Every phone, road, and building starts as rock torn from the ground, and every city paves over land that once absorbed rain and grew food. Mining and urbanization are two of the biggest ways humans reshape land — and both trade short-term gains for lasting environmental costs. This lesson looks at how we extract minerals (and the scars it leaves), how cities sprawl outward (and why that matters for water, farmland, and habitat), and how to measure our total demand on the planet with the ecological footprint. It closes with the recurring question of the whole unit: how do we meet human needs while staying within the land's limits?
Mining extracts mineral and energy resources. Ore is rock containing enough valuable mineral to be worth mining. Methods fall into two categories:
Surface mining (for shallow deposits): - Open-pit mining — digging a large pit (copper, gold). - Strip mining — removing surface layers in strips (coal, minerals). - Mountaintop removal — blasting off mountaintops to reach coal seams; overburden (removed rock/soil) is dumped into valleys, burying streams.
Surface mining is cheaper and safer for workers but causes massive land disturbance, habitat destruction, and erosion.
Subsurface (underground) mining (for deep deposits): tunneling underground. Less surface disturbance, but more dangerous for miners (collapse, toxic gases, explosions) and can cause subsidence.
Environmental impacts of mining: - Habitat destruction and land disturbance. - Acid mine drainage — water reacts with exposed sulfide minerals to form sulfuric acid, which runs off and acidifies/contaminates streams with dissolved metals. A major, long-lasting pollution problem. - Tailings — leftover waste (often laced with toxic metals or processing chemicals) stored in ponds that can leak or fail. - Erosion and sedimentation of waterways. - Air pollution (dust, smelting emissions).
Reclamation — restoring mined land (regrading, replacing topsoil, replanting) — is required by law in many places (e.g., the US Surface Mining Control and Reclamation Act), though full recovery is difficult.
Urbanization is the growth of cities and the shift of population from rural to urban areas. Urban sprawl is the low-density, spread-out expansion of cities into surrounding land.
Impacts of urbanization/sprawl: - Impervious surfaces (roads, roofs, parking lots) prevent infiltration → increased runoff, flooding, and nonpoint-source pollution (Lesson 13), and less groundwater recharge. - Loss of farmland and habitat as cities expand outward; habitat fragmentation (Lesson 5). - Urban heat island effect — dark, dry, built surfaces absorb and re-radiate heat, making cities warmer than surrounding areas. - Increased resource and energy demand, waste, and air pollution (traffic). - Reduced tree cover, altered local water cycle.
Smart growth solutions: higher-density, mixed-use development; public transit; preserving green space; infill development (building on vacant urban lots rather than expanding outward); permeable pavement; urban green roofs and parks.
[DIAGRAM: Two watersheds side by side. NATURAL land: rain mostly infiltrates (large downward arrow), little runoff, groundwater recharged. URBAN land: mostly impervious surface, rain becomes runoff (large sideways arrow to storm drain/river), little infiltration, flooding and pollutant transport, minimal recharge.]
The ecological footprint is the amount of biologically productive land and water required to supply the resources a person (or population) consumes and to absorb their wastes, usually expressed in hectares or "Earths."
Carrying capacity for humans is contested because technology and consumption levels change how much land each person needs — but the footprint framework shows that consumption, not just population, drives environmental demand.
Mining impacts (especially acid mine drainage) and urbanization impacts (impervious surfaces, heat island, farmland loss) are common MC and FRQ topics. The ecological footprint is a favorite for connecting consumption to sustainability, and it can appear as a simple calculation or comparison.
Compare surface and subsurface mining in terms of land disturbance and worker safety.
Solution: Surface mining causes more land disturbance (habitat destruction, erosion) but is safer and cheaper for workers. Subsurface mining disturbs less surface land but is more dangerous (collapse, toxic gases) and costlier.
Interpretation: Surface = more land damage, safer workers; subsurface = less surface damage, riskier workers.
Explain how acid mine drainage forms and one impact on a stream.
Solution: When mining exposes sulfide minerals to air and water, chemical reactions produce sulfuric acid (and dissolve toxic metals). This acidic, metal-laden water runs off into streams, lowering pH and harming or killing aquatic life.
Interpretation: Exposed sulfides + water + air → sulfuric acid → acidified, metal-contaminated water.
Explain two ways urban sprawl affects the local water cycle.
Solution: (1) Increased runoff and flooding — impervious surfaces prevent rainwater from infiltrating, so it rushes to storm drains and streams. (2) Reduced groundwater recharge — less infiltration means aquifers are replenished less, and runoff carries pollutants (nonpoint-source) into waterways.
Interpretation: Pavement redirects water from into the ground to across the surface — more flooding, less recharge, more pollution.
