Transcript Subsurface mining

MILLER/SPOOLMAN
LIVING IN THE ENVIRONMENT
17TH
Chapter 14
Geology and Nonrenewable
Mineral Resources
Plate Tectonics
• Tectonic plates have rearranged the earth’s
continents and ocean basins over millions of years
like pieces of a gigantic jigsaw puzzle. (sea floor
spreading, etc.)
• The plates have three types of boundaries –
Convergent (together), divergent (apart) and
transform (sliding past).
• Natural hazards such as earthquakes and volcanoes
are likely to be found at plate boundaries. (ring of
fire around the Pacific)
Theory of Plate Tectonics
A
Divergent
B
Convergent
•plates are
moving apart
•plates are
coming together
•new crust is
created
•Magma is
coming to the
surface
•crust is
returning to the
mantle
C
Transform
•plates are
slipping past
each other
•crust is not
created or
destroyed
Types of Rocks
• Rocks are large, natural, continuous parts of the
earth’s crust.
• There are three major types of rocks:
1. Igneous – formed by crystallization of magma
2. Sedimentary – formed by weathering, erosion,
deposition, cementation
3. Metamorphic – formed from the other 2 adding
high heat and pressure
• Rocks are affected by changes of physical and
chemical conditions that change them over time
from one type to another through the rock cycle.
The Rock Cycle
• The rock cycle
is the continuous
changing and
remaking of rocks.
Resources
• Mineral resources include all naturally occurring
materials that are used for human purposes. (Ex.
metals and fossil fuels).
• Resources are distributed unevenly around the
world (e.g., diamonds in Angola or oil in Saudi
Arabia).
• This unequal distribution can lead to conflicts and
has implications for national security and
international relations.
Mineral resources
• All mineral resources are finite but the
lifetime of materials varies with the rate of
use and the size of the resource.
• Recycling of mineral resources leads to a
longer depletion time compared to those that
cannot be reused or recycled.
Mineral resources
• Scientists are developing new types of
materials as substitutes for many metals.
• Mineral conservation and more sustainable
manufacturing processes are helping to
decrease our use and waste of such resources.
• Recent, dramatic increases in the cost of
minerals are driving aggressive recycling of
many resources and particularly metals (e.g.,
copper).
Mining
• Mineral resource extraction methods include
surface and subsurface mining.
• Resource extraction technologies are
constantly changing but always create some
environmental disturbance.
• In some cases, the environmental impacts of
mineral extraction can be severe.
There Are Several Ways to Remove
Mineral Deposits (1)
• Surface mining
• Shallow deposits removed
• Overburden removed first
• Spoils: waste material
• Subsurface mining
• Deep deposits removed
There Are Several Ways to Remove
Mineral Deposits (2)
• Type of surface mining used depends on
• Resource
• Local topography
• Types of surface mining
• Open-pit mining
• Strip mining
• Contour strip mining
• Mountaintop removal
Open-Pit Mine in Arizona
Fig. 14-13, p. 357
Area Strip Mining in Wyoming
Fig. 14-14, p. 357
Mining Has Harmful Environmental Effects
(1)
• Scarring and disruption of the land surface
• Mountain top removal for coal
• Loss of rivers and streams
• Air pollution
• Groundwater disruption
• Biodiversity decreased
Mining Has Harmful Environmental Effects
(2)
• Subsurface mining
• Subsidence
• Acid mine drainage
• Major pollution of water and air
• Effect on aquatic life
• Large amounts of solid waste
Spoils Banks in Germany from Area Strip
Mining
Fig. 14-16, p. 358
Mountaintop Coal Mining in West Virginia
Fig. 14-17, p. 359
Ecological Restoration of a Mining Site in
Indonesia
Fig. 14-18, p. 360
Chapter 12
• Food production has leveled off in the last 25
years, but still produces enough food to meet
the basic nutritional needs of people.
• The food cannot be evenly distributed
throughout the world, leading to malnutrition
and starvation.
• Modern agricultural techniques create
significant environmental harm, but is also
responsible for large increases in agricultural
productivity.
• Three systems produce foods for human
consumption.
• Croplands produce mostly grains, about 77% of
the world’s food.
• Rangelands provide meat, about 16% of the
world’s food.
• Ocean fisheries supply about 7% of the world’s
food.
• Soils are degraded and eroded by water, wind,
and people.
• Soil erosion is primarily caused by flowing
water and wind.
• Human activities, such as farming, logging,
construction, off-road vehicles, etc., also
disturb soil and hasten erosion.
• Crops can be planted today with less soil
disturbance through conservation-tillage,
tillage, contour farming, and strip farming.
• Farmers may also use cover crops to help hold
the soil in place.
