296
A. Gnamus and M. Horvat
the concentration levels, behaviour and chemical species of mercury in naturally
exposed animals. As they are vigorous feeders, the uptake of the element from
food is of importance and high accumulation of contaminants in their tissues is
found (Borg et al. 1969; Hoellerer and Coduro 1977; Krynski et al. 1982; Lutz 1985;
Fr0slie et al. 1986; Babinska-Werka and Czarnowska 1988; Holm 1993). Reviewing
the data obtainable for terrestrial wild mammals (Wren 1986), relatively high
concentrations of mercury were established in roe deer tissues in various studies,
despite the position of roe deer at the bottom of the terrestrial food webs as
herbivores. Additionally, it is possible to study certain processes in vivo, such as
possible biomethylation in the gastrointestinal tract. Another very important
feature is that these animals have certain characteristics close to those of humans
- both are placental mammals with a similar life range. Roe deer often live very
close to human residences, especially in small towns, closely surrounded by
woodlands and grasslands, such as Idrija. Our results from the wider Idrija
region and their comparison with former data from the same areas (Byrne et al.
1971; Kosta et al. 1972, 1974a) confirm the feature that long-term anthropogenic
intervention in Idrija mostly prevents discrimination between the natural and
anthropogenic contributions of Hg in the surrounding environment. As concerns
animal tissue Hg concentrations, the predominant role of anthropogenic
pollution is suggested, although no pre-anthropogenic environmental data from
the area are of course available for comparison. In this respect, comparison with
the data measured in corresponding samples from the Podljubelj area (see Fig. 2),
where Hg mining was abandoned approx. a century ago, is instructive.
4.3
Do Biota Reflect a Mercury Exposure Gradient Related
to the Distance from the Source of Contamination?
A summary ofT-Hg concentrations in composite soil profiles from the polygons
I-Sm and 1-1 to 1-7 in the Idrija area is presented graphically in Fig. 3a. The
original results on soil T -Hg content in the Idrija area were first clustered in the
four concentration ranges, following airborne contamination from the smelter
chimney and geological Hg deposits (see Fig. 3a). However, biota mercury
concentrations in the Idrija area do not follow such distinctive geological spatial
contamination pattern. Especially in roe deer tissues from the polygons 1-1 to 1-4
in the wider smelter/mine area, i.e. from forestal town suburbs of Idrija, mercury
concentration differences as concerns the distance from the source of pollution
were not so distinctive. Therefore, in order to attain a better insight into the
complex features of mercury contamination in the affected area, the results
obtained from individual animals, as well as from composite plant and soil
samples were grouped into three differentiated contamination zones. Thus,
related to the distance from the smelter as the primary source of mercury
contamination in the active mining area, three contamination clusters were
formed (see Fig. 3b).
As shown in Fig. 3a,b, the confined small area in the immediate vicinity of the
smelter with highest Hg values was identified as the smelter zone (identification
A. Gnamus and M. Horvat
the concentration levels, behaviour and chemical species of mercury in naturally
exposed animals. As they are vigorous feeders, the uptake of the element from
food is of importance and high accumulation of contaminants in their tissues is
found (Borg et al. 1969; Hoellerer and Coduro 1977; Krynski et al. 1982; Lutz 1985;
Fr0slie et al. 1986; Babinska-Werka and Czarnowska 1988; Holm 1993). Reviewing
the data obtainable for terrestrial wild mammals (Wren 1986), relatively high
concentrations of mercury were established in roe deer tissues in various studies,
despite the position of roe deer at the bottom of the terrestrial food webs as
herbivores. Additionally, it is possible to study certain processes in vivo, such as
possible biomethylation in the gastrointestinal tract. Another very important
feature is that these animals have certain characteristics close to those of humans
- both are placental mammals with a similar life range. Roe deer often live very
close to human residences, especially in small towns, closely surrounded by
woodlands and grasslands, such as Idrija. Our results from the wider Idrija
region and their comparison with former data from the same areas (Byrne et al.
1971; Kosta et al. 1972, 1974a) confirm the feature that long-term anthropogenic
intervention in Idrija mostly prevents discrimination between the natural and
anthropogenic contributions of Hg in the surrounding environment. As concerns
animal tissue Hg concentrations, the predominant role of anthropogenic
pollution is suggested, although no pre-anthropogenic environmental data from
the area are of course available for comparison. In this respect, comparison with
the data measured in corresponding samples from the Podljubelj area (see Fig. 2),
where Hg mining was abandoned approx. a century ago, is instructive.
4.3
Do Biota Reflect a Mercury Exposure Gradient Related
to the Distance from the Source of Contamination?
A summary ofT-Hg concentrations in composite soil profiles from the polygons
I-Sm and 1-1 to 1-7 in the Idrija area is presented graphically in Fig. 3a. The
original results on soil T -Hg content in the Idrija area were first clustered in the
four concentration ranges, following airborne contamination from the smelter
chimney and geological Hg deposits (see Fig. 3a). However, biota mercury
concentrations in the Idrija area do not follow such distinctive geological spatial
contamination pattern. Especially in roe deer tissues from the polygons 1-1 to 1-4
in the wider smelter/mine area, i.e. from forestal town suburbs of Idrija, mercury
concentration differences as concerns the distance from the source of pollution
were not so distinctive. Therefore, in order to attain a better insight into the
complex features of mercury contamination in the affected area, the results
obtained from individual animals, as well as from composite plant and soil
samples were grouped into three differentiated contamination zones. Thus,
related to the distance from the smelter as the primary source of mercury
contamination in the active mining area, three contamination clusters were
formed (see Fig. 3b).
As shown in Fig. 3a,b, the confined small area in the immediate vicinity of the
smelter with highest Hg values was identified as the smelter zone (identification