Transcript Document

Environmental Science
PowerPoint Lecture
Principles of Environmental
Science - Inquiry and Applications,
2nd Edition
by William and Mary Ann Cunningham
Chapter 11 familiarize you with:
•Understand some basic geologic principles, including how plate-tectonic
movements affect conditions for life on earth
•Explain how the three major rock types form and how the rock cycle
works
•Summarize economic mineralogy,
strategic minerals
•Discuss environmental effects of mining
and mineral processing
•Recognize geologic hazards:
earthquakes, volcanoes, floods, and erosions
Key Terms – Chapter 11
•Barrier islands
•Metamorphic rocks
•Core
•Midocean ridges
•Crust
•Mineral
•Earthquakes
•Flood
•Floodplains
•Heap-leach extraction
•Igneous rocks
•Landslides
•Magma
•Mantle
•Rock
•Rock cycle
•Sedimentary rocks
•Sedimentation
•Smelting
•Strategic metals &
minerals
•Tectonic plates
•Volcanoes
•Weathering
Chapter 11 - Topics
•
•
A Dynamic Planet
Minerals and Rocks
• Economic Geology and
Mineralogy
• Environmental Effects of Resource
Extraction
• Conserving Geologic Resources
• Geologic Hazards
Part 3: Economic Geology
and Mineralogy
• Economic mineralogy = the study
of minerals that are valuable for
manufacturing and trade (most
metal ores); need economically recoverable levels
(non-metal geologic resources – graphite,
feldspar, quartz crystals, diamonds)
• Public policy in the U.S. has encouraged
mining on public lands as a way of boosting
the economy and utilizing natural resources
Living things
C, N, O, H
Atmosphere
C, N, O,
Earth, rocks
Economic metals
O,
Ar, Ne, He
Al, Fe, Ni,
Si, Mg, Ca, Na
Al, Fe, Ni,
Cr, Cu, Pb, Mn
Ni,
Primary toxins
Pb,
Hg, Se, Br,
Cd, Be, Rn, As
Fe used most followed by Al
What common - living things, atmosphere, earth, rocks?
Are any economic metals important for living things?
O
NO
What elements are common between atmospheric element &
economic metals?
None
What elements common between earth & economic metals?
Pb, Ni
Al
Fe
Ni
What common elements for economic metals & primary toxins?
Metals consumed in highest quantity
globally
• Iron (most consumed) > aluminum >
manganese > copper > chromium > nickel
[earths crust = 8.2% Al, 5.8% Fe]
• Most metals consumed in the following order
of highest consumption = US > Japan >
Europe
• Most metals produced primarily in South
America, South Africa, Russia
Sources of Minerals:
E.A. Keller. 1992.
Environmental
Geology
Extensive marine evaporite
deposits in US – deposits left after
water evaporates (large inland
lake with no outlet)
Major deposits of mercury in red, small deposits in green, bulk of
productive deposits highlighted in blue = global occurrence mercury
deposits along subduction zones, with volcanic systems
Tectonic plate boundaries
related to origin of ore
deposits such as iron, gold,
E.A. Keller. 1992. Environmental Geology copper, mercury
US deposits of copper, beryllium, zinc, gold –
not all deposits along tectonic boundaries
E.A. Keller. 1992. Environmental Geology
Global Metal Trade
Suppliers
Consumers – US, Japan, Europe
Nonmetal Mineral Resources
• Silicate minerals (gemstones, mica, talc, asbestos)
Sand and gravel (for road and building construction)
Salts
Limestone (like sand, gravel mined and quarried for concrete,
crushed for road rock)
[greatest volume and dollar value of all nonmetal mineral
resources]
• Evaporites –
halite (rock salt – deice roads in winter; table salt),
gypsum (plaster board; wall covering Egyptians 5,000 yrs ago),
potash (make fertilizers)
• Sulfur deposits –
mined mainly for sulfuric acid production (industry, car batteries, some
medicinal products)
• Graphite, feldspar, quartz crystals, diamonds –
useful or demand for beauty
• World industry
dependent on 80
minerals / metals;
18 short supply (i.e. tin,
platinum, gold, silver,
lead) – 1/3 to ½ strategic metals &
minerals
U.S.
Stock
piles of
strategic
metals
• Strategic metals and
minerals - those a
country uses but cannot
produce itself
• Wealthy industrial
nations often stockpile
strategic resources,
especially metals
E.A. Keller. 1992.
Environmental Geology
•Much of cycle connected to waste
•Environmental impacts related to wastes
•Not recycle – enormous economic burden & environmental impact
•Metal recycling important difficult to find concentrated sources
Percent of US consumption recycled:
aluminum, copper, lead
Al - more
energy to
extract from ore
than recycle; is
strategic metal
E.A. Keller. 1992. Environmental Geology
Pb – short supply, is
strategic metal
Part 4: Environmental Effects
of Resource Extraction
• Geologic resource extraction involves:
1) the physical processes of mining,
2) the physical or chemical processes of
separating minerals, metals, and other
geologic resources from ores or other
materials.
