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Environmental Science

College9 units and 79 lessons. Helio talks each one through and draws each step on a board.

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Units

  1. The living world: ecosystems

    11 lessons
    1. Introduction to ecosystemsName the biotic and abiotic parts of an ecosystem and the roles of producers, consumers and decomposers, explain that matter cycles while energy flows through once, and use the photosynthesis and respiration equations to trade the same atoms.
    2. Terrestrial biomesExplain that temperature and precipitation set a biome, name the nine biomes with their vegetation and soil, and read a climatogram to identify a biome.
    3. Aquatic biomesSort aquatic biomes by salinity, name the zones of a lake, and compare productivity per area with total productivity for estuaries, reefs, lakes and the open ocean.
    4. The carbon cycleName the carbon reservoirs and their sizes, describe the fast and slow fluxes between them, and do the bookkeeping that shows how burning fossil fuels changes the atmosphere.
    5. The nitrogen cycleExplain why nitrogen gas is unusable, name the five processes of the nitrogen cycle with the organisms that run them, and calculate the nitrogen in fertilizer and what leaches away.
    6. The phosphorus cycleExplain that phosphorus has no gas phase and cycles slowly through rock, water and living things, why it often limits growth in lakes, and calculate how phosphorus loads become algae.
    7. The hydrologic cycleDescribe the processes that move water between the oceans, air, land and groundwater, say where Earth's freshwater is stored, and use a water balance to see when pumping outruns recharge.
    8. Primary productivity: GPP and NPPDefine gross and net primary productivity, calculate NPP = GPP − R and its share and area totals, tell a rate from a stock of biomass, and rank biomes by productivity per area.
    9. Trophic levelsAssign trophic levels in a food chain, read an arrow as the direction energy moves, handle omnivores, and place decomposers correctly.
    10. Energy flow and the 10 percent ruleUse the 10 percent rule to find the energy at any trophic level, go down the chain by dividing by 0.10, and explain the pyramids of energy, biomass and numbers and why food chains are short.
    11. Food chains and food websRead a food web, define a keystone species and a trophic cascade, and predict the direct and indirect effects of removing a species by tracing arrows.

  2. The living world: biodiversity

    6 lessons
    1. Levels of biodiversityName the three levels of biodiversity, tell species richness from evenness and from abundance, and explain why genetic diversity protects a population.
    2. Ecosystem servicesSort ecosystem services into provisioning, regulating, supporting and cultural, value a service by its replacement cost, and weigh trade-offs between services.
    3. Island biogeographyRank islands by size and distance, explain the equilibrium where immigration equals extinction, and apply the theory to habitat fragments.
    4. Ecological toleranceRead a tolerance curve with its optimum, stress and intolerance zones, compare narrow and wide ranges, and say what a limiting factor does.
    5. Natural disruptions and adaptationsName natural disruptions and judge how fast ecosystems recover, define adaptation and tell it from acclimation, and explain why fire suppression can backfire.
    6. Ecological successionTell primary from secondary succession, give the sequence of pioneer to late species with the soil that builds up, and explain the trends and the limits of the climax idea.

  3. Populations

    8 lessons
    1. Generalists, specialists, r and K strategistsTell generalists from specialists, describe r-selected and K-selected life histories as the ends of a continuum, and say which does better in stable and in disturbed environments.
    2. Survivorship curvesRead a survivorship curve as the survivors of one cohort against age, tell Type I, II and III curves, and link each to parental care and reproductive strategy.
    3. Carrying capacityDefine carrying capacity, sort limiting factors into density-dependent and density-independent, and explain overshoot, die-off and why K moves.
    4. Population growth: exponential, logistic and the rule of 70Tell exponential from linear and logistic growth, calculate a percent growth rate, and use the rule of 70 to find a doubling time and a later population.
    5. Age structure diagramsRead an age structure diagram by its three age bands, tell the shapes of growing, stable and shrinking populations, and explain why growth continues after fertility falls, which is population momentum.
    6. Total fertility rateDefine total fertility rate and replacement level, calculate how far a TFR is from replacement, and name the factors that lower and raise it.
    7. Human population growth calculationsCalculate a growth rate in percent from birth, death and migration rates per 1,000, find a doubling time and a later population, and avoid the unit slips that cost marks.
    8. The demographic transitionDescribe the four stages of the demographic transition model by birth and death rates, explain what drives the falls in each rate, and see why growth is fastest in stage 2 and varies by country.

