Unit 5: Impacts of Mining, Forestry, and Urbanization Flashcards
Open-pit Mining
Definition: surface mining technique in which a large pit or hole is dug to extract ore and minerals that are close to the Earth’s surface. This method is commonly used for extracting resources like copper, gold, and iron.
Environmental Impacts:
Habitat destruction – Large-scale land clearing disrupts ecosystems.
Soil erosion and degradation – Removal of topsoil can lead to desertification.
Water pollution – Runoff can carry toxic heavy metals and acids (acid mine drainage).
Air pollution – Dust and emissions from mining equipment contribute to air quality issues.
Economic and Efficiency Benefits:
More cost-effective than underground mining.
Allows extraction of large amounts of minerals.
Strip Mining
Removal of soil and rock with dragline shovel to expose coal seam.
Mountaintop Removal
Carries strip mining to a higher level by removing entire formations of mountaintops
Overburden
The layer of soil, rock, and other materials that lie above a mineral deposit and must be removed during mining. When overburden is removed, it increases vulnerability to erosion.
Spoils
waste material (such as rock, soil, and other debris) that is removed during surface mining operations. often piled up in spoil banks or tailings piles post mining
What are the environmental impacts of mining? (land use)
- Removal of topsoil leads to more erosion and landslides due to lack of vegetation -> loss of habitat and biodiversity
- In general there are more sediments and heavy metals
(not nutrients!) that run off into nearby bodies of water → this means there is an increase in tubidity (more suspended particles in water) and more contamination of groundwater.
What are the environmental impacts of mining? (water use)
- Acid mine drainage; FeS2 (pyrite) mixes with H2O to make H2SO4 (sulfuric acid) which is toxic in water
- Leftover mine waste (called “slag” or “tailings”) acidifies and contaminates groundwater resources
- Cyanide heap leaching (in gold mines): Ore is treated with a cyanide salt solution to refine and extract the gold mineral. This solution could leach into the soil and nearby bodies of water, leading to contamination of groundwater and aquatic ecosystems, poisoning wildlife and potentially harming human populations.
Surface Mining Reclamation and Control Act of 1977
Restore areas that have been actively mined
No mining in “sensitive areas”
Ways to remediation for mining damage
Revegetate the land: This includes: plant natives species (increase biodiversity), restore fertility, minimize erosion
- Correct the conditions of acid mine drainage by:
- add nase (like limestone) to
raise the pH
- remove tailings (leftover mine
waste)
- apply bioremediation
techniques (vegetate with
plants that can absorb heavy
metals)
Clearcutting
A timber harvesting practice where all (or most of) the trees in an area are removed at once
Drawbacks of Clearcutting
- After clear-cutting, tree plantations are (often) created to replace the harvested forest
- Then quickly replanted with single, fast-growing species
- Will never mature into diverse ecosystems; nutrient depletion from soil takes place
Benefits of Clearcutting
- Easiest, (usually) most economical timber practice
- Stands are often replanted
Selective Cutting
- Removal of single trees or small amounts of trees in a given area
- Young seedlings grow next to established old-growth trees
Why is selective cutting more sustainable compared to clearcutting?
- Optimizes growth for shade-tolerant species
- Less erosion, loss of biodiversity, etc. (compared to clear-cutting)
Ecologically Sustainable Forestry Practices + Their Limitations
- Selective cutting: more expensive, reduces short-term profitability
- Use horses to pull logs which reduces soil compaction: difficult to compete with mechanized practices that are faster
- prescribed burns: air quality concerns and expensive
Prescribed Burns
Fire is a natural process (when controlled and prescribed) because it leads to nutrient cycling which liberates nutrients tied up in dead biomass and regeneration where openings provide habitats for early-successional species
What happens without prescribed burns?
Dead biomass builds up when fires are suppressed
If small, controlled burns don’t occur, large wildfires may rage out of control (remember what we read about the causes of the CA fires)
How can we mitigate (offset) deforestation?
- Reforestation
- Use and buy wood harvested by ecologically sustainable forestry techniques
- Reuse wood
How can we protect forests from disease?
- integrated Pest Management (IPM)
- selected removal of affected trees
NEPA: National Environmental Policy Act (1969)
Mandates a company/institution to file an environmental assessment of all projects involving federal money or permits
Two parts of the assestment:
1. Environmental Impact Statement: outlines project’s scope and purpose and describes the environmental context
2. Environmental Mitigation Plan: describes how environmental impact issues will be addressed. May need to apply protection measures of Endangered Species Act (1973). Public comments and concerns often influence decisions (but not always)
urban sprawl
The change in population distribution as cities expanded into rural areas
This phenomenon has occurred around the world and has had economic, health, and environmental consequences
What methods can be used to reduce urban runoff?
- Permeable pavement (They help regulate the flow of water by absorbing it, making the ground more permeable → less runoff!)
- Plant more trees
- Increase the use of public transportation: When less people drive, that means less cars on the road, less stormwater pollution → less runoff!
