AP Environmental Science Study Guide (Ultimate – Every Unit)

This AP Environmental Science Study Guide will teach you about every unit in AP Environmental Science. There are 9 Units in APES. This is your ultimate AP Environmental Science Study Guide! This AP Environmental Science Study guide can be used to help you score a 5 on the AP exam by giving you a quick review of topics you need to know that you might have forgotten about.

Unit 1 AP Environmental Science Study Guide

Below is an AP Environmental Science Study guide for Unit 1:

ap environmental science study guide


  • general location of major terrestrial biomes (i.e. tropical rainforest around  equator, Taiga in northern latitudes)  
    • Be able to use degrees of latitude. Equator = 0°; tundra = 90°
BiomeImportant Characteristics
                          Temperate Grasslands Moderate temperatures, low precipitation, fires, 30-45° latitude
DesertHigh temperatures, low precipitation, 30° latitude
Temperate RainforestModerate temperatures, high rainfall, 30-45° latitude
Temperate Deciduous Forest (Chicago!)Moderate temperatures, moderate rainfall, 30-45° latitude
Shrubland (Chaparral)Moderate temperatures, moderate to low precipitation, frequent fires, 30-40°  latitude 
TundraLow temperatures, low precipitation, 60-90° latitude
Tropical RainforestHigh temperatures, high precipitation, poor soil health, 0° latitude
Taiga (Boreal Forest)Moderate to low temperatures, moderate rainfall, 45-60°
SavannaHigh temperatures, moderate rainfall, 20-30° latitude
  •   the general climate of major terrestrial biomes 
    •    match a climatogram to a particular biome 
  •    the major characteristic animals and plants of each major biome  
  •   the general characteristics of aquatic biomes
BiomeImportant Characteristics

Streams & 


Freshwater, begin at a sourcewater, fast moving and clear water,  

Ponds & 


Freshwater, lots of phytoplankton and zooplankton, 
OceansSaltwater, houses the majority of aquatic life
Coral ReefsSaltwater, high biodiversity,
MarshlandCan be freshwater or saltwater, lots of wetland plants
EstuariesWhere saltwater and freshwater meet, low biodiversity due to how difficult it is to live in this type of environment.  

Species Interactions 

  • recognize and explain ecological relationships between organisms 
  • Mutualism 
  • Both organisms benefit 
  • Commensalism 
  • One organism benefits; other organism unaffected 
  • Parasitism  
  • One organism benefits; other organism harmed 
  • Predator/prey 
  • Predator organism eats other organism (prey)
  • Competition  
  • Occurs within or between species in areas where resources such as food, shelter, and mates are limited
  • Resource partitioning
  • Resources are used in a different way, place, or time & reduce the impact of competition 

BioGeoChemical Cycles

  • **I highly recommend watching youtube videos about these on your own time
  • Know the major cycles and be able to identify the major reservoirs and fluxes
    • Hydrological (Water) cycle
      • Reservoir: Ocean
      • Major fluxes:
        • Evaporation/Transpiration (powered by light, not heat!)
        • Sublimation
        • Precipitation
        • Snowmelt/Runoff
        • Infiltration/Percolation
      • How have people affected the water cycle?
        • We use significant amounts of groundwater for drinking
        • Deforestation
    • Carbon Cycle
      • Main reservoir: the lithosphere! (fossil fuels, rocks)
      • Major fluxes: 
        • Photosynthesis
        • Respiration
        • Combustion
        • Sedimentation
        • Absorbed into the ocean
      • How have people affected the carbon cycle?
        • Combustion of fossil fuels
        • Deforestation
        • Animal Agriculture
    • Nitrogen Cycle
      • Main reservoir: the atmosphere!
      • Major fluxes:
        • Nitrogen fixation
        • Nitrification
        • Denitrification
        • Fluxes are facilitated by bacteria!
      • How have people affected the nitrogen cycle?
        • Fertilizers
        • Fossil fuel combustion
    • Phosphorus Cycle 
      • Main reservoir: the lithosphere!
        • No significant atmospheric residency
      • Major fluxes:
        • Weathering
      • How are people affecting the phosphorus cycle?
        • Fertilizer
        • Animal agriculture
        • Mining
        • Municipal waste systems

Energy Flow

  •   the basics of energy
      • Energy conversions, 1st and 2nd law of thermodynamics
  •   how to calculate GPP, NPP, and/or Respiration Rate given enough information
      • NPP = GPP – R 
      • GPP = NPP + R 
      • Be aware the units for this can vary wildly
      •  Most commonly the unit is Kcal/m2/year 
  •    estimate the amount of energy transferred from each trophic level 
        • PP: 100,000
        • PC: 10,000
        • SC: 1,000
        • TC: 100
  •     draw and interpret food webs based on feeding relationships 
    • Producers: plants (autotrophs)
    • Primary consumers: herbivores (eat producers)
    • Secondary consumers: carnivores or omnivores (eat primary consumers) 
    • Tertiary consumers: carnivores (eat secondary consumers) 
    • Autotrophs: organisms that can produce their own food using light energy
    • Heterotrophs: organisms that eat other plants and/or animals for energy & nutrients
    • Herbivores: organisms that eat plants 
    • Omnivore: organisms that eat plants and other organisms
    • Carnivore: organisms that eat other organisms

AP Environmental Science Unit 2 AP Environmental Science Study Guide (biodiversity)

Below is an AP Environmental Science Study guide for Unit 2:

Species Concepts

○ Keystone Species 

  • Species that other species depend on in an ecosystem to maintain the food chain and order
  • Stop one species from taking over and overpopulating
  • Ex: starfish, wolves
  • Indicator species: serve as a measure of environmental conditions and give scientists a quick idea about the health, quality, and characteristics of an area 

○ Generalist and Specialist species 

  • Specialists
  • Organisms that require very unique resources and need a specific habitat to survive; very high maintenance
  • Specialists more likely to decline in ecological disturbance because of exact needs
  • Specialists are commonly found on islands
  • This is because there is a high habitat diversity
  • More sensitive to economic disturbances 
  • Generalist
  • Organisms that are able to thrive in many different conditions and can use a variety of resources; very flexible

○ Ecological tolerance 

  • Range of conditions like temperatures, salinity, sunlight that an organism can endure before injury or death
  • Evolution and Natural Selection                                                                                                                                        
  • Ecological disturbance
    • Organisms can alter behavior, move, or perish/die

■ Natural Selection 

  • Theory that certain traits are favored among a population and passed down
  • Happens over a long period of time
  • 4 principles:
  • Individuals in a population have a genetic variation that can be passed down
  • More individuals are born in a population than can be supported by the environment
  • Individuals with the best variations of genes are more likely to survive and reproduce
  • Adaption: traits that are uniquely suited to an organism’s survival in a particular habitat
  • Traits best suited to survival are passed down to offspring

○ How do new species arise? 

■ Arise through speciation

■ Geographic isolation 

  • Species are separated by a physical barrier such as a river, mountain, landmass causing new populations of a species to come into being due to new adaptations to new locations 

■ Reproductive isolation 

  • When species evolve and become so genetically diverse they can no longer reproduce with one another

○ How do we lose species? 


○ The special case  ;of island biodiversity: 

■ Island biogeography. 

  • The closer an island is to the mainland and the bigger it is, the more species will inhabit it
  • Islands inhabited through colonization
  • Mammals least likely to colonize islands as they don’t have a designed mode of transportation such as flying or swimming for long periods of time

■ Unique adaptations on islands from unique selective pressures. 

  • Biodiversity 

Species richness

  • The total variety of species in a designated area 

○ Species evenness 

  • How close in population is the distribution of each species
  • Factors affecting biodiversity 

What leads some areas to have more diversity than others? 

  • Climate

○ How do human activities affect biodiversity? 

  • Human pollution can damage biodiversity in an ecosystem (pollution can be toxic to species). 
  • Humans can damage or destroy habitats as well.

○ Resilience 

■ What is meant by the resiliency of an ecosystem? 

  • is the ability of an ecosystem to maintain its normal conditions after being affected by an ecological disturbance.

■ What helps an ecosystem be more resilient? 

