307

CHAPTER

14
Abandoned Underground Gold Mines

Gold has been mined since antiquity at numerous locations throughout the world
(Kirkemo et al. 2001). The Republic of South Africa is the major commercial global
producer of gold; secondary producers include the United States, the former Soviet
Union, Canada, Australia, the People’s Republic of China, Brazil, the Philippines,
the Dominican Republic, Papua New Guinea, Ghana, Tanzania, and Ecuador (Ele-
vatorski 1981; Gasparrini 1993; Greer 1993). Underground gold mines are usually
abandoned or closed owing to poor yields or adverse economic conditions. At
present, the most environmentally responsible gold mining companies spend millions
of dollars restoring the sites of closed mines and developing technologies to minimize
the impact of active mines, although many attempts are ineffective (Fields 2001).
Data are currently scarce or incomplete on the influence of inactive underground
gold mines on the surrounding biosphere.
This chapter briefly synthesizes available information on abandoned underground
gold mines as habitats for animals and plants, as deterrents to land development, as
sources of drainage water toxic to natural resources, and as science sites. These
findings may have application to other inactive or abandoned underground mines.

14.1 HABITAT FOR BIOTA

Abandoned underground gold mines constitute unique habitats for recently iden-
tified species of microorganisms. In South Korea, for example, three new species of
fungi were isolated from the soils of gold mines:

Catellatospora



koreensis

(Lee et al.
2000a),

Saccharothrix



violacea

, and

S.



albidocapillata

(Lee et al. 2000b). Because
gold mine ores usually contain high concentrations of arsenic (Kirkemo et al. 2001),
many species of arsenic-resistant bacteria are found there. In one case, a new species
of unique anaerobic bacterium,

Chrysiogenes




arsenatis

, was isolated from waste-
water of an Australian gold mine. This organism grew with As

+3

as the electron
donor, and CO

2

or HCO

3
–

as the carbon source; growth was rapid with a doubling
time of 7.6 hours (Macy et al. 1996; Santini et al. 2000). More research seems

2898_book.fm Page 307 Monday, July 26, 2004 12:14 PM

308 PERSPECTIVES ON GOLD AND GOLD MINING

needed on physiological mechanisms of action of microorganisms in coping with
chemically hostile conditions, and their possible role in detoxification of mine
drainage waters containing arsenic and other potentially harmful substances.
Abandoned underground gold mines are also used as habitat by representative

species of local vertebrates, although much of the evidence available is tenuous. In
Arkansas, for example, between 1870 and 1890, subterranean habitat from mining
was formed during the gold rush (Saugey et al. 1988). During the period of greatest
activity, 1885 to 1888, over a dozen gold mines were in operation, some extending
over 150 meters into the surrounding mountains. The gold and silver boom ended
in 1888 with the issuance of a federal report stating that there were no precious
metals in paying quantities to be found within the area. Soon thereafter, the mines
were abandoned as proprietors moved west. The legacy has been the creation of
unusual and unique wildlife habitat for six species of salamanders and nine species
of bats, including some that were considered threatened. Salamanders found in
abandoned Arkansas mines included the Ouachita dusky salamander (

Desmognathes
brimleyorum

), the many ribbed salamander (

Eurycea



multiplicata

), and four species
of

Plethodon

; bat species identified included the eastern pipistrelle (


Pipistrellus
subflavus

), the big brown bat (

Eptesicus



fuscus

), five species of

Myotis

, the red bat
(

Lasiurus borealis

), and the silver-haired bat (

Lasionycteris



noctivagans)

. A total of
27 vertebrate species were identified in these abandoned mines (Saugey et al. 1988).

