Lamb Mortality Rate)

The investigation comprised 12 herds, totalling 660 sheep, in the counties of Stockholm and Uppsala. The selenium content of specimens of forage, whole blood, muscle, liver, and kidney was determined by a fluorimetric method. Data on the number of born and dead lambs were collected 4—5 months after lambing. Dead and sick lambs were subjected to necropsy and to clinico-chemical analyses, respectively. The selenium content of hay and corn was lower than 60 ng per g, which some authors regard as the minimum level of Se requirement for protection against white muscle disease in sheep. The analyses of forage mixtures containing oil concentrates and beet pulp showed selenium levels that were about 2—5 times as high as this minimum level. In herds in which the animals had not been treated with selenium preparations prior to sampling, there was a significant positive correlation between the selenium content of the forage and that of whole blood. A relationship was also noted between the selenium content of forage and of organs. In 9 out of the 12 herds the selenium concentrations in whole blood were on the level that is considered to be representative of white muscle disease. A high mortality rate was recorded for lambs whose mothers had low selenium levels in their blood. Prophylactic and curative treatment with selenium plus vitamin E orally and/or parenterally probably reduced lamb mortality rate in the herds fed a low-selenium diet.     

Beneficial effect of goat milk on bioavailability of copper, zinc and selenium in rats

We studied the effects of dietary inclusion of freeze-dried goat and cow milk on the utilization of copper, zinc and selenium, and on the metabolic fate of copper and zinc, in rats using a standard (non-milk) control diet recommended by the American Institute of Nutrition and diets based on goat or cow milk. For animals given the goat milk diet, the apparent digestibility coefficient (ADC) of copper is similar to that obtained with the standard diet and higher than that in animals given the cow milk diet. The copper balance was higher among the rats given the goat milk and the standard diets than among those given cow milk. The ADC and retention of zinc and selenium were higher for the goat milk diet than for the other two diets. The copper content in the kidneys and in the femur was greater when the animals consumed a goat milk diet than a cow milk diet. Zn deposits in femur, testes, liver, kidney, heart and longissimus dorsi muscle were greatest with the goat-milk diet, followed by the standard diet and were lowest for the rats given cow-milk diet. This study shows that the goat-milk has an important and beneficial effect on the bioavailability of copper, zinc and selenium.     

Liver and kidney concentrations of selenium in wild boars (<Emphasis Type="Italic">Sus scrofa</Emphasis>) from northwestern Poland

The aim of this study was to determine liver and kidney concentrations of selenium in wild boars from the northwest part of Poland, depending on season of the year, age, sex, and body weight. Altogether, samples of livers and kidneys from 172 wild boars that were shot in 2005–2008 were investigated. Liver and kidney concentrations of selenium were determined using spectrofluorometric method. In all the animals studied, selenium concentration was several times lower in the liver than in the kidneys. Selenium concentration averaged 0.19 μg/g wet weight (w.w.) in the liver and 1.20 μg/g w.w. in kidneys. The present study showed that season (P ≤ 0.05), age (P ≤ 0.01), and body weight (P ≤ 0.01) have a significant effect on selenium concentration in the liver of wild boars. Liver selenium concentration was the highest in spring (0.23 μg/g w.w.) and the lowest in autumn (0.16 μg/g w.w). Young animals (up to 1 year of age) and those with the lowest body weight (up to 20 kg) were characterized by a slightly lower selenium concentration in the liver compared to older and heavier animals. No significant differences were found in organ selenium concentration between males and females. According to biochemical criteria for the diagnosis of selenium deficiency in pig liver, which were used to evaluate selenium concentration in the liver of wild boars, no individuals were found to have optimal levels. Considering that in Se deficiency higher selenium concentrations are found in kidneys than in the liver, it can be presumed that the wild boars had Se deficiency. However, this is difficult to state conclusively because there are no reference values for this species.     

Multielemental assay of autopsy tissues of smeltery and refinery workers pertinent to possible health effects

A multielemental assay (i.e., of 23 elements) in kidney, liver, and lung tissue of autopsy specimens from deceased workers in a smeltery and refinery in North Sweden, as well as from a control group, is discussed in the light of possible health effects. The following topics have been surveyed: Brief history of the occupational exposure conditions; nuclear and other techniques used as tools in the multielemental assay; accumulation of the various elements in kidney, liver, and lung; estimation of retention times—long retention times were observed for antimony, arsenic, cadmium, chromium, cobalt, lanthanum, lead, or selenium in certain tissues, especially pronounced in the lung tissue; elevated levels of antimony, arsenic, cadmium, lead, and lanthanum in lung tissue of exposed workers—a contribution to a multifactorial cause behind the excess mortality from lung cancer of the smeltery and refinery workers; and the protective effect of selenium on lung cancer of exposed workers.     

