AP Environmental Science -

Unit 1: Ecosystems

1.1 Introduction to Ecosystems

• Predator-prey relationship:
  • Predator: Organism that eats another organism.
  • Prey: Organism eaten by a predator.
• Symbiotic Relationships (Symbiosis): Relationship between two species in an ecosystem.
  • Mutualism: Both species benefit.
  • Commensalism: One species benefits, and the other is not affected.
  • Parasitism: One species benefits (parasite), and the other is harmed (host).
• Competition: Occurs when resources are limited, reduced by resource partitioning.

1.2 Terrestrial Biomes

• Biome: Area with characteristic plants and animals defined by climate (temperature and precipitation).
• Types of Biomes:
  • Taiga (Boreal, Northern coniferous forest)
  • Temperate rainforests
  • Temperate seasonal forests (deciduous)
  • Tropical rainforests
  • Shrubland
  • Temperate grasslands
  • Savanna
  • Desert
  • Tundra
• Factors Influencing Global Distribution of Resources: Climate, Geography, Latitude, Altitude, Nutrient availability, Soil.

1.3 Aquatic Biomes

• Freshwater Biomes: Streams, Rivers, Ponds, Lakes; vital resource for drinking water.
• Marine Biomes: Oceans, coral reefs, marshland, estuaries; Algae supplies large amount of O2 and removes CO2 from the atmosphere (through photosynthesis).
• Factors Influencing Global Distribution of Resources: Salinity, depth, turbidity, nutrient availability, temperature.

1.4 Carbon Cycle

• Reservoirs: Plants, animals, fossil fuels, atmosphere.

1.5 Nitrogen Cycle

• Reservoirs: Atmosphere, plants, animals.
• Nitrogen fixation: N2 converted to NH3, NO2^-, NO3^-.

1.6 Phosphorus Cycle

• Reservoirs: Rocks, soil, water, plants.
• No atmospheric component (no gaseous form).
• Limiting Factor in ecosystems because it is scarce.

1.7 Hydrologic (Water) Cycle

• Reservoirs: Oceans, ice caps, groundwater.

1.8 Primary Productivity

• Rate at which solar energy (sunlight) is converted into organic compounds through Photosynthesis.
• GPP (Gross Primary Productivity): Total rate of photosynthesis in an area.
• NPP (Net Primary Productivity): NPP = GPP - Respiration

1.9 Trophic Levels

(No specific information given in the transcript)

1.10 Energy Flow & 10% Rule

• 1st Law of Thermodynamics: Total amount of energy stays the same.
• 2nd Law of Thermodynamics: As energy changes from one form to another, some is lost as heat.

1.11 Food Chains & Food Webs

• Food Chain
• Food Web
• Feedback loops compared

Unit 2: Biodiversity

I. Levels of Diversity

• Species diversity (biodiversity)
• Ecosystem diversity
• Genetic diversity

II. Benefits of Biodiversity

• Species are connected to ecosystems
• For species and population survival
• Medical, industrial, and agricultural uses
• Ethics, aesthetics, and recreation

III. Species at Risk

• Small populations in limited areas
• Those that migrate
• Those that need large or special habitats
• Exploited by humans

IV. How Humans Affect Biodiversity (HIPPO)

• H – Habitat Destruction/Alteration/Fragmentation
• I – Invasive/exotic/alien species
• P – Pollution
• P – Human population growth
• C – Climate Change
• O – Overexploitation – harvesting, hunting, poaching
• Disease - can sometimes be caused/spread by us

V. Areas of Critical Biodiversity

• Tropical Rain Forests
• Coral Reefs & Coastal Ecosystems
• Islands

VI. Ways to Protect Biodiversity

• Captive-breeding programs
• Preserving genetic material (germ-plasm banks)
• Zoos, Aquariums, Parks, Botanical Gardens
• Education
• Preserving habitats and ecosystems (BEST METHOD)

VII. Endangered Species Act

• Established by US Congress in 1973
• USFWS must compile a list of endangered & threatened species
• Species on the list may not be caught or killed, uprooted from federal lands, sold or traded
• The federal government may not carry out any project that jeopardizes species on the list
• USFWS must prepare a recovery plan for species on the list

