Chapter 18-19

April 21, 2023

Minerals

• Minerals– Inorganic– Naturally occurring– Solid material with a definite composition– Atoms arranged in a specific pattern

Single Elements or Compounds

• Can be single elements:– Gold (Au), silver (Ag), copper (Cu), iron (Fe)

• Can be compounds :– Quartz (SiO2)

• Can be metals: – Fe, Al, Au, Ag, Cu

• Can be nonmetals– Sulfur, Gypsum

Examples

Metals and Nonmetals

• d

Metals Vs. Non Metals

• d

Smelting

• The process of heating and refining an ore to separate the valuable metals.

Some minerals and their uses

Metals in International Trade

• Industry and agriculture rely on metals for machinery and building materials

• Unequal distribution of metals in the environment creates an interdependence between countries.

• Nations that depend on resources from unstable regions are vulnerable to the changes in those regions.

• d

Three types of Mining

• Surface Mining

• Subsurface Mining

• Dredging

Surface Mining

• Surface Mining – Removes minerals at or near the surface. – Layers of rock, soil, and vegetation are

removed to uncover mineral deposits.

Open Pit Mining is an example of Surface Mining

Uses large machines to dig ore from huge holes in the ground.

Hazards of Surface Mining

• Tailings:– Large deposits of discarded material are left

near the mines. – Often contain toxic substances in the form of

heavy metals such as lead and copper.

Environmental Hazards of Tailings

• Heavy metals are poisonous to living things• Wind may carry these metals to new

habitats• Rainwater may leach through tailings and

pollute groundwater, or carry toxic materials into fields or streams.

• Open pits eventually fill with water, which leaches into the ground and pollutes ground water.

Tailings

Subsurface Mining

• s

Subsurface Mining

• A shaft is dug into the crust.

• Explosives are used to expose the minerals

• Machinery is then lowered into the shaft to retrieve the mineral deposits.

Hazards of Subsurface Mining

• Less environmental damage

• More dangerous to the workers– Walls, ceilings, and underground tunnels can

collapse – Explosions of natural gas and dust – Dust inhalation causes lung diseases.

Dredging

• Scraping or vacuuming minerals from the bottoms of bodies of water. – Ocean floors, lake bottoms, stream beds.

Hazards of Dredging

• Removes organisms and nutrients, potentially altering aquatic ecosystems.

•

Other Hazards from Mineral Mining

• Smelting – Emits sulfur dioxide, arsenic, and lead into

atmosphere. – Create areas where plant and animal life cannot

live.

• Heap Leaching– Liquid cyanide is sprayed over gold ores. – The cyanide dissolves gold and leaches it from

the ore. – Gold is then collected from the cyanide liquid.

Soil

• Results from the weathering of solid bedrock.

2 ways that exposed rock can be weathered?

1. Mechanically:a. processes that cause physical disintegration of exposed rock without any change in the chemical composition of the rock

1. Chemicalb. Chemical breakdown of rock.

Mechanical Weathering

• d

Chemical Weathering

What is bedrock? Why is it important to soil formation?• Bedrock: igneous, metamorphic, and

sedimentary rock of lithosphere.

• As bedrock weathers, it supplies material needed to build soil

• Parent rock: – Bedrock source for an area of soil.

Soil Formation

• s

Soil Formation.

• Soil: mixture of mineral particles, air, H2O, & living and decaying organisms

1. Outer layer of bedrock weathers (cracks and holes)

2. Cracks reach deeper & outer layer becomes broken into small particles

– Burrowing animals & plant roots break down bedrock & aerate soil

4 distinct layers form.

• Soil profile: a vertical cross section of soil from the ground surface down to the bedrock

• A Horizon: topsoil

• B Horizon: subsoil

• C Horizon: weathered parent bedrock

• R Horizon: bedrock

Soil Profile

• d

3 major soil textures.

