AP Environmental Science Study Outline

Kui Tang

August 2008

This guide follows the College Board's Topic Outline. Environmental Sci-ence: Earth as a Living Planet by Botkin and Keller, 6th edition, was the mainsource for these notes.

Contents

1 Earth Systems and Resources 21.1 Earth Science Concepts . . . . . . . . . . . . . . . . . . . . . . . 31.2 The Atmosphere . . . . . . . . . . . . . . . . . . . . . . . . . . . 31.3 Global Water Resources and Use . . . . . . . . . . . . . . . . . . 51.4 Soil and Soil Dynamics . . . . . . . . . . . . . . . . . . . . . . . . 7

2 The Living World 82.1 Ecosystem Structure . . . . . . . . . . . . . . . . . . . . . . . . . 82.2 Energy Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112.3 Ecosystem Diversity . . . . . . . . . . . . . . . . . . . . . . . . . 112.4 Natural Ecosystem Change . . . . . . . . . . . . . . . . . . . . . 122.5 Natural Biogeochemical Cycles . . . . . . . . . . . . . . . . . . . 13

3 Populations 143.1 Population Biology Concepts . . . . . . . . . . . . . . . . . . . . 143.2 Human Population . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3.2.1 Human Population Dynamics . . . . . . . . . . . . . . . . 153.2.2 Population Size . . . . . . . . . . . . . . . . . . . . . . . . 153.2.3 Impacts of Population Growth . . . . . . . . . . . . . . . 16

4 Land and Water Use 164.1 Agriculture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

4.1.1 Feeding a Growing Population . . . . . . . . . . . . . . . 164.1.2 Controlling Pests . . . . . . . . . . . . . . . . . . . . . . . 18

4.2 Forestry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184.3 Rangelands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194.4 Other Land Uses . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

4.4.1 Urban Land Development . . . . . . . . . . . . . . . . . . 194.4.2 Transportation Infrastructure . . . . . . . . . . . . . . . . 21

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4.4.3 Public and Federal Lands . . . . . . . . . . . . . . . . . . 224.4.4 Land Conservation Options . . . . . . . . . . . . . . . . . 224.4.5 Sustainable Land-Use Strategies . . . . . . . . . . . . . . 22

4.5 Mining . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224.6 Fishing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254.7 Global Economics . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

5 Energy Resources and Consumption 265.1 Energy Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . 265.2 Energy Consumption . . . . . . . . . . . . . . . . . . . . . . . . . 27

5.2.1 History . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275.2.2 Present Global Energy Use . . . . . . . . . . . . . . . . . 275.2.3 Future Energy Needs . . . . . . . . . . . . . . . . . . . . . 28

5.3 Fossil Fuel Resources and Use . . . . . . . . . . . . . . . . . . . . 285.4 Nuclear Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295.5 Hydroelectric Power . . . . . . . . . . . . . . . . . . . . . . . . . 325.6 Energy Conservation . . . . . . . . . . . . . . . . . . . . . . . . . 335.7 Renewable Energy . . . . . . . . . . . . . . . . . . . . . . . . . . 34

6 Pollution 366.1 Pollution Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

6.1.1 Air Pollution . . . . . . . . . . . . . . . . . . . . . . . . . 366.1.2 Noise Pollution . . . . . . . . . . . . . . . . . . . . . . . . 416.1.3 Water Pollution . . . . . . . . . . . . . . . . . . . . . . . . 426.1.4 Solid Waste . . . . . . . . . . . . . . . . . . . . . . . . . . 45

6.2 Impacts on the Environment and Human Health . . . . . . . . . 496.2.1 Hazards to Human Health . . . . . . . . . . . . . . . . . . 496.2.2 Hazardous Chemicals in the Environment . . . . . . . . . 50

6.3 Economic Impacts . . . . . . . . . . . . . . . . . . . . . . . . . . 51

7 Global Change 527.1 Stratospheric Ozone . . . . . . . . . . . . . . . . . . . . . . . . . 527.2 Global Warming . . . . . . . . . . . . . . . . . . . . . . . . . . . 547.3 Loss of Biodiversity . . . . . . . . . . . . . . . . . . . . . . . . . . 57

7.3.1 Habitat loss; overuse; pollution; introduced species; en-dangered and extinct species . . . . . . . . . . . . . . . . 57

7.3.2 Maintenance Through Conservation . . . . . . . . . . . . 587.3.3 Laws and Treaties . . . . . . . . . . . . . . . . . . . . . . 58

1 Earth Systems and Resources

1. Average Residence Time (ART): ratio of size of reservoir to rate of transferthrough reservoir:

ART = S/F

Where S is size of reservoir and F is rate of transfer.

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1.1 Earth Science Concepts

1. Lithosphere is crust.

2. Geological cycles include

(a) Tectonic: can create ecological islands.

i. Divergent plates boundaries occur at a spreading ocean ridge(sea�oor spreading).

ii. Convergent plate boundaries occur when plates collide.

A. Subduction is the heavy ocean rock diving beneath the lightcontinental rock. May produce coastal mountain ranges (An-des).

B. Continental collisions may produce continental mountains.

iii. Transform fault boundaries occur when one plate slides past an-other.

(b) Hydrologic

(c) Rock

(d) Biogeochemical

3. Earthquake occurs when tectonic plates under pressure rupture, releasinghuge amounts of energy (more than a large nuclear explosion), usually at10�15 km along faults.

(a) Fault planes bar groundwater. Rocks crushed, then altered into clay.Water forced to surface, creating vital habitats, especially where arid.

4. Volcanic eruption occurs when magma rises to the surface. Energyreleased varies broadly. Volcanoes occur along tectonic plate boundaries,where active melting of rocks favors extrusion of magma, or along centralparts of plates where local hot spots heat and melt rock.

5. Tsunami is a series of large waves produced after the vertical disturbanceof ocean. 80% are produced by earthquakes. They travel at jet aircraftspeeds but slow and get taller as they approach the surface.

1.2 The Atmosphere

1. Composition is 78% N2, 21% O2, 0.9% Ar, 0.03% CO2.

2. Structure in order is: troposphere, tropopause (condensation traps watervapor), stratosphere (O3), stratopause, mesosphere, mesopause, thermo-sphere.

3. 25% of incoming solar radiation re�ected straight into space, 25% absorbedby atmosphere.

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4. Atmospheric circulation: (1) rotation and (2) di�erential heating.

(a) Low pressure at equator, 50�60◦.

(b) High pressure from descending air 25�30◦ → arid. Sandwiched be-tween two zones of high precipitation (low pressure).

(c) Easterlies at poles and Westerlies from 30�60◦ meet at 60◦.

(d) Trade winds blow to west; meet at equator, where doldrums occur(regions with little air movement).

5. El Niño events (also ENSO) occur every 2�7 years, lasting for 1�1 12 years.

East-west trade winds weaken and eastern Paci�c waters warm→ tropicalrainfall shifts from Indonesia to South America. Floods in Peru; droughtsand �res in Indonesia and Australia. Upwelling at South American coast-line is suppressed. Natural.

(a) La Niña opposite; exaggerate normal patterns.

6. Tornadoes are funnel-shaped clouds of rapidly rotating wind. They formout of severe thunderstorms that occur when a cold air mass collides witha warm one. Water vapor in the warm part is forced upwards, cools, thenprecipitates.

7. Hurricanes are tropical storm with circulating winds of at least 120 km/hthat moves across tropical ocean.

(a) An organized mass of thunderstorms with low pressure begin to cir-culate, forming a tropical depression.

(b) Huge amounts of energy are stored as latent heat�vaporization.Condensation releases this energy, warming air. As this air rises,more water is drawn, increasing the size of the hurricane.

(c) Rain bands form as the warm air rises.

(d) Nearing landfall, hurricanes may slow down in shallower water, butwarm water increases intensity.

(e) Storm surges occur when the hurricane winds push water towardsthe coast, which may rise to be over 10 m and may be exacerbatedby high tide.

8. Heat waves are extended periods of unusually hot weather caused byheating of atmosphere and moving of air masses. They are consideredmost deadly of all weather-related hazards. Global warming may haveincreased their severity and incidence.

9. Droughts are long-term (months to years) periods of usually dry weatherthat are related to natural cycles of wet and dry years, which in turn arenot well understood.

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10. Coriolis e�ect is apparent de�ection of moving objects when viewed froma rotating frame of reference.

(a) Free objects on surface appear to go right in Northern hemisphereand left in southern.

(b) Air and water �ows right in north, left in south.

(c) Responsible for cyclones.

1.3 Global Water Resources and Use

1. Groundwater is water below the water table, which is saturated. 20%.

(a) Surface water enters at recharge and exit at discharge zones.

(b) Vadose zone is unsaturated area above water table where water moves.

(c) Aquifer is underground zone where water can be extracted at a usefulrate. Gravel or sand.

(d) Cone of depression occurs where well is: water level is locally lower.

(e) E�uent streams maintain �ow during dry weather by groundwaterseepage (they are below water table). Most perennial streams aree�uent.

(f) In�uent streams are entirely above water table; �ows only in re-sponse to precipitation. Called ephemeral stream.

(g) Reaches are sections of a stream that may be e�uent, in�uent, orintermediate.

(h) Though reserves are huge (conservatively 200 years of Mississippi�ow), pumping costs limit amount that can be economically recov-ered.

i. Overdraft occurs when withdrawal rate > natural in�ow.

ii. Essentially nonrenewable because it can → damage ecosystems,land subsidence.

iii. Texas�Oklahoma�High Plains area (Ogallala aquifer): primeexample. Used 20 times faster than being renewed.

2. Surface and ground-water related:

(a) Use groundwater → decrease surface levels

(b) Divert surface water → decrease ground levels and quality OR in-crease pollutants if divert to recharge zone. Pollution interrelatedtoo.

3. Ocean circulation

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(a) �Oceanic conveyor belt:� (Gulf Stream) water 12�13◦C arrives atGreenland. Cooled and becomes more saline in North America (2�4◦C), sinks to bottom. Flows south, east, north into Paci�c. Up-welling starts warm shallow current. Keeps N. Europe 5�10◦C cooler.

(b) Forces include: rotation, wind, temperature and salinity di�erences,gravity of moon.

4. Only 50% of precipitation is considered available 95% of the time.

5. Desalination will remain expensive because it has place value: it is veryexpensive to transport water.

(a) Discharge of brine waste may damage ecosystems.

6. Stream usage

(a) O�-stream use is removal and return (power plant).

(b) Consumptive use is not returned (drinking, irrigation).

(c) In-stream use uses the stream itself or modi�es it. Each use requiresdi�erent rates of discharge that cannot be met simultaneously.

i. Hydroelectric power prefers large �uctuations.

ii. Fish and wildlife prefer larger �ows in spring and summer, asdoes recreation.

iii. Navigation prefers constant �ow.

(d) Aral Sea demonstrates that removing too much water is deleterious toecosystems. The sea area has been reduced by 40%, volume by 50%.Economically important �sh are dying, and �shing towns borderingthe sea are now inland. Restoration just beginning.

7. Industrial and domestic use (U.S.)

(a) Agriculture, industry began leveling o� around 1980. Suggests con-servation working.

(b) Water for public supply continue to increase.

