Comprehensive Study Notes: Cambridge IGCSE Environmental Management

ROCKS AND MINERALS AND THEIR EXPLOITATION

Formation of Rocks and the Rock Cycle

• Definition of Rock: Rock is the solid, naturally occurring material forming the Earth's hard outer layer or crust. It is typically composed of an aggregate of grains of various minerals (chemical elements).

• Igneous Rocks: Formed from the solidification of molten rock.

  • Plutonic (Intrusive): Created when magma cools and crystallises slowly within the crust. Example: Granite (e.g., Combestone Tor, Dartmoor).

  • Volcanic (Extrusive): Formed when lava solidifies on the surface. Example: Basalt (e.g., Giant's Causeway).

• Sedimentary Rocks: Formed via Cementation.

  • Process: Rocks are broken down by weathering (e.g., freeze-thaw) and erosion. Sediments (mud, silt, sand, gravel, skeletons) build up in layers at the bottom of seas and are compressed over millions of years into strata.

  • Limestone: Primarily calcium carbonate from shells and marine skeletons.

  • Sandstone: Small sand grains, usually quartz, cemented by clay.

  • Shale: Consolidated mud, silt, and clay; splits into flat pieces.

• Metamorphic Rocks: Formed when existing rocks are subjected to heat and extreme pressure, causing chemical changes in minerals.

  • Slate: Formed from shale (used for roofing).

  • Marble: Formed from limestone (used for construction/design).

• The Rock Cycle: A continuous process of change. Weathering (physical, chemical, biological) breaks rock into sediments. Deposition and lithification create sedimentary rock. Heat and pressure create metamorphic rock. Melting produces magma, which cools into igneous rock.

Extraction of Rocks and Minerals from the Earth

• Surface Mining: Used when the ore body is near the surface.

  • Process: The overburden (soil/rock above) is removed using heavy machinery. Ore is excavated from flat terraces called benches. Includes open-cast, open-pit, or strip mining.

• Subsurface Mining: Removes minerals from deep underground.

  • Declines: Circular tunnels descending to the ore body.

  • Vertical/Inclined Shafts: Deep tunnels adjacent to ore; removed by lifts.

  • Adits: Horizontal shafts excavated into hillsides following ore levels.

• Economic Factors Affecting Mining Decision:

  • Ore Grade: The concentration of the desired chemical element in the mineral.

  • Reserves: The amount of ore available and its expected lifespan.

  • Market Price: Scaled against Capital Costs (set up) and Operating Costs (extraction/refining).

  • Geological Difficulties: Complexity of tunnels vs. open-cast.

  • Location: Remote environments increase costs for power, water, housing, and transport links.

Impact and Management of Rock and Mineral Extraction

• Economic Impacts:

  • Multiplier Effect: Creation of indirect jobs in supply companies (catering, security, machinery).

  • Trickledown Effect: Wages spent in the local community creating secondary jobs in services.

• Social Impacts:

  • Benefits: Infrastructure (transport, water), community projects (sports halls), and employee training.

  • Problems: Crime/drug use due to sudden disposable income, displacement from land, and erosion of traditional/indigenous ways of life.

• Environmental Impacts: Habitat/biodiversity loss (land clearance), water pollution (Acid Rock Drainage from toxic sulfides), air pollution (dust/heavy metals), and soil erosion/sedimentation leading to flooding.

• Managing Impacts:

  • Remediation: Making sites safe by demolishing plants/machinery and disposing of hazardous waste in tailing ponds.

  • Restoration: Returning land to pre-mine use, typically open countryside or nature reserves (e.g., Stanwick Lakes, UK).

  • Reuse: Converting sites for economic benefit, such as motor racing circuits (Gotland Ring, Sweden), gardens (Butchart Gardens, Canada), or aquaculture (Homase mine, Ghana).

Sustainable Use of Rocks and Minerals

• The Sustainability Challenge: Minerals are non-renewable and finite (e.g., Copper exhausted by $2050-2070$, Uranium by $2085$, Indium by $2035$).

• Sustainable Development: Balancing growth with resource preservation.

  • Extending Reserves: Use of modern technology for efficient extraction; substituting scarce minerals (e.g., Al for Cu in power lines); recycling ($EU$ rule: $65\%$ of electronic waste by $2019$).

  • Increasing Reserves: Exploration of sea beds (manganese nodules carrying nickel, cobalt) at depths of $4000-5000\,metres$.