Absorption, distribution, half-life and possible routes of elimination of dietary selenium in juvenile rainbow trout (Salmo gairdneri)

1. The influence of different levels of dietary selenium on the metabolism of selenium in rainbow trout was studied using 75Se as an indicator. 2. Gastric absorption of selenium by the trout appeared to be very efficient. 3. Highest tissue concentrations of selenium were noted in the liver and kidney. 4. Blood did not concentrate selenium and the plasma was the major transport medium. 5. The liver and kidney appeared to be involved in selenium excretion based on high tissue concentrations and variations in half-lives with selenium loading. 6. The biological half-life of selenium in the tissues decreased with increased selenium loading except in the liver, which at toxic dietary selenium concentrations became longer, suggesting a rate-limiting metabolic transformation of selenium for excretion in this organ.     

Selenium status inCharadriiformes

The distribution of selenium in a marine wader, the Oystercatcher (Haematopus ostralegus) is given by the levels in 15 tissues and plasma. Red blood cells (RBC) contain the highest level (23 mg/kg dry wt) followed by liver, lung, and kidney (17–19 mg/kg). Most other tissues range from 3–10 mg/kg. The average kidney and liver concentrations of the Oystercatcher belong to the concentrations characteristic in birds. However, the Oystercatcher's tissue selenium concentrations are in general four-to fivefold mammalian levels, but in liver and lung, 11- to 13-fold and in the RBC, 12- to 33-fold. The selenium plasma and RBC levels of the Oystercatcher vary during the year from 280 to 410 μg/L and 13 to 30 mg/kg dry wt, respectively; the plasma concentrations are positively correlated with the RBC selenium concentrations. An overview of literature data shows that the selenium kidney and liver concentrations of birds do not vary with geographical latitude and size (length) of the birds. In species of the ordersCharadriiformes andProcellariiformes, high selenium kidney, and to a lesser extent liver, concentrations may occur. A function of selenium in antioxidation is suggested.     

Concentrations and interactions of selected essential and non-essential elements in ringed seals and polar bears of arctic Alaska.

In this study, we evaluated concentrations of twelve essential and non-essential elements (As, Cd, Co, Cu, Pb, Mg, Mn, Hg, Mo, Se, Ag, and Zn) in tissues of ringed seals (Phoca hispida) and polar bears (Ursus maritimus) of arctic Alaska (USA). All samples were collected between 1995-97 in conjunction with subsistence harvests. The essential elements are reported to help develop reference ranges for health status determination and to help assess known or suspected interactions affecting toxicoses of cadmium (Cd) and mercury (Hg). In some tissues, Cd, Hg, and selenium (Se) were present at concentrations that have been associated with toxicoses in some domestic animals. Nevertheless, tissue levels of all elements were within ranges that have been reported previously in other pinnipeds and polar bears. Significant associations included: Cd with Zn or Cu; Cu with Zn or Ag; and Hg with Se, Zn, or Cu. This study found hepatic Hg:Se molar ratios to be lower than unity and different between the two species. Based upon significant differences in mean tissue elemental concentrations for polar bear versus ringed seal, we concluded that biomagnification factors (bear/seal) were significant for: Cu in liver and muscle; Pb in kidney; Se in kidney and muscle; Zn in liver and muscle; and Hg in liver. Possible explanations for observed elemental correlations (i.e., interactions) and ancillary mechanisms of Cd and Hg detoxification are discussed.     

Comparative distributions of zinc, cadmium and mercury in the tissues of experimental mice

Different groups of mice were injected with cadmium, zinc and mercury. Zinc injections had no effect on zinc tissue levels while both mercury and cadmium accumulated in various tissues. Cadmium persisted in the tissues much longer than mercury, and while the mercury concentrations began to decline as soon as dosing ceased, cadmium concentrations in kidney and intestine increased even after dosing ceased. There appeared to be an interrelationship between cadmium concentrations in spleen and intestine which warrants some further investigations. There was a linear, but discontinuous, effect of cadmium on zinc concentrations in liver, kidney and pancreas which may depend on metallothionein biochemistry. Mercury injections had no effect on zinc metabolism. It is proposed that differences in the rate of excretion of cadmium and mercury from the kidney could explain the differential accumulation of cadmium and mercury in animals.     