1. Sandy: largest mineral size.

2. Silt: Medium sized mineral grains.

3. Clay: flat and traps H2O, preventing H2O drainage; smallest mineral size

Soil Textures (cont)

• d

Characteristics of soil

• Sandy soil– drains well, good aeration, but dries out

quickly. – Not good for plants

• Clay soils– Hold water very well, but does not drain well– Not good aeration, so not good for plants.

Loam Soils

• Mixture of sand, silt, and clay

• Are ideal for plants because loam holds water and air.

Soil & Climate

• Deserts and Tundra – Thin profile because there is less water to

break down the bedrock

• Grasslands – More precipitation and more plants/animals

increase rate of weathering bedrock– Thicker profile

• Temperate and tropical soils– Thickest profiles– Abundant precipitation increases weathering.

Soil Mismanagement

• Vegetation removal• Overgrazing • Deforestation • Pesticides • Fertilizers• Irrigation

Abiotic Agents of Soil Erosion

• 2.5 billion tons lost to water

• 1.5 billion tons lost to wind

• TOTAL=4 billion metric tons!

4 types of soil conservation

1. Strip-farming: plowed strips separated by planted strips

2. Contour Farming: plowing along a slope instead of across it; furrows collect H2O which reduces erosion

3. Terracing: series of platforms (terraces) are built into the slope; separated by vertical steps

4. Shelter belts: rows of trees planted along outer edges of field

How do we define solid wastes?

• All garbage, refuse, & sludge products from agriculture, forestry, mining, and municipalities–Examples: garbage trash

junk sewage scrap refuse

Describe how garbage disposal has changed over the years. • Hunter-gatherers: left it and moved on

• Athens, Greece 500BC: trashed dumped outside of city walls– Rest of Europe dumped in the streets

• NYC/NJ 1892-1900: garbage loaded onto ships and dumped in Atlantic Ocean

• Now we use landfills

What is a landfill? How much garbage is dumped there?

• Site where wastes are disposed of by burying them

• 70%

Why are open landfills no longer allowed in the US?

• It supported large populations of rats, insects, etc.

• Foul odor and disease

Describe what a sanitary landfill is & identify 2 problems.• Wastes are spread in layers ~3m deep &

compacted by bulldozers

• Soil spread on top of refuse & compacted

• Repeated until garbage reaches certain heights

1. Methane produced

2. Leaching of toxic substances

What are hazardous wastes?

• Solid, liquid, or gaseous wastes that are potentially harmful to humans and environment

• Love Canal, NY: Town built next to old chemical plant– Steel containers holding waste leaked– Birth defects and cancer affected the people– Government relocated them ($190 million)

Name 6 types of hazardous waste.

1. Reactive Waste: can explode 2. Corrosive Waste: can eat through steel,

clothing, and burn skin3. Ignitable Waste: can burn at low temp;

toxic fumes when lit4. Toxic Waste: chemicals that are poisonous

to people5. Radioactive Waste: gives off radiation

(given off when mining Uranium)6. Medical Waste: old medicine, medicine

containers, lab equipment and specimens

Identify & explain 4 methods for reducing volume of waste.

1. Recycle: paper, plastic, aluminum, glass, etc.

2. Reuse: cloth diapers

3. Biodegradable: leaves, grass clippings, food waste*, composting

4. Repair: old appliances, shoes, cars

Name 6 ways of disposing of hazardous waste.1. Waste exchange: use haz. waste in

production of other materials

2. Deep Well Injection: inject waste into porous rock under water table; LIQUID

3. Secure Chem. Landfill: waste is stored on nonporous bedrock

• pipes to monitor and collect leaks; cover with clay

4. Controlled Incineration: burn waste at high temp

• Expensive

5. Biological and Chemical Treatment Plants: turn harmful things into harmless

6. Radioactive Waste Disposal: put in H2O or bury underground

What does EPA stand for?

• EPA = Environmental Protection Agency

• Established in 1970

Briefly describe Superfund.

• Law designed to protect communities from dangers of hazardous wastes

• CERCLA (1980): got $9 billion dollars to implement

What are some countries doing to combat high cost of disposal?

• Ship waste to developing nations and leave it there

–Examples: West Africa and Zimbabwe