8. Conservation expects to reduce total withdrawals yet allow consumptionto increase.

(a) Agriculture can reduce 20�30%:

i. Don't subsidize water.

ii. Integrate surface and groundwater use: use store surface water(in�ltration pool or injection well) when abundant, groundwaterwhen not.

iii. Use high-tech to maximize delivery e�ciency. Irrigate whenevaporation is minimal. Use improved irrigation (drip).

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iv. Improve soil: ↑ in�ltration, ↓ runo�.v. Use crops that require less water or are more salt-tolerant.

(b) Domestic use is only 10%, but concentrated in urban.

i. Don't do lawns in semi-arid regions!

ii. Use e�cient bathroom �xtures�1.6 gpf instead of 5.0.

iii. Utilities should price water based on non-linear curve to encour-age consumption.

(c) Industry can reduce electricity generating water 25�30% by using lowwater/no water evaporation tower, in-plant water reuse.

(d) Perception impacts people's attitudes toward water conservation.

i. Tucson: people think it's desert; conserve. Water expensive. Forexample, price per unit increases if usage increases past baseline.

ii. Phoenix: water cheap; people don't bother conserving.

9. In wet years, plenty of surface water, and groundwater is recharged. Dryyears, need emergency plans to minimize hardship:

(a) Plan to drill and connect wells for deep groundwater, even thoughtoo expensive to normally use.

(b) Prepare to treat waste water for reuse when needed.

1.4 Soil and Soil Dynamics

1. Rock Cycle

(a) Igneous rock forms from lava. Cracking, weathering split.

(b) Sedimentary rock forms from pressure of lots of sediment: depo-sition + lithi�cation.

i. Weathered rock.

ii. Carbon sediments by life.

(c) Metamorphic rock forms from sedimentary rocks transformed throughheat, pressure, or chemicals. May be uplifted into open.

2. Soils are earth materials modi�ed by physical, geological, and biologicalprocesses into horizons:

(a) O: black organic layer. Decomposing stu�.

(b) White powder�bleached of organic compounds.

(c) A: mineral and organic. Brown/light-black. Minerals leach here.

(d) E: lighter-colored because clay, minerals leached.

(e) B: zone of accumulation (of leached stu� above).

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(f) C: parent material�partially weathered bedrock.

3. Rainwater (pH = 5.5) leaches minerals.

4. Soil fertility

(a) Young rocks fertile: corn belt (recent glacier).

(b) Semiarid regions fertile; need water.

(c) Humid areas/tropics infertile: leaching due to rainfall. Most nutri-ents in vegetation. Succession di�cult if forest cleared.

5. Semiarid soils expand and contract with water. Damage buildings.

6. Clay hold water. Sand allows water to drain. Combination retains waterenough for growth but still drains. Coarser soils more easily eroded.

7. Loams are best soils; have all particle sizes.

8. Landslides occur when driving forces (gravity) that tend to move soiland things in the soil down a slope overcome resisting forces that holdthe ground in place (interlocking grains, natural cementing, plant roots,strength of materials on slope). Addition of water or removal of vegetationreduces resisting forces. Some landslides are reactivations of prehistoricslides; these areas repeatedly experience landslides (see La Conchita).

(a) In mountains, create lakes by damming valleys.

9. Floodplain is river and �atland draining into it. Naturally, �oods annu-ally.

(a) Deposit nutrients on �oodplain.

(b) Wetlands provide habitat.

(c) Floodplain is distinct from adjacent environments → diversity.

2 The Living World

2.1 Ecosystem Structure

1. Ecosystem is the simplest entity that can sustain life. Support chemicalcycling and energy �ow.

2. Habitat is where a species lives; niche is what it does.

(a) Conservation requires paying attention to both, as well as obligatesymbionts.

(b) Predation can increase diversity by mitigating competitive exclusion.

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3. Watershed de�nition of ecosystem: delineated by land that drains intosame stream.

4. Community-level interactions occur when a species indirectly a�ectsanother by a�ecting intermediary species or the environment.

(a) Sea otters eat key urchins → allow kelp to grow.

(b) Keystone species are necessary for the basic nature of a community.

5. Biotic provinces are geographic regions (including ocean) inhabited bycharacteristic set of taxa sharing common evolutionary history and repro-ductively isolated from other provinces.

(a) Formed by continental drift.

(b) Safer to introduce species within its biotic province.

6. Biomes are de�ned by climate, which selects for common traits (conver-gent evolution).

7. Island biogeography: smaller and more distant islands have fewer species.Migration and evolution supply new species.

(a) Ecological island is a separated small habitat: park, oceanic island(over�shing), patches of uncut forest.

8. Major biomes

(a) Tundra�grasses, mosses, lichens; dwarf shrubs.

i. Arctic tundra has large animals; alpine tundra does not.

(b) Taiga/Boreal Forest�conifers. Low biodiversity; commercially im-portant.

i. Northern America and Eurasia.

ii. Moose, deer, wolves, bears, foxes, squirrels, rabbits.

iii. Water foul, owls, eagles.

iv. Disturbances, esp. �re, frequent.

(c) Temperate Deciduous�hardwood trees.

i. China, Japan, W. Europe, U.S., urbanized Canada.

ii. Most changed by humans.

iii. Small mammals, birds, insects.

(d) Temperate Rain Forests�conifers.

i. North America, New Zealand.

ii. Rare. Conifers because they photosynthesize during non-freezingwinter.

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(e) Temperate Woodlands�small trees, open.

i. Drier than deciduous forest, same temperature.

ii. Fire regular.

iii. Forest plantations in this biome.

(f) Temperate Shrublands (chaparral) � shrubs.

i. Mediterranean, SoCal, Chile, S. Africa.

ii. Most attractive to people; little native left.

iii. Sage plant. Aromatic.

iv. Reptiles, small mammals.

v. Fire regular.

(g) Temperate Grasslands�midpoint between forest and desert.

i. N. American prairie, steppes of Eurasia, plains of Africa, pampasof South America.

ii. Rich organic soil.

iii. Most important agriculturally.

iv. Largest abundance and diversity of large mammals.

v. Fire and grazing maintain identity as grassland.

(h) Tropical Rain Forests

i. Soil low in nutrients; plants adapted to rapidly uptake.

ii. Found in very remote regions.

(i) Tropical Seasonal Forests and Savannas

i. India, Southeast Asia, Africa, South/Central America.

ii. High temperature, variable rainfall.

iii. Fire and grazing maintain identity.

(j) Deserts�rainfall < 50 cm/year.

(k) Wetlands�soil has little oxygen; slow decay. Flooded and saturatedat least several days a year.

i. Bogs have water entry but no outlet.

ii. Swamps and marshes have entry and exit.

iii. Produce fossil fuels.

iv. Bacteria produce CH4, H2S.

v. Saltwater marsh: breeding ground for oceanic animals.

vi. Services:

A. Reservoir. Hold high �ow; release to augment low �ow.

B. Important areas of groundwater recharge or discharge.

C. 45% endangered animals, 26% endangered birds depends onwetlands.

D. Natural �lters: plants trap sediment and toxin.

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E. Important production and storage of biomass, rich soil.

vii. Perhaps 90% of freshwater wetlands lost.

viii. Urbanization usually on coast, riverbank, or other place favorableto wetlands.

ix. Most wetlands now privately owned.

(l) Freshwaters

i. Estuaries�mouth of rivers�rich in nutrients.

ii. Important source of water for animals, civilization.

(m) Intertidal�major economic resource, algae (including kelp).

i. Easily polluted; manipulated by people, recreation, urbanization.

ii. Extreme changes are part of life.

(n) Open Ocean�pelagic region. Low in N, P.

(o) Benthos�deeps. Food is dead stu� that falls from above. Too dark.

(p) Upwellings�deep ocean water rich in nutrients. Flows bring nutri-ents to surface. West coast of America, Africa, ice caps. Sometimeswind pushes coastal waters away, pulling deep water up.

(q) Hydrothermal Vents�chemosynthesis. Unusual life-forms. High pres-sure, extremely variable temperature.

2.2 Energy Flow

1. Photosynthesis and cell respiration

2. Biological production is capture of energy into organic molecules; netproduction is the biomass/energy stored, not used.

3. Food webs and trophic levels

(a) Species that feed on multiple levels classi�ed by the highest.

(b) Naturally 1% energy transferred between trophic levels.

(c) Many freshwater ecosystems depend on detritus, as benthic.

4. Herbivores can eat stu� humans can't eat (algae) or graze without damag-ing land. Vegetarianism for everybody does not maximize food resources.

2.3 Ecosystem Diversity

1. Biodiversity is expressed as number of species in an area, but popularusage varies.

(a) About 1.4M named species, mostly insects and plants and mostly intropics.

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(b) Genetic diversity is total number of genetic characteristics of group(species, subspecies, arbitrary, etc.)

(c) Habitat diversity is di�erent kinds of habitats in given area.

(d) Species diversity

i. Species richness is total number,

ii. Species evenness is relative abundance,

iii. Species dominance is the most abundant species.

2. Ecosystem services

2.4 Natural Ecosystem Change

1. Ecological Succession: early-succession species are adapted to harsh en-vironment with plentiful resources (r -selected); later species are moreresource-e�cient but cannot withstand harsh environment (K -selected).

(a) Dune Succession�constantly formed and destroyed along sandy shores.

i. Dune grass forms runners underground. Stabilize other seeds.

ii. Small, hardy plants grow.

iii. Eventually, trees.

(b) Bog Succession�sedge (grass-like herbs) put �oating runners.

i. Wind blows stu� onto sedge mat; soil forms.

ii. Plants grow on sedge; sedge thickens. Really �oating mat.

iii. Sediments deposit.

iv. Eventually, wetland forest.

(c) Old-Field Succession�small, hardy plants, eventually trees.

(d) Biodiversity, biomass increase peaks during middle succession.

(e) Gross production ↑; net production ↓.(f) Vegetation retards erosion.

(g) Ecosystem eventually runs out of biomass.

(h) Species-interaction

i. Facilitation�one species prepares way for another (bog).

ii. Interference�early plants prevent entrance of later (dense grassesprevent other seeds from reaching ground).

iii. Life history di�erence�slowly-propagating species reachessuccession site later than do quickly-propagating species.

iv. Chronic patchiness�environment dominates and successionnever occurs.

2. Wild�res occur when vegetation cannot be decomposed quickly enoughto balance the carbon cycle, resulting in an accumulation of fuel.

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2.5 Natural Biogeochemical Cycles

Chemicals with a gas phase use atmosphere as reservoir and cycle quickly; chem-icals lacking gas phase often exist in unusable forms and are often insoluble inwater and cycle slowly.

1. Carbon

(a) Reservoirs: atmosphere, ocean, rocks, soil, fossil fuels.

(b) Assimilation: photosynthesis.

(c) Cycling: predation, weathering and erosion.

(d) Loss: respiration, decomposition (release CO2), forest �res, burningfossil fuels, volcanic eruption. Fossil fuel formation where too cold ornot enough to decompose.

(e) Missing carbon sink�about 3 GtC (billion metric tons of C) un-accounted for.

i. Sink changes size.

ii. Believe sink is terrestrial.

(f) Carbon-silicate cycle:

H2CO3 +XSiOn + CaCO3 → Ca2+ +HCO−3 + SiO2

These minerals precipitate and are extracted by marine organismsand form sediment in the ocean. Metamorphosis in subduction zonesreleases CO2 and reforms silica products.