Country A has a per-capita ecological footprint of 8 global hectares (gha) and 50 million people; Country B has 2 gha and 200 million people. (a) Which nation has the larger total footprint? (b) What does this show about consumption vs. population?
Strategy: total footprint = per-capita × population.
Solution:
Country A: 8 gha × 50,000,000 = 400 million gha
Country B: 2 gha × 200,000,000 = 400 million gha
(a) They are equal (400 million gha each). (b) Despite Country B having 4× the people, its lower per-capita consumption gives it the same total footprint — showing that consumption per person, not just population size, drives environmental demand.
Interpretation: High per-capita consumption can offset smaller population; both factors matter.
(B) Wealthy high-consumption nation.
Any three impacts with a smart-growth fix: Increased runoff/flooding (impervious surfaces) → permeable pavement/green space/detention ponds. Loss of farmland/habitat → infill development, urban growth boundaries, preserving green space. Increased driving/air pollution → public transit, mixed-use higher-density development to shorten trips. (Also heat island → tree cover/green roofs.)
(a) X: 6 × 30,000,000 = 180 million gha; Y: 1.5 × 150,000,000 = 225 million gha. (b) Country Y is larger despite lower per-capita use, because its population is much larger — showing both population and consumption drive total footprint.
FRQ rubric (10 pts):
- (a) 1 pt impervious surfaces reduce infiltration → more/faster runoff → flooding; 1 pt runoff carries diffuse pollutants (oil, nutrients, sediment) into waterways (nonpoint source). (2)
- (b) 1 pt exposed sulfide minerals react with air/water to form sulfuric acid; 1 pt impact: lowers creek pH / releases toxic metals, harming aquatic life. (2)
- (c) 1 pt setup 5 gha × 2,000,000; 1 pt = 10 million gha. (2)
- (d) Sprawl solution (permeable pavement, smart growth, green infrastructure) 1 pt + justification 1 pt; mining solution (reclamation, treat/neutralize acid drainage, cap tailings, prevent sulfide exposure) 1 pt + justification 1 pt. (4)
A metropolitan area is expanding rapidly through low-density sprawl, paving farmland and forest. Flooding and stormwater pollution are worsening. Meanwhile, a nearby open-pit mine has caused acid drainage in a creek.
(a) Explain how the sprawl increases both flooding and nonpoint-source pollution. (2 pts) (b) Explain the cause of the acid mine drainage and one impact on the creek. (2 pts) (c) A city of 2 million has a per-capita ecological footprint of 5 gha. Calculate its total ecological footprint. Show work. (2 pts) (d) Propose two solutions — one addressing sprawl and one addressing mining impacts — and justify each. (4 pts)
MC: 1. (B) Burial of valley streams with overburden. 2. (B) Sulfide minerals + air + water → sulfuric acid. 3. (B) Less surface disruption but more dangerous to workers. 4. (B) Increased runoff and flooding. 5. (B) Built surfaces absorb and re-radiate heat. 6. (B) Productive land/water for consumption and waste. 7. (B) Regrading, replacing topsoil, replanting. 8. (C) Low-density sprawl is the opposite of smart growth. 9. (B) Using resources faster than Earth regenerates. 10. (B) Wealthy high-consumption nation.
Any three impacts with a smart-growth fix: Increased runoff/flooding (impervious surfaces) → permeable pavement/green space/detention ponds. Loss of farmland/habitat → infill development, urban growth boundaries, preserving green space. Increased driving/air pollution → public transit, mixed-use higher-density development to shorten trips. (Also heat island → tree cover/green roofs.)
(a) X: 6 × 30,000,000 = 180 million gha; Y: 1.5 × 150,000,000 = 225 million gha. (b) Country Y is larger despite lower per-capita use, because its population is much larger — showing both population and consumption drive total footprint.
FRQ rubric (10 pts):
- (a) 1 pt impervious surfaces reduce infiltration → more/faster runoff → flooding; 1 pt runoff carries diffuse pollutants (oil, nutrients, sediment) into waterways (nonpoint source). (2)
- (b) 1 pt exposed sulfide minerals react with air/water to form sulfuric acid; 1 pt impact: lowers creek pH / releases toxic metals, harming aquatic life. (2)
- (c) 1 pt setup 5 gha × 2,000,000; 1 pt = 10 million gha. (2)
- (d) Sprawl solution (permeable pavement, smart growth, green infrastructure) 1 pt + justification 1 pt; mining solution (reclamation, treat/neutralize acid drainage, cap tailings, prevent sulfide exposure) 1 pt + justification 1 pt. (4)
⭐ Exam strategy: For urbanization questions, the reflex answer involves impervious surfaces → more runoff, more flooding, less recharge, plus the heat island. For mining, remember acid mine drainage (sulfuric acid) as the signature water impact. And for footprint math, total = per-capita × population.
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