Case Study: Island Copper Mine, Vancouver Island

• Details: Operated $1971-1995$. Third-largest copper mine in Canada. Excavated $1\,billion\,tonnes$ of rock reaching $400\,metres$ below sea level.

• Restoration: The open pit was flooded with seawater in $1996$ to create a meromictic lake ($2.2\,sq\,km$). Bacteria separate sulfides and metals, which precipitate to the lake bottom.

• Reuse: Ore processing plant decontaminated; facilities sold to local businesses for wood processing and aquaculture (salmon hatcheries).

ENERGY AND THE ENVIRONMENT

Fossil Fuel Formation

• The Basics: Fossil fuels (coal, oil, natural gas) provided approximately $86\%$ of global energy in $2014$. They are hydrocarbons formed millions of years ago.

• Coal Formation: Formed from dead plants in swamps during the Carboniferous period ($300-400\,million$ years ago).

  • Stages: Peat (partially decomposed) → Lignite (compressed) → Bituminous coal (≈$86\%$ carbon) → Anthracite (hardest, highest carbon/heat).

• Oil and Natural Gas Formation: Formed from microscopic marine organisms (plankton) buried under mud in oxygen-poor environments. Heat ($100-160^{\circ}C$) breaks organic matter into hydrocarbon chains. They rise through porous rock until trapped by impermeable cap rock.

Energy Resources and Electricity Generation

• Thermal Power Generation: Water is heated (by fossil fuels, nuclear, or biofuels) to produce steam, which turns turbines to drive a generator.

• Renewable vs. Non-renewable:

  • Non-renewable: Coal, Oil, Natural Gas, Nuclear (Uranium).

  • Renewable: Biofuels, Geothermal, Hydroelectric (HEP), Tidal, Wave, Solar, Wind.

• Comparisons:

  • Nuclear: No $CO_2$ emissions during operation, but high build costs and radioactive waste storage issues.

  • Solar: Clean and renewable but intermittent; high initial setup costs.

  • HEP: Multipurpose (flood control, irrigation), long-lasting, but causes social displacement and ecosystem disruption.

Energy Demand and Conservation

• Factors Affecting Demand: Domestic (heating/cooling/appliances), industrial (iron/steel/petrochemicals), transport (passenger vehicles), national wealth, and climate.

• Conservation Strategies:

  • Smart Buildings: Connecting buildings to grids to manage demand (reducing lighting/elevators during surges).

  • Education: Reducing standby use, boiling only necessary water amounts.

  • Vehicles: Improving fuel efficiency; moving to Bioethanol (e.g., $≈22\%$ mixture in Brazil) or Hybrid/Electric vehicles.

  • Government Policy: Congestion charges (London) or Electronic Road Pricing (Singapore).

Oil Pollution Management

• Causes: Offshore rig blowouts, leaky pipelines (corrosion/fatigue), and tanker accidents (e.g., $Exxon\,Valdez$ in $1989$ spilled $42\,million\,litres$).

• Ecosystem Impact: Poisoning of birds/mammals, destruction of insulation in fur-bearing animals leading to exposure, chemical burns, and poisoning of the food chain in coral reefs/beaches.

• MARPOL (International Convention): Bans release of oil waste; requires double-hulled tankers.

• Clean-up Methods: Booms (floating barriers), skimmers, chemical dispersants, absorbing sorbents, and controlled burning.

Case Study: Deepwater Horizon Disaster (2010)

• Location: $66\,km$ off Louisiana, Gulf of Mexico.

• Event: Blowout and rig explosion; leaked $4.9\,million\,barrels$ ($795\,million\,litres$) over $3\,months$.

• Costs: US$18.7\,billion fine for BP; total charges associated reached US$53.8\,billion.

• Impact: $1770\,km$ of coastline affected; thousands of recorded animal deaths; collapse of fishing and tourism (US$23\,billion loss in tourist income).

AGRICULTURE AND THE ENVIRONMENT

Soil Composition and Soils for Plant Growth

• Soil Constituents: Inorganic mineral particles ($40-45\%$), Organic matter/Humus ($5\%$), Water ($25\%$), and Air ($25\%$).

• Texture Classes:

  • Clay: Particles <0.002\,mm. Heavy, retains water, but can waterlog or crack when dry.

  • Silt: Particles $0.002-0.05\,mm$. Fairly well-drained but compacts when wet.