  4. Earth systems and resources

    9 lessons
    1. Plate tectonicsDescribe the three plate boundary types and what each builds, place earthquakes and volcanoes (including hot spots) by boundary type, and calculate spreading distances and times from a rate in cm per year.
    2. Soil formation and erosionExplain how soil forms from weathered rock and organic matter, name the soil horizons, calculate how long erosion takes to strip topsoil, and give the practices that conserve it.
    3. Soil composition and the soil texture triangleSort soil particles into sand, silt and clay, turn a jar test into percents that sum to 100 and a texture class, and link texture to porosity, permeability, water holding and fertility.
    4. Earth's atmosphereName the atmospheric layers and how temperature changes through them, give the composition of dry air, separate the ozone layer from the greenhouse effect, and calculate a percent change in CO₂.
    5. Global wind patternsExplain why air rises at the equator and sinks near 30 degrees, name the three circulation cells and the prevailing winds, and use them to place rainforests, deserts and sailing routes.
    6. WatershedsDefine a watershed and its divides, explain why upstream actions affect downstream users, calculate how development changes runoff volume, and name ways to manage a watershed.
    7. Solar radiation and seasonsExplain why the equator gets more energy per area than the poles, why Earth's fixed tilt causes the seasons, find the noon sun angle for a latitude, and use albedo to compare surfaces.
    8. Geography and climate: rain shadowsExplain how mountains make a wet windward side and a dry rain shadow, use the lapse rate of 6.5 °C per km, and show how large water bodies and ocean currents moderate climate.
    9. El Nino and La NinaDescribe the normal Pacific pattern of trade winds and upwelling, how El Nino and La Nina change it, their effects around the world, and calculate percent changes in a fishery.

  5. Land and water use

    11 lessons
    1. The tragedy of the commonsExplain why individuals overuse a shared resource, test a choice by comparing private gain with private share of the cost, and name solutions including community rules.
    2. Forests: clearcutting and sustainable forestryCompare clearcutting with selective methods, explain the effects of deforestation on soil, biodiversity and carbon, and calculate a sustainable yield.
    3. The Green Revolution and agricultural impactsDescribe what the Green Revolution changed and its benefits, name the environmental and social costs of its inputs and of common farming practices, and calculate percent changes in yield and fertilizer.
    4. Irrigation methodsRank flood, furrow, spray and drip irrigation by efficiency, calculate the water applied and saved, and explain waterlogging, salinization and over-pumping with their solutions.
    5. Pest control and integrated pest managementCompare chemical, biological, cultural and physical pest control, explain pesticide resistance as natural selection with numbers, and describe integrated pest management as an escalation that still allows pesticides.
    6. Meat production methodsCompare feedlots with grazing systems and their environmental costs, and use feed conversion ratios and the 10 percent rule to compare the feed needed for beef, pork and chicken.
    7. Overfishing and aquacultureExplain overfishing with the cod collapse and a stock calculation, name harmful fishing methods and management tools, and weigh the benefits and costs of aquaculture.
    8. MiningCompare surface and subsurface mining, calculate ore grade and waste, explain acid mine drainage and other impacts, and say what reclamation can and cannot restore.
    9. Urbanization and urban runoffExplain how paving raises runoff using runoff coefficients, calculate runoff volume and its reduction, and describe the urban heat island, sprawl and solutions.
    10. Ecological footprints and sustainabilityDefine ecological footprint and biocapacity, calculate the number of Earths and overshoot day from them, compare countries, and define sustainability as use no faster than renewal.
    11. Sustainable agricultureName soil-conservation, fertility and diversity practices, calculate soil saved by no-till, and weigh the trade-offs of sustainable and organic farming.

  6. Energy resources and consumption

    10 lessons
    1. Energy resources and global consumptionSort energy sources into renewable and nonrenewable, read the world energy mix, compare energy use per person, and name an environmental impact of each source.
    2. Fuel types and usesTell young organic fuels from fossil fuels, rank coal, compare the energy and emissions of coal, oil and natural gas, and calculate CO₂ from a fuel's emission factor.
    3. Fossil fuels: distribution, extraction and frackingExplain how coal, oil and gas formed, where the large reserves lie, how each is extracted including fracking, and what the impacts are.
    4. Nuclear power and half-lifeExplain how fission in a reactor makes electricity and how it is controlled, use half-life to calculate how much radioactive waste remains, and weigh nuclear power's trade-offs.
    5. Biomass energyName the forms of biomass energy, explain why biomass is not automatically carbon neutral, calculate the net energy of ethanol, and weigh its trade-offs including biogas.
    6. Solar energyExplain how photovoltaic and solar thermal systems work, calculate the area and payback of a rooftop system, and separate efficiency from capacity factor and the limits of solar power.
    7. Hydroelectric and geothermal powerExplain how dams and geothermal plants make electricity, name the impacts and limits of each, and calculate the energy and homes served from a plant's rating and capacity factor.
    8. Hydrogen fuel cells and windExplain how a hydrogen fuel cell works and why hydrogen is an energy carrier, not a source, and calculate wind energy including the cube law for wind speed, with wind's impacts.
    9. Energy conservationTell conservation from efficiency, name ways buildings, transport and industry save energy, and calculate savings including the rebound effect and the true efficiency of electric heat.
    10. Energy calculations: kWh, efficiency and costCalculate energy in kilowatt-hours and its cost, work out efficiency and overall efficiency of a chain, and compare payback and lifetime cost.