Other abandoned underground mines in Arkansas — originally constructed for
gold extraction, but eventually used commercially for lead and zinc production —
were examined between December 1991 and March 1995 (McAllister et al. 1995).
These mines were considered home to 16 species of vertebrates, including eight
species of amphibians (two species of salamanders, one species of toad, and five
species of frogs), three species of reptiles (northern fence lizard,

Sceloporus undu-
latus hyacinthinus

; southern copperhead,

Agkistrodon contortix

; and broadhead
skink,

Eumeces laticeps

), house wren (

Troglodytes



aedon

), two species of bats
(


Myotis

spp.), and two species of mice (

Peromyscus

spp.). Another four species of
mammals (coyote,

Canis latrans

; opossum,

Didelphis



virginiana

; raccoon,

Procyon
lotor

; and striped skunk,

Mephitis




mephitis

) were not collected but presumably
present because their tracks were identified in the mine entrance (McAllister et al.
1995).
Abandoned mines play an important role in the ecology of many species, serving
as permanent or temporary habitats (Heath et al. 1986), especially for bats (Taylor
1995). About 30 species of North American bats — including six endangered species —
use abandoned underground mines for rearing young and for hibernation (Taylor 1995).
In fact, nearly half of all species of bats in North America live in regions where
abandoned underground mines provide suitable temperatures for year-round use; of
more than 6000 underground mines surveyed in Arizona, California, Colorado, and
New Mexico, about half showed signs of use by bats, and 10% contained important
colonies. The closure of abandoned mines without first evaluating their importance
to bats is considered a major threat to North American bat populations (Taylor 1995).
The Millionaire mine in Beaverhead National Forest, Montana, is now home to
feral rock doves,

Columba



livia

. These pigeons nested on the ground 91 meters below

2898_book.fm Page 308 Monday, July 26, 2004 12:14 PM

ABANDONED UNDERGROUND GOLD MINES 309


the surface in near or total darkness at 6

°

C when the outside temperature was 22

°

C,
presumably to protect against predators and fluctuating temperatures (Hendricks
1997). The Millionaire mine was active between 1911 and 1921, but produced only
11 troy ounces of gold during that period, as well as 2556 troy ounces of silver and
at least 24 metric tons of lead. Nesting in abandoned underground mines is also
reported for house sparrows,

Passer



domesticus

(Hendricks 1997). Hibernating bats
(little brown bat,

Myotis



lucifugus


; northern myotis,

Myotis



septentrionalis

) fre-
quented a 150-meter adit of an abandoned underground mine near Windsor, Quebec
(Thomas 1995). Of 676 abandoned mine sites examined in northern Utah, 196 (24%)
were occupied by day-roosting Townsend’s big-eared bat,

Plecotus



townsendii

(Sher-
win et al. 2000). Similar studies conducted throughout the western United States
indicated a trend toward use of abandoned gold mines by

P

.

townsendii

, with up to

40% occupancy of known bat roosts in California, Oregon, and western central
Nevada. It was suggested that abandoned mines may be colonized by pioneering
individuals or groups of bats that have not had sufficient time to build large colonies
relative to groups in caves (Pierson 1989, Sherwin et al. 2000). The U.S. Forest
Service (USFS) considers abandoned mines unique subterranean habitat and is
actively acquiring and managing lands containing abandoned mines, including aban-
doned gold mines, as protected wildlife areas (Saugey et al. 1988). Further, the USFS
has prohibited additional mining from these abandoned mines, has designated key
areas immune from logging, and is closing the protected areas and associated above-
ground habitat during critical parts of the year to offer additional protection to species
of concern (Saugey et al. 1988).
Monitoring and research efforts now seem warranted on the suitability of aban-
doned underground gold mines and environs as habitat for macrofauna, with emphasis
on suitability for sensitive species now classified as threatened or endangered, and on
changes in species abundance and diversity due to seasonal food availability and
migratory patterns.

14.2 LAND DEVELOPMENT

Abandoned mines at shallow depth represent a serious problem in areas that are
being developed or redeveloped (Bell et al. 2000) throughout the world. In many
areas where gold deposits have been worked for more than 100 years, abandoned
mine sites are frequently unrecorded. In England, the first statutory obligation to
keep mine records dates from 1850, and it was not until 1872 that the production
and retention of mine plans became compulsory. And if old records exist, they may
be inaccurate. For example, in Johannesburg, Republic of South Africa, early under-
ground gold mines, circa 1886, now abandoned, were at shallow depths and their
presence has resulted in subsidence, imposing limitations on development. In fact,
the erection of buildings on the honey-combed land is now controlled by the Gov-
ernment Mining Engineer, who determines whether building is permissible as well

as the permissible heights of buildings in relation to the depth at which mining
occurred. Existing building regulations in Johannesburg prohibit development or

