Download Understanding Our Environment

Principles of
Environmental Science
Inquiry and Applications
Third Edition
Cunningham • Cunningham
Chapter 11
Lecture Outlines*
*See PowerPoint Image Slides for all figures and tables
pre-inserted into PowerPoint without notes.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
1
Outline:
•
•
•
•
•
•
Tectonic Processes
Minerals and Rocks
Economic Geology and Mineralogy
 Strategic Resources
Environmental Effects of Resource Extraction
 Mining
- Restoration
Conserving Geologic Resources
Geologic Hazards
2
A DYNAMIC PLANET
•
A Layered Sphere
 Core - Interior composed of dense,
intensely hot metal. Generates magnetic
field enveloping the earth.
 Mantle - Hot, pliable layer surrounding the
core. Less dense than core.
 Crust - Cool, lightweight, brittle outermost
layer. Floats on top of mantle.
3
A Layered Sphere
4
Tectonic Processes
5
Tectonic Processes
•
Upper layer of mantle contains convection
currents that break overlaying crust into a
mosaic of tectonic plates.
 Slide slowly across earth’s surface.
- Ocean basins form where continents
crack and pull apart.
- Magma forced up through cracks in
oceanic crust form mid-oceanic ridges.
6
Tectonic Processes
7
Tectonic Processes Cont’d
•
Earthquakes are caused by grinding and
jerking as plates slide past each other.
 Mountain ranges pushed up at the margins
of colliding plates.
- When an oceanic plate collides with a
continental landmass, the continental
plate will ride up over the seafloor and
the oceanic plate will subduct down into
the mantle.
 Deep ocean trenches mark
subduction zones.
8
Pangea
•
Geologists suggest
that several times in
earth’s history most,
or all, of the
continents gathered
to form a single
super-continent,
Pangea, surrounded
by a single global
ocean.
9
Extinctions
Almost all professional football players are still alive. 4% of all human beings that have
ever lived are still alive. What percent of all species that have ever lived are still alive?
0.1%; thus 99.9 % are extinct. Looking ahead, things look numerically bad for humans:
chances are that we will go extinct.
What is extinction? => Termination of a lineage. What are the units of extinction? Genus
Family? Do we determine extinction of a genus by the last remaining species that makes
up that genus? What happens if 99% of the genus goes extinct and one "hanger-on" last
millions of more years? No solution to the problem, these are the sorts of biases that are
inherent in tabulating higher-level phenomena.
What can we say about adaptation and extinction rates? Is extinction due to: Bad luck or
Bad genes?
As to the causes of extinction here are some questions to "ask" the fossil record:
intrinsic/extrinsic: was extinction due to a characteristic of the organism (intrinsic) or of
the physical environment (extrinsic)? Was extinction due to competition (mutituberculates
and rodents) or was it due to major events like sea level changes or asteroid impact? One
"asks" the fossil record by looking at the data.
10
•
Dinosaurs, along with an
estimated 70 percent of all life
on Earth, are believed to have
gone extinct 65 million years
ago as a result of a series of
dramatic temperature changes.
What killed the dinosaurs?
Geologists and paleontologists
often entertain the idea of a
large asteroid or comet
impacting the Earth as the
culprit.
•
Besides the firestorms, tidal
waves, earthquakes, and
hurricane winds such an impact
would generate, the debris
thrown into the atmosphere
would have a serious global
environmental impact -creating extended periods of
darkness, low temperatures, and
acid rains.
This picture shows the "meteor crater" in arizona which
is 180 meters deep and 1.2 km in diameter with an
eroded rim standing 30-60 m high. this crater is believed
to have been made 50,000 years ago by a 46-meter wide
meteorite composed of nickel-iron rock.
11
Extinction Timelines
12
GEOLOGIC HAZARDS
•
Earthquakes - Sudden movements of the
earth’s crust that occur along faults where
one rock mass slides past another.
 Gradual movement - creep.
- When friction prevents creep, stress
builds up until eventually released with a
sudden jerk.
 Frequently occur along subduction
zones.
 Tsunami - Seismic sea swells.
13
14
15
16
17
18
Country where
deaths occurred
Deaths
Injured
Missing
Displaced
1
Confirmed
Estimated
130,736
167,736
—
35,322
35,322
21,411
India
12,405
18,045
—
5,640
647,599
Thailand
5,395
8,212
8,457
2,817
7,000
Somalia
78
289
—
—
5,000
Myanmar (Burma)
61
400-600
45
200
3,200
Maldives
82
108
—
26
15,000+
Malaysia
68– 69
75
299
6
—
Tanzania
10
13
—
—
—
Seychelles
3
3
57
—
200
Bangladesh
2
2
—
—
—
South Africa
2
2
—
—
—
Yemen
2
2
—
—
—
Kenya
1
1
2
—
—
Madagascar
—
—
—
—
1,000+
Total
~184,168
~230,210
~125,000
~45,752
~1.69 million
Indonesia
Sri Lanka
2
3
4
37,063
500,000+
516,150
edit
19
Volcanoes
•
Volcanoes and undersea magma vents are
the sources of most of the earth’s crust.