  • Greater biodiversity at the ecosystem, species, and individual level can help an ecosystem to be more resilient.
  • This is because if an invasive species destroys a certain species, the other species will still be there and not be affected

■ What is meant by disturbance? 

  • Periodic 
  • disturbances occur with regular frequency 
  • Ex. wet and dry seasons
  • Episodic 
  • disturbances occur occasionally with irregular frequency
  • Ex. Droughts, fires, severe hurricanes
  • Random 
  • disturbances with no regular frequency
  • Ex. Volcanic eruptions, earthquakes, and asteroids 
  • Why Biodiversity is important 

○ Ecosystem Services (be able to provide examples of each) 


  • are non-material benefits that people get from ecosystems. 
  • Examples: Ecotourism, recreation, culture heritage or spiritual purposes, etc

■ Regulating

  • are things that moderate natural phenomena within an ecosystem
  • Examples: Pollination, water purification, erosion and flood control, decomposition, etc

■ Supporting 

  • are necessary for the production of things within an ecosystem
  • Examples: Nutrient and water cycling, soil formation, provisioning of habitats, etc

■ Provisioning 

  • are when we get things directly from an ecosystem
  • Examples: Lumber, freshwater, natural gas, oil, plants that can be made into other things, etc
  • Succession 

○  Primary and secondary succession 

Primary Succession: Starts from bare rock, developing a completely new ecosystem with no pre-existing ecosystem in that area.  

  • Pioneer species: species to first colonize barren rock
  • Soil formed through weathering
  • Biological
  • Performed by lichens and mosses
  •  Chemical 
  • Ex: acid
  • Physical 
  • Ex: rain

Secondary Succession: When plants and animals recolonize an area that was destroyed by a major ecological disturbance. 

Primary succession takes much longer than secondary succession because it starts from ‘nothing’, whereas secondary succession starts from ‘something.’

■ What events might cause an ecosystem to return to an earlier stage of succession? 

  • Fire, drought, volcano, catastrophic weather events

Unit 3: Population Ecology and “AP Human Geo” AP Environmental Science Study Guide

Below is an AP Environmental Science Study guide for Unit 3:

  • Population Ecology: 
    • Density-dependent: affect the population differently depending on how many individuals there are
      • Disease, competition 
    • Density-independent: affect the population regardless of how many individuals there are 
      • Pollution, severe weather
    •  Generalist: wide niche, adaptable, able to survive in a variety of environments and conditions
      • Birds, raccoons, rats
    • Specialist:  narrow niche, very specific environment and conditions
      • Koala, panda
    • Understand the different reproductive strategies (r and K). 
      • In graphs: 
        • K → carrying capacity
        • R → reproductive/growth rate
      • K-selected: 
        • Low reproductive rates
        • Large 
        • Few offspring
        • Expend lots of energy to raise young
        • Mature slowly
        • Competition for resources in habitats high 
          • elephants 
          • humans 
      • r-selected: 
        • High reproductive rates
        • Small
        • Many offspring 
        • Expend little or no energy raising young
        • Mature quickly
        • Competition for resources in habitats low 
          • rabbits 
          • mice
  • Be able to analyze population growth curves (exponential and logistic) 
  • Exponential: exponential (continuously increases), does not take limiting factors into account
  • Logistic: population grows exponentially at first but is eventually limited by carrying capacity
  • Biotic potential: maximum growth rate of a population under optimal environmental conditions; highest growth rate 
    • Steepest part of the graph 
  • If a population overshoots carrying capacity:
    • Depletion of resources leads the population to die back down below K
    • K itself can lower as a result of long-term resource depletion
  • Identify and describe the different survivorship curves. 
    • Type I (k-selected): humans
      • Few offspring
      • Higher chance of survival to adulthood
      • Longer lifespans
      • Mature slowly
    • Type II (in between): birds
      • Linear relationship between time and number of survivors 
    • Type III (r-selected): mice
      • Many offspring 
      • Lower chance of survival
      • Shorter lifespans 
      • Mature quickly 
  • Identify the carrying capacity of a population. 
    • Carrying Capacity: maximum # of individuals an area can support
    • Explain how resource availability can affect population size. 
      • Greater resource availability = bigger population
      • Less resource availability = smaller/decrease in population
    • What are common limiting factors for organisms? 
      • Food, shelter/habitats, water
  • Human populations: 
    • Be able to describe characteristics of a population-based on age structure diagrams
      • total fertility 
      • growth rates 
      • infant mortality 
    • Explain factors that affect the total fertility rate in human populations 
      • Average age of first child
      • Average marriage age
      • Amount of education opportunities available to women  
      • Access to birth control and family planning
    • Encourage low fertility rate
      • Increase educational opportunities for women
      • Increase access to birth control and family planning services
      • Laws
        • China’s One-Child Policy
        • can lead to decrease in working-age people in future (affects economy)
        • High elderly dependency ratio
    • Encourage high fertility rate
      • Paid maternity/paternity leave
      • Stimulus checks and other financial incentives
      • Free/cheap government-run child care programs.
    • How do people affect the environment?
      • Deforestation
      • oil drilling
      • pollution (air, water, etc)
      • nutrient overabundance
      • Desertification
      • Loss of biodiversity
    • What is replacement level TFR? 
      • 2.1 for more developed countries
        • Differs in less developed countries
    • Explain the steps in the demographic transition. Be able to provide example countries. 
      • Stage 1: high CBR; high CDR; stable pop
        • None
        • High TFR, High IMR, no growth 
      • Stage 2: high CBR; rapidly decreasing CDR; rapid population growth 
        • Nigeria, Kenya, Subsaharan Africa
        • High TFR, high growth rate, slowly decreasing IMR
      • Stage 3: decreasing CBR; slowly decreasing CDR; slowly increasing population 
        • Mexico, India
        • Decreasing TFR, stable growth rate, low IMR  
      • Stage 4: low CBR; low CDR; population decreases then stabilizes 
        • Low TFR, Negative or low growth rate, low IMR
        • Netherlands, Sweden, Canada, Japan, U.S.
  • Population Math: equations not given on exam. These should be memorized. 
    • Crude Birth Rate: births/total pop * 1000
    • % Birth Rate: CBR/1000
    • Crude Death Rate:  deaths/total pop * 1000 
    • % Death Rate: CDR/1000
    • Growth Rate:  ((CBR+CIR) – (CDR+CER))/10 or (%BR+%IR) – (%DR+%ER)
    • Doubling Time: 70/r  
    • Population Density: number of people/area of land

Unit 4 AP Environmental Science Study guide: Earth Systems 

Below is an AP Environmental Science Study guide for Unit 4:

The unit 4 exam has 30 multiple choice questions evenly split between the 3 major earth spheres discussed. 10 questions about lithosphere stuff, 10 about atmosphere stuff, and 10 about hydrosphere stuff. There are 4 FRQ prompts on this exam that are all written and do not contain math. (As always, all FRQs are the same length, having 10 total questions) 

Know the major Systems 

  • Hydrosphere, Atmosphere, Lithosphere, Biosphere 


  • Know the general structure of Earth’s interior 

■ Transform

  •  Two plates slide opposite ways against alongside each other
    • Earthquakes common and most intense due to plates getting stuck, then slipping forward

■ Divergent

  • Two plates move away from each other creating a rift
  • Ridge
    • Slow trickle of magma will cool into new crust 

■ Convergent 

  • Two plates converge with one another/move towards one another
    • Subduction Zone
      • Oceanic plate (more dense) sinks below Continental plate (less dense) 
  • Trench 
    • Continental plate folds down creating a deep pit 
  • Volcano
    • Because of the pressure caused by the subducting plate, magma is forced up and creates a volcano
  • Mountains
    • O + C plates – uplift mountains
    • C + C – fold mountain
      • Continental plate have same density so push against each other and move upwards

○ Be able to explain how plate tectonics results in some natural disasters 

■ Volcanoes from subduction zones 

  • Because of the pressure caused by the subducting plate, magma is forced up and creates a volcano

■ Hotspot Volcanoes

  • An area where the mantle is hotter than surrounding mantle due to fresh heated, rising magma
  • As the plate moves over the hotspot very slowly, causing magma to cool and form volcanoes/islands
    • Ex: Hawaii

