366
T.G. Laperdina et al.
The results of measurements at dredges have shown that the mercury vapour
content near the gravity concentration board during the amalgamation process is
relatively low, and accounts for 1800-2000 ng/m3, if amalgamation is performed
at the stage of schlich concentrate, finishing in a non-isolated ventilated place
(Laperdina et al. 1995, 1996). The mercury content in the air of dredges increases
sharply during the process of sluice amalgamation and may reach enormous
values in the isolated dredge compartments, exceeding MPC of mercury vapours
for industrial sites (5000 ng/m3) by 7.4-10 (Bodienkov 1984) or by 20-50 times
(Laperdina et al. 1995, 1996) under different technological and climatic
conditions. The level of mercury vapour content in the air of GEP and GDP
depends on the amalgamation technology applied, the volume of processed ore,
gravel and concentrates, the insulation of working places, the availability of a
powerful ventilating system with condensation of mercury vapours, and it can
vary from 50-1000 ng/m3 at GEP of the Baleyzoloto mine (T.G. Laperdina,
unpubl. data) to 1000-9000 ng/m3 (Rukavishnikov 1984). With the use of
external amalgamation at GEP and GDP the mercury vapour concentrations in
the air of working places, especially in the process of mercury application and
amalgam removal, may exceed MPC values by tens of times. Ineffective refining
of gas wastes with high vapour mercury content (230000 ± 45000 ng/m3) from
burning furnaces causes a high level of mercury contamination in the
atmospheric air (Rukavishnikov 1984).
Elevated mercury concentrations in the air (11-43 ng/m3) were found also in
areas of the gold reception centre (GRC) and were associated with mercury
pollution of the industrial buildings and the soils surrounding them. Refining of
gold-bearing concentrates and alloys at refining plants in Novosibirsk and
Krasnoyarsk is accompanied by the evolution of technologic gases with high
mercury concentrations, that leads to the environmental contamination of the
territory around the plants due to incomplete mercury vapour condensation.
Thus, gaseous mercury plays a significant part in the contaminated soils
surrounding the refining plant in Novosibirsk (Roslyakov and Kirillova 1995).
5.3
Soils
The mercury content in the soils of background areas of Siberia ranges from 0.01
to 0.33 mg/kg (d.w.) (Anoshin et al. 1995; Laperdina et al. 1995, 1996; Malgin and
Puzanov 1995), where the elevated values are registered in the soils near mercury,
ore gold and some other deposits and over a large tectonic fault zone.
As the results of the studies carried out in gold-mining areas have shown
(Table I), high mercury contamination of the soils (1.24-3.59 mg/kg) is
characteristic only for objects directly using metallic mercury (GDP, GEP,
GRC). Thus, maximum mercury concentration in the soil (3.59 mg/kg) was
registered at the Kavykta site, in the area of the former GRC, where amalgamated
gold burning had been performed previously. The mercury contamination halo is
not large here. The mercury content in the soil at approximately 100 m from the
GRC was 0.037 mg/kg. Similar local soil contamination (2.41-2.91 mg/kg),
T.G. Laperdina et al.
The results of measurements at dredges have shown that the mercury vapour
content near the gravity concentration board during the amalgamation process is
relatively low, and accounts for 1800-2000 ng/m3, if amalgamation is performed
at the stage of schlich concentrate, finishing in a non-isolated ventilated place
(Laperdina et al. 1995, 1996). The mercury content in the air of dredges increases
sharply during the process of sluice amalgamation and may reach enormous
values in the isolated dredge compartments, exceeding MPC of mercury vapours
for industrial sites (5000 ng/m3) by 7.4-10 (Bodienkov 1984) or by 20-50 times
(Laperdina et al. 1995, 1996) under different technological and climatic
conditions. The level of mercury vapour content in the air of GEP and GDP
depends on the amalgamation technology applied, the volume of processed ore,
gravel and concentrates, the insulation of working places, the availability of a
powerful ventilating system with condensation of mercury vapours, and it can
vary from 50-1000 ng/m3 at GEP of the Baleyzoloto mine (T.G. Laperdina,
unpubl. data) to 1000-9000 ng/m3 (Rukavishnikov 1984). With the use of
external amalgamation at GEP and GDP the mercury vapour concentrations in
the air of working places, especially in the process of mercury application and
amalgam removal, may exceed MPC values by tens of times. Ineffective refining
of gas wastes with high vapour mercury content (230000 ± 45000 ng/m3) from
burning furnaces causes a high level of mercury contamination in the
atmospheric air (Rukavishnikov 1984).
Elevated mercury concentrations in the air (11-43 ng/m3) were found also in
areas of the gold reception centre (GRC) and were associated with mercury
pollution of the industrial buildings and the soils surrounding them. Refining of
gold-bearing concentrates and alloys at refining plants in Novosibirsk and
Krasnoyarsk is accompanied by the evolution of technologic gases with high
mercury concentrations, that leads to the environmental contamination of the
territory around the plants due to incomplete mercury vapour condensation.
Thus, gaseous mercury plays a significant part in the contaminated soils
surrounding the refining plant in Novosibirsk (Roslyakov and Kirillova 1995).
5.3
Soils
The mercury content in the soils of background areas of Siberia ranges from 0.01
to 0.33 mg/kg (d.w.) (Anoshin et al. 1995; Laperdina et al. 1995, 1996; Malgin and
Puzanov 1995), where the elevated values are registered in the soils near mercury,
ore gold and some other deposits and over a large tectonic fault zone.
As the results of the studies carried out in gold-mining areas have shown
(Table I), high mercury contamination of the soils (1.24-3.59 mg/kg) is
characteristic only for objects directly using metallic mercury (GDP, GEP,
GRC). Thus, maximum mercury concentration in the soil (3.59 mg/kg) was
registered at the Kavykta site, in the area of the former GRC, where amalgamated
gold burning had been performed previously. The mercury contamination halo is
not large here. The mercury content in the soil at approximately 100 m from the
GRC was 0.037 mg/kg. Similar local soil contamination (2.41-2.91 mg/kg),