Melissa Farlow/NG Image Collectiondrainage from such mines, along with the removal of top-
soil, which was buried or washed away by erosion, prevented
most plants from naturally recolo-
nizing the land. Streams were pol-
luted with sediment and acid mine
drainage, which is produced when
rainwater seeps through iron sul-
fide minerals exposed in mine
wastes (see Chapter 12). Danger-
ous landslides occurred on hills
that were unstable due to the lack
of vegetation.
One of the most land- destructive types of surface
mining is mountaintop removal. According to Environ-
mental Media Services, mountaintop removal has leveled
between 15 and 25 percent of the mountaintops in south-
ern West Virginia. The valleys and streams between the
mountains are gone as well, filled with mine tailings and
debris. At the current rate, half the peaks in that area
will be gone by 2020. Mountaintop removal is also occur-
ring in Kentucky, Pennsylvania, Tennessee, and Virginia.
Coal burning generally contributes more of the com-
mon air pollutants than burning either oil or natural gas.
In the United States, coal-burning electric power plants
currently produce one-third of all airborne mercury emis-
sions. Some coal contains sulfur and nitrogen that, when
burned, are released into the atmosphere as sulfur ox-
ides (SO 2 and SO 3 ) and nitrogen oxides (NO, NO 2 , and
N 2 O), many of which form acids when they react with
water. These reactions result in acid deposition, which is
particularly prevalent downwind from coal-burning elec-
tric power plants (}ÕÀiʣǰÈ). Acid deposition and for-
est decline are discussed in greater detail in Chapter 9.
Because most of the energy in coal is stored in chemi-
cal bonds between carbon atoms, burning coal releases
carbon dioxide (CO 2 ) into the atmosphere. CO 2 is a po-
tent greenhouse gas that traps heat, thereby increasing
the temperature of the atmosphere. Burning coal causes a
more severe CO 2 problem than burning other fossil fuels
because coal releases more CO 2 per unit of heat energy
produced than does burning either oil or natural gas.Making Coal Cleaner
Sulfur and particulate matter emissions associated with
the combustion of coal can be reduced by using scrubbers
that clean the exhaust of power plants. As polluted air
passes through a scrubber, chemicals in the scrubber react
with the pollution and cause it to precipitate, or settle out.Surface coal mine near Cabin Creek,
7iÃÌÊ6À}>ÊUÊ}ÕÀiʣǰxÊ
In surface mining, overlying vegetation, soil, and rock are
stripped away; coal is extracted out of the ground; and rubble is
dumped into the surrounding valleys.
Coal Mining
The two basic types of coal mines are surface and subsur-
face (underground) mines. If the coal bed is within
30 m (100 ft) or so of the surface, surface mining is usually
done. In strip mining, one type of surface mining, a trench
is dug to extract the coal, which
is scraped out of the ground and
loaded into railroad cars or trucks.
Surface mining is used to obtain
approximately 60 percent of the
coal mined in the United States.
When the coal is deeper in
the ground or runs deep into the
ground from an outcrop on a hill-
side, it is mined underground.
Subsurface mining accounts for
approximately 40 percent of the
coal mined in the United States.
Surface mining has several advantages over subsurface
mining: It is usually less expensive and safer for miners,
and it generally allows more complete removal of coal
from the ground. However, surface mining disrupts the
land much more extensively than subsurface mining and
has the p otential to cause serious environmental problems.
Environmental Impacts of Coal
Coal mining, especially surface mining, has substan-
tial effects on the environment (}ÕÀiʣǰx). Prior to
the 1977 Surface Mining Control and Reclamation Act
(SMCRA), abandoned surface coal mines were usually
left as large open pits or trenches. Acid and toxic mineral
surface mining The
extraction of mineral
and energy resources
near Earth’s surface
by first removing
the soil, subsoil, and
overlying rock strata.
subsurface mining
The extraction of
mineral and energy
resources from deep
underground deposits.acid mine
drainage Pollution
caused when sulfuric
acid and dangerous
dissolved materials,
such as lead, arsenic,
and cadmium, wash
from coal and metal
mines into nearby
lakes and streams.