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310 PERSPECTIVES ON GOLD AND GOLD MINING

construction if mining has occurred 0 to 90 meters underground, limit building height
to a single story if mining has occurred 90 to 120 meters below ground, two stories
if 120 to 150 meters, three at 150 to 180 meters, four stories at 180 to 210 meters,
and no restrictions over 240 meters unless mining circumstances are unusual (Bell
et al. 2000).

14.3 EFFECTS ON WATER QUALITY

Abandoned underground gold mines in the Black Hills of South Dakota contrib-
uted acid, metals, metalloids, and cyanides to streams (Rahn et al. 1996). In some
areas of sulfide mineralization, local impacts were severe; however, in most areas
the impacts were negligible because most ore deposits consisted of small quartz
veins with few sulfides. The maximum daily discharge into nearby creeks from 11
abandoned underground gold mines in the Black Hills was 2.5 million kg of tailings
containing 15 kg of mercury, 140 kg of cyanide, 100 kg of zinc, and 10,000 kg of
arsenopyrites. The pH values for surface waters at these sites ranged from 1.6 to
9.7. The most acidic waters were associated with low discharges from tailings dumps
with sulfide-rich ores. Metal concentrations, with the exception of mercury and iron,
were usually low. The highest concentration recorded of iron was 498.0 mg/L, and
for mercury 5.48 mg/L (Rahn et al. 1996).
The Serengeti National Park (SNP) in northern Tanzania supports more than
2 million large mammals (Bowell et al. 1995). This area is also part of the Lake
Victoria gold fields, which produced 8810 kg of gold between 1933 and 1966.

Flooding of tailings from a gold mine impacted the Orangi River, an important year-
round source of water for wildlife in the northern part of SNP. Drainage water from
the tailings was characterized by low pH of 2.3 and elevated concentrations of sulfate
(3280 mg/L), aluminum (275 mg/L), arsenic (324 mg/L), copper (125 mg/L), iron
(622 mg/L), lead (21 mg/L), manganese (65 mg/L), and zinc (126 mg/L). Mixing
of these acidic waters with the alkaline river resulted in rapid precipitation as iron-
ocher coatings on clastic sediments. Buffering of the mine drainage waters confined
damage effects to within 1 km of mine workings. Protozoan bioassays indicated that
growth was inhibited, presumably by metals and metalloids, from all locations tested,
and that protozoan mortality was common at most sampling locations. The species
considered most at risk in the SNP are mature bull African elephants (

Loxodonta
africana

) which forage over a small part of the impacted area and have high bulk
requirements of vegetation and water (Bowell et al. 1995).
Tailings from an abandoned Au-Ag-Mo mine in Korea was the main contami-
nation source for cadmium (6 mg/kg DW tailings), copper (111 mg/kg), zinc
(2010 mg/kg), lead (3250 mg/kg), and arsenic (20,140 mg/kg) in the soil–water
system near the Songcheon mine (Lim et al. 2003). Similar findings were docu-
Elevated concentrations of arsenic, copper, cyanide, lead, mercury, and zinc in
drainage waters from abandoned gold mines in South Dakota (Rahn et al. 1996) and
Tanzania (Bowell et al. 1995) exceeded recommended concentrations for the pro-
tection of human health, plants, and animals (Eisler 2000a, 2000b, 2000c). For

2898_book.fm Page 310 Monday, July 26, 2004 12:14 PM
mented for an abandoned Au-Ag-Cu-Zn mine near Dongil, Korea (Table 14.1).

