Mercury in Terrestrial Food Webs of the Idrija Mining Area
305
The differences in Me-Hg concentrations between various roe deer tissues were
smaller than differences in the T-Hg values (see Fig. 4a,b). It should be noted that
in some cases only one or two samples from the particular polygon were
compared to the others, and may not be representative. Due to a small amount of
pituitary tissue sample (usually the total tissue mass was less than 150 mg) in
some cases only T -Hg was determined (see Table 6: Pituitary N*).
Me-Hg ranges in selected animal tissues from the Idrija district as a percentage
of overall Hg contents in descending order were as follows (see Table 6: Zones A
and B):
fur ("-'30-85%) > brain sections (30-80%) > masseter muscle ("-'20-70%) >
pituitary «40%) > other tissues incl. some endocrine glands, spleen, lungs, eye
sections «20%) > liver and blood ("-'1-10%) »kidney ("-'0.09-1%).
Comparison of T -Hg concentrations in roe deer tissues and their browsed diet
from the areas investigated showed some important features (see Fig. 4). Mercury
concentrations in most roe deer tissues are much lower than the values in
browsed roe deer diet of a particular sampling area. From Fig. 4 it is also evident
that Hg concentrations in various roe deer tissues differ significantly. Thus, it is
difficult to decide which animal tissue would be most appropriate for comparison
with their composite plant diet and environmental concentrations, since mercury
contents in some roe deer tissues were much smaller than in diet, and in other
tissues the ratio was reversed. The lowest animal tissue T -Hg contents were
found in brain tissues and were approx. 50 to 1000 times lower compared to their
diet browsed from the areas from which the roe deer originated. The highest
animal tissue values were found in kidneys, with approx. 1.5 to 7 times higher Hg
content than in the composite plant samples representing roe deer diet. The
exception was sampling site 1-2 where the average Hg concentration in roe deer
kidney samples was approx. 40% lower, and the brain where Hg levels were
approx. 1000 times lower than in vegetation diet. The difference probably arose
due to a disagreement between the anticipated range territories of roe deer with
identification Nos 3 and 4 (see Fig. 3b), and the sampling area 1-2 used for
collecting browsed roe deer diet. Namely, the range territories of these two roe
deer specimens probably did not coincide with the wider smelter area in the
northeastern part of Idrija from which composite plant samples representing roe
deer diet were collected. By comparing the data on Hg concentration levels in roe
deer tissues and their diet from area 1-2, it appears that roe deer in the wider
smelter area seemed to avoid the vicinity of the smelter complex, since their
tissue Hg concentrations deviate from the expected values.
4.5
Is There Any Evidence of Hg Accumulation
and Biotransformation Processes Occurring
in Roe Deer Tissues?
It is difficult to establish trends in accumulation and biotransformation of
mercury in roe deer tissues from the heavily polluted Idrija area, since a
305
The differences in Me-Hg concentrations between various roe deer tissues were
smaller than differences in the T-Hg values (see Fig. 4a,b). It should be noted that
in some cases only one or two samples from the particular polygon were
compared to the others, and may not be representative. Due to a small amount of
pituitary tissue sample (usually the total tissue mass was less than 150 mg) in
some cases only T -Hg was determined (see Table 6: Pituitary N*).
Me-Hg ranges in selected animal tissues from the Idrija district as a percentage
of overall Hg contents in descending order were as follows (see Table 6: Zones A
and B):
fur ("-'30-85%) > brain sections (30-80%) > masseter muscle ("-'20-70%) >
pituitary «40%) > other tissues incl. some endocrine glands, spleen, lungs, eye
sections «20%) > liver and blood ("-'1-10%) »kidney ("-'0.09-1%).
Comparison of T -Hg concentrations in roe deer tissues and their browsed diet
from the areas investigated showed some important features (see Fig. 4). Mercury
concentrations in most roe deer tissues are much lower than the values in
browsed roe deer diet of a particular sampling area. From Fig. 4 it is also evident
that Hg concentrations in various roe deer tissues differ significantly. Thus, it is
difficult to decide which animal tissue would be most appropriate for comparison
with their composite plant diet and environmental concentrations, since mercury
contents in some roe deer tissues were much smaller than in diet, and in other
tissues the ratio was reversed. The lowest animal tissue T -Hg contents were
found in brain tissues and were approx. 50 to 1000 times lower compared to their
diet browsed from the areas from which the roe deer originated. The highest
animal tissue values were found in kidneys, with approx. 1.5 to 7 times higher Hg
content than in the composite plant samples representing roe deer diet. The
exception was sampling site 1-2 where the average Hg concentration in roe deer
kidney samples was approx. 40% lower, and the brain where Hg levels were
approx. 1000 times lower than in vegetation diet. The difference probably arose
due to a disagreement between the anticipated range territories of roe deer with
identification Nos 3 and 4 (see Fig. 3b), and the sampling area 1-2 used for
collecting browsed roe deer diet. Namely, the range territories of these two roe
deer specimens probably did not coincide with the wider smelter area in the
northeastern part of Idrija from which composite plant samples representing roe
deer diet were collected. By comparing the data on Hg concentration levels in roe
deer tissues and their diet from area 1-2, it appears that roe deer in the wider
smelter area seemed to avoid the vicinity of the smelter complex, since their
tissue Hg concentrations deviate from the expected values.
4.5
Is There Any Evidence of Hg Accumulation
and Biotransformation Processes Occurring
in Roe Deer Tissues?
It is difficult to establish trends in accumulation and biotransformation of
mercury in roe deer tissues from the heavily polluted Idrija area, since a