■ Tsunamis 

  • Caused by underwater earthquakes

■ Earthquakes 

  • Convergent and Transform
    • Plates get stuck then shift results in earthquakes

○ Be able to explain the rock cycle, how each rock is made, and the 

characteristics thereof (*not directly assessed*) 

■ Igneous intrusive 

  • Cooled underground
  • Formed by cooled magma 

■ Igneous extrusive 

  • Cooled aboveground
  • Formed by cooled magma

■ Metamorphic 

  • Formed by heat and pressure on a sedimentary rock and igneous rock

■ Sedimentary 

  • Formed by compacting and cementing sediments
  • Has layers
  • Soils 
  • Layers
  • Zone of Leaching – forms up to down
    • O Horizon (Humus): living, dead, decaying organic material
    • A Horizon (Topsoil): sand, silt, clay (abiotic), fully decomposed humus
    • E Horizon (Eluviation): rain leaches minerals down into a layer (not in all soil types)
  • Zone of Accumulation – forms down to up
    • B Horizon (Subsoil): fully weathered rock of sand, silt, clay
    • C Horizon (Parent Material): partially weathered rock – not small enough to be considered soil
    • R Horizon (Bedrock): Not weathered rock

○ Properties 

■ Composition, Soil texture, Soil nutrients, Soil horizons 

  1. Sand 
  • Most pore space
  • Allows more water through – groundwater recharges fastest
  • less runoff in watersheds, but more percolation
  1. Silt
  2. Clay
  • Least pore space 
    • Stops water from permeating
    • Most runoff in watersheds, but less percolation
    • Has a slightly negative charge 
      • High cation exchange capacity
  • Using texture triangle 
  • NPK 
  • Nitrogen, Phosphorous, Potassium

○ Dynamics 

■ Soil movement (watersheds

○ Issues 

■ Erosion

  • Can be prevented by increasing vegetation


Know the layers of the atmosphere, their composition,and important details of each ● Troposphere 

○ Global Wind Patterns 

○ Global Circulation (Hadley Cell, Mid-latitude cell [Ferrel cell], Polar cell)

  • You should know the general latitudes where these cells have updrafts and downdrafts 
    • Hadley Cells
      • Updraft at 0 degrees, down draft at 30 degrees
    • Mid-Latitude Cells
      • Updraft at 60 degrees, down draft at 30 degrees
    • Polar cells
      • Updraft at 60 degree, down draft at 90 degrees

○ How do storms form?: 

  • Warm air rises. This is called an Updraft. Air near the ground takes the rising air’s place. These are surface winds.  Cold air is denser and begins to sink. This is called a downdraft. The air that’s falling is replaced by air in the upper atmosphere. These are the Upper Winds. This cycle of moving air is called a convection cycle. Warm air raising creates an air mass with low atmospheric pressure. Cold Air falling creates an air mass with high atmospheric pressure. Because the air masses have different densities, they do not mix.  The boundary that separates them is called a Front. Warm air holds a lot of moisture. As it rises and cools, the water vapor condenses into clouds. Upper winds carry clouds across Fronts. The higher pressure and colder temperature cause the clouds to condense into rain. But these entire cycles move, too- because as the earth spins, the sun “changes” locations in the sky. If a low pressure system is pushing towards a high pressure system, we call this a Warm Front. Because this is warm, low density air, it gently floats above the mass of cold, dense air. When the air gets high enough, it cools off, causing a gentle rain. If a High Pressure System is pushing into a low pressure system, we call that a Cold Front. The cold, Dense air acts like a battering ram, forcing the war air upwards quickly. Because this happens quickly, the water vapor in the air cools quickly, causing thunderstorms.

○ Climate: 

  • Polar Easterlies: 
    • Technically come from the east and go west, but essentially a swirling vortex. Between 60 degrees N and S and 90 degrees N and S.
  • Westerlies: 
    • Come from the west and go east. Between 30 degrees N and S and 60 degrees N and S.
  • Trade Winds (Easterlies): 
    • Come from the east and go west. Between 0 degrees and 30 degrees N and S.
  • Remember: Winds are named by what direction they come from!

■ How do geographic features (elevation, rain shadow, proximity to water, nearest ocean gyre) affect regional climates and locations  of biomes. 

  • Insolation
  • Amount of solar radiation a place in the world gets
  • Most insolation at the equator
  • Helps to create its warm and rainy environment
  • As you move towards poles, insolation decreases creating cooler and drier environments
  • Elevation:  
    • Higher → colder bc ground absorbs most heat 
  • Proximity to Water:
    • Water holds heat longer → less variability in temperature
    • Ocean currents regulate temperature throughout night and day 
    • Cities closer to the ocean will experience more moderate climates because the ocean provides heat during the winter/nighttime and cools the area during the summer/daytime
    • Meanwhile, cities that are more inland experience more dramatic and frequent fluctuations in temperature
  • Nearest Ocean Gyre: 
  • Rain shadow: Moist air follows the slope of the mountain upwards, water vapor condenses and falls as precipitation. By the time the air crosses to the other side of the mountain it is very dry.
  • Troposphere: Contains the majority of water vapor in the Earth’s atmosphere. Weather occurs here!
  • Mesosphere: BORING! (not that important)
  • Stratosphere: Contains the ozone layer which protects us from UV
  • Thermosphere: Contains the ionosphere which protects us from UV and solar winds
  • Coriolis effect 

○ How is air deflected in the northern hemisphere? 

  • Moving towards equator, winds deflect west

○ How is air deflected in the southern hemisphere? 

  • Moving away from equator, winds deflect east 

○ What causes the coriolis effect? 

  • Earth is spinning 
    • Also results in changing of seasons
      • Northern hemisphere closer to sun in june solstice while this would be winter months for the southern hemisphere 


  • Water Resources 

○ How is freshwater used? 

  • Our biggest freshwater use is irrigation (42%)
    • Second is power plants (34%)
    • Other uses include public supply (14%), household (5%), and industrial (5%)

○ Where is water found? 

■ About 97% of Earth’s water is saltwater; less than 3% is freshwater

  • Of that 3 percent freshwater:
    • Nearly 70% is stored in ice caps and glaciers
    • 30% is groundwater
    • Only about 1 percent is surface water
  • Watersheds 
  • The land that channels water/water runs through

○ How do geographic features affect movement of water? 

■ How does geography influence water flow:

  • Steepness
    • The steeper the slope, the more runoff/less groundwater recharge
    • Flatter slopes result in less runoff/increase in groundwater recharge
  • Soil permeability
    • Sandy soil increases groundwater runoff due to high porosity
    • Clayey soil reduces groundwater recharge due to low porosity
  • Also consider urban features such as concrete
    • Increased runoff in urban areas due to concrete and impervious surfaces
      • Creates more variability/faster river flow
  • Plant life or lack thereof
    • Vegetation roots absorb water slowing water flow and decreasing runoff
  • Features such as wetlands and swamps slow down the flow of water
    • Slows the flow of water and absorbs filters pollutants
  • Runoff is a major issue related to watersheds
    • Where a pollutant travels is based on its watershed(s)
    • Vegetation helps to limit the effects of runoff
    • ex.) fertilizer from farms traveling down into bodies of water, creating dead zones
  • Oceans 

○ Ocean circulation 

  • Ocean circulation patterns (gyres) follow wind patterns
    • Impacted by the coriolis effect
  • Normal condition
    • Trade winds blow West blowing the warm surface water towards Asia and Australia and cooling the Americas
    • Results in upwelling
      • Cool water from the bottom of the ocean replaces the surface water
        • Brings up lots of nutrients due to dead plankton at the bottom – very helpful for fishing
  • El Niño (every 4-5 years)
    • Trade winds (Easterlies) that typically blow from South America to Australia/Asia (across the Pacific Ocean) weaken or change direction
    • South America Result
      • Less upwelling of nutrient-rich cool water = fishing industry suffers and food chains are affected
      • Warmer temperatures resulting in storms and natural disasters
    • Asia/Australia Result
      • Cooler and dryer temperatures resulting in droughts
  • La Niña
    • Opposite of El Niño: trade winds strengthen, making South America colder and more prone to droughts, while Asia and Australia experience warmer temperatures and more rain/storms