2.1 Introduction to Biodiversity

• Biodiversity: Variety of different species
• Species: Set of individuals who can mate and produce fertile offspring
  • 8 million to 100 million species estimated
  • About 2 million identified
  • Unidentified species are mostly in rain forests and oceans
• The more genetically diverse a population is, the better it can respond to environmental stressors. Additionally, a population bottleneck can lead to a loss of genetic diversity.
• Ecosystems that have a larger number of species are more likely to recover from disruptions.
• Loss of habitat leads to a loss of specialist species, followed by a loss of generalist species. It also leads to reduced numbers of species that have large territorial requirements.
• Species richness refers to the number of different species found in an ecosystem.
• Regionally extinct: In areas a species is normally found
• Functionally extinct: To the point at which species can no longer play a functional role in the ecosystem

2.2 Ecosystem Services

• There are four categories of ecosystem services: provisioning, regulating, cultural, and supporting.
• Anthropogenic activities can disrupt ecosystem services, potentially resulting in economic and ecological consequences.

2.3 Island Biogeography

• Island biogeography is the study of the ecological relationships and distribution of organisms on islands, and of these organisms’ community structures.
• Islands have been colonized in the past by new species arriving from elsewhere.
• Many island species have evolved to be specialists versus generalists because of the limited resources, such as food and territory, on most islands. The long-term survival of specialists may be jeopardized if and when invasive species, typically generalists, are introduced and outcompete the specialists.

2.4 Ecological Tolerance

• Ecological tolerance refers to the range of conditions, such as temperature, salinity, flow rate, and sunlight that an organism can endure before injury or death results. Ecological tolerance can apply to individuals and to species.

2.5 Natural Disruptions to Ecosystems

• Natural disruptions to ecosystems have environmental consequences that may, for a given occurrence, be as great as, or greater than, many human-made disruptions.
• Earth system processes operate on a range of scales in terms of time. Processes can be periodic, episodic, or random.
• Earth’s climate has changed over geological time for many reasons.
• Sea level has varied significantly as a result of changes in the amount of glacial ice on Earth over geological time.
• Major environmental change or upheaval commonly results in large swathes of habitat changes.
• Wildlife engages in both short- and long-term migration for a variety of reasons, including natural disruptions.

2.6 Adaptations

• Organisms adapt to their environment over time, both in short- and long-term scales, via incremental changes at the genetic level.
• Environmental changes, either sudden or gradual, may threaten a species’ survival, requiring individuals to alter behaviors, move, or perish.

2.7 Ecological Succession

• There are two main types of ecological succession: primary and secondary succession.
• Primary succession begins with a lifeless area where there is no soil (ex. bare rock). Soil formation begins with lichens or moss.
• A keystone species in an ecosystem is a species whose activities have a particularly significant role in determining community structure.
• An indicator species is a plant or animal that, by its presence, abundance, scarcity, or chemical composition, demonstrates that some distinctive aspect of the character or quality of an ecosystem is present.
• Pioneer members of an early successional species commonly move into unoccupied habitat and over time adapt to its particular conditions, which may result in the origin of new species.
• Lichens – pioneer species
• Foundation species can create and enhance habitats that can benefit other species in a community. Elephants push over, break, or uproot trees, creating forest openings promoting grass growth for other species to utilize.
• Succession in a disturbed ecosystem will affect the total biomass, species richness, and net productivity over time.

Unit 3: Populations

3.1 Generalist and Specialist Species

• Generalists can live in a variety of habitats or feed on a variety of species
• Specialists are specialized to live in a specific habitat or feed on a small group of species
• Niche specialists are vulnerable to extinction if conditions change because the loss of a favored habitat or food source leaves them with few alternatives for survival
• Niche generalists fare better under changing conditions because they have a number of alternative habitats and food sources available