2. Nitrogen

(a) Reservoirs: air, soil, ocean.

(b) Assimilation: nitrogen �xation, lightning, industry (50%).

(c) Cycling: internal, erosion and runo�, sea spray. Usually plants �rst.Ruminants have nitrogen-�xing bacteria in their stomachs that prove50% of N.

(d) Loss: de-nitri�cation, marine sedimentation.

3. Phosphorus

(a) Reservoir: phosphates of Ca, K, Mg, Fe.

(b) Assimilation: uptake by plants, algae, some bacteria.

(c) Cycling: to ocean (in soluble form or suspension), ocean-feeding birds(guano deposits), upwellings (winds push surface water away fromland, exposing deeper, nutrient-rich water), uplifting of sedimentaryrock.

(d) Loss: ocean sedimentation.

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4. Sulfur

(a) Reservoirs: rock, soil.

(b) Available reservoirs: air, below ground.

(c) Assimilation: root uptake, gaseous uptake.

(d) Cycling: litter fall (to ground), root leakage.

(e) Loss: to streams, to atmosphere.

5. Water

(a) Local land-use changes can change precipitation.

(b) Drainage basin is land that drains into a particular stream/river.

6. Conservation of matter

3 Populations

3.1 Population Biology Concepts

1. Logistic growth unrealistic: relies on

(a) Constant environment

(b) Constant K

(c) Homogeneous population (each has same impact)

2. K can only be estimated if logistic curve has reached in�ection point (whengrowth rate slows).

(a) Estimates before in�ection point undershoot.

(b) Maximum sustainable yield is the highest rate of growth andoccurs at 1

2K, but unrealistic. Mis-estimates led to over-harvest in20th century.

3. Doubling time (reverse of half-life):

Td =ln 2k

≈ 0.7k

where k is the constant in N = N0ekt.

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3.2 Human Population

3.2.1 Human Population Dynamics

1. History

(a) Hunter-gatherer; few million. 0.00011%.

(b) Agriculture; 0.03%

i. A.D. 1: 5M

ii. 1600 500M

(c) Industrial; 0.1%

i. 1800: 900M

ii. Doubled twice (3B) by 1960

(d) Modern; 1.2% (Total Fertility Rate = 2.5)

2. 95% of current growth from developing countries.

3. Demographic transition:

(a) Lower death rate (medicine against acute illnesses)

(b) Then, lower birth rate (education, wealth, social change)

(c) Possibly repeat (medicine against chronic illnesses)

4. Age-structure diagrams show past, present, and future.

3.2.2 Population Size

1. Sustainability = zero population growth.

2. ↑ Age of �rst childbearing.

(a) 40�50% of needed fertility reduction.

(b) Sri Lanka.

3. Birth control.

(a) Breastfeeding.

(b) 46M abortions yearly.

4. National policies: information and access to birth control, explain prob-lems of overpopulation, explain bene�ts of fewer children, instituted re-wards and punishments.

(a) India (1952).

(b) Ghana, Malaysia, Pakistan, Singapore, Philippines use tax disincen-tives.

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(c) Tanzania restrict maternity leave.

(d) Singapore: bigger families more crowded, admission priority for smallfamily.

(e) Sri Lanka, Bangladesh, India: government pays you for sterilization.

(f) China

i. 1978: goal ZPG by 2000.

ii. Achieved 1.0%.

3.2.3 Impacts of Population Growth

1. Ultimate cause of current unsustainability and current environmental prob-lems.

2. Resources and food per capita peaked in 1960s�1970s.

3. Economics

(a) Positive feedback in poor countries: low income → more children →keeps per-capita income low.

4 Land and Water Use

4.1 Agriculture

4.1.1 Feeding a Growing Population

1. Undernourishment: insu�cient calories.

(a) Marasmus�lack of protein and calories.

i. Kwashiorkor�lack of protein → failed neural development.

ii. Chronic hunger�unproductive.

(b) Malnourishment: lack of speci�c component. Long-term. Makespeople unproductive.

i. Macronutrients: C, H, N, O, P, S; Ca, Na, K.

2. Types of agriculture

(a) Rangeland�food for grazers/browsers. No plowing.

(b) Pasture�planted to provide animal feed.

(c) Organic farming

i. More like natural ecosystem�not monoculture.

ii. Minimize negative impacts.

iii. Food does not contain arti�cial chemicals.

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(d) In monoculture, seed companies predict growing season climates andlikely strains of pests and diseases. If they're wrong, you're screwed.In contrast, organic farming plants a mixture of crops or a broadrange of genotypes, resulting in lower average yield but mitigatesrisk of very-low-production.

3. Plowing damages soil: succession to di�erent climax or much more slowly.Unnatural.

(a) Natural vegetation maintains structure and enriches soil.

(b) Plowed land destroys structure and exposes soil; crops remove nutri-ents; heat decomposes nutrients.

(c) Erosion damages water productivity.

(d) 1mm soil produced 10 to 40 years.

(e) Contour plowing is the s0ingle most e�ective way to reduce erosion.

(f) No-till agriculture allow some weeds, leave decaying plants.

4. Green Revolution is the post-war program that led to crops with higheryields, better disease resistance, or better ability to grow in marginal con-ditions.

(a) Rice hybridization at the International Rice Institute in the Philip-pines.

(b) Drip irrigation�e�cient, but expensive, so not likely used in hungryplaces.

5. Genetic engineering and crop production

(a) U.S.: 1/3 corn, > 1/2 canola oil, 3/4 soybeans.

(b) Hybridization risks: superhybrid can grow where unwanted; super-weed had genes transferred to it.

(c) Terminator gene sterilizes seeds. Prevents GMO spread.

(d) BT corn produces pesticide in every cell. Unknown e�ect on con-sumers; toxic pollen can kill monarch butter�ies.

6. Key to future food production appears to be increased production per unitarea, on increasingly worse land.

7. Global warming decrease yield because best soils have best suited climates.

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4.1.2 Controlling Pests

1. 23 harvest lost; 1

10 post-harvest lost.

(a) 10�50 species of weeds infest each farm.

(b) Devastating: cocklebur reduces soybean yield up 60%.

2. Narrow-spectrum pesticide targets one organism. Elusive magic bullet.

(a) Unexpected e�ects continue to appear.

3. Natural pesticides safe, but not as e�ective

4. Biological control uses predators and parasites to control pests.

(a) Bacillus thuringiensis (BT) infects caterpillars and others.

(b) Parasite wasps (of caterpillars): e�ective narrow-spectrum.

(c) Ladybugs.

(d) Sex pheromones to trap or confuse insects.

5. Integrated pest management uses many techniques to control ratherthan eliminate.

(a) Diminishing returns as pest removal approaches 100%.

(b) Retaining pest population reduces ecosystem damage.

(c) Move beyond monoculture. Physical complexity of habitat reducespests because it is harder for them to �nd food.

(d) No/low-till: natural predators of pests accumulate in soil.

(e) Speci�c application of chemical pesticide.

4.2 Forestry

1. Tree plantations can potentially supply world's timber in 10% of forest-land. Reduce pressure on other forests.

2. Forest �res

(a) Past suppression → accumulation of fuel. Now, �res are more dam-aging, and may even burn away organic matter and old trees thatnormally survive �res.

3. Forest management (silviculture) is complex and di�cult, but easy to getdata (tree rings).

(a) Remove poor trees

(b) Breed new strains (like crops)

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(c) Control diseases (usually fungal) and pests. Little success.

i. Gypsy moth (introduced for silk) defoliate trees.

ii. Insects eat leaves, buds, fruits, carry disease.

(d) Cutting techniques

i. Shelterwood-cutting cuts less desirable and dead trees �rst.Always young trees left.

ii. Seed-tree cutting removes all but a few good, mature ones topromote regeneration.

iii. Thinning cuts only poor, small trees.

4. National forests compose 11.2% of U.S. area; 12% Costa Rica; depend onamount of forest in country.

5. Clear-cutting is not absolutely bad or good; need to evaluate case-by-case.

(a) Level ground, moderate rainfall, clear-cut can regenerate species.

6. Ecosystem services include retarding erosion, moderating water avail-ability, habitats for endangered species/other wildlife, impacting climate.

4.3 Rangelands

1. Arid rangeland is easily damaged by grazing; 30% is done there.

2. Cattle trample and erode stream banks and pollute streams.

3. Overgrazing slows growth, reduces diversity, leads to dominance of un-desirable plants for grazing.

4. Carrying capacity decreases with aridity.

5. Deserti�cation is deterioration of dryish land due to climate change andhuman activity.

(a) Marginal lands cannot tolerate much human activity. Overstressed.

(b) Poisoned soil (persistent pesticide, . . . ) forces abandonment.

(c) Irrigation in arid areas: salt residue accumulates to toxicity.

4.4 Other Land Uses

4.4.1 Urban Land Development

1. 45% live in cities today; 62% by 2025.

(a) 75% in developed.

(b) 38% is poorer developing.

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(c) Most estimated to live in country's largest city.

2. Cities, countryside mutually dependent. Many serious environmental prob-lems occur at the interface.

3. Site is the environmental features of location.

(a) Sometimes change: silting harbors destroys economic value.

4. Situation is placement of city relative to other areas (e.g. transportationhub).

(a) Fall line is location of waterfall or rapids on major rivers. Manycities here.

(b) Usually where people would naturally meet: con�uence of rivers, riverenter lake, next to mineral or spring.

5. Developments that make city seem more independent of nature actuallyincrease dependence.

6. Buildings de�ect and channel wind, altering weather patterns. Generally,makes it more di�cult to remove pollutants.

7. Planned development: fortress city and park city.

(a) Design with nature attempts to take advantage of features that na-ture provides instead of destroying nature.

(b) Garden cities are surrounded by greenbelts.

(c) Urban trees face special stress:

i. Compacted soil. Su�er from water extremes. Specially preparesoil.

ii. Air pollution, dust, physical impact → ↑ susceptible to fungalinfection.

iii. Must not produce messy leaf, fruit, or �owers.

iv. Usually, few species used → fragile ecosystem.

v. Early succession plants do best.

vi. Endangered plants can be planted. Sometimes do well.

(d) Habitats for wildlife. Can contribute to conservation.

8. Pests usually are generalists (share people's diet), r-selected.

(a) Key to eliminate habitats. Don't leave garbage open!

(b) Identify natural �t and naturally controlling factors.

9. Adversely a�ect water cycle.

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(a) Pavement prevents in�ltration.

(b) Most cities have one sewer. During storms, runo� may exceed treat-ment capacity, ejecting raw sewage.

(c) Evaporation reduced (runo�) → higher temperature.

(d) Increased particulates → increased rain, clouds, fog.

(e) Constructed wetlands often succeed in controlling runo�, rechargeaquifer, and are cheaper than conventional drainage.

10. Soils lose vegetation → lose organic matter, organisms die, compacted.

11. Urban sprawl is uncontrolled growth, usually of suburbs.

(a) Presently, Maryland could urbanize as much land in 25 years as ithas in history.

(b) Boulder established �blue line� in 1959�no water or sewer beyond.Limited residential and job growth. Economy grew.