○ Water’s effect on climate of a region 

  • Water has a high specific heat capacity
  • Cities closer to the ocean will experience more moderate climates because the ocean provides heat during the winter/nighttime and cools the area during the summer/daytime
  • Meanwhile, cities that are more inland experience more dramatic and frequent fluctuations in temperature (Las Vegas/Deserts)

Unit 5 Study Guide (Land Use: Agriculture, Mining, Forestry, Urbanization, Ecological Footprints, National Lands) 

Below is an AP Environmental Science Study guide for Unit 5:

  • Agriculture 
    • Types: 
      • Industrial monoculture, polycultures: 
      • polyvarietal cultivation: planting a plot of land with several genetic varieties of the same crop
        • Reduces spread of disease and variety-specific pests
        • Limited abundance of a variety in high demand 
      • Polyculture: planting multiple crops in the same field
        • Reduces soil nutrient depletion rate and the number of pests, weeds, and disease
        • Difficult to mechanize and requires more labor to harvest
      • Agroforestry
        • Integration of trees and shrubs into crop and animal farming systems
        • Supports agricultural production and helps improve water and air quality, soil health, and wildlife habitat
        • Also prevents runoff and regulates temperature 
      • Vertical agriculture
        • Crops are grown indoors and use significantly less water and pesticides than traditional farming methods
    • Issues
      • Pesticides: substance used for destroying insects or other organisms that are harmful to plants and animals
        • Become less-effective over time because species become resistant to pesticides through natural selection 
      • Fertilizers: help plants grow 
      • Both Fertilizers and Pesticides:
        • are detrimental to environmental and human health when excessively used
        • can get into rivers and streams and severely pollute waterways.
        • can either be a chemical substance or an organic strategy.
      • Soil erosion: occurs when dirt is left exposed to wind and water
        • Barren landscape makes soil susceptible to erosion after crops are collected
        • Tilling → loosens soil and makes susceptible to erosion
        • Reduced by over-cropping → farmers plant something in off season to keep soil in place & contour-plowing → plowing across slope of elevation to create water break 
      • Soil salinization: dissolved salts in water tables rise to soil surface
        • Caused by Weathering of soil minerals, salts added through rain, agronomic practices such as fertilizer and pesticide application
      • Waterlogging: excess water in the root zone accompanied by anaerobic conditions
        • Overirrigation, inadequate drainage, poor irrigation management
      • Runoff: the draining away of water can flow into stream with certain toxic substances from agricultural practices and pollute water and harm animals
      • Tillage: turning the soil to control for weeds and pests and to prepare for seeding 

○ Irrigation 

  • Flood: entire field flooded
    • Cheap
    • 20% water loss
  • Furrow: cutting furrows between rows of crops
    • Inexpensive 
    • ⅓ of water lost
  • Drip: perforated hoses release small amounts of water directly to roots
    • 5% water loss
    • Very expensive & rarely used
  • Spray: water pumped into spray nozzles 
    • <25% water loss & efficient 
    • Expensive & requires energy to run pumps

○ Integrated Pest Management: ecological pest control strategy that uses a variety of methods in hopes of reducing use of chemical pesticides 

○ Green Revolution: large increase in crop production in developing countries achieve by use of fertilizers, pesticides, and high-yield crop varieties → not stable for environment 

  • Aquaculture 

○ Fish Ranching and Fish Farming: when fish populations are raised under very controlled conditions

■ Fish Farms

  • Pros: Helps prevent overfishing and protect fish populations, less general environmental impact, very efficient, help replenish population of fish that are threatened
  • Cons: fish have less diversity and if they get out into the wild it would lessen biodiversity, large concentrations of fish waste can pollute nearby ecosystems

      ■ Wild Fishing: 

  • Cons: Less sustainable, Can easily be overfished, more of an environmental impact (boats have to go out farther each time and use more fuel), 
  • Pros: generally fish have lower concentrations of disease / contaminants

○ Issues: 

  • Bycatch: Accidental capture of animals not intentionally targeted
  • Overfishing
    • Solutions: Catch limits, protected habitat areas, sustainable seal of approval
  • Ecosystem damage: forms of fishing can destroy ecosystems like ridding them of many corals and habitats
  • Animal agriculture: 
    • CAFO benefits: 
      • Quickly get livestock large enough to be slaughtered
      • Reduces amount of land occupied by animals
      • Cost-effective and more affordable meat
    • CAFO disadvantages: 
      • High risk of disease spread
        • High antibiotic use leading to resistance
      • Waste Lagoons: waste that escapes could runoff into water 
        • Can cause algal blocks → dead zones
      • Maltreatment of animals
  • Mining 
  • Rock: solid substance composed of minerals
  • Mineral: composed of the same substance throughout its entire structure
  • Ore: a rock that has a large concentration of a particular mineral

○ Types of mining

  • Surface Mining
    • Open-Pit: Removal of material from an open pit
    • Mountaintop removal: Explosives are used to remove the tops of mountains for extraction
    • Strip mining: when an area is stripped of vegetation and soil and ore is removed in subsequent strips
    • Ecological impacts: Habitat and vegetation destruction, species loss, erosion, increased flooding
    • Risks: dust 
  • Subsurface mining
    • A series of underground tunnels
    • Dangers: collapsing rocks and respiratory diseases
  • Acid mine drainage
    • Pyrite/iron sulfide comes into contact with air and water, producing sulfuric acid which can run off into streams
    • This can happen from both mining sites and from tailings
      • Tailings: a substance leftover from ore getting processed

○ Extractions of the minerals from ore 

■ Process of extraction

  • Milling: Ore is crushed by being put in a rotating drum with steel rods or balls and broken down
    • Results in rock waste forming large piles
  • Flotation: air is pumped into a water solution and minerals attach on bubbles 
    • Tailings: leftovers of flotation process 
      • Stored in tailing ponds which can harm animals and can cause runoff
  • Leaching: the use of chemicals to dissolve desired metals
    • Problems: leach piles 
  • Smelting: utilizes different melting points or densities to pour off unwanted material 
    • Problems: emissions
  • Slag Disposal: may contain unwanted toxic substances like mercury
    • Cause contamination
  • Reclamation 
    • Process of restoring land to a suitable condition
  • Remediation
    • Process of fixing, removing, or counteracting an environmental problem.
  • Forestry
    • Clear cutting: All trees in an area are uniformly cut down
      • Pros: cheaper and faster
      • Cons: Erosion, temperature increase, flooding, old-growth forests at risk, habitat destruction
      • Other info: Trees provide cooling through evapotranspiration and shade, temperature increase → less dissolved oxygen in water
    • Selective Forestry: only some trees are cut down, leaving smaller ones to continue growing
      • Pros: Less soil erosion, Temperature does not increase as drastically due to canopy cover and evapotranspiration, Some of the habitat is preserved, less flooding
      • Cons: more expensive and less convenient/more time consuming and effort
    • Slash and burn agriculture
      • Pro: Naturally fertilizes soil
      • Cons: Erosion, CO2 release
      • Mostly used in less wealthy countries
    • Forest Fires
      • Becoming more frequent and severe
      • Suppressing forest fires is dangerous/bad for the ecosystem and makes future fires more destructive
      • Controlled burns are a better alternative because natural patterns can persist, and accidental fires are less damaging
  • Ecological Footprints (Right now need 1.7 earths to provide for our consumption rate)

○ Tragedy of the commons: Individuals will use shared resources in their own self interest rather than in keeping with the common good, thereby depleting the resources

○ Sustainable yield: amount of renewable resources  that can be taken without reducing the amount of available study

  • Sustainability: use of resources without depleting resources for future generations 
  • Urbanization 
  • Urban sprawl: Expansion of poorly planned, low-density, auto dependent development, which spreads out over large amount of land putting long distances between, stores, and work
    • More space between houses greatens land footprint and highers CO2 emissions with more driving
  • Heat island effect: cities are warmer than surrounding rural areas
    • More dark colored surfaces/concrete to absorb sunlight and radiate heat
    • Less tree leads to less evapotranspiration, which uses heat to energize process, so more heat kept in
      • Extra use of AC, leading to more use of energy
  • Urban blight: Result of urban sprawlA city, or parts of a city, fall in disrepair. Results from a quick loss of population, which removes business and economic opportunity.  

