354
P.J. Lechler
range of 0.1 to 300 ~lg/g. The Hg released to the environment was mainly in the
elemental form, the form which still dominates in the sediments today. Where
these materials are transported from near-surface horizons largely in equilibrium
with atmospheric oxygen to more anoxic, reducing environments in reservoirs or
deep soil horizons, a significant proportion of HgS is formed. This occurs where
total, labile sulfur exceeds 0.05 to 0.1 wt%.
These observations come from the analysis of the speciation of Hg in these
soils and sediments by the methodology described above. As pointed out by
Wall schlager (1996), quality assurance of speciation methodologies through the
fortification of natural samples with discrete Hg species is impractical at best.
The concurrence of stability fields of different Hg species on Eh-pH diagrams
with the results of the chemical speciation analysis lends support to the validity
of this methodology. Moreover, the geochemically reasonable shifts in observed
speciation of Hg in these soils and sediments from one type of environment to
another further supports the conclusions of the speciation methodology.
Mercury contamination from historic amalgamation milling of precious metal
ores which contain associated sulfide minerals may be less bioavailable than Hg
from ores essentially devoid of sulfides. Because of the relatively high solubility
of most sulfide minerals in surface waters, most gold placer deposits (deposits
found in unconsolidated alluvium) contain few sulfide minerals. Thus, Hg
pollution resulting from the amalgamation milling of placer gold may generally
be more harmful in terms of higher solubility, mobility, and bioavailability of the
released Hg than from high-sulfur lode mining sites (mineralization formed in
hard rock deposits, with the precious metals often being accompanied by sulfide
minerals such as pyrite) because the low-S placer environments are not
conducive to the fixation of Hg as relatively insoluble HgS.
References
Ansari MB (1989) Mines and mills of the Comstock region, western Nevada. Camp Nevada Mono 8,
Univ. Nevada Press, Reno, pp 87-94
Basham EL, Lechler PI. Miller JR (1996) Database of sites of historic mercury amalgamation milling of
gold and silver ores in the United States. Abstracts Mercury Global Pollutant, 4-8, Aug 1996,
Hamburg, Germany, p 141
Biester H (1994) Moglichkeiten der Anwendung eines temperaturgesteuerten Pyrolyseverfahrens zur
Bestimmung der Bindungsform des Quecksilbers in Boden und Sedimenten. Heidelb Geowiss Abh
75, PhD Diss, Ruprecht-Karls-Univ, Heidelberg, 156 pp
Bonzongo JC, Heim KJ, Warwick JJ, Lyons WB (1996) Mercury levels in surface waters of the Carson
River-Lahontan Reservoir system, Nevada: influence of historic mining activities. Environ Pollut 92
(2):193-201
Brookins DG (1988) Eh-pH diagrams for geochemistry. Springer, Berlin Heidelberg New York, 176 pp
Di Giulio RT, Ryan EA (1987) Mercury in soils, sediments, and clams from a North Carolina peatiand.
Water Air Soil Pollut 33:205-219
Eganhouse RP, Young DR, Johnson IN (1978) Geochemistry of mercury in Palos Verdes sediments.
Environ Sci Technol12 (10):1151-1157
Fisher V, Holmes OL (1968) Gold rushes and mining camps of the early American West. Caxton
Printers, Boise, 466 pp
Henderson P (1982) Inorganic geochemistry. Pergamon, New York, 276 pp
P.J. Lechler
range of 0.1 to 300 ~lg/g. The Hg released to the environment was mainly in the
elemental form, the form which still dominates in the sediments today. Where
these materials are transported from near-surface horizons largely in equilibrium
with atmospheric oxygen to more anoxic, reducing environments in reservoirs or
deep soil horizons, a significant proportion of HgS is formed. This occurs where
total, labile sulfur exceeds 0.05 to 0.1 wt%.
These observations come from the analysis of the speciation of Hg in these
soils and sediments by the methodology described above. As pointed out by
Wall schlager (1996), quality assurance of speciation methodologies through the
fortification of natural samples with discrete Hg species is impractical at best.
The concurrence of stability fields of different Hg species on Eh-pH diagrams
with the results of the chemical speciation analysis lends support to the validity
of this methodology. Moreover, the geochemically reasonable shifts in observed
speciation of Hg in these soils and sediments from one type of environment to
another further supports the conclusions of the speciation methodology.
Mercury contamination from historic amalgamation milling of precious metal
ores which contain associated sulfide minerals may be less bioavailable than Hg
from ores essentially devoid of sulfides. Because of the relatively high solubility
of most sulfide minerals in surface waters, most gold placer deposits (deposits
found in unconsolidated alluvium) contain few sulfide minerals. Thus, Hg
pollution resulting from the amalgamation milling of placer gold may generally
be more harmful in terms of higher solubility, mobility, and bioavailability of the
released Hg than from high-sulfur lode mining sites (mineralization formed in
hard rock deposits, with the precious metals often being accompanied by sulfide
minerals such as pyrite) because the low-S placer environments are not
conducive to the fixation of Hg as relatively insoluble HgS.
References
Ansari MB (1989) Mines and mills of the Comstock region, western Nevada. Camp Nevada Mono 8,
Univ. Nevada Press, Reno, pp 87-94
Basham EL, Lechler PI. Miller JR (1996) Database of sites of historic mercury amalgamation milling of
gold and silver ores in the United States. Abstracts Mercury Global Pollutant, 4-8, Aug 1996,
Hamburg, Germany, p 141
Biester H (1994) Moglichkeiten der Anwendung eines temperaturgesteuerten Pyrolyseverfahrens zur
Bestimmung der Bindungsform des Quecksilbers in Boden und Sedimenten. Heidelb Geowiss Abh
75, PhD Diss, Ruprecht-Karls-Univ, Heidelberg, 156 pp
Bonzongo JC, Heim KJ, Warwick JJ, Lyons WB (1996) Mercury levels in surface waters of the Carson
River-Lahontan Reservoir system, Nevada: influence of historic mining activities. Environ Pollut 92
(2):193-201
Brookins DG (1988) Eh-pH diagrams for geochemistry. Springer, Berlin Heidelberg New York, 176 pp
Di Giulio RT, Ryan EA (1987) Mercury in soils, sediments, and clams from a North Carolina peatiand.
Water Air Soil Pollut 33:205-219
Eganhouse RP, Young DR, Johnson IN (1978) Geochemistry of mercury in Palos Verdes sediments.
Environ Sci Technol12 (10):1151-1157
Fisher V, Holmes OL (1968) Gold rushes and mining camps of the early American West. Caxton
Printers, Boise, 466 pp
Henderson P (1982) Inorganic geochemistry. Pergamon, New York, 276 pp