  7. Atmospheric pollution

    7 lessons
    1. Primary and secondary air pollutantsSort air pollutants into primary (emitted) and secondary (made in the air), name the six criteria pollutants and the sources of each kind, and compare a reading with a standard as a percent.
    2. Photochemical smogExplain how nitrogen oxides, VOCs and sunlight make ozone and PAN, read a daily graph for the order and timing of the peaks, and say when and where smog is worst and what it harms.
    3. Thermal inversionCompare a normal temperature profile with an inversion, say how inversions form and end, and find the inversion layer in sounding data and why it traps pollution.
    4. CO2, particulates and indoor air pollutantsTell toxic carbon monoxide from the heat-trapping but non-toxic CO₂, explain why fine particles do the most harm, name the main indoor pollutants and their controls, and calculate exposure doses and action-level ratios.
    5. Reducing air pollutantsName the devices, fuels and policies that cut air pollution from smokestacks and tailpipes, write what a catalytic converter does, explain cap-and-trade, and calculate percent reductions and permit values.
    6. Acid rainExplain how SO₂ and NOx become acid deposition, use the logarithmic pH scale to compare acidity, and say which places and things acid deposition harms and why some are protected.
    7. Noise pollutionExplain why noise is a pollutant that harms people and wildlife, use the decibel scale where each 10 dB is ten times the intensity, and rank source, path and receiver controls.

  8. Aquatic and terrestrial pollution

    10 lessons
    1. Pollution sources and impacts on ecosystemsTell point from nonpoint sources, name the main water and soil pollutants and the laws that regulate them, and calculate a pollutant load from flow and concentration.
    2. Endocrine disruptorsDefine endocrine disruptors, name common sources and effects, explain why tiny doses and treated wastewater still matter, and compare rates in a survey.
    3. Wetlands and mangrovesName the kinds of wetland, list the services they provide, explain why losing them costs more than their conversion earns, and calculate flood storage lost or restored.
    4. Eutrophication and dissolved oxygenTrace how nutrients cause algal blooms and fish kills, explain why dissolved oxygen falls with temperature and with decomposition, and calculate DO changes and oxygen demand.
    5. Thermal pollutionDefine thermal pollution and its sources, explain how warmer water stresses life through lower oxygen and higher demand, and calculate oxygen margins before and after cooling.
    6. POPs, bioaccumulation and biomagnificationDescribe persistent organic pollutants, separate bioaccumulation from biomagnification, calculate concentrations up a food chain, and recall the DDT case and the treaty that restricts POPs.
    7. Solid waste and waste reductionDescribe municipal solid waste and how landfills and incinerators handle it, order the waste hierarchy, compare energy savings from recycling, and calculate tons produced, diverted and landfilled.
    8. Sewage treatmentDescribe primary, secondary and tertiary treatment and septic systems, calculate the BOD left after each stage and the daily load released, and explain why combined sewers overflow.
    9. LD50 and dose-response curvesRead and compare LD50 values, describe the S-shaped dose-response curve, explain thresholds and why LD50 is not a safe dose, and scale doses by body mass.
    10. Pollution, health and pathogensMatch pollutants to the health effects they cause, sort pathogens by how they spread, calculate disease rates and the effect of sanitation, and explain how environmental change shifts disease.

  9. Global change

    7 lessons
    1. Ozone depletion and its reductionExplain how stratospheric ozone forms and shields the surface from UV, how CFCs destroy it catalytically, why the Antarctic hole forms, and how the Montreal Protocol is reversing the loss.
    2. The greenhouse effect and global warming potentialExplain how greenhouse gases absorb and re-emit infrared to warm the surface, separate the natural from the enhanced effect, and compare gases by lifetime and global warming potential.
    3. Rising greenhouse gasesName the human sources of CO₂, methane, nitrous oxide and halogenated gases, read the rise in CO₂ against its 800,000-year record, and show that human emissions are the net extra even though natural flows are larger.
    4. Global climate changeList the evidence of warming, describe its effects, explain positive and negative feedbacks, separate weather from climate, and distinguish mitigation from adaptation, with a sea level calculation.
    5. Ocean warming and acidificationExplain how the ocean absorbs heat and CO₂, why corals bleach, how ocean pH falls and why a 0.1 change is large, and why a warmer ocean absorbs less CO₂.
    6. Invasive speciesDefine an invasive species, name how species arrive and why some thrive, describe their impacts, and use the rule of 70 to project growth and the effect of control.
    7. Endangered species and human impacts on biodiversityName the threats to species with HIPPCO, explain which species are most vulnerable, calculate how fragmentation shrinks core habitat, and describe conservation tools.

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