(c) However, neighboring cities grew, and commuting is damaging envi-ronment.

12. Made lands are arti�cial. Unnatural. Unconsolidated�loose �ller with-out rock support. Vulnerable to earthquake.

4.4.2 Transportation Infrastructure

1. Canal have smooth, steep banks, VERY fast water. Drown!

(a) Much unforeseen environmental problems: Aswan High Dam + canals→ snails with schistosomiasis. Nile �oodwaters used to �ush them.

(b) In some parts, almost everybody is a�ected by schistosomiasis.

2. Channelization is modi�cation of existing streams (straightening, widen-ing, lining, deepening) to control �oods, improve drainage, control erosion,improve navigation.

(a) Fast �ow lose �sh habitats. Increased temperature, since trees onbanks cut.

(b) Downstream �ooding worse, since channelized section carries morewater than supposed to.

(c) Damage wetlands; depresses water table.

(d) Not always bad for environment�drainage projects bene�cial.

3. Roadless areas, when traversed by o�-road vehicles, are very sensitive toerosion.

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4.4.3 Public and Federal Lands

1. Wilderness is area undisturbed by people; the only people are visitors.

(a) U.S. Wilderness Act of 1964 de�ne wilderness to be preserved.

(b) Limited visitorship and human uses.

(c) Act recognizes ecological value.

2. Parks are open to public for recreation.

3. Parks/preserves are ecological islands; if one is too small, it will be inef-fective for conservation.

4. Management should involve minimal human activity and:

(a) Preserve undisturbed nature of wilderness,

(b) Provide people with wilderness experience.

4.4.4 Land Conservation Options

1. Restoration: controversial goals. Perhaps restore ecosystem to historicalrange of variation and ability to sustain self.

(a) Kissimmee River, FL: undo channelization, restore soil layers in cor-rect order.

(b) Prairie restoration�very popular recently. Much original prairie re-mains along railroad; they were not plowed.

(c) Early-succession grasses to restore damaged land (mining, urban).

2. Wetland restoration

(a) Saltwater marsh restoration di�cult because much more complex.

(b) 1969 National Environmental Policy Act mitigation require-ment: if developer destroys wetland, must obtain or create to com-pensate.

(c) Trying to construct wetlands to clean up runo��wetlands have somenatural bu�ering capacity.

(d) Restored wetlands have been fertilized with treated waste water.

4.4.5 Sustainable Land-Use Strategies

4.5 Mining

1. Minerals are essential for our high standard of living. Almost everythinguses them.

2. Mineral formation

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(a) Ore deposits are formed when metals are concentrated in abnor-mally high amounts by geologic processes.

(b) As gravity condensed matter dispersed around into Earth, matterwas heated. Iron and heavy metals sank toward molten center.

(c) Crust formed of lighter materials. Not uniformly distributed becauseof selective dissolution, transport, and deposition.

(d) Plate boundaries: crust is light rocks.

i. Divergent: cold water gets heated by molten rock and leachesmetals. Dissolved and deposited as sul�des.

ii. Convergent: rocks saturated with seawater are forced together,heated, and subject to intense pressure. They partially melt.Metals in magma mobilize.

A. Hg distilled out of plate as plate moves downward.

(e) Igneous processes

i. Magma cools → minerals crystallize at di�erent depths.

ii. Groundwater is heated and carries minerals. Moves to coolerrocks and deposits.

(f) Sedimentary processes concentrate materials for extraction.

i. Water and wind segregate sediments.

ii. Placer deposits are found in crevices or �ssures. They are con-centrated mineral deposits formed by deposition of stream waterthat leaches metals from river basin. California gold.

iii. A shallow marine basin may be isolated by uplifting at its bound-aries. The water eventually dries up, precipitating dissolved min-erals called evaporates.

(g) Biological processes:

i. Phosphates: guano.

ii. Iron ore: gray belts are unoxidized, red belts are oxidized. Ap-parently major iron deposition stopped when [O2] reached cur-rent level.

iii. Organisms form many minerals, such as Ca in shells and bones.31 identi�ed as biologically produced.

(h) Weathering processes concentrates some minerals in soil. More solu-ble minerals are selectively removed by biological processes.

i. Al, Ni, Co are important soil minerals.

ii. Secondary enrichment produces S2− from lower grades.

A. Near surface, primary ores and slightly acidic soil water, withoxygen, form H2SO4 and sulfates of Ag and Cu.

B. Migrate downward, leaching minerals.

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C. Below water table, where no more oxygen, deposit as sul�des,enriching metal content of ores.

3. Extraction

(a) Exploration usually minimal impact, except for sensitive areas suchas wetlands, permafrost, arid lands.

(b) As ores of lower grades are used, impact on resources increases.

(c) Subsurface mines are much smaller, less visible, less waste rock.

(d) Surface mining is cheaper, but has more direct environmental e�ects.

i. Large-scale environmental damage (beyond mine). Change to-pography. Dust pollutes air, even though attempts to control.

ii. Leaching of trace chemicals�Cd, Co, Cu, Pd, Mo can �nd theirways into soil and groundwater. Runo� ponds help, but do noteliminate.

iii. Indirect: change nutrient cycling, biomass, species diversity, ecosys-tem stability.

iv. Accidental discharges of stored waste.

(e) Strip mining removes surface layer of soil to expose coal (or otherresource). Half of coal mined this way.

i. Acid mine drainage occurs when H2O + FeS2 → H2SO4. De-bris left over from mining.

(f) Social impacts of mining: rapid urbanization, then rapid closing.

(g) Minimizing impacts:

i. Reclaim land.

ii. Stabilize contaminated soils�often remove and dispose.

iii. Control air emissions.

iv. Prevent contaminated water from leaving. Neutralize acid withlime.

v. Treat waste. Perhaps with GM bacteria.

vi. Recycling:

A. $50 B worth of metals are recycled.

B. Iron/steel 90% by mass, 40% by value.

C. Each ton saves: 1,136 kg iron ore, 455 kg coal, 18kg lime-stone. 1

3 energy.

D. Al recycling uses 5% energy.

4. Reserve is the portion of resource that is identi�ed and can be extractedlegally and economically at the time of evaluation. Resource is anythingthat can be extracted to obtain something useful.

(a) Concentration is everything�it determines usefulness.

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(b) Except for Fe, nonmetals are used far more quickly than metals.

(c) U.S. must import many �strategic minerals� (those necessary for mil-itary industrial complex) such as bauxite, Mn, graphite, Co, Sr, as-bestos.

i. Resulted in unlikely alliances between suppliers and consumers.Concessions on issues that would otherwise not happen.

5. Sustainability

(a) Find ways to not use the mineral. Fiber optic obviates Cu; digitalcamera obviates Ag.

(b) E�ciency.

(c) R-to-C ratio: R = known reserves; C = rate of consumption. Dy-namic.

6. Relevant laws and treaties

(a) 1977 Surface Mining Control and Reclamation Act required restora-tion. Success is di�cult and often dubious.

4.6 Fishing

1. Fishing techniques

(a) Bottom trawling rolls a 60m trawl net on ocean �oor, catching anddestroying everything in its path.

2. 44% of marine �shing in upwelling zones.

3. Ironically, �shing was one of the �rst human activities to be scienti�callymanaged.

(a) Wrong assumptions of logistic curve.

(b) Tragedy of the Commons: little incentive to limit harvest.

4. Currently not sustainable: increase in harvest accompanied by increase ine�ort. Total population dropping.

(a) Predator �sh at 10% of preindustrial levels.

(b) Harvest levels peaked from 1970�1990.

(c) Hunting not likely to be sustainable: bison, whales.

5. Aquaculture important protein source, growing. Ancient practice inChina.

(a) Mariculture (intertidal) much more productive than hunting foroyster, mussel.

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(b) Currently produce > 20%.

6. Laws and Treaties

(a) 1972 Marine Mammal Protection Act sought to bring optimumsustainable population rather than yield.

(b) 1982 International Whaling Commission's moratorium on com-mercial whaling protect 12 out of 80 species of whales.

4.7 Global Economics

1. Tragedy of the Commons: individuals' personal share of gain from ex-ploitation usually outweighs share of loss. Everybody wins in short termbut loses in long term.

(a) Forests (38% publicly owned), international water, Antarctica, air.

2. Low growth rate means not exploiting yields low pro�t, therefore exploita-tion maximizes pro�t. Instead of slowly making money on the naturalgrowth rate, better to exploit all of the resources now and invest money.

3. Relative scarcity of resource a�ects value and price. Can you pro�t fromthe resources harvested after your death? Then no interest in makingthem extinct. Do pro�ts end when you die? Then harvest all you canbefore you die. Can you earn your desired income from the resourcesinde�nitely? Then sustain.

4. Ralph d'Arge: developing countries did not share bene�ts of IndustrialRevolution, but now are sharing harms. They think that industrial na-tions, who have bene�ted, should bear most future costs.

5 Energy Resources and Consumption

5.1 Energy Concepts

1. Energy is the ability to accomplish work , which is force × distance.

2. A distinguishing feature of life is that it increases local order.

3. Units

(a) Energy is measured in joule, 1 newton-meter.

i. Exajoule = 1018 joules ≈ 1015 Btu (quad).

ii. Newton is force necessary produce force of acceleration of 1 m/s2

to a mass of 1 kg.

(b) Power is the rate of energy use ( energytime

) measured in watt, 1 joule-second.

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i. Multiplying watt by time (kWh) returns a unit of energy.

4. Amount of energy per unit times radiated from a body varies as the fourthpower of the absolute temperature of the body.

5.2 Energy Consumption

5.2.1 History

1. Greeks, Romans depleted wood → used solar power widely.

2. U.S.: wood peaked in 1880, coal peaked in 1920.

3. Exponential growth (consumption) from 1950�1980: 30 → 80 exajoules.Since 1980, → 100 exajoules, showing that new policies partially worked.Production leveled o� around 1970s.

4. Industrial energy consumption has leveled o� since 1970s due to increasede�ciency, cogeneration.

5. Car e�ciency (avg.) rose from 14 mpg in 1970s to 28 mpg in 1996. Im-provements slowed since then, largely because regulation loophole permitsless fuel-e�cient SUVs and light trucks.

5.2.2 Present Global Energy Use

1. Cogeneration can double e�ciency by using �waste� heat. For example,natural gas combined cycle power plant generates electricity from both gasturbine and steam turbine.

2. Energy Policy Act of 2005 was �rst national energy policy in over adecade:

(a) Promote conventional energy to reduce reliance on foreign energy.

(b) Promote nuclear power; build new ones by 2010.

(c) Subsidies for alternative energy, make geothermal competitive, in-creases amount of ethanol in fuels.

(d) Promote conservation: in federal buildings, for cars, credits for home-owners to install energy e�ciency measures or automobiles.

(e) Research to improve coal plants, goal for zero emissions, hydrogencars, research shale and tar pits.

(f) Incentives to expand energy infrastructure and improve reliability.

3. Hard path favors increased energy production while decreasing environ-mental impact. Supporters argue that much environmental damage isfrom developing countries using local energy, such as wood.

4. Soft path favors renewable resources, �exibility, and match to uses toincrease second-law e�ciency. Amory Lovins, champion, argues that mostenergy needs are of low quality, so expensive electricity is often wasted.