3.2 K-selected and r-selected Species

• K-Selected Species have a low intrinsic growth rate and their abundance is determined by the carrying capacity of the environment.
  • Traits of K-selected species: large organisms, reach reproductive maturity relatively late in life, have few, large offspring, provide substantial parental care (ex. elephants)
• r-Selected Species have a high intrinsic growth rate and do not remain near their carrying capacity, but exhibit cycles of overshoots and die-offs.
  • Traits of r-selected species: small organisms, reach reproductive maturity relatively early in life, reproduce frequently and have many, small offspring, provide little or no parental care (ex. insects)

3.3 Survivorship Curves

• Survivorship curves are species’ distinct patterns of survival over time.
  • Type I survivorship curves: high survival rates throughout most of the species’ life spans with large numbers of die-offs as they approach old age (K- selected)
  • Type II survivorship curves: relatively constant decline in survivorship throughout the species’ life spans (ex. small birds and mammals)
  • Type III survivorship curves: low survivorship early in life with few individuals reaching adulthood (r-selected)

3.4 Carrying Capacity

• The exponential growth model describes a continuously increasing population that grows at a fixed rate; produces a J-shaped curve when it is graphed
• The logistic growth model describes a population whose growth is initially exponential, but slows as the population approaches the carrying capacity of the environment; produces an S-shaped curve when it is graphed.
• If a population overshoots the environment’s carrying capacity there is less food available than needed to feed the offspring; this can produce a die-off, or population crash

3.5 Population Growth and Resource Availability

• Density-dependent factors have a greater effect on the population as its density increases. (ex. food availability, parasites, diseases)
• A limiting resource is a resource that a population cannot live without and which occurs in quantities lower than the population would require to increase in size.
• Density-independent factors affect a population’s size regardless of its density. (ex. natural disasters)

3.6 Age Structure Diagrams

• Age structure diagrams are visual aids that show the distribution of males and females in each age group.
• If a country has more young people than old people, its age structure diagram will be wider at the bottom, this is called a population pyramid.
• Countries with little difference between the numbers of individuals in different age groups looks more like a column.
• A country with more older than younger people has a diagram that resembles an inverted pyramid.

3.7 Total Fertility Rate

• Total fertility rate (TFR) is an estimated of the average number of children that each woman in a population will bear throughout her reproductive years. (2.1 in the US)
• Replacement-level fertility is the TFR required to offset the average number of deaths in a population so that the current population size remains stable.
• Infant mortality rate is the number of babies out of every 1,000 born who die before their first birthday; availability of prenatal care is an important predictor of infant mortality.

3.8 Human Population Dynamics

• In 1798 Thomas Malthus noticed that the human population was growing exponentially while the food supply was only growing linearly; he concluded that the human population would eventually exceed its food supply.
• Doubling time is the number of years it takes for a population to double, assuming the growth rate is constant.; doubling time (in years) = 70/growth rate

3.9 Demographic Transition

• The theory of demographic transition states that as a country moves from a subsistence economy to industrialization and increased affluence, it undergoes a predictable shift in population.
  • Phase One: preindustrial; early steady state (high birth & death rates); short life expectancy, high infant mortality rate; subsistence economy
  • Phase Two: transitional; death rates decline while birth rates remain high (large TFR); better sanitation, clean drinking water, increased access to food, goods & health care (vaccines)
  • Phase Three: industrial; birth rate & death rates decrease (return to steady state); economy & educational system improve, income increases
  • Phase Four: postindustrial; declining population, higher proportion of elderly people; pension programs and social security strained; people need to immigrate in to care for elderly

Unit 4: Earth Systems and Resources

4.1 Plate Tectonics

• Earth’s structure
  • Lithosphere
  • Mantle
  • Core
• 3 Plate Boundary Types
  • Convergent
  • Divergent
  • Transform
• Subduction Zones
• Earthquakes (Richter scale)
• Volcanoes

4.2 Soil Formation & Erosion

• Weathering (biological, chemical, physical)
• Transportation
• Erosion
• Deposition
• Soil Horizons
  • O
  • A
  • E
  • B
  • C
  • R

4.3 Soil Composition & Properties

• Water Holding Capacity
• Porosity (pore space)
• Permeability (rate of water flow)
• Soil Testing
  • Nutrients (N, P, K)
  • pH
  • Texture
• Soil Triangle
  • Sand
  • Silt
  • Clay

