Mercury in the Town of Idrija (Slovenia) After 500 Years of Mining and Smelting
267
As is evident from Fig. 5, the content in lichens increased considerably during
the exposure period at all three locations. The total Hg concentrations in lichens
transplanted to the school garden (C) are significantly higher than those of the
other environments. Probably the anomaly could be explained by the relief, since
the garden is situated in a weakly ventilated valley. It is possible that polluted air
collects here. Another source of Hg could be the Idrija Municipal Museum, which
is located in the castle in the vicinity. In the past, this castle was used for storage
of mercury. High values were also obtained in the northern mining area (A),
which is in accordance with the concentrations of total Hg in lichens sampled
in situ from this part. The Hg content in lichens from transplanted location B was
the lowest, although we expected the highest. We discovered later that the
location for transplantation was too close to the mine's ventilation shaft. The
lichens were transplanted in a forest environment, which could reduce the dry
and wet deposition.
It is known that biomonitoring using lichens excludes all momentary factors
and integrates the level of air pollution during the entire exposure period. The
results obtained confirmed the usefulness of epiphytic lichens for the routine
monitoring of air pollution with Hg. The only precondition for the utilization of
this method is the study of the natural geographical conditions in the Idrija
region, particularly of air flows and the microclimate in order to enable the
selection of suitable permanent locations for objective monitoring of air
pollution with Hg over longer periods of time with the help of epiphytic lichens.
Samples of carrot and bean were collected in the autumn of 1995 from ten
different locations in Idrija town. The sampling locations are shown on Fig. 2.
Results for total Hg in carrot and bean are presented in Table 2. Total Hg was
determined in dry samples.
The results for Hg content in carrot were in the interval between 60760 ng Hg g-I of dry sample. The highest value (760 ng Hg g-I d.s.) was
measured close to the smelting plant. High values (738 ng Hg g-I d.s.,
489 ng Hg g -I d.s.) were found at some locations where we could not explain
Table 2. Total mercury content in samples of carrot and bean (collected in autumn 1995) in ng I1g g 1
of dry sample
Sampling
Carrot
Bean
location
760 ± 38
18 ± 5
2
489 ± 69
3
151 ± 18
6.6 ± 3.5
4
738 ± 54
5
321 ± 39
6
275 ± 29
23 ± 0.4
7
396 ± 30
8
60 ± 9
2.0 ± 0.6
9
78 ± 19
6.4 ± 4.2
10
163 ± 10
4.0 ± 2.0
Results of three independent analyses are expressed as means ±95% confidence limits.
267
As is evident from Fig. 5, the content in lichens increased considerably during
the exposure period at all three locations. The total Hg concentrations in lichens
transplanted to the school garden (C) are significantly higher than those of the
other environments. Probably the anomaly could be explained by the relief, since
the garden is situated in a weakly ventilated valley. It is possible that polluted air
collects here. Another source of Hg could be the Idrija Municipal Museum, which
is located in the castle in the vicinity. In the past, this castle was used for storage
of mercury. High values were also obtained in the northern mining area (A),
which is in accordance with the concentrations of total Hg in lichens sampled
in situ from this part. The Hg content in lichens from transplanted location B was
the lowest, although we expected the highest. We discovered later that the
location for transplantation was too close to the mine's ventilation shaft. The
lichens were transplanted in a forest environment, which could reduce the dry
and wet deposition.
It is known that biomonitoring using lichens excludes all momentary factors
and integrates the level of air pollution during the entire exposure period. The
results obtained confirmed the usefulness of epiphytic lichens for the routine
monitoring of air pollution with Hg. The only precondition for the utilization of
this method is the study of the natural geographical conditions in the Idrija
region, particularly of air flows and the microclimate in order to enable the
selection of suitable permanent locations for objective monitoring of air
pollution with Hg over longer periods of time with the help of epiphytic lichens.
Samples of carrot and bean were collected in the autumn of 1995 from ten
different locations in Idrija town. The sampling locations are shown on Fig. 2.
Results for total Hg in carrot and bean are presented in Table 2. Total Hg was
determined in dry samples.
The results for Hg content in carrot were in the interval between 60760 ng Hg g-I of dry sample. The highest value (760 ng Hg g-I d.s.) was
measured close to the smelting plant. High values (738 ng Hg g-I d.s.,
489 ng Hg g -I d.s.) were found at some locations where we could not explain
Table 2. Total mercury content in samples of carrot and bean (collected in autumn 1995) in ng I1g g 1
of dry sample
Sampling
Carrot
Bean
location
760 ± 38
18 ± 5
2
489 ± 69
3
151 ± 18
6.6 ± 3.5
4
738 ± 54
5
321 ± 39
6
275 ± 29
23 ± 0.4
7
396 ± 30
8
60 ± 9
2.0 ± 0.6
9
78 ± 19
6.4 ± 4.2
10
163 ± 10
4.0 ± 2.0
Results of three independent analyses are expressed as means ±95% confidence limits.