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5.2.3 Future Energy Needs

1. Oil production expected to peak in 2020�50. A�uence will be determinedas much by energy conservation and e�ciency as by production.

2. If hard path, then 120 exajoules by 2030. Else if soft path, 60 exajoules(1991 prediction; overly optimistic, closer to 110 exajoules now).

3. To stabilize global warming, cut fossil fuels 50%.

5.3 Fossil Fuel Resources and Use

1. Source rock is �nely grained organic matter (mostly plant) are buried insediments�depositional basins�at least 500 m deep. Carbon must notbe completely oxidized.

(a) Pressure and temperature compresses sediment into oil and gas.

(b) Light fuels migrate up to reservoir rock with lower pressure.

i. Porous; usually sandstone or limestone.

ii. A trap blocks upward �ow.

A. Cap rock is �ne-grained sedimentary rock.

B. Anticline is an arch-fold that favors retention of fuel.

C. A fault also traps the reservoir.

(c) Usually at young rock at plate boundaries. Exceptions:

i. Texas

ii. Gulf of Mexico

iii. North Sea

2. Primary production pumps oil from well; only recover 25%.

3. Enhanced recovery pumps stu� (steam, water, gas) injected to push oiltoward well.

4. Oil is 2nd most crust liquid, but 62% of proven reserves occupy 1% of oil�eld.

(a) Proven reserves = 1 trillion barrels; estimated 3 trillion barrels re-coverable from remaining resources.

(b) World consumption = 30 billion barrels/year.

(c) Today, consumption = 3 × discovery.

(d) Oil shale is �ne-grained sedimentary rock with organic matter (kero-gen). Destructive distillation: when heated to 500◦C, yields 60 Loil/1 ton shale. U.S. has 2/3 of world supply. Produces more volumewaste than mined because shale retorted�crushed and heated.

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(e) Tar sands are rocks or sands covered with tar oil, asphalt, or bi-tumen. 75% in Alberta, Canada. Mine sands (di�cult), then washoil with hot water. Supplies 15% of North American oil productiontoday.

5. Natural gas has only recently been seriously used for energy; used to beburned as waste, some places still do. 70�120 year supply. Main transitionfuel, since clean and releases less CO2.

(a) Coal-bed methane is methane stored in coal mines.

(b) 7× more can be stored in coal mine because of internal surfaces.

(c) 5 year supply at present rate can be recovered economically now;estimated 20 trillion m3.

(d) Cheap to extract. Reduces methane emissions when mining. Disposalof saltwater waste is a problem.

(e) Methane hydrates exist 1000 m beneath sea�oor: methane trappedin ice. On land, known as marsh gas. Spontaneously erupt fromocean �oor. May have twice as much energy as all known fossil fuelreserves today, but mining will be di�cult.

6. Coal swamps form from partially decomposed vegetation (peat). Rise insea levels add sediment, compression peat into coal.

(a) Most abundant fossil fuel; 250 years at current rate.

(b) Rank: anthracite, bituminous (high sulfur), sub-bituminous, lignite.

(c) Most polluting of fuels, in all stages.

7. Environmental disadvantages

(a) Toxic brine is pumped with water; oil leaks.

(b) Pollutants, including hydrocarbons and H2S can be released into air.

(c) Drilling muds (liquids injected into bore hole during drilling to keepit open) contain heavy metals.

(d) Re�neries leak (or spill).

5.4 Nuclear Energy

1. A neutron strikes 235U, producing �ssion fragments and 3 free neutronsand lots of energy. Chain reaction. Fast neutrons must be moderated�slowed�to improve �ssion.

2. Nuclear fuel

(a) 1 kg UOx ≈ 16 MT coal.

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(b) Only 235U is �ssile. Enrichment increases [235U] to 3%.

3. Types of reactors

(a) Light water reactor (U.S.) uses water as moderator.

i. Reactor core (fuel and moderator) encased in steel reactor vessel,then contained in reinforced concrete.

ii. Fuel pins (enriched uranium pellets in tubes) packaged into fuelsubassemblies.

iii. A minimum amount of fuel keeps reactor critical�self-sustaining.

iv. Coolant must remove heat at the same rate it is produced. Elsemeltdown�core gets so hot it melts and breaches containment.

(b) Pebble-bed reactors are gas-cooled and have billiard-sized pebbles asfuel. Graphite shell with sand-grain particles of UO.

i. Mixed with unfueled graphite spheres to control heat.

ii. Continuously refueled. Always at optimal production�safetyfeature.

iii. Passive stability means a reactor does not fail/meltdown due topump failure.

iv. Modular�each core 120 MW. 25% more e�cient.

(c) Burner reactors consume more �ssile material than they produce.

(d) Breeder reactors make low-grade or waste U �ssile. Can last 2,000years.

4. Nuclear fusion: 2H+3 H→10 n+4

2 He.

(a) Need very high temperature and density to form plasma.

(b) Plasma must be con�ned and energy released by fusion must exceedenergy required to maintain plasma.

(c) Nearly in�nite fuel reserves; cheap to produce.

5. Environmental impacts

(a) Uranium mines produce radioactive waste. Mine tailing have beenused for structures.

(b) Enrichment produces waste.

(c) Concern that waste cannot be isolated for required period of time.

(d) Nuclear plants must be decommissioned. May be the highest cost.

(e) Radioisotopes can �nd their way into food chain; circulate like theirnormal isotopes.

6. Radioactive Wastes and Human Health�causes cancer.

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(a) Units of radioactivity

i. Curie (Ci) = 37× 109 nuclear transformations/sec.

ii. Becquerel (Bq) = 1 radioactive decay/sec.

iii. For isotopes, pC/L (picocurie per liter), or Bq/m3.

iv. Actual dose of radiation: rads and rems.

A. SI gray (Gy) = 100 rads = absorbed dose. Energy retainedby tissue after radiation exposure.

B. sievert (Sv) = 100 rems = e�ective equivalent dose = ab-sorbed dose × relative biological e�ectiveness.

v. Gamma rays: roentgen (R) or SI coulombs per kilo (C/kg).

(b) American average 2�4 mSv/yr.

i. 66% natural (0.35 mSv/yr is human; 40K and 14C).

ii. 33% is other, mostly medical.

(c) α must be very close to cell. Blocked by paper. Dangerous if inhaledor ingested; radiation absorbed by tissue.

(d) β particles are electrons. Block by thin metal or block of wood.Moderately toxic; mostly absorbed when ingested.

(e) γ rays require a meter of concrete or centimeters of lead. Wheningested, some radiation exits body.

(f) Chronic radiation health problems are not well known or understood.

7. Accidents: acceptable risk of 0.01%/yr is unacceptable if there are 1,000plants. Also, often not planned to respond in accidents.

(a) Three Mile Island: valve malfunction + human error.

i. Containment structure functioned as designed.

ii. 1 mSv released into atmosphere; surrounding 0.012 mSv.

iii. But, on site, very high radiation: 12 mSv/hr.

(b) Chernobyl: human error caused meltdown; explosion blew top ofbuilding o�, graphite burned. Radioactive particles rise into air.

i. 237 con�rmed radiation sickness; 31 deaths.

ii. Did not tell world until 2 days later when confronted by Sweden'smeasurements of increased radiation.

iii. 24,000 estimated to have received 430 mSv.

A. Expected (based on Japan) 122 spontaneous leukemias.

B. No signi�cant increase yet, but possibly future.

iv. Childhood thyroid cancer increase.

v. Outside 30 km, probably negligible e�ect.

A. Vegetation with 7 km dead or severely damaged.

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(c) In last 34 years, about 10 accidents released radiation.

8. Radioactive wastes

(a) Low-level wastes in not hazardous is properly disposed. Residues,solutions, sludges, acids, slightly contaminated equipment. 3/6 sitesclosed because they have polluted groundwater.

(b) Transuranic waste is human-made materials heavier than U. Mostlyfrom weapons.

(c) High-level wastes is spent fuel, military reprocessing waste, weaponsmaterials.

i. Currently stored, mostly at commercial reactors.

ii. Geological disposal controversial�some don't think it should beburied.

iii. Nuclear Waste Policy Act of 1982 initiate disposal program.

A. 1987 amendment and Energy Power Act of 1992 specifydeep underground repository: Yucca Mountain.

B. Could receive waste starting 2010.

C. Need to evaluate earthquake, volcano, groundwater, escapefrom deteriorating containers, impact of heat generated bywaste, geological processes that control transfer of radioac-tive material.

(d) Waste isolation pilot plant in Carlsbad, New Mexico:

i. Rooms excavated in rock salt (easy to mine) store wastes.

ii. Slow-�owing salt naturally seal in 75�200 years.

(e) Sites that have been stable in past may not be stable in future.

9. Energy Policy Act of 2005 advocates increase of nuclear power.

5.5 Hydroelectric Power

1. Dams are multifunctional, but functions may not be harmonious (drainingfor agriculture con�icts with high levels for high power and recreation) anddams have many environmental impacts:

(a) Lose land and resources to make lake.

(b) Trapped sediment (silting) limits life of reservoir and prevents depositwhere needed.

(c) Change entire river downstream.

(d) Fragment ecosystems.

(e) Increases evaporation → change local climate.

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(f) High pressure nitrogen can kill �sh when swimming under waterfallas gas expands (bends).

2. Most good sites already dammed; not expected to grow in U.S.

3. Dams also give false sense of security: �oods can occur from tributaries,dams may fail, and higher-than-designed-for-�oods may occur.

4. Good dam sites are often good scenic nature sites.

5. Dams are expensive. Their cheap water is subsidized.

6. Water power is ultimately solar power.

7. 10% of U.S. power. Majority in Norway, Canada. 20% worldwide.

8. Pump storage: pump water into reservoir during low demand; �ow outduring high demand.

9. Several dams have been removed or have been planned for removal. Manyold ones are not useful at all. If lots of sediment, most remove slowlyto minimize impact. May be many times more expensive to remove damthan to build it.

10. Colorado river is most heavily managed river; 80% of water in reservoirsbehind Glen Canyon Dam and Hoover Dam.

(a) River has been tamed: average �ow increase, high �ow decreased.

(b) Natural �oods helped restore ecosystem, as did experimental �oods.

(c) Treaty supplies 1.845 km3 of water to Mexico. Very salty.

i. Desalinization plant built in Yuma on standby after its canalswere �ooded.

ii. Coachella Canal can provide Mexico with water.

iii. All American Canal delivers water to San Diego. Leaks billionsof gallons that recharge groundwater used by Mexican farmers.Proposed concrete lining has been heavily impugned.

5.6 Energy Conservation

1. E�ciency: food measured in energy stored ; consumption measured in workaccomplished.

2. First-law e�ciency = energy deliveredenergy supplied

. Average 50% in U.S.

(a) Second-law e�ciency = minimum energy necessaryenergy used

. Average 10�15%in U.S.

i. Lighting candle with match is more e�cient than with acetylenetorch.

33

ii. Water can be heated better by sun, not humongous furnace�ames.

(b) Thermal e�ciency is the maximum e�ciency of a heat engine (suchas power plant, internal combustion); discovered by Sadi Carnot.Modern power plants, about 1

3 .

5.7 Renewable Energy

1. Solar energy arrives at 7,000 times current demand.

2. Passive solar energy uses architecture to adjust to seasonal changes.

(a) South-facing building and windows and overhangs shade summer sunbut allow winter sun to penetrate.