4.4 Earth’s Atmosphere

• Current Composition
  • 78% Nitrogen
  • 21% Oxygen
  • 0.9% Argon
  • 0.03% CO_2
• Layers & Characteristics
  • Troposphere
    • Weather
    • Greenhouse Gases
  • Stratosphere
    • Ozone (UV filter)
  • Mesosphere
    • Meteors burn up
  • Thermosphere
    • Aurora Borealis
  • Exosphere
• Temperature Changes

4.5 Global Wind Patterns

• Winds blow from high to low pressure (from sinking cool air to rising warm air)
• Convection Cells
  • Hadley
  • Ferrel
  • Polar
• Coriolis Effect

4.6 Watersheds

• Topography
• Precipitation
• Percolation
• Tributaries
• Rivers
• Groundwater
• Divide

4.7 Solar Radiation & Earth’s Seasons

• Earth’s Axis has 23^o Tilt
• Rotation
• Insolation
• Angle of Incidence (zero at the equator, 90^o at the poles)
• Latitude
• Hemispheres
• Hours of sunlight

4.8 Earth’s Geography & Climate

• Ocean Currents move heat from equator
• Temperature moderating effect of large bodies of water
• Land heats/cools faster than oceans
• Rainshadow Effect

4.9 El Nino & La Nina

• Pacific Ocean
• Normal/Neutral
  • Winds blow E-W
  • Upwelling in S. America
  • Warm & wet in Asia
• El Nino
  • Winds weaken or stop
  • Upwelling stops
  • Warm & wet in S. America
• La Nina
  • “extreme” normal

Unit 5: Land & Water Use

5.1 The Tragedy of the Commons

• Individuals use shared resources selfishly, resulting in depleted resources.

5. 2 Clearcutting

• Removal of all trees from an area
  • Advantage: More land for crops/animals leading to economic benefit
  • Disadvantages: Increases soil erosion, soil & stream temps., flooding, atmospheric CO2

5.3 The Green Revolution

• Use of mechanization, GMOs, fertilization, irrigation, pesticides to INCREASE food production
  • Advantage: Increases profits & efficiency
  • Disadvantage: Increased use of fossil fuels

5.4 Impact of Agricultural Practices

• Practices include tilling, slash-and-burn farming, use of fertilizers
• Causes eutrophication, soil degradation, habitat destruction, erosion

5.5 Irrigation Methods

• 70% of freshwater used for irrigation
• Excess irrigation leads to Waterlogging - excess water in soil, raises water table, inhibits plant root absorption of O2
• Types:
  • Furrow irrigation: furrows flooded between crop rows
    • Inexpensive
    • Low efficiency (approx. 50% water loss)
  • Flood irrigation: flooding field
    • Low efficiency (approx. 20% water loss)
    • Leads to waterlogging
  • Spray irrigation: spray water across field from sprinkler system
    • Low efficiency (approx. 25% water loss)
    • Expensive
    • Requires energy to run (fossil fuels)
  • Drip irrigation: water released through perforated hoses at plant roots
    • Higher efficiency (approx. 5% water loss)
    • Expensive
• Salinization: salts in groundwater remain in soil after water evaporates, causing soil to become toxic to plants
• Aquifers: underground freshwater reservoirs depleted due to overuse for agricultural irrigation EX: Ogallala Aquifer

5.6 Pest Control Methods

• Common methods include: pesticides, herbicides, fungicides, rodenticides, insecticides
• Leads to Resistance -decreases crop damage -increases crop yields
• GMOs (Genetically Engineered Crops) increase resistance to pests, crops -leads to loss of genetic diversity

5.7 Meat Production

• CAFOs (Confined Animal Feeding Operation)
  • Produces large amounts of food fast
  • Crowded - so use antibiotics more
  • Feed is grains, not grass
  • Produce large amounts of waste
  • Less expensive & consumer costs are decreased
• Free range grazing
  • Feed on grass
  • Less crowded - use less antibiotics
  • Requires lots of land
  • More expensive product for consumer
• Meat production is less productive than agriculture
  • Takes approx. 20 times more land to produce same amount of calories from meat as from plants
• Overgrazing
  • Causes decreased vegetation, soil erosion, desertification
• Advantages of Reduced Meat Consumption
  • Reduces CO2, CH4, N_2O gas emissions
  • Conserves water
  • Reduces use of antibiotics, growth hormones
  • Improves topsoil