ABANDONED UNDERGROUND GOLD MINES 311


arsenic, sensitive aquatic species were damaged at water concentrations between 19
and 48

µ

g/L (Eisler 2000c). Inorganic arsenic levels recommended for human health
protection include <10

µ

g As/m

3

air, and <10

µ

g As/L in drinking water. Copper
was lethal to representative species of freshwater plants and animals at 5.0 to 9.8

µ

g
Cu/L, lethal to sensitive species of freshwater biota at 0.23 to 0.91

µ

g Cu/L, toxic

to terrestrial plants at >40

µ

g Cu/L irrigation water, and harmful to human infants
at >3.0 mg Cu/L drinking water (Eisler 2000a). Cyanide was lethal to freshwater
biota at water concentrations from 20 to 76

µ

g/L as HCN and produced adverse
effects on swimming and reproduction of fishes at 5.0 to 7.2

µ

g HCN/L. The
recommended cyanide drinking water criterion for human health protection is <10

µ

g
HCN/L (Eisler 2000b). For lead, concentrations >25

µ

g total Pb/L at acidic pH were
associated with adverse effects on fish embryo survival and growth, and for crops
it was recommended that irrigation waters not exceed 5 mg Pb/L (Eisler 2000a).
Mercury was lethal to representative aquatic organisms at 0.1 to 2.0


µ

g total Hg/L
and produced significant adverse effects to sensitive aquatic organisms at 0.03 to
0.1

µ

g total Hg/L. Recommended safe levels of total mercury in drinking water for
human health protection ranged from 0.2

µ

g/L in Brazil to 1.0 to 2.0 elsewhere
(Eisler 2000a). Zinc was lethal to sensitive species of aquatic organisms at concen-
trations from 32 to 66

µ

g Zn/L; significant adverse effects on growth and reproduction
were documented from 10 to 25

µ

g Zn/L among sensitive species of aquatic plants
and invertebrates, fishes, and amphibians (Eisler 2000a).

Table 14.1 Metals and Arsenic in Tailings,
Soils, Rice, and Groundwater
near an Abandoned Gold-

Silver-Copper-Zinc Mine,

Dongil, Korea, 2000–2001
Sample and Element Concentration

Tailings (mg/kg dry weight)
Arsenic 8720
Lead 5850
Copper 3610
Zinc 630
Cadmium 6
Farm soils (mg/kg DW) vs.
paddy soils (mg/kg DW)
Arsenic 40 vs. 31
Lead 39 vs. 27
Copper 139 vs. 31
Rice grains (

µ

g/kg DW) vs.
groundwater (

µ

g/L)

a

Arsenic 150 vs. 24

Cadmium 300 vs. ND

b

Copper 6900 vs. 7
Lead 2160 vs. 4
Zinc 38,200 vs. 15

a

Groundwater used as drinking water

b

Not detectable

Source:

Lee and Chon 2003b.

2898_book.fm Page 311 Monday, July 26, 2004 12:14 PM

312 PERSPECTIVES ON GOLD AND GOLD MINING

To protect sensitive species of fish and other wildlife from toxic components in
drainage waters from abandoned underground gold mines, it seems necessary to
reduce discharges and to detoxify the waste stream. More studies are recommended
on evaluation of detoxifying properties of metals-resistant strains of microorganisms
isolated from underground gold mines, with emphasis on mercury- and iron-resistant
strains.


14.4 SCIENCE SITE POTENTIAL

An abandoned underground gold mine in Lead, South Dakota, with a 2500-meter-
deep shaft, is being considered by physicists as a facility to shelter sensitive instru-
ments from cosmic radiation and to serve various educational and visitor needs
(Malakoff 2001). This facility has more than 1000 km of tunnels equipped with
electrical wiring and ventilation (Malakoff 2001). Abandoned underground gold
mines and other abandoned underground mines should be reexamined for research
and recreational potential.

14.5 SUMMARY

Abandoned underground gold mines provide habitat and unique environments
for certain microorganisms and local vertebrate fauna, and show potential as science
education centers. Uncontrolled mine drainage waters, however, may be toxic to
aquatic life and other wildlife that depend on clean water. Land development is
curtailed in certain heavily mined areas.
Additional studies seem warranted on the suitability of abandoned underground
gold mines as habitat for local biota, on physiological mechanisms of resistance to
metals by bacterial strains found in abandoned gold mines, and on biological detox-
ification processes of acidic gold mine drainage waters.

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