(b) Walls can absorb energy then radiate into rooms.

(c) Deciduous trees block sun during summer but allow sun during win-ter.

3. Active solar energy requires mechanical power to circulate a �uid fromsolar collection site to usage site.

(a) Solar collectors have a glass plate and black background with tubesin between. Water heated to 38�98◦C.

(b) Evacuated tube collector has each tube pass through a larger tube toreduce heat loss.

4. Photovoltaics are the fastest-growing source of energy at 35% annually.

(a) Standardized modules; build the system you need.

(b) Di�erent electronic properties of semiconductor layers cause electronsto �ow into wires when hit by photons.

(c) Developing countries: cheap, simple, o�-grid rural electricity.

(d) Springerville Generating Station in Tucson produce 24 MW.

5. Power tower concentrates sunlight to a central collector to boil water.

(a) Can store heat with liquid salt.

(b) By 2030, estimated by be economically competitive.

6. Luz International Solar Farm: synthetic oil pumped through solar collec-tors; boil water; steam superheated by natural gas. Combination allowsuninterrupted power.

7. Environmental disadvantages of solar:

(a) Dispersed�problem for centralized power. Need lots of land.

34

(b) Metals, plastics, and �uids for equipment (esp. photovoltaics) maybe toxic; production releases greenhouse gases.

8. Hydrogen is clean and can be burned like fossil fuels.

(a) Fuel cell works like battery to generate electricity by oxidizing H2

and capturing e− in external circuit (redox). Increase second-lawe�ciency.

i. Electrolyte solution; electrodes separated by Pt membrane.

(b) Most economical way to produce hydrogen: H2O+CH4 → C+CO2+H2.

(c) Can be used to bu�er electrical generation.

9. Tidal power dam opening, then release water on turbines when tidalmovement increases/decreases ocean height su�ciently.

(a) Few locations have su�ciently strong tides.

(b) Can damage ecosystems of estuaries/bays.

(c) Rapid �lling and emptying of the bay damages intertidal habitats.

10. Wind power

(a) Winds are produced by di�erential heating of Earth's surface, result-ing in air masses with di�erent heat and density.

i. Wind concentrated on mountain top or mountain pass.

(b) Small mills (for farm) produce 1 kW. Modern windmills 60�75 kW.

i. High-tech ones 100 m, 30 stories, 3�5 MW. One is in Germany.

(c) Wind power currently cheaper than natural gas, approaching coal.

(d) World total 48,000 MW (34,000 MW in E.U.).

i. 1 large fossil or nuclear = 1,000 MW.

ii. 1% of total electricity.

(e) High potential�many countries have more potential than currentuse.

11. Micro-hydropower is best in mountains. Evaluate case-by-case.

(a) Prone to being �lled by sediment.

(b) In large scale, can have signi�cant environmental detriment.

12. Biofuels are organic matter, burned or converted (gasify, distill), thenburned.

(a) 35% of developing countries�usually �rewood.

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(b) Digestion�bacteria digest matter to produce methane.

(c) Land�lls, wastewater treatment plant can produce biogas (mainlymethane).

i. China, produced in sewage treatment.

ii. India, produced locally from cow manure.

(d) Waste incineration releases pollutants, as not all hazardous trash canalways be removed.

(e) Land unsuited for food crop can grow biomass crop (like trees).

(f) By 2030, biomass can produce 100,000 MW (12%), using 2/5 ofbanked farmland.

13. Geothermal energy harnesses natural heat from earth's interior.

(a) 9,000 MW�0.15%.

(b) Competitive with other sources.

(c) At plate boundaries, heat �ow is unusually high.

(d) Hot geothermal system (> 80◦C) resource base > fossil + nuclear.

i. Hydrothermal convection: steam and/or hot water pumped todepths to transfer heat to surface.

ii. Geysers Geothermal Field produce 1,000; near San Francisco.

(e) Lower temperature systems can be used for heating.

i. Groundwater is geothermal: at 100 m, groundwater is 13◦C andcan heat/cool homes.

(f) Environmental impact

i. Releases some CO2, SO2.

ii. Thermal pollution. Hot wastewater can be corrosive and saline.

(g) Future

i. Known reserves 20,000 MW, 10% for West.

ii. Undiscovered potentially 4×.

6 Pollution

1. Heavy metals include Hg, Pb, Cd, Ni, Au, Pt, Ag, Bi, As, Se, V, Cr, Tl.

6.1 Pollution Types

6.1.1 Air Pollution

1. Particulates are small dust particles (including asbestos). Sometimesheavy metal.

36

(a) Coal power plants.

(b) Industrial boilers.

(c) Cars.

2. Stationary pollution includes point sources (single sites), fugitive sources(open areas exposed to wind), area sources (well-de�ned area that has sev-eral sources).

3. E�ects include damage to vegetation, increased susceptibility to diseasesand pests, disruption of reproduction. In humans, poisoning, cancer, birthdefects, irritation, susceptibility to viral infections, heart disease, aggra-vation of respiratory diseases.

4. Criteria pollutants are 6 most common ones.

(a) Sulfur dioxide is oxidized into sulfate, forming sulfuric acid. Fromcoal, oil re�ning, industrial processes. Bleaches leaves. Increaseschronic respiratory disease, shortening of breath. Reduced 50% since1970s.

(b) Nitrogen oxides (most commonly NO, NO2) contribute to smog andion NO2−

3 , reducing visibility. Emitted from stationary and mobilesources. Acid rain. May suppress plant growth; may be bene�cial atlow concentrations.

(c) Carbon monoxide bonds 250× more easily to hemoglobin than doesoxygen.

i. Worst for heart or respiratory disease or at high altitudes.

ii. 10% man-made. Most emissions from tailpipes.

(d) Ozone/photochemical oxidants result from interactions between NO2

and sunlight.

i. Unstable, so oxidizes better than does oxygen.

ii. Retards plant growth at low concentrations; kills leaves andplants at high concentrations. Lungs decrease elasticity, scarsin airways.

iii. Peak ozone level is one of the best indicators of air pollution.

(e) Particulate matter (PM 10) is composed of particles < 10µm. PM 2.5(< 2.5µm) is of special concern because they are absorbed throughlungs into bloodstream.

i. Total suspended particulates measures this pollution. Much higherin cities of developing countries.

ii. 2�9% of human mortality in cities.

iii. Dust can su�ocate plants. Large particulate pollution (e.g., fromconstruction) can damage entire ecosystems.

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iv. Global dimming cools atmosphere. Jet travel is a signi�cantcause.

(f) Lead is emitted through leaded gasoline, which protects engines.Transported as particulate or uptaken by organisms.

5. Primary pollutants are emitted directly into air.

(a) CO (58%), VOC (11%), NOx (15%), SOx (13%), particulates (3%).

(b) Natural emissions: SO2 from volcano, H2S, wild�res, hydrocarbonseeps: La Brea Tar Pits. Exceed human pollution.

6. Secondary pollutants result from reaction between primary pollutantsand normal atmospheric compounds.

7. Acid rain can precipitate or be deposited as sulfate and nitrate, acid an-hydrides.

(a) Can travel very far: 13 > 500 mi, 1

3 [200, 500] mi.

(b) CaCO3 (limestone) can bu�er acids; granitic rocks cannot.

(c) Forests: trees weaken, die → less habitat; leaves fall o� → changesurface microclimate.

(d) Lakes: interferes biologically, dissolves nutrients → �ow out and arelost. Algae die.

i. Acid leaches metals from soils. Al hazardous to �sh�clog gills.Heavy metals!

(e) Acid fog occurs when water vapor, mixed with pollutants, condensenear ground around smog particulates. Drops of acid may be left asfog dissipates and can be inhaled deeply within lungs.

8. Air toxics are hazardous at low concentrations; many carcinogenic. Clas-si�ed into gas, metal, organic, then whether carcinogenic.

(a) H2S from re�neries and smelters, or geysers, swamps, bogs.

(b) HF from Al production, coal gasi�cation, burning coal. Extremelytoxic. Can damage grazers because plants are exposed.

(c) Methyl isocyanate burns on contact (irritation). Few ppm causesviolent coughing, swelling of lungs,death. Used in pesticides. InBhopal, India leaked from tank. Catastrophic.

(d) Volatile organic compounds (VOC) are used as solvents. Hydrocar-bons react to produce smog. Cars. Lowered 50% since 1970s.

(e) Benzene is solvent and gasoline additive.

(f) Arcolein produced in industrial combustion of petroleum. Extremelyirritating.

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9. Heat island occurs due to burning fuels and solar collection of buildingsand pavement.

10. Temperature inversions occur when warmer air is above cooler air.Caps on pollution altitude.

(a) Coast: descending warm air forms semi-permanent inversion. Seabreeze pushes pollution towards canyons.

(b) Valley: cloud cover decreases temperature at surface and increasestemperature in clouds, forming warm air. At surface, dew point(temperature where vapor condenses) may be reached → fog.

(c) Chimney e�ect: polluted air may spill over mountains.

11. Smog

(a) Photochemical (L.A., brown air): NOx emitted by cars accumu-late; sun breaks down to NO+O; O+O2 → O3. Organic compoundsreact with NO to increase NO2. Ozone maximum at noon.

(b) Sulfurous (London, gray air, industrial). From burning fossil fuels.

12. Indoor air pollutants

(a) Legionella pneumophila, pond-water bacteria can spread to air con-ditioners. Cause Legionnaire's disease.

(b) Molds may release toxic spores. Chronic in�ammation and scarringof lungs. 1

2 of all health complaints.

(c) Pesticides.

(d) Formaldehyde used in insulation, manufactured wood. Emit gas.

(e) Dust mites, pollen.

(f) Environmental tobacco smoke exposed to workers may be equivalentto 10 cigarettes per day.

(g) Radon is natural: radium → radon → polonium-218 → lead-214 →lead-206. α decays.

i. Estimated 10% of lung cancers. Very large threat if true.

ii. Synergistic with smoking.

iii. α particles break DNA strands.

iv. Radon enters through rock and soil into basement, dissolved ingroundwater, or contaminated construction materials.

v. Techniques to remove:

A. Gas permeable layer (often gravel) beneath �oor.

B. Plastic sheeting on top of gas permeable layer preventsradon from entering.

C. Sealing and caulking in foundation �oor.

39

D. Vent pipe from gas permeable layer to roof.

(h) Often more highly concentrated.

i. Many potential indoor sources.

ii. Energy e�ciency = sealing building. Cannot dilute pollutants.

(i) Control:

i. Ventilation: use more fresh air; open windows.

ii. Source removal: restrict or prohibit use of certain material,ban smoking indoors.

iii. Source modi�cations: change designs (more energy e�cient,use non-polluting materials); apply barriers (coat lead paint).

iv. Air cleaning: �ltering.

v.

13. Chimney e�ect occurs due to temperature gradient between indoor andoutdoor.

(a) If inside is warmer, warm air rises and draws in air from lower. En-vironmental tobacco smoke can be drawn in from outside.

14. Sick building have two types:

(a) Building-related illness (BRI) has identi�able problems, such aspathogenic molds or bacteria.

(b) Sick building syndrome (SBS) cannot be traced. Non-pollutionfactors (environmental stress, labor-management relations) may con-tribute.

