Gold Mining in Siberia as a Source of Mercury Contamination of the Environment
365
0.028 mg/kg) is observed in the background areas, heaps of open pits. More
substantial (ten and more times) enrichment of weathering products with
mercury (0.65-0.78 mg/kg) is registered in the heaps of shafts and drifts
(Laperdina et al. 1995, 1996). Most likely, the cause is mercury degassing from
original ores and rocks raised to the surface and its accumulation in secondary
clay minerals. Besides, additional enrichment of friable sediments may be
determined by an upward gaseous mercury migration through the zones of
tectonic faults and underground driftages and pits, and also by mercury
absorption from atmospheric precipitation. Accumulation of mercury in clay
sediments, which can strongly bind metal, assists in some localization of mercury
pollution, especially in zones of permafrost. Therefore, the methods suggested to
estimate mercury emission to the environment due to gold mining, which lie at
about 100 kg mercury/t of gold mined or 1-3 t of mercury from 1 million t of
mining heaps actively migrate into the environment (Roslyakov and Kirillova
1995) we consider insufficiently substantiated. Mercury contamination of the
areas broken by mining operations is, as a rule, of local and less intensive
character than predicted by these methods.
S.2
Atmospheric Air and the Air of Technogenic Zones
The background mercury concentrations in the air of Siberia account for 1-11 ng/
m 3 and depend on the vicinity of tectonic fault zones and also on the elevated
mercury geochemical background near mercury, ore gold and some other
deposits (Laperdina et al. 1995, 1996; Malgin and Puzanov 1995).
Mercury contamination of the atmosphere in the gold-mining areas is caused
by two factors: a slight increase in mercury background levels due to processing
of gravels and rocks with elevated mercury contents, and a greater increase due
to the direct use of metallic mercury in concentration processes. The extent of air
contamination is determined by intensity and duration of mercury use,
concentration technology and equipment used (Table 1). Besides, landscape
and climatic conditions determining the intensity of geochemical and biochemical processes, causing mercury redistribution between the environmental
compartments, play an important role.
As the results of the study carried out in Zabaikalye have shown, the use of
metallic mercury in concentration processes at GEP and GDP leads to a
contrasting (25-183 ng/m3), steady and, as a rule, local air contamination of these
sites. In this case, contamination sources are gas wastes due to incomplete
mercury condensation in the process of amalgam burning, mercury degassing
from former and present tailing dumps and contaminated soil surface. Thus, near
the Baleyzoloto GDP a local halo of gaseous mercury (25-40 ng/m3) was
registered, whose localization is most likely caused by the use of an effective
system of vapour mercury condensation. Unlike the Baleyzoloto mine, in the zone
impacted by the Lyubov mine, a total increase in mercury content in the
atmosphere of both industrial (16-183 ng/m3) and residential (12-152 ng/m3) areas
was observed. Maximum value was found at the former tailings dump of the GEP.
365
0.028 mg/kg) is observed in the background areas, heaps of open pits. More
substantial (ten and more times) enrichment of weathering products with
mercury (0.65-0.78 mg/kg) is registered in the heaps of shafts and drifts
(Laperdina et al. 1995, 1996). Most likely, the cause is mercury degassing from
original ores and rocks raised to the surface and its accumulation in secondary
clay minerals. Besides, additional enrichment of friable sediments may be
determined by an upward gaseous mercury migration through the zones of
tectonic faults and underground driftages and pits, and also by mercury
absorption from atmospheric precipitation. Accumulation of mercury in clay
sediments, which can strongly bind metal, assists in some localization of mercury
pollution, especially in zones of permafrost. Therefore, the methods suggested to
estimate mercury emission to the environment due to gold mining, which lie at
about 100 kg mercury/t of gold mined or 1-3 t of mercury from 1 million t of
mining heaps actively migrate into the environment (Roslyakov and Kirillova
1995) we consider insufficiently substantiated. Mercury contamination of the
areas broken by mining operations is, as a rule, of local and less intensive
character than predicted by these methods.
S.2
Atmospheric Air and the Air of Technogenic Zones
The background mercury concentrations in the air of Siberia account for 1-11 ng/
m 3 and depend on the vicinity of tectonic fault zones and also on the elevated
mercury geochemical background near mercury, ore gold and some other
deposits (Laperdina et al. 1995, 1996; Malgin and Puzanov 1995).
Mercury contamination of the atmosphere in the gold-mining areas is caused
by two factors: a slight increase in mercury background levels due to processing
of gravels and rocks with elevated mercury contents, and a greater increase due
to the direct use of metallic mercury in concentration processes. The extent of air
contamination is determined by intensity and duration of mercury use,
concentration technology and equipment used (Table 1). Besides, landscape
and climatic conditions determining the intensity of geochemical and biochemical processes, causing mercury redistribution between the environmental
compartments, play an important role.
As the results of the study carried out in Zabaikalye have shown, the use of
metallic mercury in concentration processes at GEP and GDP leads to a
contrasting (25-183 ng/m3), steady and, as a rule, local air contamination of these
sites. In this case, contamination sources are gas wastes due to incomplete
mercury condensation in the process of amalgam burning, mercury degassing
from former and present tailing dumps and contaminated soil surface. Thus, near
the Baleyzoloto GDP a local halo of gaseous mercury (25-40 ng/m3) was
registered, whose localization is most likely caused by the use of an effective
system of vapour mercury condensation. Unlike the Baleyzoloto mine, in the zone
impacted by the Lyubov mine, a total increase in mercury content in the
atmosphere of both industrial (16-183 ng/m3) and residential (12-152 ng/m3) areas
was observed. Maximum value was found at the former tailings dump of the GEP.