• Ore - a rock in which a valuable or useful
metal occurs at a concentration high
enough to make mining it economically
attractive
Mining and Air, Water Pollution
• EPA lists > 100 toxic air pollutants released
from US mines every year
• Gold and other metals often found in sulfide
ores found in hydrothermal deposits
- sulfur-bearing minerals exposed to air
produce highly mobile and strong acids
- vast quantities of ores crushed and washed
to extract metals, uses lots of water (Nevada
60 million gallons/day) that gets contaminated
Mining
• Placer mining
• Strip-mining or open-pit mining – most common
• Underground mining – tunneling deep
• Tailings - surface waste deposits
• Groundwater contamination
• Spoil banks - acid and sediment runoff
• Surface Mining Control and Reclamation Act (1977)
• By 2000, cumulative land used for mining was less
than 1 percent (0.2%) globally
Hydraulic
miners, 1910,
in PNW
Since CA gold rush of 1849, placer miners used water cannons
to blast away hillsides
Placer mining – ancient method of accumulating gold,
diamonds, coal
Bingham Canyon, Utah
drainage into
Blackfoot River
2.5 mi
wide
2,640
feet
deep
Montana –
HOW
RECLAIM,
RESTORE?
No soil or
biological legacy;
Ground water in
pits toxic
(technology to
detoxify not
known
Metals extracted from ores by heating (smelting)
or chemical solvents – these more negative than mining
Smelting – roasting ore to release metals using heat or
chemical solvents
Ducktown, Tennessee
– most ecological devastating
smelting operations created
wastelands
Heap-Leach Extraction – chemical
extraction to dissolve pulverized ore (GOLD)
Process for
low-grade
ores
Uses cyanide
trickling
through
crushed ore to
extract gold,
other precious
metals
Thick
clay pad
& plastic
liner
Kola peninsula – arctic border of
Russia, Finland and Norway has
biggest air polluting industries in
Europe
• Ni and Cu mines, rich in S
• Around 1985, about 700 thousand tons of
SO2/year
• In 1994, about 350 thousand tons of SO2/yr
(more than the total emissions of Norway,
Sweden and Finland combined)
Kola peninsula – all forests gone close to source,
soil eroding, effects of nickel smelters extending from Russia
into Finland and Norway, air pollution reaches critical limits
Chemical legacy hard to
restore back to natural
High in:
sulfur,
copper,
zinc,
gold, iron
700 F
Hydrothermal vents
or ‘black smokers’
http://www.pbs.org/wnet/savageearth/hellscrust/html/sidebar2.html
http://www.pmel.noaa.gov/vents/geology/MOR.html
Ocean mining
of rich
mineral
deposits a
technological
challenge
Mid-ocean
ridges
E.A. Keller. 1992. Environmental Geology
Geologic Hazards, Climate and
Human Health
Volcanic
eruption in
Indonesia in
1963 < air
temperatures
by 0.2 C for 2
years
Natural volcanic eruptions result in similar
Air Pollution and Human Health problems
as mining causes
Hekla eruption 1991
• Snow on North and Eastern Iceland pH 3
• Water close to Hekla was very toxic when it
melted.
• Gas movement from underground sources
polluted groundwater (e.g.SO4).
Lakagígar 1783-1784 eruptions
Ash from eruption
in Iceland fell in
mainland Europe
Gas aerosols
released caused
cooling in Northern
Hemisphere (by 1
degree C).
Lakagígar eruption 1780’s
• More than 50 million tons of SO2 emitted
(more than the current total annual emission
of Europe)
• Thick carpet of particulate and gaseous
pollution over Iceland.
• Pollution probably very acidic
Lakagígar eruption – consequences in
Iceland (1780s eruptions)
•
•
•
•
Grass and other vegetation withered
Birds fell dead from the sky
Fish disappeared from the rivers
Large part of livestock died due to eating
fluorine contaminated grass (poisoned)
• crop failure (by acid rain)
• People experienced respiratory problems,
death of 9,000 people (1/4 of residents of
Iceland) due to famine
Geology and Human Health
Released during volcanic eruptions
SO2 – sulfur dioxide
HCl – hydrochloric acid
HF – hydrogen fluoride [ aluminum smelters next
biggest sources; very toxic to grazing animals]
Asbestos
Asbestos = ferromagnesium silicate, used brake lining &
insulation, very heat resistant so prevents overheating of
machinery & prevents fires
LUNG DISEASE – can result in lung cancer
Iodine deficiency in drinking water
correlated to goiter frequency
Lithium
naturally in
water in
southwest
results in
less
depressed
Keller 1992people
Environmental
Geology
Heart Disease and the Geochemical
Environment
Correlation between chemistry of drinking
water (esp. hardness of water) and heart
disease mortality
Occurrence of heart attack death correlated to sulfate-rich
and bicarbonate rich surface water, Ohio
Cause-effect relationship:
-soft water acidic & corrodes pipes releases trace
elements into water that cause heart disease
-hard water dissolves trace elements into water may
prevent heart disease.
Some trace elements in soil – manganese, chromium,
vanadium, and copper, have been found to prevent heart
disease