Atmospheric Mercury in Abandoned Mine Structures
251
elevator to reach the mine galleries (dug to a depth of 400 m), cinnabar crushing
and sorting systems, a dryer, roasting furnaces, mercury condensation towers, a
water purification plant, and all the buildings needed for bottling and storage.
About 2 million flasks of mercury (34.5 kg each) were produced during the 80
years of activity (Bargagli 1990).
Inside the mine complex two types of furnaces are found, with condensation
towers connected to two smokestacks: a modern, efficient Nesa furnace, and an
older Cermak-Spirek furnace.
Some buildings located a few tens of meters from the old roasting ovens were
converted to commercial activities such as the manufacture of leather bags,
draperies, and so forth.
The remediation work basically consisted of completely replastering the walls
and laying new flooring. One building was entirely rebuilt alongside the old ones,
apparently with the partial use of materials from the primitive roasting furnace of
the mine complex.
Figure 1 also shows the roasted cinnabar bank located a few hundred meters
from the Abbadia mining structure. Formed by the accumulation of processing
residues, the spoil bank covers an area of about 120 000 m
2 •
3
Experimental
Air mercury concentrations were determined using point monitors based on
preconcentration of the metal on gold traps and analysis, after thermal
desorption, by atomic absorption spectrophotometry. Each determination is
the result of two simultaneous samplings made by drawing in air at a rate of 1 lJ
min by means of a battery-powered diaphragm pump (Ferrara et al. 1992). The
intake time was just a few minutes for the measurements made inside
the buildings, whereas outdoor sampling times were 5-15 min. In the zone of
the mine complex these times were further reduced to avoid collecting excessive
amounts of mercury on the gold traps, which could result in problems of trap
cleanliness and loss of instrument response linearity.
The measurements inside the buildings were continued over a I-year period to
check the effects of ambient temperature variation.
Determinations of the mercury flux from the mine complex were performed
with the remote sensing technique known as LIDAR (light detection and
ranging), developed at Lund University (Sweden). This laser spectroscopy
technique, described by Edner et al. (1987), gives a three-dimensional picture of
the distribution of mercury concentrations in the atmosphere; once wind speed
and direction are known, it is possible to arrive at the amount of mercury emitted
over time from a localized or diffuse source. The mobile LIDAR is housed in a
Volvo F610 truck. Electric power for field work is supplied by a 20-kV A diesel
generator installed in a trailer towed behind the truck.
Data from horizontal or vertical scans are presented as a two-dimensional plot
with the concentration value indicated by a gray scale. The LIDAR system is
251
elevator to reach the mine galleries (dug to a depth of 400 m), cinnabar crushing
and sorting systems, a dryer, roasting furnaces, mercury condensation towers, a
water purification plant, and all the buildings needed for bottling and storage.
About 2 million flasks of mercury (34.5 kg each) were produced during the 80
years of activity (Bargagli 1990).
Inside the mine complex two types of furnaces are found, with condensation
towers connected to two smokestacks: a modern, efficient Nesa furnace, and an
older Cermak-Spirek furnace.
Some buildings located a few tens of meters from the old roasting ovens were
converted to commercial activities such as the manufacture of leather bags,
draperies, and so forth.
The remediation work basically consisted of completely replastering the walls
and laying new flooring. One building was entirely rebuilt alongside the old ones,
apparently with the partial use of materials from the primitive roasting furnace of
the mine complex.
Figure 1 also shows the roasted cinnabar bank located a few hundred meters
from the Abbadia mining structure. Formed by the accumulation of processing
residues, the spoil bank covers an area of about 120 000 m
2 •
3
Experimental
Air mercury concentrations were determined using point monitors based on
preconcentration of the metal on gold traps and analysis, after thermal
desorption, by atomic absorption spectrophotometry. Each determination is
the result of two simultaneous samplings made by drawing in air at a rate of 1 lJ
min by means of a battery-powered diaphragm pump (Ferrara et al. 1992). The
intake time was just a few minutes for the measurements made inside
the buildings, whereas outdoor sampling times were 5-15 min. In the zone of
the mine complex these times were further reduced to avoid collecting excessive
amounts of mercury on the gold traps, which could result in problems of trap
cleanliness and loss of instrument response linearity.
The measurements inside the buildings were continued over a I-year period to
check the effects of ambient temperature variation.
Determinations of the mercury flux from the mine complex were performed
with the remote sensing technique known as LIDAR (light detection and
ranging), developed at Lund University (Sweden). This laser spectroscopy
technique, described by Edner et al. (1987), gives a three-dimensional picture of
the distribution of mercury concentrations in the atmosphere; once wind speed
and direction are known, it is possible to arrive at the amount of mercury emitted
over time from a localized or diffuse source. The mobile LIDAR is housed in a
Volvo F610 truck. Electric power for field work is supplied by a 20-kV A diesel
generator installed in a trailer towed behind the truck.
Data from horizontal or vertical scans are presented as a two-dimensional plot
with the concentration value indicated by a gray scale. The LIDAR system is