Energy Unit Review

  • Concepts in Energy
    • Laws of thermodynamics 
      • 1: energy cannot be created or destroyed
      • 2: energy conversions not exact bc some energy is lost as heat
    • Units (Watt, watt-hour, BTU, Joule)
      • 1000 J = 1 kJ
      • 1000 cal = 1 kcal
      • 1 cal = 4.184 J
      • 1 BTU = 1.05 kJ
      • 1 therm = 100,000 BTU
  • 1 kWh = 1kW * 1 hr = 3.6 * 10^6 J
  • 1 W = 1 J/1 second
  • Tera = 1 * 10^12
  • Giga = 1 * 10^9
  • Mega = 1 * 10^6
  • Kilo = 1000
  • Hecta = 100
  • Deca = 10
  • Base Unit = 1
  • Deci = 0.1
  • Centi = 0.01
  • Mili = 0.001
  • Energy Use
    • Where does US energy come from? : most from natural gas (40%), nuclear (20%), renewables (20%), petroleum (1%), coal (19%)
    • What is the general trend in energy use around the world?
      • Increased demand in developing countries
      • Most energy still obtained from nonrenewable sources
      • Less nuclear energy used 
    • Which countries use the most? Least? Why? 
      • Most: China, USA, India, Russia, Japan
        • Large reserves and better access to energy sources
      • Least: Haiti, South Sudan, Niger, Eritrea, Ethiopia, Benin, Tanzania, Democratic Republic of Congo
        • Less access to energy sources 
  • Energy conservation
    • Co-generation:
      • produces electricity and heat simultaneously 
      • Traditional methods → 60% fuel lost
      • Cogeneration → 8% lost 
      • use less fuel to cover their demand which leads to lower expenses. 
      • Emissions are also lower → efficient
      • Runs on any renewable energy source. 
    • Fuel efficiency 
      • measures the distance a motor vehicle can travel on a single gallon of gas
    • How to save energy
      • Carpool or use public transportation
      • Unplug unused chords
      • Switch to LEDs 
  • Non-Renewable Energy
    • Oil
      • How are different chemicals from oil extracted? 
        • Oil is mechanically pressed if there are seeds or nuts with oil in them. Rendering can also be used which applies heat to extract oil. Another method of oil extraction is drilling. Once the site has been drilled, fracking occurs to extract oil and natural gas from the mined rocks. Fracking fluids are pumped into the site and high pressures create thin cracks in the rock, releasing the oil and natural gas inside. 
        • Used for plastics, gasoline, electricity, heat homes and buildings, power vehicles, lipstick, deodorant, vaseline, MRIs, pacemakers
        • Electric cars would decrease oil use  
      • How is oil extracted?
        • Traditional drilling: Traditional drilling
        • Fracking: an unconventional oil produced from oil shale rock fragments by pyrolysis, hydrogenation, or thermal dissolution
        • Shale, Sand, Crude: an unconventional oil produced from oil shale rock fragments by pyrolysis, hydrogenation, or thermal dissolution
      • Advantages: cheap, reliable, provides jobs 
      • Disadvantages
        • Water pollution
          • Wastewater disposal → can pollute bodies of water
        • Oil spills
          • Significantly impact wildlife 
          • Contaminate soil & water 
        • Restoration of extraction sites
          • Although restoration efforts are conducted, no environment is left the same as it once was 
        • Wildlife concerns
          • Drilling & extraction disturbs wildlife 
    • Natural Gas
      • How is extracted? 
        • Natural gas flows through the plant along with regular air which combusts in the combustion chamber. When it combusts it also expands through the turbine which makes the generator spin a magnet which releases electricity.
      • Advantages: easily transported & abundant 
      • Disadvantages 
        • Air pollution
          • Nitrogen oxides 
            •  linked with problems such as asthma, bronchitis, lung cancer, and heart disease 
        • Water pollution: 
          • clearing sites to prepare for natural gas extraction results in soil erosion
            • Runoff into streams 
          • Contamination risk to bodies of water (from leaks & spills of chemical materials)
        • Increased risk of earthquakes → injection-induced seismicity 
        • Danger to animals
          • Disrupted migration & less range 
          • Habitat loss →  build sites for extraction 
    • Coal
      • Coal is burnt in a boiler to produce steam. The heat produced from the burnt coal turns water in the boiler into steam that flows into a turbine that will spin a generator to create electricity. Afterwards, the steam is cooled and returned to its liquid state so that it can be sent to the boiler to begin the process again. 
      • Benefits: 
        • Abundant & cheapest source of fossil fuels
        • Can be used with renewables to reduce emissions 
        • Scrubbers: an apparatus that cleans the gases passing through the smokestack of a coal-burning power plant → remove sulfur emissions from coal &lessen the formation of acid rain.
      • Disadvantages: 
        • Process releases CO2 & Nitrogen oxides which result in acid rain 
          • Respiratory issues 
          • Destroys aquatic life 
        • Airborne toxins and pollutants: mercury, lead, sulfur dioxide, nitrogen oxides, particulates, other heavy metals
          • Asthma & other respiratory issues
          • Brain damage & neurological disorders 
          • Heart problems 
          • Cancer 
          • Premature death 
  • Nuclear 
    • Fission of Uranium-235: nucleas spilts
      • Additional neutron forced into nucleus → 1 krypton, 1 barium, 3 neutrons
    • Nuclear chain reaction: neutrons hit atoms → break apart → hit other atoms → cycle
    • Half-life: how long it will take for half of a radioactive material to decay into more stable atoms 
    • How nuclear reactors work
      • Waste storage: Disposal of low-level waste is straightforward and can be undertaken safely almost anywhere. Storage of used fuel is normally under water for at least five years and then often in dry storage. Deep geological disposal is widely agreed to be the best solution for final disposal of the most radioactive waste produced.
      • Refinement: After the uranium ore is extracted from an open pit or underground mine, it is refined into uranium concentrate at a uranium mill. The ore is crushed, pulverized, and ground into a fine powder. Chemicals are added to the fine powder, which causes a reaction that separates the uranium from the other minerals.
  • Renewable Energy
    • Advantages and disadvantages of each method of production; Environmental impacts
      • Biofuels (biologically produced ethanol, biomass)
        • Air pollution
          • carbon monoxide, volatile organic compounds, and nitrogen oxides
          • Many cannot be sequestered by new plants
        • Deforestation & habitat loss for planting crops
          • Water use → water needed for crops
      • Wind energy: 
        • Threat to local wildlife  
          • Birds and bats can collide with turbines 
            • Up tp 500k birds killed every  year
        • Cannot be recycled 
          • Made of class & carbon material
            • Disposed in landfills
      • Hydropower
        • Tidal: As the tides proceed and recede, the flow of the water spins a turbine which spins a generator which will then generate electricity. 
          • Disrupted migration & negative impact on animals 
          • Displacement 
        • Dams (mot important): Dams collect water in reservoirs. The water in the reservoirs is then released through the dam. The flowing water will spin a turbine which spins a generator thus creating electricity. 
          • Sedimentation 
            • builds up on the face of the dam which can take up space & lead to flooding upstream
          • Siltation: sediments get stuck and create murky water conditions
            • Increased turbidity can cause problems with producers → not enough sunlight for photosynthesis 
            • Disrupts food webs and alters water quality
          • Wildlife
            • Disrupted migration & reproduction for fish 
            • Less range in area 
          • Reduction in river flow speed
            • Less water available for humans and animals 
  • Solar
    • photovoltaic cells: Uses layers of silicon with one side made of phosphorus (one more electron than phosphorus) and the other made of boron (one less electron than phosphorus). When a photon hits one side of the cell, electrons will leave their atoms and all of them will flow to the side with a slight positive charge (boron) to conduct electricity.  
    • solar towers: mirrors focus on tower to create steam
    • Passive-solar: energy not collected or stored; In passive solar building design, windows, walls, and floors are made to collect, store, reflect, and distribute solar energy, in the form of heat in the winter and reject solar heat in the summer. 
  • Geothermal 
    • Energy from within the earth is used to heat water. The steam from the heated water us used to spin a turbine which spins a generator to produce electricity. 
    • Hydrogen sulfide gas leaks
      • Poisonous 
        • Fluid in lungs
        • Neurological problems
        • Eye irritation and ulcers
    • Sites on geothermal “hot spots”
      • Can increase risk of earthquakes 
    • Land subsidence
      • land surface sinks
        • caused by the removal of water from geothermal reservoirs
  • Remember, most energy (except PV cells and the HFC) are still old-school turbines. Know the basics behind how a turbine works. 
    • Wind turbines use kinetic energy of moving air to spin a turbine. The turbine then spins a rotor which will spin a generator, resulting in electricity. 