 Many of world’s fertile soils are weathered
volcanic material.
- Human / Environmental Dangers
 Volcanic Ash
 Mudslides
 Sulfur Emissions
20
21
22
Volcanic ash from Pinatubo Volcano in the Philippines partly buries
this village. The great 1991 eruption of Pinatubo was the second
largest in the world during the 20th Century.
23
Floods
•
•
•
Excess water that overflows stream banks and covers
adjacent land.
 Biggest economic loss is usually contamination, not
direct property losses.
- Carpet, furniture, drywall, etc.
 Many human activities increase both severity and
frequency of floods.
- Soil compaction
Floodplains often help mitigate flooding.
 Usually flat, fertile, and easily farmed.
- Flood control structures have separated floodplains
from rivers.
Flood Control
 Governmental air of flooding victims seems to have
encouraged building on floodplains.
24
Floods Cont’d
•
•
Floodplains often help mitigate flooding.
 Usually flat, fertile, and easily farmed.
- Flood control structures have separated
floodplains from rivers.
Flood Control
 Governmental air of flooding victims seems
to have encouraged building on
floodplains.
25
Erosion
•
Landslides



A general term for rapid down-slope movement of soil or
rock.
- Many human activities such as forest clearing and
building homes on steep, unstable slopes increase
both frequency and damage done by landslides.
Barrier Islands
Stand between mainland and open sea.
Contain many of world’s sandy beaches.
- Many people place a high value on the view and
beach access, and thus these are highly prized areas
to build structures.
 Assume modern technology will provide protection.
26
ECONOMIC GEOLOGY AND MINERALOGY
•
Metals
 Metals consumed in greatest quantity by
world industry (metric tons annually):
- Iron
(740 million)
- Aluminum
(40 million)
- Manganese
(22.4 million)
- Copper and Chromium (8 million ea)
- Nickel
(0.7 million)
27
Non-Metal Mineral Resources
•
•
•
•
Sand and Gravel
 Brick and concrete construction, paving,
sandblasting and glass production.
Limestone
 Concrete and building stone
Evaporites
 Gypsum and Potash
Sulfur
 Sulfuric Acid
28
Strategic Metals and Minerals
•
Durable, highly valuable, and easily portable,
gemstones and precious metals have been a
way to store and transport wealth.
 These valuable materials have bankrolled
despots, criminal gangs, and terrorism in
many countries.
 Much of the illegal trade ends up in the
$100 billion per year global jewelry trade,
two-thirds of which sells in the U.S.
29
Strategic Metals and Minerals
30
ENVIRONMENTAL EFFECTS OF
RESOURCE EXTRACTION
•
Mining
 Placer Mining - Hydraulically washing out
metals deposited in streambed gravel.
- Destroys streambeds and fills water with
suspended solids.
 Strip-Mining or Open-Pit Mining
- Large scars on land surface.
- Tailings
 Toxic runoff
31
Strip mines
32
Mining
•
Underground Mining
 Very Dangerous
- Gas
- Inhaling Particulate Matter
- Tunnel Collapse
33
Restoration
•
Surface Mining Control and Reclamation Act
(1977) requires better restoration of stripmined lands, especially if land classed as
prime farmland.
 Difficult and expensive.
- Often more than $10,000.00 per hectare.
 50% of U.S. coal is strip-mined.
34
Processing
•
Metals are extracted from ores by heating or
treatment with chemical solvents.
 Smelting - Roasting ore to release metals.
- Major source of air pollution.
 Heap-Leach Extraction - Crushed ore piled
in large heaps and sprayed with a dilute
alkaline cyanide solution which percolates
through the pile to dissolve the gold.
- Effluent left behind in ponds.
35
CONSERVING GEOLOGIC RESOURCES
•
Recycling
 Aluminum must be extracted from bauxite
by electrolysis.
- Recycling waste aluminum consumes
one-twentieth the energy of extraction
from raw ore.
 Nearly two-thirds of all aluminum
beverage cans in U.S. are recycled.
 Other metals commonly recycled:
- Platinum, gold, copper, lead, iron, steel.
36
Substituting New Materials For Old
•
Reduce metal consumption by using new
materials or new technologies.
 Plastic pipes in place of metal pipes.
 Fiber-optics in place of metal wires.
 Metal alloys in place of traditional steel.
 Ceramics!
37