Mercury in Terrestrial Food Webs
of the Idrija Mining Area
A. GNAMUS and M. HORVAT
To evaluate the degree of contamination with mercury and its transfer in food webs in the active
mercury mining area of Idrija, concentrations in soil profiles, plants and animal tissues were analyzed
during the period from 1990 to 1996. Total mercury (T ~Hg) and methylmercury concentrations (Me~
Hg) were determined in body tissues and fur of roe deer, Caprealus caprealus L. (n = 20), their diet
(composite plant samples of a minimum of 40 plant species), soil samples, and in tissues of their
predators such as the wolf, Canis lupus L. (n = 2), and lynx, Lynx lynx L. (n = 8). The study was
focused on the wider area of the active mercury mine in Idrija, the abandoned mercury mining area in
Podljubelj, where mining and smelting ceased in 1900, and five non~polluted locations in Slovenia.
Special attention was paid to proper sample collection, preparation and storage. The concentration
levels of total and methylmercury in roe deer tissues are correlated with those in their composite
vegetal diet, and soil samples from the polluted area. A correlation with the distance from the mercury
source was observed (T~Hg: r' < 0.62; Me~Hg: r' < 0.73). Herbivore tissues which originate from the
active mining area contain up to 350 times higher concentrations of mercury than controls. The tissues
of old animals mostly contain high Hg concentrations compared to the corresponding tissues of young
animals. However, in the Idrija area the relationship with the age of roe deer was less distinctive due to
the influence of the particular spatial exposure gradient. Total mercury concentrations in roe deer
organs descend as follows: kidney» liver> fur > pineal gland » suprarenal gland> spleen>
masseter muscle > lung> pituitary gland > eye sections > sections of the central nervous system
(CNS). A large portion ofHg (20 to 85% ) in animal tissues from the contaminated area was present as
methylmercury (except in the liver and kidney), despite the fact that inorganic Hg and elemental Hg
are the primary sources of pollution in the area. The percentage of Me~Hg in composite plant samples
and soil profiles was very small (0.14 to 2%). Our data indicate that in the terrestrial environment, roe
deer tissues can be successfully used as an indicator of mercury contamination, transfer and
accumulation processes. Furthermore, a positive correlation between mercury concentrations in
certain roe deer and human tissues from residents of the mining area suggests that roe deer tissues
may be successfully used as biomonitors and thus as an early warning of elevated mercury
concentration levels in man. However, mercury levels in selected predator species do not follow locally
enhanced Hg concentrations in their prey (roe deer) or in vegetation and soils from the polluted area.
Since the predators selected occupy larger territories and their prey contains different mercury levels,
they are considered less suitable for monitoring of locally enhanced Hg contamination.
1
Mercury in the Terrestrial Environment
Due to its high tOXICIty, persistence, biogeochemical cycling, widespread
distribution throughout the global environment, accumulation and concentra~
tion in food chains, mercury is receiving a great deal of interest. Although Hg is a
natural component of the Earth's crust, its concentrations in the biosphere have
increased significantly during the last few decades due to anthropogenic
Environmental Science
Mercury Contaminated Sites (ed. by R. Ebinghaus et al.)
© Springer-Verlag Berlin Heidelberg 1999
- - - - -
of the Idrija Mining Area
A. GNAMUS and M. HORVAT
To evaluate the degree of contamination with mercury and its transfer in food webs in the active
mercury mining area of Idrija, concentrations in soil profiles, plants and animal tissues were analyzed
during the period from 1990 to 1996. Total mercury (T ~Hg) and methylmercury concentrations (Me~
Hg) were determined in body tissues and fur of roe deer, Caprealus caprealus L. (n = 20), their diet
(composite plant samples of a minimum of 40 plant species), soil samples, and in tissues of their
predators such as the wolf, Canis lupus L. (n = 2), and lynx, Lynx lynx L. (n = 8). The study was
focused on the wider area of the active mercury mine in Idrija, the abandoned mercury mining area in
Podljubelj, where mining and smelting ceased in 1900, and five non~polluted locations in Slovenia.
Special attention was paid to proper sample collection, preparation and storage. The concentration
levels of total and methylmercury in roe deer tissues are correlated with those in their composite
vegetal diet, and soil samples from the polluted area. A correlation with the distance from the mercury
source was observed (T~Hg: r' < 0.62; Me~Hg: r' < 0.73). Herbivore tissues which originate from the
active mining area contain up to 350 times higher concentrations of mercury than controls. The tissues
of old animals mostly contain high Hg concentrations compared to the corresponding tissues of young
animals. However, in the Idrija area the relationship with the age of roe deer was less distinctive due to
the influence of the particular spatial exposure gradient. Total mercury concentrations in roe deer
organs descend as follows: kidney» liver> fur > pineal gland » suprarenal gland> spleen>
masseter muscle > lung> pituitary gland > eye sections > sections of the central nervous system
(CNS). A large portion ofHg (20 to 85% ) in animal tissues from the contaminated area was present as
methylmercury (except in the liver and kidney), despite the fact that inorganic Hg and elemental Hg
are the primary sources of pollution in the area. The percentage of Me~Hg in composite plant samples
and soil profiles was very small (0.14 to 2%). Our data indicate that in the terrestrial environment, roe
deer tissues can be successfully used as an indicator of mercury contamination, transfer and
accumulation processes. Furthermore, a positive correlation between mercury concentrations in
certain roe deer and human tissues from residents of the mining area suggests that roe deer tissues
may be successfully used as biomonitors and thus as an early warning of elevated mercury
concentration levels in man. However, mercury levels in selected predator species do not follow locally
enhanced Hg concentrations in their prey (roe deer) or in vegetation and soils from the polluted area.
Since the predators selected occupy larger territories and their prey contains different mercury levels,
they are considered less suitable for monitoring of locally enhanced Hg contamination.
1
Mercury in the Terrestrial Environment
Due to its high tOXICIty, persistence, biogeochemical cycling, widespread
distribution throughout the global environment, accumulation and concentra~
tion in food chains, mercury is receiving a great deal of interest. Although Hg is a
natural component of the Earth's crust, its concentrations in the biosphere have
increased significantly during the last few decades due to anthropogenic
Environmental Science
Mercury Contaminated Sites (ed. by R. Ebinghaus et al.)
© Springer-Verlag Berlin Heidelberg 1999
- - - - -