Feeding of a low-zinc diet lowers the tissue concentrations of alpha-tocopherol in adult rats

Previous work has shown that a low dietary intake of zinc for a short duration significantly lowers the lymphatic absorption of α-tocopherol (αTP) in adult male rats. The present study investigated whether the nutritional status of zinc is critical in maintaining the tissue levels of the vitamin. One group of rats was fed an AIN-93G diet containing 3 mg zinc/kg (low zinc, LZ) and the other was fed the same diet but containing 30 mg zinc/kg (adequate zinc, AZ). Food intakes between groups were matched by feeding two meals per day. At 6 wk, the body weights (356±8 g) of LZ rats reached 98% those (362±10 g) of AZ rats. Feeding of the LZ diet for 6 wk significantly lowered the concentrations of both αTP and zinc in the liver, kidney, heart, testis, and brain. No consistent relationships between αTP and zinc concentrations were observed in other tissues such as spleen, lung, gastrocnemius muscle, and retroperitoneal fat tissues. The concentrations of αTP in the liver, testis, brain, spleen, heart, and kidney were significantly correlated with the tissue concentrations of zinc. The LZ diet slightly but significantly increased the total lipid contents (mg/g) of liver, kidney, heart, and spleen. However, the tissue levels of phospholipid (μmol/100 mg lipid) in the heart, lung, testis, and spleen were decreased significantly in LZ rats. These findings indicate that low zinc intake results in a pronounced decrease in the animal’s αTP status under the conditions of matched food intakes, body weights, and feeding patterns. The lower tissue levels of αTP may explain in part the compromised antioxidant defense system and increased susceptibility to oxidative damage observed in zinc deficiency.     

Influence of Dietary Sodium Selenite on Tissue Selenium Levels of Growing Pigs

Twenty Norwegian Landrace pigs were divided into 5 groups and fed a basal diet consisting of a mixture of dried skim milk and whey powder together with ground barley. The diet was supplemented with 0, 0.2, 0.8, 1.2 and 2.2 μg selenium as sodium selenite and was fed for 12 weeks. The muscle selenium level was increased by a factor of about 4 and the liver selenium by a factor of about 12 when the dietary selenium supplement was increased from zero to 2.2 μg/g. There was a significant linear correlation between dietary selenium and selenium concentrations in tissues. Possible benefit for humans consuming meat from animals having received the selenium doses used in this experiment are discussed. dietary selenium; tissue levels; pigs.     

Cd, Cu, Zn, Se, and Metallothioneins in Two Amphibians, Necturus maculosus (Amphibia, Caudata) and Bufo bufo (Amphibia, Anura)

The accumulation of cadmium, its affinity for metallothioneins (MTs), and its relation to copper, zinc, and selenium were investigated in the experimental mudpuppy Necturus maculosus and the common toad Bufo bufo captured in nature. Specimens of N. maculosus were exposed to waterborne Cd (85???g/L) for up to 40?days. Exposure resulted in tissue-dependent accumulation of Cd in the order kidney, gills > intestine, liver, brain > pancreas, skin, spleen, and gonads. During the 40-day exposure, concentrations increased close to 1???g/g in kidneys and gills (0.64?C0.95 and 0.52?C0.76; n?=?4), whereas the levels stayed below 0.5 in liver (0.14?C0.29; n?=?4) and other organs. Cd exposure was accompanied by an increase of Zn and Cu in kidneys and Zn in skin, while a decrease of Cu was observed in muscles and skin. Cytosol metallothioneins (MTs) were detected as Cu,Zn?Cthioneins in liver and Zn,Cu?Cthioneins in gills and kidney, with the presence of Se in all cases. After exposure, Cd binding to MTs was clearly observed in cytosol of gills as Zn,Cu,Cd?Cthionein and in pellet extract of kidneys as Zn,Cu,Cd?Cthioneins. The results indicate low Cd storage in liver with almost undetectable Cd in liver MT fractions. In field trapped Bufo bufo (spring and autumn animals), Cd levels were followed in four organs and found to be in the order kidney > liver (0.56?C5.0???g/g >0.03?C0.72???g/g; n?=?11, spring and autumn animals), with no detectable Cd in muscle and skin. At the tissue level, high positive correlations between Cd, Cu, and Se were found in liver (all r?>?0.80; ???=?0.05, n?=?5), and between Cd and Se in kidney (r?=?0.76; n?=?5) of autumn animals, possibly connected with the storage of excess elements in biologically inert forms. In the liver of spring animals, having higher tissue level of Cd than autumn ones, part of the Cd was identified as Cu,Zn,Cd?Cthioneins with traces of Se. As both species are special in having liver Cu levels higher than Zn, the observed highly preferential Cd load in kidney seems reasonable. The relatively low Cd found in liver can be attributed to its excretion through bile and its inability to displace Cu from MTs. The associations of selenium observed with Cd and/or Cu (on the tissue and cell level) point to selenium involvement in the detoxification of excessive cadmium and copper through immobilization.     