  • Sand: Particles $0.05-2\,mm$. Light, drains easily, but leaches nutrients and dries fast.

  • Loam: Ideal mixture of sand, silt, and clay.

• Essential Minerals:

  • Nitrogen (N) (as Nitrate $NO_3^-$): Protein/cell growth.

  • Phosphorous (P) (as Phosphate $PO_4^{3-}$): DNA and respiration/growth.

  • Potassium (K): Enzymes for photosynthesis/respiration.

  • Magnesium (Mg) (as $Mg^{2+}$): Chlorophyll production.

• Soil pH: Measure of acidity/alkalinity ($1-14$ scale). Optimal for most plants is $6$ to $7.5$.

  • Acidic soils (<7): Found in rainforests; leached of nutrients; metal ions like $Al$ can reach toxic levels. Managed via Liming.

  • Alkaline soils (>7): Common in deserts; lack iron/zinc. Managed by adding organic manure/sulfur.

Increasing Agricultural Yields

• Rotation: Sequence of crops (e.g., following maize with nitrogen-fixing legumes like clover/peas).

• Fertilisers: Replacement of nutrients ($N, P, K$).

  • Impact: Eutrophication (algal blooms depleting oxygen in lakes); release of Nitrous Oxide (greenhouse gas).

• Irrigation: Artificial water supply (Surface, Drip, Sprinkler, Sub-irrigation).

  • Problems: Salinisation (salt build-up) and waterlogging.

• Mechanisation: Substituting human labor with machinery; leads to Precision Agriculture (using GPS and robot guidance).

• Genetic Modification (GM): Artificially swapping genes for traits like herbicide resistance (e.g., $85\%$ of world maize is GM for glyphosate resistance).

Soil Erosion and Sustainability

• Causes of Erosion: Overcultivation, overgrazing, and deforestation.

• Land Degradation: When vegetation is stripped and soil structure fails.

• Desertification: Once-fertile land resembling desert due to erosion, dropping water tables, and salinisation. (e.g., $24\,billion\,tonnes$ of topsoil lost annually).

• Management Strategies:

  • Vegetation Cover: Roots anchor soil. Use of Wind Breaks (tree lines) and Cover Crops (clover/oats).

  • Ploughing: Contour Ploughing (across slopes) to slow run-off. Use of Bunds or Terraces (flat steps on hills).

• Sustainable Agriculture: Stewardship approach. Uses Biocontrol (encouraging natural predators like wasps to kill mealybugs) and organic enrichment (manures/compost).

Case Study: The Aral Sea

• History: Once the 4th largest inland water body. Shrunk to $10\%$ of its size since the $1960s$.

• Cause: Former Soviet Union diverted tributary water for cotton irrigation ($100\,million\,cubic\,metres$ annually).

• Impact: Wiped out fishing communities and $90\%$ of fish species; created the Aralkum salt desert; increased concentration of pesticides in water.

WATER AND ITS MANAGEMENT

Global Water Distribution and the Water Cycle

• Total Water: $≈1386\,cubic\,metres$.

  • $96.6\%$ is saline (Oceans).

  • $2.5\%$ is Fresh Water ($68.7\%$ in glaciers/ice, $30.1\%$ groundwater, only $1.2\%$ surface/fresh water).

• Processes: Evaporation, Transpiration (plant loss), Condensation (clouds), Precipitation, Percolation (into rock), Infiltration (into soil).

Water Supply and Usage

• Groundwater: Extracted from Aquifers (permeable sandstone/limestone).

  • Example: Great Artesian Basin, Australia (underlies $23\%$ of the country).

• Desalination: Removing salt from seawater. Costs ≈US$3 per cubic metre; energy-intensive. Largest users: Saudi Arabia, Israel.

• Usage Patterns:

  • Global Average: $70\%$ Agriculture, $20\%$ Industry, $10\%$ Domestic.

  • LEDCs (Zambia): High agriculture use ($76\%$), low domestic ($16.5\%$ due to lack of appliances/piped water).

  • MEDCs (Belgium): High industrial ($62\%$ for nuclear cooling/steel) and domestic ($34\%$).

Multipurpose Dam Projects

• Functions: Irrigation, Hydroelectric Power ($24\%$ of global consumption; $90\%$ of renewable electricity), water supply, and flood control.

• Evaluating Impacts:

  • Benefits: Renewable energy, water security, trade improvement (navigation).

