Geology and Nonrenewable Minerals

Chapter 14

Core Case Study: Environmental Effects of Gold Mining Page 345

Gold producers• South Africa

• Australia

• United States

• Canada

Cyanide heap leaching• Extremely toxic to birds and mammals

• 2000: Collapse of a dam retaining a cyanide leach pond• Impact on organisms and the environment

14-1 What Are the Earth’s Major Geological Processes and Hazards?

1) The earth is a dynamic planet

a) Geology: study of dynamic process occurring on the earth’s surface & interior

b) 3 major zones: core, mantle, crust

c) Core: inner, extremely hot & has a solid inner part surrounded by a liquid core of molten material

d) Mantle: thick, most solid rock

e) Athenosphere: zone of hot, partly melted rock that flows like soft plastic

f) Crust: outer, thinner layer

14-1 What Are the Earth’s Major Geological Processes and Hazards?

2) The earth moves

a) Convection cells: move large volumes of rock & heat in loops within the mantle

b) Tectonic plates: rigid plates that move atop the mantle

c) Lithosphere: combination of the continental & oceanic crust & the outer part of the mantle

d) Most geologic activity occurs at the boundaries of the plates

Fig. 14-2, p. 348

Fig. 14-3, p. 348

Fig. 14-4, p. 349

14-1 What Are the Earth’s Major Geological Processes and Hazards?

e) Causes mountains, earthquakes & volcanoes

f) oceanic ridges form when magma rises as plates move apart

g) Subduction occurs when the continental plate slides over an oceanic plate (subduction zone)

h) Trench: forms at the boundary of 2 converging plates

i) Transform fault: plates slide & grind past one another

Fig. 14-5, p. 350

14-1 What Are the Earth’s Major Geological Processes and Hazards?

3) Building up and wearing down the surface

a) Internal geologic processes: build up the earth’s surface in the form of crusts

b) External geologic processes: wear down the surface & move material from one place to another

c) Weathering: breaks down rock, helps form soil

d) Erosion: Chapter 12

4) Volcanoes: Occur where magma reaches the surface through a fissure (lava)

Fig. 14-6, p. 351

14-1 What Are the Earth’s Major Geological Processes and Hazards?

5) Earthquakes: a) shifting or breaking forming a transform faultb) Seismic waves: energy produced by an earth quakec) Points1. focus: where it begins below the surface2. epicenter: found on the surface above the focus3. Magnitude: severity of the earthquake

4. Amplitude: size of the wave5. Seismograph: used to measure earthquakes

14-1 What Are the Earth’s Major Geological Processes and Hazards?

d) Richter scale: measures intensity, with each number being 10X that of the lower number

e) Aftershock: smaller earthquake

f) Reducing loss of life and damage:

1. locate active fault lines

2. Establish codes that regulate placement and design of buildings

Fig. 14-7a, p. 351

14-1 What Are the Earth’s Major Geological Processes and Hazards?

4) Tsunamis (tidal waves):

a) large waves generated when part of the ocean floor suddenly rises or drops

b) Can be detected by ocean buoys and pressure recorders on the ocean floor

c) Between 1900-2007 killed 278000 people in the Pacific Ocean region.

d) Coral reefs & mangrove forests reduce damage

Fig. 14-8, p. 352

Indonesia June 23, 2004 before tsunami

Dec. 28, 2004 after tsunami

14-1 What Are the Earth’s Major Geological Processes and Hazards?

5) Gravity and earthquakes can cause landslides

a) Mass wasting: loose soil & rock slide down a slope

b) Can occur quickly

c) Human activities increase problem

ex: clear cutting, road building, crop growing

and building on slopes

14-2 How Are the Earth’s Rocks Recycled?

1) Types of rocks

a) Mineral: element or compound occurring naturally in the crust as a solid

b) Rock: solid combination of 1 or more minerals in the crust

c) Classes:

1. Sedimentary: formed as sediments accumulate over time and the weight puts pressure on the lower layers (sandstone & shale-sand) (dolomite & limestone-shells/skeletons) (coal- plant remains)

14-2 How Are the Earth’s Rocks Recycled?

2. Igneous: forms below (granite) or on (lava rock) the surface when magma reaches the crust and cools, forms the bulk of the crust

3. Metamorphic: preexisting rock is subjected to high temperatures, high pressures, chemically active fluids or a combination (anthracite coal, slate, marble)

2) Rock Cycle: process of rocks changing from one form to another (know page 354)

Fig. 14-10, p. 354

14-3 What Are Mineral Resources, and what are their Environmental Effects?