Effects of long-term selenium yeast supplementation on selenium status studied in the rat

To investigate the selenium status during long-term dietary supply of selenium yeast, 30-day-old male rats were fed for 379 days a methionine-adequate low-selenium diet supplemented with 0.2 mg Se/kg (selenium-adequate diet) or 1.5 mg Se/kg (high-selenium diet) in the form of selenium yeast that contained 60% of the element as l-selenomethionine. Their selenium load was determined at several intervals by neutron activation analysis of the selenium concentrations in the main selenium body pools, skeletal muscle and liver. After 64 days the tissue selenium concentrations plateaued in both groups and then stayed at that level. Compared with the selenium-adequate group, elevated tissue selenium concentrations were found in the high-selenium group, but the increase by a factor of 3.5 in the muscle and by a factor of 2.3 in the liver was smaller than the 7.5-fold increase in the selenium intake. In the selenium-adequate group about 50% of the muscle selenium and 30% of the liver selenium and in the high-selenium group about 85% of the muscle selenium and 70% of the liver selenium were estimated to be present in non-selenoprotein forms. During selenium depletion the liver glutathione peroxidase activity in the high-selenium group remained unaffected for 4 weeks and then decreased more slowly than that in the selenium-adequate group. From these results it can be concluded that selenium incorporated from the selenium yeast diet into non-selenoprotein forms can serve as an endogenous selenium source to maintain selenoprotein levels in periods of insufficient selenium supply.     

Copper, zinc, iron, and manganese accumulation in cattle from Asturias (northern Spain)

Monitoring levels of mineral concentrations in animal tissues is important for assessing the effect of contamination on animal health and safety of animal origin products in human nutrition. This study evaluated the levels of certain trace elements (copper, zinc, iron, and manganese) in cattle from an industrial and mining region in the north of Spain (Asturias). Samples of 312 animals aged 9–12 mo were collected from the whole region and analyzed after acid digestion using atomic absorption spectrophotometry (AAS). The geometric mean concentrations obtained per wet weight for the liver, kidney, muscle, and blood were 34.3 mg/kg, 4.04 mg/kg, 1.65 mg/kg, and 0.651 mg/L for copper, respectively, and 38.5 mg/kg, 23.0 mg/kg, 47.0 mg/kg, and 2.44 mg/L for zinc, respectively. For iron, blood was not analyzed and results were 96.2 mg/kg, 105 mg/kg, and 56.0 mg/kg for the liver, kidney and muscle, respectively. For manganese, only the liver and kidney were analyzed, and the results were 3.11 mg/kg and 1.19 mg/kg, respectively. There was no evidence of an accumulation of toxic levels of trace metals in Asturian cattle. Females accumulated more iron in the liver (p<0.001, F _1,310=18.4) and the kidney (p<0.001, F _1,310=13.5) and more manganese in the liver (p<0.01, F _1,310=9.55) than males.     

Effects of different levels of dietary zinc on the gilthead,Sparus aurata during the growing season

Gilthead were fed three diets. Diet A was the control diet, whereas diets B and C were supplemented with 300 and 900 mg Zn/kg, respectively. Fish fed with diet C, at the end of the experiment, showed the lowest weight. Zinc concentrations presented the higher values in gills, liver, and kidney. Muscle and brain had the lower mean values and showed a tight control of zinc levels. These results reinforce the hypothesis that zinc in the CNS should be strictly controlled in order to maintain the functional role of the metal. Significant differences in tissue zinc concentrations were obtained between fish fed different amounts of zinc, the metal concentrations being higher in tissues of fish fed diet C. The tissue decrease of zinc, found at the end of the experiment, may depend on a lower feed consumption or on different zinc requirements during the cold season. These changes, even if not univocal among the three diets, may be associated with the life cycle of fish. Furthermore, copper concentrations were little affected by the different concentrations of zinc in the three diets; liver and kidney presented the highest concentrations; liver showed a significant decrease in copper content at the end of the experiment. We conclude that: zinc concentrations of the diet may affect the gilthead weights and the tissual metal content; and zinc concentrations in the diets, depending on the growth rate, may be varied depending on the season.     

Zinc,cadmium, mercury and selenium in minke whales,belugas and narwhals from West Greenland

Summary Samples of muscle, liver and kidney from 24 minke whales (Balaenoptera acutorostrata), 43 belugas (Delphinapterus leucas), and 98 narwhals (Monodon monoceros) were analyzed for zinc, cadmium, mercury, and selenium. Highly significant age accumulation of mercury was found. A lower level of significance of age accumulation of cadmium in belugas and narwhals is probably due to the fact that some of the highest cadmium concentrations are in subadults and young adults. The maximum concentrations of cadmium and mercury are very high: 1.68, 73.7, and 125 g cadmium, and 9.88, 42.8, and 4.61 g mercury per g wet weight of narwhal muscle, liver and kidney, respectively. The cadmium concentrations are correlated in the three organs, as are mercury and to a lesser extent selenium concentrations. The concentrations of mercury and selenium in liver are highly correlated.