  • Costs: Resettlement (e.g., $1\,million$ people for Three Gorges), habitat destruction, increased methane emissions from rotting vegetation in reservoirs, and disease breeding ground (mosquitoes/snails).

Case Study: Three Gorges Dam, China

• Metrics: Cost US$25\,billion. Opened $2012$.

• Impacts: Generates $85\,billion\,kilowatt\,hours$/year (replaces $50\,million\,tonnes$ of coal). Displaced over $1.5\,million$ people from $1351$ villages. Dam blocks fish migration and nutrients reaching downstream farmland.

Managing Water-Related Disease

• Malaria: Vector-borne (Anopheles mosquito). Causes anaemia and seizures; $400\,000$ deaths/year. Managed via Prophylaxis (drugs), Vector Control (nets), and Indoor Residual Spraying.

• Cholera: Water-borne ($Vibrio\,cholera$ bacteria). Causes severe diarrhea/vomiting. Long-term management requires improved sanitation and Oral Rehydration Therapy.

THE ATMOSPHERE AND HUMAN ACTIVITIES

Structure and Pollution Causes

• Layers: Troposphere (weather), Stratosphere (ozone layer), Mesosphere, Thermosphere.

• Smog: Smoke + Fog. Caused by coal burning, vehicle emissions, and Photochemical Reactions triggered by sunlight on nitrogen oxides and VOCs (Volatile Organic Compounds).

• Enhanced Greenhouse Effect: Excess $CO_2$ and methane trap additional heat. Observed levels went from <300\,ppm historically to $407\,ppm$ in $2016$.

• Acid Rain: Sulfur/Nitrogen oxides mixing with water into sulfuric/nitric acid ($pH\,4$). Leaches aluminium from soil; kills fish/forests.

• Ozone Depletion: Caused by CFCs (Chlorofluorocarbons) used in aerosols/fridges. Leads to increased cataracts and skin cancer.

Management of Atmospheric Pollution

• Flue-Gas Desulfurisation: Scrubbing sulfur from power station emissions.

• Catalytic Converters: In cars, converting CO and nitrogen oxides to less toxic pollutants.

• International Policies: Montreal Protocol (1989) banned CFCs. Paris Agreement (2016) aims to limit global temperature rise to below $2^{\circ}C$.

• Carbon Sequestration: Planting forests (Afforestation/Reforestation) or injecting carbon into deep aquifers.

HUMAN POPULATION

Distribution and Structure

• Distribution Factors: Climate (temperate), Relief (flat land preferred), Soils (fertile loam), and Accessibility (coastal/valleys).

• Population Change: Birth Rate - Death Rate ± Net Migration.

• Demographic Differences:

  • LEDCs: Wide-based pyramids (high birth rate), many young dependents, high infant mortality, low life expectancy.

  • MEDCs: Narrow-based/straight-sided pyramids, ageing population (many older dependents), high life expectancy.

• Policies:

  • Anti-Natalist: Reduce birth rates. (e.g., China's One Child Policy prevented $≈400\,million$ births but created gender imbalance and shrinking workforce).

  • Pro-Natalist: Increase birth rates. (e.g., France offering $40\,weeks$ paid maternity and tax allowances for 3-child families).

NATURAL ECOSYSTEMS AND HUMAN ACTIVITIES

Foundational Concepts

• Ecological Niche: The unique way an organism is adapted to its habitat.

• Trophic Levels: Producers (level 1) → Primary Consumers (Level 2) → Secondary → Tertiary.

• Energy Flow: Energy is lost at each level ($90\%$ loss typical in transfer to respiration/waste).

• Interactions: Competition, Predation, Pollination, and Mutualism (e.g., oxpeckers on buffalo).

Deforestation

• Causes: Conversion for cattle ranching (Amazon), timber/logging, mining, oil palm (shared by Malaysia/Indonesia), and infrastructure (Trans-Amazonian Highway).

• Management: Sustainable harvesting of non-timber forest products (latex, Brazil nuts). SFI Certification for sustainable timber. Seed Banks (e.g., Millennium Seed Bank, UK) for preserving biodiversity.

Case Study: Conserving the Mountain Gorilla

• Status: Critically endangered ($880$ wild individuals).

• Threats: Hunting for ornaments, habitat fragmentation, and human disease (gorillas share $98\%$ human DNA).