Things you should know how to do:

Convert between Units (e.g. from Joules to BTUs). The conversion values will be given to you. 

Convert between prefixes (e.g. from Watts to Terawatts) ← prefixes must be memorized

Calculating Watts (Watt = J/s) ← must be memorized

Percent Change formula %change =final – initialinitial x100 ← must be memorized 

Unit 7 (Air Pollution) Exam

Below is an AP Environmental Science Study guide for Unit 7:

    • Experimental Design: 
      • Formulating a god hypothesis
        • If-then-because
        • Must predict how the independent variable will affect the dependent variable
      • Identifying variables
        • dependent variable → value depends on that of another variable
        • Independent variable → value does not depend on that of another variable
        • Control variable → does not change throughout experiment 
        • Constants 
      • Procedure: should be enough for the person grading your response to replicate your experiment to a reasonable margin
      • Data
        • Qualities of a good graph: Title, Axes, Scale, Units
      • Conclusions: 
        • What data supports your hypothesis? What kind of data rejects your hypothesis? 
        • What can be done to improve an experiment? 
    •     the chemistry, causes, concerns, and solutions to issues related to air pollutants.
  • Ozone (O3)
  • Nitrogen Oxides (NOX)
  • Sulfur Oxides (SO2)
  • Carbon Monoxide (CO)
  • Lead
      • Mercury
  • Particulate Matter (especially PM 2.5)
    • Radon Gas
    • VOC’s
    • Asbestos
  • Emissions from combustion of coal
    • Sulfur dioxide (SO2), which contributes to acid rain and respiratory illnesses
    • Nitrogen oxides (NOx), which contribute to smog and respiratory illnesses
    • Particulates, which contribute to smog, haze, and respiratory illnesses and lung disease
    • Carbon dioxide (CO2), which is the primary greenhouse gas produced from burning fossil fuels (coal, oil, and natural gas)
    • Mercury and other heavy metals, which have been linked to both neurological and developmental damage in humans and other animals
  • Differentiate between primary and secondary pollutants/point-source and nonpoint-source
    • Point-source: pollutants enter the environment from one, easily identified place such as factories, power plants, volcanoes
    • Nonpoint-source: pollutants are released in a wide area (mobile) 
    • Primary: an air pollutant emitted directly from a source
    • Secondary: form when primary pollutants react in the atmosphere
    • Noise pollution
      • can interfere with animals echolocation, which can prevent those animals from locating and catching their prey
    • Thermal inversion
      • Cold air displaces warm air at the bottom 
      • Causes warm air to rise and create a “blanket” trapping pollutants like VOCs and Ozone 
      • Makes ground air more dangerous and polluted
    • Acid deposition 
      • Be able to explain how Sulfur Oxides and Nitrogen Oxides lead to acid rain
        • Fossil fuels (coal) is combusted in a power plant which releases SO2 and NOx
        • SO2 and NOx reacts with H2O in the atmosphere to produce sulfuric acid and nitric acid
        • Both mix with rain which falls to the ground
      • Neutralized by limestone and marble
      • Environmental Impacts (affecting abiotic parts of the environment)
      • Ecological impacts (affecting biodiversity, food webs, and symbioses)
      • Economic (affecting trade, jobs, taxes)
      • Human Health (affecting birth/death rates, illnesses, disease spread)
    • Photochemical Smog
      • NO2 is released from combustion of fossil fuels, gas combustion in cars
      • NO2 -(sun)- NO + O
      • O + O2 = O3
      • O3 + NO – NO2 + O2 (good)
      • NO + VOC’s = a lot of different toxic particles (bad)
        • This gets rid of NO so there is nothing to dissipate ozone which forms photochemical smog
    • Industrial Smog
      • Industrial smog contains two primary components: sulfur dioxide and particulates, which include dust and soot from burning coal or other Energy / Manufacturing practices 
      • Doesn’t necessarily contain ozone
  • Solutions to pollution
    • Clean Air Act 
      • 1970: Ambient Air Quality Standards 
        • Funded development and implementation
        • EPA regulatory control for 6 criteria pollutants
      • 1990: Cap and Trade
        • Government sets a limit on amount of pollutants that can be released
          • Older power plants struggle to reach this goal while newer plants can easily stay below
        • Allows more efficient power plants to sell whatever pollutants they don’t release to less efficient ones 
        • The older plants will purchase these shares allowing them to emit above the cap resulting in overall lowering of emissions
    • Know how these technical solutions work: 
      • Electrostatic precipitator:  filterless device that removes fine particles, like dust and smoke, from a flowing gas using the force of an induced electrostatic charge minimally impeding the flow of gases through the unit.
      • Scrubbers: Scrubbers are found on power plants. They use water and filters to reduce the amount of particulate matter, CO, NOx, SOx, and mercury released into the air 
      • Catalytic converters: Catalytic Converters are found in cars and reduce the amount of CO and NOx cars release
      • Vapor recovery nozzle: prevents fumes from escaping when fueling a motor vehicle 

Unit 8 (aquatic and terrestrial pollution, toxicology and disease) study guide 

Below is an AP Environmental Science Study guide for Unit 8:

  •     chemical tests that affect WQI
  • pH
    • The level of acidity in water
    • Low pH = Acidic
  • Turbidity
    • Relative clarity of water
    • Construction site up stream would cause higher turbidity
  • Temperature
  • Nitrates
  • Dissolved oxygen
  • Phosphates
  • Fecal Coliform Bacteria
    • Caused by sewage 
  • Biological Oxygen Demand
    • Aerobic decomposition is at its highest when biological oxygen demand is the highest.
    • Oxygen is required for aerobic decomposition to take place
  • Sewage Treatment 

○ Know the steps 

    • Primary
    • Secondary
      • Aeration Tank: Bacteria are held in an aeration tank to naturally break down the organic matter
  • Tertiary (Sometimes not done)
  • Disinfection 
      • CHLORINE
      • OZONE
      • UV LIGHT
  • Water pollutants 

○ Point vs. nonpoint pollution

  •  Point: pollutants that enter the environment from one, easily ex identifiable place
    • Factories, power plants, volcanoes
  • Non-point: pollutants are released in a wide-area
    • Mobile, cars
  • Eutrophication
    • A process that occurs when a body of water is enriched with nutrients
      • Too many nutrients flow into water
        • Runoff from agriculture, urban areas
      • Algae overgrows due to the abundance of nutrients
      • All the nutrients are used up, so algae can no longer be supported and dies
      • Bacteria decompose dead algae which uses up majority of dissolved oxygen
      • Fish and other aquatic creatures die without oxygen
      • Water ecosystem collapses
      • If the source of nutrients is farm run-off, it’s nonpoint.
      • If the source of nutrients is from a sewage outflow pipe, it’s a point source. 
    • Mercury
      • Enters from coal power plants
      • Absorbed by bacteria in water and converted to methylmercury (very toxic)
      • Can cause…
        • Brain damage
        • Impair growth/development
        • Lead to high mortality and intellectual problems in humans
    • Lead
      • Get into water through old service pipes by the coating chipping and releasing lead
      • Can cause limb weakness, loss of senses, cognitive/behavioral problems, etc.
    • Oil Spills
      • Ecological impacts
        • Organisms die due to hydrocarbons present
        • Coat feathers and fur reducing insulation and preventing flight of birds
        • Sink to bottom of ocean and kill aquatic organisms
  • Economic impacts
    • If oil washes up on beach, tourism industry problems
    • Expensive and lengthy to clean up
  • How to clean
    • Dispersion
      • Uses chemicals that remove oil from water by breaking up into smaller droplets
        • Toxicity of dispersants can affect marine organisms
    • Burning
      • Oil is burned directly on water
        • Toxic fumes can cause damage to marine life
    • Skimming
      • Remove thin layers of oil from surface 
      • Oil can still be recovered and used
        • Can get clogged because of trash
  • Heat Pollution
    • Occurs when heat is released into water
      • Industrial operations 
    • Warmer water has lower dissolved oxygen holding capacity 
      • Results in decrease in fish population who cannot survive
  • Microplastics 
    • All plastic released into water
    • Causes… 
      • Intestinal blocking
      • Choking hazards
      • Introduce toxic substances into food chain
      • Big garbage patches in ocean
  • Wetlands
    • Water filtration
    • Habitat for species (inc. endangered species)
    • Flood control