15. Remediation and reduction strategies

(a) Conservation and e�ciency.

(b) Capture particulates from point sources in settling chambers or col-lectors.

(c) Cover waste or dirt piles to reduce dust.

(d) Recirculate exhaust to reduce NOx.

(e) Dilute air-fuel mixture�less NOx, more hydrocarbons.

(f) Catalytic converter: decompose hydrocarbons and oxidizes CO.

i. Old cars pollute more because people don't take care of pollutiondevices.

ii. Charge fees for pollution�require annual testing.

(g) Washing coal removes pyrite, but organic carbon remains. Expensive.

(h) Coal gasi�cation produces expensive synthetic gas.

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(i) Scrubbing: calcium removes sulfur: CaCO3 + SO2 → CaSO3 ·12H2O+ CO2 (or CaO).

16. 4 processes remove particles and chemicals for air:

(a) Sedimentation: heavier-than-air particles eventually settle out.

(b) Rain out: precipitation physically or chemically removes substances.

(c) Oxidation.

(d) Photodissociation: energy from solar radiation breaks bonds.

17. Coal-burning power plants produce 70% of SO2, 30% of NOx, 35% of CO2.

18. Clean Air Act Amendments of 1990 are comprehensive regulations.

(a) 50% cut in SO2 achieved.

(b) 2 Mton reduction in NOx�more di�cult because cars emit most.

(c) Permits comprise total amount of allowed pollution. Environmental-ists can also buy permits to prevent them from being used, but nota major factor. Makes pollution expensive.

(d) Goal: end all CFC and chlorine chemicals by 2030.

(e) National Ambient Air Quality Standards asminimum acceptable levelset to reduce health hazards in old and young�most susceptible.Supreme Court unanimously upheld standards.

19. Economic impacts: incremental cost di�ers. Much more expensive for Alplant to reduce emissions than for utilities. Some argue stricter standardsfor utilities and fewer for Al. Others prefer taxes or pollution vouchers�same environmental e�ect but more cost e�ective because driven by mar-ket pressure.

6.1.2 Noise Pollution

1. E�ects

(a) Up to 60 dB is safe.

(b) > 80 dB is potentially dangerous.

(c) 140 dB is threshold of pain; 180 dB is injurious.

(d) Lawn mower, motorcycle damages after 8 hours. 110 dB loud musicafter 1

2 hour.

(e) 50�60 dB noise interferes with sleep; fatigued awakening.

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6.1.3 Water Pollution

1. Thermal: ↑ heat →↓ [O2]. Warmer water decreases �sh �tness; some mayonly tolerate ∆1.5◦C.

2. Types include heavy metals, sediment, radioisotopes, heat, fecal coliformbacteria, P, N, Na, pathogens.

(a) Surface water is not immune to outbreaks. Cryptosporidium devas-tated Milwaukee: it is resistant to chlorine. Cryptosporidium mustbe �ltered, but it doesn't usually enter water supply.

(b) Fecal coliform bacteria is a measure of disease potential. Usuallyharmless bacteria in animal intestines. Pathogens are more likely tobe present where more feces is deposited.

i. E. coli can be deadly. Walkerton, Ontario: 5 died, 500 ill becausestorm waters contaminated wells with E. coli and utilities did notreport.

(c) N, P: from fertilizer, detergent, wastewater treatment. Culturaleutrophication (human caused).

i. Promotes plant, cyanobacteria, and algae growth.

ii. Algae form surface mats → kills stu� below.

iii. Decomposing bacteria grow, remove oxygen, eventually lots ofstu� dies.

iv. Eutrophic lakes have naturally high levels of nutrients.

v. Oligotrophic lakes have naturally low levels, pleasant water.

vi. Coasts, reefs may also su�er from eutrophication: Great BarrierReef, Hawaii.

(d) Oil�normal shipping probably releases most pollution. Long-terme�ects unknown.

(e) Sediment (small rock and mineral fragments) is by volume highestlevel of pollutant.

i. Agriculture increases erosion. Conservation cannot eliminateloss.

ii. Urbanization even greater: large amounts erosion during con-struction, but on-site control measures can be e�ective (35% re-duction in a Maryland sediment control program).

(f) Acid mine drainage is water with lots of H2SO4 formed fromweathering of pyrite.

i. Abandoned mines are problematic because groundwater is nonlonger pumped out, so it can �ood and over�ow.

3. Sources include all sectors of society:

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(a) Surface water occurs when in�ow of pollutant exceeds natural capac-ity to remove, convert, or dilute it.

i. Runo�: urban (oil, chemicals), agricultural.

ii. Accidental spills, release of radioactive stu� (from accidents).

iii. Leakage from storage sites.

iv. Air fallout.

v. Sediment from agriculture and construction sites.

(b) Groundwater is the source of 12 of domestic water supply. It is actu-

ally easy to pollute. Channels for groundwater are small, so dilutionopportunity is limited.

i. Leaks�waste disposal, buried pipes. Estimated that 75% of haz-ardous waste disposal sites are polluting groundwater. Land�llsover porous soils pollute water quickly.

ii. Seepage: acid water and waste from mines, cesspools/septic sys-tems, spills, radioactive materials.

iii. Saltwater intrusion in coastal aquifers: when water is pumped, itno longer �ows out into saltwater aquifer, allowing salty ground-water to in�ltrate.

4. Biochemical oxygen demand (BOD) is amount of oxygen requiredfor organic decomposition. Amount of oxygen consumed by decompsermicroorganisms.

(a) Inversely related to dissolved oxygen.

(b) 5 mg/L is threshold for water pollution of DO.

5. Wastewater treatment deals with addition of suspended solids, salts,nutrients, bacteria in water due to human use.

(a) Septic-tank separates solid and liquids and digests (biochemicallychange) organic matter.

i. Water then moves into absorption �eld/drainage �eld and seepsinto soil.

ii. Further treated by oxidation and �ltering. Not suitable for allland.

iii. Failures occur when tank is not pumped, for poor drainage allowswastewater to rise to surface.

(b) Wastewater treatment plants remove BOD and chlorinate bacteria.

i. Primary treatment involves screens to remove large �oatingmaterial, grit chamber to remove rocks, primary sedimentationtank where particulates settle to form sludge.

A. Digester processes sludge. Relatively new.

43

B. Removes 30�40% of BOD.

ii. Secondary treatment�activated sludge method (most com-mon).

A. Aeration tank mixes wastewater with air and some sludgefrom �nal sedimentation tank.

B. Activated sludge is rich in aerobic bacteria, which consumeBOD.

C. Final sedimentation tank settles sludge out (again). Mostsludge goes to digester.

D. Removes 90% of BOD.

iii. Advanced wastewater treatment use sand �lters, carbon �l-ters, chemicals to remove speci�c pollutants such as N, P, heavymetals.

iv. Chlorine produces toxic by-products.

v. Methane is released by digestion; used as fuel or burned as waste.

vi. If sludge isn't polluted, used to improve soil, else land�lled.

6. Wastewater renovation and conservation cycle involves using treatedwastewater to irrigate, then allowing water to renovate (natural puri�ca-tion through slow percolation in soil), recharging groundwater, and reuseof groundwater.

7. Resource recovery wastewater plants capture methane and use plants grownin controlled environment (sell �owers to �nance operation) in lieu of sec-ondary treatment. More greenery can purify water even more.

8. Wastewater can be applied to isolated wetlands. Promote growth andreduce downstream BOD.

9. 1792/1977 Amended Clean Water Act (Federal Water Pollution ControlAct) provides billions in grants for sewage treatment plants, encourages in-novation, including alternative wastewater treatment and aquifer recharge.

10. Other relevant laws:

(a) 1956 Federal Water and Pollution Control Act enhances water qualityand controls pollution.

(b) 1958 Fish and Wildlife Coordination Act mandates conservation mea-sures with U.S. Fish and Wildlife Service for dams, power plants, and�ood control.

(c) 1969 National Environmental Policy Act requires impact statementsprior to federal actions that signi�cantly a�ect environment: dams,channelization, power plants, bridges.

(d) 1970 Water Quality Improvement Act expands 1956: control oil andhazardous waste; research for Great Lakes and mine drainage.

44

(e) 1974 Federal Safe Drinking Water Act sets containment levels forpollutants and pathogens.

(f) 1980 Comprehensive Environmental Response, Compensation, andLiability Act establishes revolving fund (Superfund) to clean up haz-ardous waste sites to reduce pollution.

(g) 1984 Hazardous and Solid Waste Amendments to the Resource Con-servation and Recovery Act regulates underground gasoline storagetanks.

(h) 1987 Water Quality Act establish policy to control non-point pollu-tion. Led to development of state management plans to control.

6.1.4 Solid Waste

1. Types.

(a) 35% paper

(b) 12% yard trimmings

(c) 12% food scraps

(d) 11% plastics

(e) 8% metals

(f) 7.4% rubber, leather, textiles

(g) 5.3% glass

(h) 5.8% wood

(i) 3.4% other

i. Infectious wastes should be sterilized and are not consideredtoxic.

ii. Hazardous waste is produced 700 Mton/year in U.S.

A. 50% chemical industry.

B. Electronic, petroleum, coal each 10%.

C. Destroyed buildings.

D. Tons of abandoned waste sites. 1,000 may threaten publichealth and environment.

E. Management of hazards may be most serious environmentalproblem.

2. Hazardous waste legislation

(a) 1976 Resource Conservation and Recovery Act (RCRA) iden-ti�ed hazardous wastes and life cycles��cradle to grave� manage-ment.

45

(b) 1980 Comprehensive Environmental Response, Compensa-tion, and Liability Act (CERCLA) de�ned policies and proce-dures for release of hazardous substances into environment.

i. List of sites where hazardous substances likely or already im-pacted environment.

ii. Superfund to clean up worst cases.

iii. 1984 and 1986 amendments:

A. Improve standards for disposal and cleanup.

B. Ban disposal of certain chemicals: dioxin, PCB, solvent.

C. Timetable for phasing out disposal of all untreated liquidhazardous waste in land�ll or surface impoundment.

D. Increase Superfund.

E. Environmental audits permit defense against liability. Studyold maps, photographs, reports, drilling, sampling. Now rou-tine.

F. �Toxic 500� become public. Pressure industries.

3. Disposal:

(a) Composting is rapid partial decomposition of organic matter byaerobic organisms. Popular in Europe and Asia due to intense farm-ing. Large-scale in mechanical composters.

(b) Incineration burns at temperatures high enough to consume allcombustible material (900◦C�1,000◦C).

i. Ideally 75�95% reduction.

ii. Practically 50% due to maintenance and waste supply problems.

iii. Can supplement other fuels.

iv. Pollute air. Trapping pollutants expensive. Need subsidies. Notoptimal investment.

(c) Open dumps have waste piled and unprotected. Closed and bannedin U.S. and many other places.

i. Sometimes ignited.

ii. Other places periodically compacted.

(d) Sanitary land�ll is designed to concentrate and contain. Coverswaste with soil every day or more often.

i. Leachate is water percolating into refuse that carries pollutantsand bacteria.

ii. Siting is everything. Arid, impermeable places with low watertable.

iii. Often located in poor and minority places.

iv. Monitoring involves continual sampling (even if land�ll aban-doned) of water and gas at special monitoring wells.

