R. Dietz et al., ZINC, CADMIUM, MERCURY AND SELENIUM IN POLAR BEARS (URSUS-MARITIMUS) FROM CENTRAL EAST GREENLAND, Polar biology, 15(3), 1995, pp. 175-185
Muscle, liver, and kidney tissues from 38 polar bears (Ursus maritimus
) caught in the Scoresby Sound area, Central East Greenland, were anal
ysed for zinc, cadmium, mercury and selenium. In general, cadmium conc
entrations were low in muscle, liver and kidney tissue, with geometric
means (g.m.) of 0.022 (range: < 0.015-0.085), 0.841 (range: 0.092-3.2
9) and 13.1 (range: 1.04-115) mu 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 mu g Hg/g ww), whereas concentrations in
liver and kidney tissue were relatively high (liver: g.m. 7.87; range
: 1.35-24.8 mu g Hg/g ww, and kidney: g.m. 15.2; range: 1.59-66.6 mu g
Hg/g ww). Mercury and cadmium were positively correlated with age in
liver and kidney. Zinc was positively correlated with age in kidney, a
nd 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 c
admium levels than ringed seals from the same area. Mercury levels wer
e likewise significantly lower in the muscle tissue of polar bears tha
n in ringed seals, whereas levels in the liver and kidney were signifi
cantly higher. The previous geographic trend for cadmium and mercury f
ound 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 h
ad higher mercury and cadmium contents in livers and kidneys than pola
r bears from Svalbard. The mercury levels in muscle and liver tissue f
rom polar bears from East Greenland were twice as high as found in bea
rs 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 mo
lar ratios close to unity with the highest concentrations occurring in
kidney tissue, while the levels of zinc exceeded cadmium in muscle an
d liver tissue by up to several decades. Mercury and selenium showed m
olar ratios close to unity in liver and kidneys.