Mercury in Terrestrial Food Webs of the ldrija Mining Area
287
Idrija area, similar samples were collected from the abandoned Hg mining area in
Podljubelj and five control areas without mercury contamination (see Fig. 2). In
the present chapter, sampling procedures are described, the existence of some
biogeochemical mechanisms related to the soil-plant-animal Hg transfer under
natural conditions of terrestrial environment are suggested and analytical data
from the 6-year survey are summarized and discussed. Some aspects related to the
mercury concentrations in vegetation and wildlife as subjects in the food-chain
transfer and biotransformations of mercury in the terrestrial environment have
been presented recently (Gnamus et al. 1995; Gnamus 1996). A thorough statistical
evaluation, further discussion and final conclusions will be presented when other
environmental quality data have been collected and analyzed.
3.1.1
Soil Samples
Nine equal-sized forest sampling sites of approx. 1.5 km 2 were selected (Fig. 2: I-I
to 1-7, PI, Ctr-l). Seven of them cover the Idrija district (Fig. 3a: 1-1 to 1-7). In
order to reveal the extent of intensive anthropogenic contamination, soil samples
were collected in the immediate vicinity of the active smelter complex of the
Idrija Hg mine (Fig. 3a: I-Sm) and the abandoned smelter complex of the
Podljubelj Hg mine (PI-Sm). However, these two sampling polygons were much
smaller than the remaining sampling sites.
Four polygons (1-1 to 1-4) were near the Idrija town centre:
1-1 covers the northeastern suburbs of Idrija including the heavily contaminated
area in the vicinity of the smelter complex,
1-2 covers the northwestern and northern suburbs,
1-3 covers the southeastern suburban forest edges near the town centre in the
vicinity of the mine ventilation shafts, and
1-4 covers the southern and southwestern suburbs of Idrija.
The other three sampling polygons were selected in the wider Idrija area:
1-5 at approximately 2 km to the east-northeast,
1-6 at approx. 4 km to the northwest, and
1-7 at approx. 5 km to the southeast.
The control sampling site (Ctr-l) was located 40 km away in the forest near
Ljubljana Zoo (see Fig. 2). In addition, corresponding samples were collected in
the abandoned mercury mining area in Podljubelj (Fig. 2: PI), where mining and
smelting ceased in 1900. Although the production of the Podljubelj mercury mine
was much smaller compared to the Idrija mine, the aim of collecting the samples
in its vicinity was to reveal the extent of contamination approx. 100 years after
cessation of production. A standard soil sampling procedure (Rump and Krist
1992) was used. The depth of forest soil important for Hg distribution studies is
considered to be 0 to -20 cm (Padberg 1991; Padberg and Stoeppler 1991). Since
the forest soils in the studied areas are rather shallow, only soil profile blocks of
depth from the surface (0 cm) to approx. -10 or -15 cm were found. In order to
287
Idrija area, similar samples were collected from the abandoned Hg mining area in
Podljubelj and five control areas without mercury contamination (see Fig. 2). In
the present chapter, sampling procedures are described, the existence of some
biogeochemical mechanisms related to the soil-plant-animal Hg transfer under
natural conditions of terrestrial environment are suggested and analytical data
from the 6-year survey are summarized and discussed. Some aspects related to the
mercury concentrations in vegetation and wildlife as subjects in the food-chain
transfer and biotransformations of mercury in the terrestrial environment have
been presented recently (Gnamus et al. 1995; Gnamus 1996). A thorough statistical
evaluation, further discussion and final conclusions will be presented when other
environmental quality data have been collected and analyzed.
3.1.1
Soil Samples
Nine equal-sized forest sampling sites of approx. 1.5 km 2 were selected (Fig. 2: I-I
to 1-7, PI, Ctr-l). Seven of them cover the Idrija district (Fig. 3a: 1-1 to 1-7). In
order to reveal the extent of intensive anthropogenic contamination, soil samples
were collected in the immediate vicinity of the active smelter complex of the
Idrija Hg mine (Fig. 3a: I-Sm) and the abandoned smelter complex of the
Podljubelj Hg mine (PI-Sm). However, these two sampling polygons were much
smaller than the remaining sampling sites.
Four polygons (1-1 to 1-4) were near the Idrija town centre:
1-1 covers the northeastern suburbs of Idrija including the heavily contaminated
area in the vicinity of the smelter complex,
1-2 covers the northwestern and northern suburbs,
1-3 covers the southeastern suburban forest edges near the town centre in the
vicinity of the mine ventilation shafts, and
1-4 covers the southern and southwestern suburbs of Idrija.
The other three sampling polygons were selected in the wider Idrija area:
1-5 at approximately 2 km to the east-northeast,
1-6 at approx. 4 km to the northwest, and
1-7 at approx. 5 km to the southeast.
The control sampling site (Ctr-l) was located 40 km away in the forest near
Ljubljana Zoo (see Fig. 2). In addition, corresponding samples were collected in
the abandoned mercury mining area in Podljubelj (Fig. 2: PI), where mining and
smelting ceased in 1900. Although the production of the Podljubelj mercury mine
was much smaller compared to the Idrija mine, the aim of collecting the samples
in its vicinity was to reveal the extent of contamination approx. 100 years after
cessation of production. A standard soil sampling procedure (Rump and Krist
1992) was used. The depth of forest soil important for Hg distribution studies is
considered to be 0 to -20 cm (Padberg 1991; Padberg and Stoeppler 1991). Since
the forest soils in the studied areas are rather shallow, only soil profile blocks of
depth from the surface (0 cm) to approx. -10 or -15 cm were found. In order to