• Successes: IGCP funding for anti-poaching patrols, snare collection, and controlled Ecotourism that channels the viewing fee income back into building local schools and clinics.

Formation of Rocks and the Rock Cycle

• Definition of Rock: Rock is the solid, naturally occurring material forming the Earth's hard outer layer or crust. It is typically composed of an aggregate of grains of various minerals (chemical elements).

• Igneous Rocks: Formed from the solidification of molten rock.

  • Plutonic (Intrusive): Created when magma cools and crystallizes slowly within the crust. Example: Granite (e.g., Combestone Tor, Dartmoor).

  • Volcanic (Extrusive): Formed when lava solidifies on the surface. Example: Basalt (e.g., Giant's Causeway).

• Sedimentary Rocks: Formed via Cementation.

  • Process: Rocks are broken down by weathering (e.g., freeze-thaw) and erosion. Sediments (mud, silt, sand, gravel, skeletons) build up in layers at the bottom of seas and are compressed over millions of years into strata.

  • Limestone: Primarily calcium carbonate from shells and marine skeletons.

  • Sandstone: Small sand grains, usually quartz, cemented by clay.

  • Shale: Consolidated mud, silt, and clay; splits into flat pieces.

• Metamorphic Rocks: Formed when existing rocks are subjected to heat and extreme pressure, causing chemical changes in minerals.

  • Slate: Formed from shale (used for roofing).

  • Marble: Formed from limestone (used for construction/design).

• The Rock Cycle: A continuous process of change. Weathering (physical, chemical, biological) breaks rock into sediments. Deposition and lithification create sedimentary rock. Heat and pressure create metamorphic rock. Melting produces magma, which cools into igneous rock.

Extraction of Rocks and Minerals from the Earth

• Surface Mining: Used when the ore body is near the surface.

  • Process: The overburden (soil/rock above) is removed using heavy machinery. Ore is excavated from flat terraces called benches. Includes open-cast, open-pit, or strip mining.

• Subsurface Mining: Removes minerals from deep underground.

  • Declines: Circular tunnels descending to the ore body.

  • Vertical/Inclined Shafts: Deep tunnels adjacent to ore; removed by lifts.

  • Adit: Horizontal shafts excavated into hillsides following ore levels.

• Economic Factors Affecting Mining Decision:

  • Ore Grade: The concentration of the desired chemical element in the mineral.

  • Reserves: The amount of ore available and its expected lifespan.

  • Market Price: Scaled against Capital Costs (setup) and Operating Costs (extraction/refining).

  • Geological Difficulties: Complexity of tunnels vs. open-cast.

  • Location: Remote environments increase costs for power, water, housing, and transport links.

Impact and Management of Rock and Mineral Extraction

• Economic Impacts:

  • Multiplier Effect: Creation of indirect jobs in supply companies (catering, security, machinery).

  • Trickledown Effect: Wages spent in the local community creating secondary jobs in services.

• Social Impacts:

  • Benefits: Infrastructure (transport, water), community projects (sports halls), and employee training.

  • Problems: Crime/drug use due to sudden disposable income, displacement from land, and erosion of traditional/indigenous ways of life.

• Environmental Impacts:

  • Habitat/biodiversity loss (land clearance), water pollution (Acid Rock Drainage from toxic sulfides), air pollution (dust/heavy metals), and soil erosion/sedimentation leading to flooding.

• Managing Impacts:

  • Remediation: Making sites safe by demolishing plants/machinery and disposing of hazardous waste in tailing ponds.

  • Restoration: Returning land to pre-mine use, typically open countryside or nature reserves (e.g., Stanwick Lakes, UK).

  • Reuse: Converting sites for economic benefit, such as motor racing circuits (Gotland Ring, Sweden), gardens (Butchart Gardens, Canada), or aquaculture (Homase mine, Ghana).

Sustainable Use of Rocks and Minerals

• The Sustainability Challenge: Minerals are non-renewable and finite (e.g., Copper exhausted by $2050-2070$, Uranium by $2085$, Indium by $2035$).

• Sustainable Development: Balancing growth with resource preservation.

• Extending Reserves: Use of modern technology for efficient extraction; substituting scarce minerals (e.g., Al for Cu in power lines); recycling ($EU$ rule: 65 ext{%} of electronic waste by $2019$).

• Increasing Reserves: Exploration of seabeds (manganese nodules carrying nickel, cobalt) at depths of $4000-5000 \, ext{metres}$.