○ Water availability and Management 

  • Clean Water Act: eliminate discharge of pollutants in US waters 
    • Effluent standards 
    • Permits for discharging → must meet effluent standards
    • NPDES
  • Safe Drinking Water Act: set guidelines for
    • Safe drinking water standards
    • Monitoring procedures
    • Procedures for certification of operators of public water systems
    • Technical, managerial, & financial capacities for public water systems
    • Grants & funding for implementation of the SDWA
  • Environmental Hazards 
  • Chemical
    • Synthetic chemicals that pose a risk like pesticides, disinfectants, and some drugs
    • Can be natural like arsenic and lead
  • Biological
    • Viruses, bacteria, and other pathogens
    • Infectious disease: diseases that can be transmitted between humans
  • Physical
    • Occur naturally and we cannot do much to prevent them like earthquakes, volcanoes, floods
    • We can prepare for them
  • Cultural 
    • Result from where we live, our jobs, behavioral choices
      • Drug use, diet, crime
  •     the major toxins from the chart 

○ Where are they found? 

○ What are the effects on Environment and/or Human Health 

○ How do they get into ecosystems / humans 

  • The general effects of toxins 

○ Carcinogen 

  • Substances that cause cancer by damaging DNA
    • Asbestos, sun exposure

○ Endocrine disruptor 

  • Chemicals that affect the ways your hormones work
    • Endocrine system
  • Hormones: chemical signals your cells to communicate

○ Teratogen 

  • Chemicals that cause birth defects
    • PFOA

○ Mutagen 

  • A substance that causes genetic mutation

○ Neurotoxin 

  • Substances that can damage nerve tissue including your central nervous systems and brain 
    • Lead, mercury, ethanol
  • Measuring Toxicity 

○ Dose Response Curve 

  • Describes the effect on an organism or mortality rate in a population based on the dose of a particular toxin or drug
  • Measured based on mg of substance/kg of body weight

○ LD-50 

  • The dosage of a substance it takes to kill off 50% of a population
  • The lower the LD-50, the more toxic the substance is

○ Threshold of Toxicity 

  • The lowest concentration of a substance that is toxic to an organism

○ “The dose makes the poison.” 

  • Other issues involving toxins 

○ Bioaccumulation 

  • Selective absorbance and concentration of compounds by cells in a living organism
  • Substances are usually stored in fatty tissue

○ Biomagnification 

  • Increase in concentration of substance per unit of body tissue in higher trophic levels

○ Regulatory strategies / Agencies 

■ EPA 



  • Know the major vectors and sources of the notable diseases from the chart 

○ Special focus is placed on 

  • SARS
    • Vector is animals and humans
    • Health impacts such as high fever, chills, headache, muscle pain
    • No vaccine 
    • Caused major problems in China
  • Cholera
    • Bacteria in untreated water
    • Diarrhea, vomiting, death
    • Eliminated in USA however very common in less developed countries who don’t have resources to clean their water
    • Single dose oral vaccine
  • West Nile
    • Vector is mosquitoes
    • High fever, headache, tremors, vision loss
    • Common in less developed countries like Africa, Middle East, West Asia
    • No vaccine
  • AIDS
    • Passed through blood or other bodily fluids
    • Flu-like symptoms, weight loss, fever, sweats
    • No cure
    • Antiviral medication can help
  • Malaria
    • Vector is mosquitoes
    • Causes anemia, kidney failure, seizures, death
    • Common in Africa, South Asia, places with lower development
    • There is a vaccine
  • Measles 
    • Pathogen is contact with other people
    • Affects the lungs, brain, kidneys
    • Vaccine exists 
      • Rates are increasing due to decreasing levels of vaccination
  • How to avoid the spread of diseases 

○ Hygiene, how to deal with mosquitos, travel restrictions, etc… 


  • Types of waste 

○ Municipal Solid Waste 

  • consists of everyday items such as product packaging, yard trimmings, furniture, clothing, bottles and cans, food, newspapers, appliances, electronics and batteries.

○ Industrial Solid Waste 

  • produced by industrial activity which includes any material that is rendered useless during a manufacturing process such as that of factories, mills, and mining operations.

○ Hazardous Waste 

  • waste that has substantial or potential threats to public health or the environment.

■ Types and special regulations

■ Disposal and management 

  • Liquid is disposed of in a surface impoundment
    • Shallow depression lined with plastic and clay
    • Goal to let liquid evaporate and solid is disposed of safely
  • Deep well injection
    • Injects hazardous waste well below water table
    • Well may corrode and leak waste in soil

○ Wastewater 

generated after the use of fresh water in a variety of applications, and usually involves leaching, flushing, or washing away waste products and nutrients added to the water during these applications

  • “Reduce, Reuse, Recycle.”  
  • Reduce food waste
  • If you cannot reduce: reuse what you can
  • If you can’t reuse: recycle
    • Solid waste processed & converted into new products
    • Reduce global demand on minerals
    • Energy intensive & costly
  • E waste → metal extracted from circuit boards
  • Composting
  • Organic matter decomposition
  • Product can be used as fertilizer
  • Can attract odor and rodents: organic matter decomposition → product used as fertilizer, but drawbacks are odors & rodents
  • Sanitary Landfills 

○ Structure

  • Plastic and clay line around and at top to keep waste in
  • Methane can be burned off or used as energy in a natural gas plant
    • Burning can be dangerous and release toxic gasses
  • Leachate: water that has infiltrated and percolated through the trash in a landfill
  • The special case of e-waste → special sites to recycle; metal is extracted from circuit boards when recycled 
  • Nuclear Waste
  • Held onsite in concrete lined pools of water : short-term storage on-site in underwater tanks; long-term storage at Yucca Mountain
  • Yucca Mtn. concerns: 
    • Somewhat close to water table
    • Rock has cracks, fissures, & is a little porous
  • Volcanically active & prone to earthquakes  
  • Laws and Regulations 

○ Resource Conservation and Recovery Act (RCRA) 


○ Comprehensive Environmental Response Compensation and Liability Act (CERCLA) (1980) 

■ Sometimes referred to as Superfund


Unit 9 Study Guide 

Below is an AP Environmental Science Study guide for Unit 9:

o Be able to explain the mechanisms and related issues with global warming 

  • Albedo
    • The measure of the amount of light reflected off of a surface
      • High albedo = very reflective surface that doesn’t absorb a lot of light
      • Low albedo = generally dark surface that does absorb lots of light
  • Radiative forcing
    • a change in Earth’s energy balance between incoming solar radiation energy and outgoing thermal IR emission energy when the variable is changed while all other factors are held constant
  • Greenhouse gas effect 
    • Greenhouse gasses: chemicals that absorb and emit energy in the infrared (heat), thus trapping heat on a planet
    • How it increases air temperature
      • Light energy is shined into the ground from the sun
      • Some is reflected back up as light energy while some is absorbed into the ground and released as heat energy
      • Some of this heat travels up and escapes atmosphere
      • The rest of this heat (photons) is bounced back into the Earth and trapped due to the greenhouse gasses
      • This traps more heat therefore increasing the temperature

o     Earth’s Energy budget and the factors that affect it. 