5.8 Impacts of Overfishing

• Decreased fish populations and biodiversity
• Reduced income and food sources

5.9 Impacts of Mining

• Habitat destruction, soil degradation, increased turbidity due to erosion/sedimentation, increased fossil fuel use, increases waste & pollution acid mine drainage
• Surface mining: removal of soil/rock (overburden) increases erosion
• Slag/tailings: waste remaining when mineral is extracted from ore
• Subsurface mining: deeper, underground removal of ores more expensive

5.10 Urbanization

• Urban sprawl: change in population distribution from cities to suburbs Results in:
  • Increased impervious surfaces (roads, buildings, sidewalks, parking lots) which decreases water infiltration and increases flooding
  • Decreases vegetation (less infiltration - more erosion)
  • Increased CO_2
  • Habitat destruction
  • Increased temperatures
  • Depletion of groundwater sources (aquifer depletion, saltwater intrusion)

5.11 Ecological Footprints

• Shows resource use and waste production required for individual or group

5.12 Introduction to Sustainability

• Sustainability: using resources in ways that don’t deplete amounts available for future use
• Sustainable yield: amount of a renewable resource that can be taken without reducing available supply

5.13 Methods to Reduce Urban Runoff

• Increase water infiltration by:
  • Use permeable pavement
  • Plant trees
  • Use public transportation
  • Build vertically

5.14 Integrated Pest Management

• Pest control methods that minimize environmental damage Reduces pesticide use complex and expensive Include:
  • Biocontrol
  • Intercropping
  • Crop rotation
  • Natural predators

5.15 Sustainable Agriculture

• Soil conservation methods
  • Contour plowing
  • Windbreaks
  • Perennial crops
  • Terracing
  • No-till
  • Strip cropping
  • Crop rotation
  • Rotational grazing

5.16 Aquaculture

• Fish and aquatic plants farming
  • Advantages: efficient, uses small areas of water & amounts of fuel
  • Disadvantages: contamination from wastes, escapees competing/breeding with wild fish (decreases biodiversity, introduces diseases into wild population)

5.17 Sustainable Forestry

• Ways to decrease Deforestation
  • Reforestation
  • Use ecologically sustainable wood
  • Reuse wood
• Reduction of Pests
  • Integrated Pest Management
  • Removal of infected trees
• Prescribed burns: controlled fires in forests to reduce occurrence of natural fires

Unit 6: Energy Resources & Consumption

Important Concepts

• Fossil Fuels, Nuclear Fuel, Nonrenewable vs. Renewable Resources, Turbine, Electrical Grid, Energy Carrier, Cogeneration, Capacity, Combined Cycle, Commercial vs. Subsistence Energy Source, Energy Efficiency

6.1 Renewable and Nonrenewable Energy Sources

• Nonrenewable energy sources are those that exist in a fixed amount and involve energy transformation that cannot be easily replaced.
• Renewable energy sources are those that can be replenished naturally, at or near the rate of consumption, and reused.

6.2 Global Energy Consumption

• The use of energy resources is not evenly distributed between developed and developing countries.
• The most widely used sources of energy globally are fossil fuels.
• As developing countries become more developed, their reliance on fossil fuels for energy increases.
• As the world becomes more industrialized, the demand for energy increases.
• Availability, price, and governmental regulations influence which energy sources people use and how they use them.

6.3 Fuel Types and Uses

• Wood is commonly used as fuel in the forms of firewood and charcoal. It is often used in developing countries because it is easily accessible.
• Peat is partially decomposed organic material that can be burned for fuel.
• Three types of coal used for fuel are lignite, bituminous, and anthracite. Heat, pressure, and depth of burial contribute to the development of various coal types and their qualities.
• Natural gas, the cleanest of the fossil fuels, is mostly methane.
• Crude oil can be recovered from tar sands, which are a combination of clay, sand, water, and bitumen.
• Fossil fuels can be made into specific fuel types for specialized uses (e.g., in motor vehicles).
• Cogeneration occurs when a fuel source is used to generate both useful heat and electricity.