1) We use a variety of nonrenewable resources

a) Mineral resource: concentration of naturally occurring material from the crust that can be extracted and processed into useful products at an affordable cost

b) Ore: rock containing a large enough concentration to make it profitable to mine

c) Sand & gravel are the most widely used nonmetallic mineral

d) Reserve: estimated supply of a resource

14-3 What Are Mineral Resources, and what are their Environmental Effects?

2) Minerals use has advantages and disadvantages

a) Life cycle

b) Benefits: generates income, government revenue, employment

c) Disadvantages: uses enormous energy, disturbs land, erodes soil, produces waste & pollutants

14-3 What Are Mineral Resources, and what are their Environmental Effects?

3) Surface Mining: a) Equipment removes overburden (soil & rock)b) This waste material is called spoilsc) Tailings: unused material from dredgingd) Open-pit: Dig holes and remove the oree) Area strip mining: strip away overburden and power shovels remove the mineral depositf) Contour strip mining: Power shovels cut a series of terraces into the side of a hillg) Mountain top removal:

Open pit

Fig. 14-14, p. 357

Fig. 14-17, p. 357

Contour strip

Fig. 14-16, p. 358

Coal strip mine in Germany

Fig. 14-17, p. 359

Mountain top removal

14-3 What Are Mineral Resources, and what are their Environmental Effects?

4) Harmful effects:a) Scarring & disruption of land surface b) Spoils & tailings are susceptible to weathering & erosionc) Mountain top: destroys forests & buries streamsd) Toxic wastese) Degrades biodiversityf) Pollutes streams and riversg) Cleanup is expensive ($70 billion in US, trillions world wide)

14-3 What Are Mineral Resources, and what are their Environmental Effects?

h) Subsurface disturbs less than 1/10 the amount of land, but leaves more mineral behind

i) Subsurface is more expensive and dangerous

j) Causes subsidence

k) Solid waste (3/4 of all US solid waste)

l) Causes air and water pollution

m) Uses huge amounts of water

5) Removing metals from ores has harmful effects

a) Gangue: waste from extracted ore

14-3 What Are Mineral Resources, and what are their Environmental Effects?

b) Tailings produced may release toxic metals into water sources

c) Smelting (heating ore to remove the metal) produces air pollutants

d) Liquid & solid hazardous wastes are produced

14-4 How Long Will Supplies of Nonrenewable Mineral Resources Last?

1) Uneven distribution of mineralsa) Massive exports can deplete supplies of a countries

resources

b) 5 nations ( US, Canada, Russia, S. Africa & Australia) supply most of the non-renewable mineral resources

c) Since 1950, there has been a sharp rise in the total & per capita use in the US

d) The US has depeted some of its resources & currently imports 50% or more of the 24 most important mineral resources

14-4 How Long Will Supplies of Nonrenewable Mineral Resources Last?

e) Concern for 4 strategic metals (MN, Co, Cr, & Pt)

2) Economic depletion

a) Future supply depends on actual supply & rate of use

b) Economically depleted means it costs more to find, remove and process than it is worth

c) 5 choices: recycle, reuse, waste less, use less, find substitute or do without

14-4 How Long Will Supplies of Nonrenewable Mineral Resources Last?

d) Depletion time: time it takes to use up a certain proportion (80%) of the reserves

e) This time has several variables (page 361)

f) Concern that if all nations used metals at the rate of developed countries, there would not be enough

3) Market prices affect supplies

a) Increase in price leads to increased supplies & encourage more efficient uses

b) Price reflects supply & demand

Fig. 14-19, p. 361

Science Focus: The Nanotechnology Revolution page 362

Nanotechnology, tiny tech

Nanoparticles• Are they safe?

Investigate potential ecological, economic, health, and societal risks

Develop guidelines for their use until more is known about them

Case Study: The U.S. General Mining Law of 1872 page 363

Encouraged mineral exploration and mining of hard-rock minerals on U.S. public lands

Developed to encourage settling the West (1800s)

Until 1995, land could be bought for 1872 prices

Companies must pay for clean-up now

14-4 How Long Will Supplies of Nonrenewable Mineral Resources Last?

4) Is mining lower-grade ores the answer?

New methods may allow lower grade ores to be used. However, several factors can limit the mining of these ores

5) Can we extend supplies by getting minerals from the ocean?

a) Most elements are in low concentrationb) Hydrothermal ore deposits is a potential source

b) Manganese nodules on the pacific floor

c) Some believe seabed mining would causes less environmental harm. However, they are concerned it would destroy seafloor organisms

14-5 How Can We Use Mineral Resources More Sustainability? (page 365-366)

Fig. 14-22, p. 366

Case Study: Industrial Ecosystems: Copying Nature page 366

Mimic nature: recycle and reuse most minerals and chemicals

Resource exchange webs

Ecoindustrial parks

Industrial forms of biomimicry• Benefits