  • the balance between the radiant energy that reaches Earth from the sun and the energy that flows from Earth back out to space.
  • Depends on…
    • atmospheric aerosols, greenhouse gasses, the planet’s surface albedo (reflectivity), clouds, vegetation, land use patterns
  • Global warming can lead to parts of the world becoming cooler
    • Jet-stream: fast-moving air currents in polar regions
      • Kept stable because of big temperature difference between arctic and mid-latitude
        • As the arctic gets warmer, this difference becomes smaller and widens the jet stream
        • Allows arctic air to enter North America and Europe causing decrease in temperature

o     the relative radiative forcing of common greenhouse gasses 

  • Global Warming Potential: A measurement of how much energy the emission of 1 ton of a gas will absorb over a period of time, relative to the emissions of 1 ton of CO2
  • Water Vapor
    • Released from fossil fuel combustion
    • Largest contributor to the GHG effect however not a worry of humans as there is nothing we can do about the amount of water in the atmosphere
  • Carbon Dioxide
    • Released from fossil fuel combustion
    • Highest radiative forcing
    • Kyoto Protocol (1992)
      • Formal acknowledgement CO2 emissions are leading to global warming
      • Asked the signing countries to work on reducing CO2 emissionsx
    • Paris Agreement (2016)
      • Signed by almost every country
      • Countries got to pick target for CO2 emissions 
      • Formal acknowledgement of rich/developed countries that they were the cause of pollution and agreed to pay a fee to poor countries being most affected to develop more sustainably
  • Methane
    • Released from fossil fuel combustion/fracking
    • Combustion equation: CH4 + O2 → CO2 + 2H2O
  • Halocarbons
    • CFCs (Chlorofluorocarbon)
      • Made of Chlorine, Fluorine, Carbon
      • Refrigerator disposal and air conditioner disposal most associated with CFC release
      • When a CFC travels to the stratosphere, gets hit by a UV ray causing a Chlorine atom to be knocked off
      • Ozone depletion: Cl + O3 – > ClO + O2
      • ClO molecule is very unstable resulting in it breaking really easily and causing a chain reaction
      • Effects of Ozone depletion
        • Lower crop production
        • More skin cancer
        • Less primary productivity in ocean 
      • Montreal Protocol *global agreements & treaties are hard to enforce
        • Agreement to stop using chemicals that depleted the ozone layer in 1987, signed in 89
        • Banned production of CFCs
      • Alternative to CFCs is HFCs
        • Hydrofluorocarbon
          • However, these are a GHG and have negative effects as well
    •  HFCs
  • Nitrogen Oxides 
    • Released from fossil fuel combustion

o Know the “climate indicators” 

    • Greenhouse Gasses
      • Increase in greenhouse gasses, leads to more infrared trapped in the atmosphere, leads to increase in temperature
    • Weather & Climate
      • Earth’s surface temperature has been increasing for 150 years
        • 799,850 years before that, we had a variability based on volcanic activity and other cycles
        • Today’s rapid change, caused by CO2 increase, is happening faster than any change we’ve ever seen. Changes that would naturally take 10,000 years are happening in less than 100 years. 
    • Oceans
      • Sea levels are rising
      • Ocean acidification
        • Increasing amounts of CO2 being dumped into the water
          • Humans pumping increased amounts of CO2 in the air and deforestation reduces the capacity of ecosystems as carbon sinks, all additional CO2 cannot be immediately used by photosynthesis resulting in lots of excess CO2
          • This then reacts with water to form Carbonic Acid
            • CO2 + H2O -> H2CO3
            • H2CO3 → H + HCO3
        • Ocean acidification results in corals becoming weaker 
          • Calcium Carbonate is used to make shells
            • CO3- + Ca = CaCO3
          • Acidified water has lots of H- atoms in it, and when the react with carbonate, they form HCO3 which can no longer bond with Ca to make shells
      • Ocean temperatures
        • Fish that are adapted to live in colder water have metabolic stress when the water gets warmer
        • Warmer water holds less dissolved oxygen decreasing fish populations
        • Causes coral bleaching
          • When water is too warm, the corals kick out the algae that color them making them whiter. 
            • Results in lack of support of wildlife and habitat
    • Snow & Ice
      • If there is more sea ice melting, there will be a rise in ocean levels, which would damage coastal ecosystems and cause flooding
        • To control ocean levels, preserve/plant/restore mangrove forests
      • Positive feedback loop: Melting ice exposes bedrock which has a low albedo, more light is absorbed and released as heat energy increasing the temperature, increase in temperature causes faster melting of ice repeating the cycle
        • Results in loss of ice habitats leading to decrease in biodiversity, higher sea levels causing flooding, and gasses that are trapped in ice are released causing problems such as methane
    • Health & Society
      • Longer periods for vectors like mosquitoes to reproduce 
  • Ecosystems
    • Wildfires → increase in severity and strength
      • Prevented by proper forest management → controlled burns 
      • Result of increased temperature and drought/decreased water availability
      • Fires can start and burn more easily 

Be able to reason out relationships between climate change and each category (for example, if there is more sea ice melting, there will be a rise in ocean levels, which would damage coastal 


  • What types of things lead to an increase in GHGs in Earth’s atmosphere? 
    • Anthropogenic: Burning fossil fuels, livestock farming, other industrial activities, deforestation, etc
    • Natural: Volcanic Eruptions, Methane release from Wetlands
  • Invasive Species 

o Examples of specific species. 

  • What makes species invasive?
    • Buckthorn, Zebra Mussel, Asian Carp, Autumn Olive
    • Non-native species species that can cause harm to an ecosystem by out-competing native organisms for food and habitat; often time causes damage to an ecosystem
    • All invasive species are Non-native, but not all non-native species are invasive.
      • No predators
      • Generalist species
      • R-selected
        • High reproductive rates in larger amounts
        • Small amounts of parental care
      • Allelopathic
        • Secret chemicals that alter immediate environment to prevent growth of competing plants
  • 10-10-01- rule 
    • 1 out of every 10 imported organisms will begin to appear in the wild
    • 1 out of those 10 will establish in the ecosystem
    • 1 out of 10 established non-native species will become invasive
  • Management strategies 
  • Endangered species 
  • Examples of specific species
    • Pandas, elephants, rhinos, california condors 
  • Causes for endangerment
    • Species competition
    • Habitat destruction, overhunting, outcompeted by invasive species
    • Specialist species
    • K-selected
      • Few offspring
      • Lots of parental care
  • Management strategies
    • Protected areas
    • Specific programs for species
      • Breeding programs
    • CITES (Convention on international trade in endangered species)
      • International treaty ensuring any international trade in plants or animals doesn’t threaten their survival in the wild by banning and regulating trade in endangered or threatened species
    • Habitat restoration programs most important
  • Factors affecting biodiversity 

○ What leads some areas to have more diversity than others? 

○ How do human activities affect biodiversity? 

○ Effect of Climate Change on biodiversity 


  • Habitat Loss 
  • Destruction
  • Fragmentation
    • Large habitats are broken into smaller isolated areas
      • Due to human activity such as roads, pipelines, etc
    • Areas are not large enough or connected enough to support full populations
    • Leads to the edge effect
      • Transition between 2 different habitats (Ecotone)
        • Naturally occurring have higher biodiversity
        • Artificially created results in lower biodiversity
          • Ex: when an area is cleared of forests, secondary succession begins, first species to colonize is a generalist species, makes early colonizers great competitors who can push further to forets, changing the structure of the ecosystem and decreasing biodiversity
    • Can be mitigated by… 
      • Being strategic with land use
        • Bigger fragments and closer together
        • Include habitat corridors for extended habitats
  • Degradation
    • A habitat that remains intact but is harmed
    • 2 big drivers
      • Pollution
        • Pollutants from human activity can be deposited into ecosystem and affect water or soil quality
          • Creates a habitat that can’t support biodiversity
  • Invasive species (Above)
  • Population Growth  
  • Pollution 
  • Climate Change
  • Ozone depletion leads to less primary productivity in oceans
  • Coral bleaching
  • Ocean acidification 
  • Over-exploitation 
  • Overgrazing 
  • Soil erosion
  • Deforestation
  • Overfishing 

I hope you enjoying this AP Environmental Science study guide. These are the sources we used to make this AP Environmental Science study guide:





Want to find an internship in high school? Horizonworldwide.org (the website you’re on now) has a master list of high school internships on the home page. You can also read my guide on how to find an internship in high school.

About me
sarah lim
I'm Sarah Lim
My Skills

Web Developer

Social Media + SEO