6.4 Distribution of Natural Energy Resources

• The global distribution of natural energy resources, such as ores, coal, crude oil, and gas, is not uniform and depends on regions’ geologic history.

6.13 Energy Conservation

• Some of the methods for conserving energy around a home include adjusting the thermostat to reduce the use of heat and air conditioning, conserving water, use of energy-efficient appliances, and conservation landscaping.
• Methods for conserving energy on a large scale include improving fuel economy for vehicles, using BEVs (battery electric vehicles) and hybrid vehicles, using public transportation, and implementing green building design features
• Ecological Disasters Occurred with fossil fuels and nuclear energy
  • Oil spills kill wildlife and are difficult to contain/clean up
  • Nuclear meltdowns cause cancer and make the land unsafe for decades
  • Coal mining is dangerous
• Energy Units
  • Joule = basic unit of energy
  • Gigajoule (GJ) = 1 billion joules
  • Exajoule (EJ) = 1 billion gigajoules
  • 1 quad = 1 quadrillion BTU = 1.5 EJ
• World Energy Consumption
  • Development → increased energy use
  • Subsistence energy use is higher in rural areas; commercial energy sources are more important in urban centers/developed nations
• US energy usage
  • 1973 OPEC Oil Embargo Oil was used as a political weapon
  • So much is tied to oil production, if oil prices rise other areas suffer
  • Today oil > natural gas > coal > renewable > nuclear
• Energy Return on Energy Investment (EROEI)
  • How does EROEI exacerbate the concept of peak oil?
• Powerplants
  • Most US power plants have a capacity of 500 MW.
  • Why should a power plant’s capacity always be greater than the town’s average or even maximum electrical use?
  • Half of power plant capacity additions in 2013 came from natural gas
  • Natural gas-fired power plants accounted for just over 50% of new utility-scale generating capacity added in 2013. Solar provided nearly 22%, a jump up from less than 6% in 2012. Coal provided 11% and wind nearly 8%. Almost half of all capacity added in 2013 was located in California.
  • In total, a little over 13,500 megawatts (MW) of new capacity was added in 2013, less than half the capacity added in 2012