• Windbreaks are used to prevent soil from
being blown away.
• Conservation and fertilization can be used to
restore soil fertility, but fertilizing with
commercial pesticides brings its own set of
problems.
• The green revolution uses particular methods
to raise crops.
• Monocultures are developed and planted,
bred selectively, or genetically engineered to
produce high yields of particular crops.
• Large amounts of fertilizer, pesticides, and
water are added to the crops. Yields of crops
are increased through multiple cropping
throughout the year.
• The second green revolution since 1967 involved
using fast-growing dwarf varieties of wheat and rice
in countries with tropical and subtropical climates.
• Traditional agriculture:
• uses interplanting, several crops grown together on
the same area of land;
• uses agroforestry, which grows crops and trees
together;
• applies polyculture, where various plants are planted
together but mature at different times.
Pesticides
• Pesticides - chemicals that kill or control populations
of organisms we consider undesirable. Types include
insecticides, herbicides, fungicides, and rodenticides.
• Advantages include:
•
•
•
•
increase food supplies,
lower food cost,
increase profit for farmers,
work fast.
Pesticides
• Disadvantages include:
• acceleration of pest resistance to pesticides and
pesticides dispersing widely,
• harming wildlife,
• threatening human lives.
• The Federal Insecticide, Fungicide, and Rodenticide
Act established in 1947 and amended in 1972, as
well as the 1996 Food Quality Protection Act
regulate pesticide use in the United States.
Pesticides
• Alternatives:
• integrated pest management, cultivation practices,
food irradiation, genetic engineering, biological
control, hot water, and pheromones.
• These all reduce pesticide use but may prove timely,
costly, and not as reliable.
Earth’s Forests
• Conservation biology - attempting to slow down loss
of earth’s biodiversity through the use of rapid
response strategies.
• Why are forests important?
1. provide important ecological and economic services,
2. are storehouses of biodiversity,
3. affect weather and climate throughout the world.
• Forests in the United States should be managed
sustainably. Selective cutting is the most reasonable
way to harvest trees.
Deforestation
• Deforestation is one of the most serious ecological
problems of this century. Forests have been reduced by
20–50% . Deforestation has many harmful environmental
effects:
•
•
•
•
•
reduces ecological services of forests,
releases large amounts of carbon dioxide in the air,
produces a drier and hotter climate;
reduces the control of water movements,
increases soil erosion.
• Tropical deforestation is one of the biggest threats to
world economic health and climate. To help sustain
tropical forests, nations of the world must unite to
discourage deforestation and degradation.
What are the major threats to forest
ecosystems?
• Conservation attempts to slow down the rate at
which we are destroying and degrading the earth’s
biodiversity through the use of rapid response
strategies.
• Hot spots, the most endangered and species-rich
ecosystems, receive emergency action to slow
down/stop the loss of biodiversity in these systems.
What are the major threats to forest
ecosystems?
•
•
•
Forests provide important ecological and economic
services, are storehouses of biodiversity, and affect
weather and climate throughout the world.
Forest resource management varies according to
the type of forests. In diverse forests, the age and
size of trees are preserved to foster natural
regeneration.
Government policies will primarily determine the
future of forests, including old-growth forests.
How should we manage and sustain
forests?
• Forests in the United States should be managed so
as to retain as much of the forests as possible.
• Clear-cutting and seed-tree cutting methods of
harvesting are scourges on the forest; selective
cutting is the most reasonable way to harvest trees.
• Deforestation is one of the most serious ecological
problems of this century. The earth’s forests have
been reduced by 20–50% and the destruction
continues to this day.
How should we manage and sustain
forests?
• Deforestation has many harmful environmental
effects:
•
•
•
•
•
reduces ecological services of forests
releases large amounts of carbon dioxide in the air
produces a drier and hotter climate
reduces the control of water movements
increases soil erosion.
• Tropical deforestation is one of the biggest threats to
world economic health and climate - nations of the
world must unite to discourage deforestation and
degradation.
How should we manage and sustain parks
and nature reserves?
• Problems affecting parks:
• little/no protection from their governments
• being too small to sustain large animal species
• being too popular and, therefore, overused by people.
• Some methods for managing parks include:
• limiting the number of visitors,
• raising entry fees to provide funds for maintenance and
management,
• managing parks in reference to nearby federal lands,
• discouraging development around already established parks,
• providing more volunteers and better paid employees to
maintain the parks.
How should we manage and sustain parks
and nature reserves?
• Only about 7% of the world’s terrestrial areas are
protected from potentially harmful human activities;
these areas need to be expanded throughout the
world.
• In order to adequately conserve biodiversity, at least
20% of the earth’s land area should be protected in a
global network of reserves.