6.5 Fossil Fuels

• The combustion of fossil fuels is a chemical reaction between the fuel and oxygen that yields carbon dioxide and water and releases energy.
• Energy from fossil fuels is produced by burning those fuels to generate heat, which then turns water into steam. That steam turns a turbine, which generates electricity.
• Humans use a variety of methods to extract fossil fuels from the earth for energy generation.
• Hydrologic fracturing (fracking) can cause groundwater contamination and the release of volatile organic compounds.
• Coal combustion releases air pollutants including carbon dioxide, sulfur dioxide, toxic metals, and particulates.
• The combustion of fossil fuels releases nitrogen oxides into the atmosphere. They lead to the production of ozone, formation of photochemical smog, and convert to nitric acid in the atmosphere, causing acid rain. Other pollutants produced by fossil fuel combustion include carbon monoxide, hydrocarbons, and particulate matter.
• Air quality can be affected through the release of sulfur dioxide during the burning of fossil fuels, mainly diesel fuels.
• Through the Clean Air Act, the Environmental Protection Agency (EPA) regulated the use of lead, particularly in fuels, which dramatically decreased the amount of lead in the atmosphere.
• Air pollutants can be primary or secondary pollutants.
• Global climate change, caused by excess greenhouse gases in the atmosphere, can lead to a variety of environmental problems including rising sea levels resulting from melting ice sheets and ocean water expansion, and disease vectors spreading from the tropics toward the poles. These problems can lead to changes in population dynamics and population movements in response.
• Fossil Fuel Formation
  • The formation of fossil fuels requires the burial and compression of organic materials under anaerobic conditions → prevents decomposition.
  • Three Types of Fossil Fuels:
    • Coal (solid), Oil/Petroleum (liquid), Natural gas (gas), Terrestrial life → coal Aquatic life → oil/natural gas
• Three primary types of coal:
  • Lignite (lowest energy and lowest %carbon)
  • Bituminous (US has the most, but high sulfur content)
  • Anthracite (highest energy and most %carbon)
  • More carbon = fewer impurities, cleaner
• Peat is a precursor to coal and is composed of partially decomposed organic matter
  • Coal requires mining, usually strip mining
• Coal Formation When vegetation is rapidly buried and compressed it forms peat → lignite → coal Peat: soil-like material consisting of partly decomposed vegetable matter. Lignite: a soft brownish coal showing traces of plant structure, intermediate between bituminous coal and peat. Coal: a combustible rock consisting mainly of carbonized plant matter, found mainly in underground deposits and widely used as fuel
• Coal Reserves Top 5: US, Russia, China, India, Australia
• Coal Advantages and Disadvantages
  • Advantages: Cheap, plentiful, easily mined
  • Disadvantages: Combustion of coal produces CO_2, Very dirty- lots of impurities like sulfur → acid rain and other ecological effects, Produces lots of ash as waste
• Petroleum Types Crude oil: liquid petroleum pumped from the ground
• Oil sands and oil shale: “solid petroleum”, petroleum mixed with soil. Heavy and viscous form of oil. Also called tar sand.
• Petroleum Reserves
  • Petroleum forms in a similar manner to coal. Requires burial, compression and time. The other major difference is that petroleum is liquid, but coal is solid and petroleum forms from phytoplankton. The Middle East has the greatest reserves of petroleum and has dominated the market for decades.
• Peak Oil There is effectively a fixed amount of oil available on Earth.
  • Oil production will increase until we reach the 50% mark (50% of oil has been extracted) and then reduce continually. Price of oil decreases before the 50% mark and then increases continuously after the 50% mark. This is similar to the concept of maximum sustainable yield, except the population (oil) has no growth rate
• Hubbert Curve
  • Production of any resource will increase until it reaches peak production. This model predicts that peak production occurs when 50% of the resource has been extracted. After this point, production will decrease. Increasing production increases supply and lowers price. The opposite is also true
    How has technology prevented the predictions of the Hubbert Curve from becoming true?
• Petroleum Advantages and Disadvantages
  • Liquid → easy to transport, Cleaner and more energy dense than coal
  • Still has impurities, More mobile → oil spills, Greenhouse gases produced by combustion
• Natural Gas The primary ingredient of natural gas is methane (80-95%). The remaining portion is a combination of ethane, propane and butane
• Natural Gas is recovered through wells. These are generally drilled into shale rock. Natural Gas Advantages and Disadvantages Arguments: Great for heating (cogeneration), Cleaner than oil or coal (fewer impurities), Less CO_2 released than other fossil fuels Disadvantages: Methane (primary component of natural gas) is a terrible greenhouse gas, Exploration is disruptive (thumper trucks), Extraction is damaging (fracking)

6.6 Nuclear Power

• Nuclear power is generated through fission, where atoms of Uranium-235, which are stored in fuel rods, are split into smaller parts after being struck by a neutron. Nuclear fission releases a large amount of heat, which is used to generate steam, which powers a turbine and generates electricity.
• Uranium-235 remains radioactive for a long time, which leads to the problems associated with the disposal of nuclear waste.
• Nuclear power generation is a nonrenewable energy source. Nuclear power is considered a cleaner energy source because it does not produce air pollutants, but it does release thermal pollution and hazardous solid waste.
• Uranium-235 remains radioactive for a long time, which leads to the problems associated with the disposal of nuclear waste
• Three Mile Island, Chernobyl, and Fukushima are three cases where accidents or natural disasters led to the release of radiation. These releases have had short- and long-term impacts on the environment.
• A radioactive element’s half-life can be used to calculate a variety of things, including the rate of decay and the radioactivity level at specific points in time
• Originally deemed risky/expensive compared to fossil fuels. But interested peaked in 1970s with the gas crisis, Accidents limited public interest
• Light Water Nuclear Reactors Cheaper than other types of reactors though not as effective (1% efficiency) Fuel