46

v. Entry of pollutants into environment:

A. Gas release.

B. Heavy metals retained in soil and uptaken by plants.

C. Soluble materials move to groundwater.

D. Polluted groundwater can seep into surface water.

E. Wind blows toxins away.

vi. Multiple barriers include clay and plastic liners to limit leachate,drainers to collect leachate, gas collection, groundwater monitor-ing. Vital to prevent leachate from reaching groundwater, wherecleanup will be very expensive.

vii. Resource Conservation and Recovery Act of 1980 strengthenand standardize design, operation, and monitoring of sanitaryland�lls. Fail → close.

4. All methods of hazardous waste disposal causes some environmental dis-ruption.

(a) Secure land�ll con�nes waste, controls, collects, and treats leachate,and detects leaks.

i. Drains concentrate leachate to collection basin.

ii. Animals can chew or burrow through �impervious� liners.

iii. Some argued no such thing as secure land�ll.

(b) Land application is intentional spreading of waste on land. Biodegrad-able stu�, like oil waste.

i. Micro�ora (microorganisms in soil) attack material in microbialbreakdown.

ii. Restricted to top 15�20 cm.

(c) Surface impoundment uses depressions or excavations. Aerationpits and lagoons. Seepage. Controversial; many closed.

(d) Deep-well disposal injects waste to place isolated from aquifers�porous rock sealed by impervious rock.

i. Oil-�eld brine.

ii. Not quick and easy solution�few sites, must monitor.

5. Alternative methods for toxic waste

(a) Recover valuable materials for future use in waste.

(b) Neutralization, oxidation, and separation of heavy metals.

(c) Incineration can destroy hazards, but some may escape as pollution.

6. Ocean dumping and pollution along shipping lanes

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(a) Most pollution in the most productive parts of ocean.

(b) Threaten �sheries�shell�sh contain polio- and hepatitis-causing or-ganisms.

(c) Algal blooms kill almost all marine life in area.

(d) Microlayer, top 3 mm, extremely fragile. Phytoplankton, �sh larvahere.

i. Heavy metals 10�1,000 more concentrated here.

(e) Plastics �oat and accumulate in convergent currents.

i. Northwestern Hawaiian Islands, very remote, is one zone of con-vergence.

ii. 80 tons of marine debris collected there.

iii. Birds eat plastics. Rings seal mouths.

7. Industrial ecology is the study of relationships among industrial systemsand linkages to natural ecosystems. Essentially, waste is a resource outof place. As extraction costs increase, �nancial feasibility of reusing andrecycling increases.

(a) For example, coal power plant heats homes, scrubs SO2 to makegypsum, CO2 sequestered and pumped to greenhouses, ash used tosurface roads.

(b) Canberra, Australia hopes to achieve zero-waste by 2010.

8. Integrated waste management includes reuse, reduction, recycling,composting, land�lling, incinerating.

(a) At least 50% waste stream can be reduced:

i. Better packaging (10%)

ii. Large-scale composting (10%)

iii. Recycling (30%).

A. U.S. recycles 30% of waste stream.

B. 50% reached in some parts of U.S.

C. Intensive recycling can reduce 80�90%; pilot program 84%.

D. 50% of U.S. steel from scrap.

E. Must develop market for recycled products.

(b) Using sewer sludge is widespread, but getting rid of toxins is di�cult.

i. Separate urban and industrial wastes.

ii. Require factories to pretreat their waste.

(c) Materials management is resource conservation.

i. Eliminate subsidies for virgin material and incentivize use of re-cycled.

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ii. Fine poor material management processes.

9. Pollution prevention (P-2): Wisconsin cheese factory deposited 2,000gal of salt water into lands�common for corporations that cannot dis-charge into municipal treatment plants�and damaged crops. DNR lim-ited salt discharge. Factory developed evaporator, which reduced waste by75% and decreased salt purchases by 50%. Recovered costs in 2 months.We are moving away from regulating disposal to eliminating as much of itas possible.

6.2 Impacts on the Environment and Human Health

6.2.1 Hazards to Human Health

1. Synergism: toxins acting simultaneously may be >∑

parts. E�ectsoften unknown.

2. Environmental risk analysis (risk assessment) is the determinationof health hazards to people exposed to pollutants and possible toxins.

(a) Identify hazard (whether exposure is detrimental). Observe otherhumans, animal testing, cellular/molecular research.

(b) Dose-response assessment. Administer varying doses to humans oranimals. Di�cult. Doesn't prove causality.

(c) Exposure assessment. How many exposed, how much area contam-inated, ecological gradients, length of exposure? Di�cult like dose-response.

(d) Risk characterization. Conclude health risks based on exposure.

3. Asbestos are �ber-shaped minerals. Asbestosis is related lung condition.

(a) Fibers embed in lung tissue → cancer.

(b) White asbestos (chrysolite) is not particularly harmful. 95% of U.S.

i. No recorded nonoccupational disease.

ii. Belief that much removal was unnecessary.

(c) Blue asbestos (crocidolite) very harmful.

4. Lead is apparently biologically useless but impacts every system, espe-cially nervous system and in small children.

(a) Poisoning of patricians may have contributed to Roman fall.

(b) In children, may promote antisocial/criminal behavior.

5. Electromagnetic �elds have been suspected of increasing cancers, butquestion not yet answered.

49

6. Voluntary exposure is commonly smoking, drinking, and drugging.

7. Acute e�ect occurs soon, usually large exposure. Chronic opposite.

8. Dose response means the e�ect of a chemical depends on the dosage(concentration).

(a) (Very) low concentrations harmful.

(b) High concentrations harmful, eventually lethal.

i. LD-50 is dosage where 50% of population dies. Crude.

ii. ED-50 is dosage that causes desired e�ect in 50% of population.

iii. TD-50 is dosage that is toxic to 50%. Often reduced enzymeactivity, decreased reproduction, other speci�c symptoms.

iv. Therapeutic index = LD-50ED-50

and ↑= safer.

(c) Curve crests where maximum bene�t occurs (plateau).

(d) Threshold values unknown for most substances, especially transitionfrom bene�t to harm.

6.2.2 Hazardous Chemicals in the Environment

1. Biomagni�cation.

(a) Cd: coal → ash → plant → herbivore → carnivore (50�60×)

(b) Hg: Hg2+ bacteria−−−−−→ [CH3Hg+] accumulates more, stronger e�ect.

2. Persistent organic pollutants are now banned.

(a) Example

i. PCBs (heat-stable oils).

ii. Dioxin, perhaps most toxic man-made chemical. Byproduct ofchlorine combustion in herbicide synthesis.

A. Damages wildlife in very small amounts.

B. Human impact controversial.

(b) Often contain Cl.

(c) Do not biodegrade.

(d) Fat soluble; likely to accumulate.

(e) Able to be transported long distances in wind, water, sediment.

(f) Hormonally active agents

i. Atrazine (herbicide) feminizes frogs.

ii. Detriment reproductive viability.

3. Ecological gradients can be de�ned by distance to pollution source.

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4. Tolerance is ability to resist or sustain stress due to toxin or environment.

(a) Behavioral.

(b) Physiological: body adjusts. Does not mean damages ceases.

i. Detoxi�cation.

ii. Transport of toxin to non-harmful place (fat).

(c) Genetic tolerance: selection.

6.3 Economic Impacts

1. Cost-bene�t analysis.

(a) Risk of death from pollutants is low. Lowering air pollution increasesquality of life, not length.

(b) Risks that a�ect a small proportion of people are more acceptable.

(c) Novel risks are less acceptable.

(d) More desirable activities carry greater acceptable risk. Sports, recre-ation vs. working.

(e) RAND study �nds that direct measures (i.e., not bettering the envi-ronment) to increase longevity are cheaper. But do we value lengthof or quality of life more?

(f) Cost of pollution = costs to control pollution + loss from damages.

i. May have have opposite trends. Minimum at intersection.

A. If minimum cost results in too much pollution, then reduc-ing pollution beyond this point may be considerably moreexpensive.

ii. Total cost may stabilize or decline as pollution control becomesmore e�cient and external costs decline.

iii. Estimated cost of pollution control per family is $30�60.

2. Externalities, or indirect costs are e�ects not normally accounted forin cost-bene�t analyses and are often not recognized as a cost or a bene�t.

(a) Knowing true cost is necessary for rational consumer choice.

(b) Clean air and water and traded largely as if they cost nothing.

(c) Dollar value can sometimes be determined: water by �ow and storagein rivers and lakes; forest by inventory of trees and yield; mineral byestimated reserves. Now standard procedure.

(d) Who should pay? Polluters (then pass costs to consumers) or tax?Consensus that �polluter pays� approach o�ers stronger incentives.

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(e) Public service functions have tremendous economic e�ects. We onlyrecognize them when we begin to lose one. What may previouslyhave been an externality may now become a direct cost.

i. Natural capital estimated $3�$33 trillion/year.

(f) Landscape aesthetics is di�cult to quantize because of di�erent pref-erences.

i. Some say, coherence, complexity, mystery.

ii. Others, unity, vividness, variety.

(g) Value of the future: economically, pro�t now is worth more thanpro�t in future, but humans tend to think about the future.

i. Many believe we have obligation to future generations to notdamage environment.

ii. Spending on environment can be viewed as diverting funds fromother productive investments (which may bene�t future genera-tions).

iii. As wealth increases, so does value placed on environment. Im-plication: protecting environment is taking from today's poor togive to tomorrow's future.

iv. Future value depends of future consumers' view of consumption.How do you know which sacri�ces are important for future?

v. If future value is greater than present value, eventually futurevalue will be in�nite. That's not possible.

vi. Rule of thumb: do not throw away something that cannot be re-placed if you are unsure of future value (precautionary principle).

3. Marginal costs is the cost for one additional unit. Often increases ex-ponentially.

4. Empirically, individual transferable quotas have been most e�ective.

5. New York Catskill Mountains case shows that it doesn't take much capitalto get people to act because they value a clean environment.

7 Global Change

7.1 Stratospheric Ozone

1. 90% in stratosphere�15�40km.

2. Blocks 99% of UV.

(a) UVC is shortest λ. Decomposes O2 → 2O, then O + O2 → O3.Negligible amounts reach surface

(b) UVA is longest λ and is not a�ected by ozone layer. Some damage.

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(c) UVB is energetic; O3 is only gas known to absorb it.

3. Dobson unit (DU) = 1 ppb O3.

4. Hypothesis: CFCs emitted in lower atmosphere are extremely stable�unreactive, 100 year residence time. (Soils remove an unknown amount,though). Eventually disperse to upper atmosphere. UV decomposes CFC,releasing Cl, which reacts with O3 in a catalytic chain reaction:

(a) Cl+O3 → ClO+O2

(b) ClO+O→ Cl+O2

(c) Estimated each Cl destroy 100,000 O3.

(d) May be interrupted removed up to 200 times, but UV may decomposeCl compound again at any time:

i. ClO+NO2 → ClONO2

ii. Cl+ CH4 → HCl (end for most Cl).

5. CFCs used in aerosol (not problem anymore), coolant (growing problemin developing countries), Styrofoam production.

6. Many solvent contain Cl and react similarly, as does halon (Br).

7. Naturally, ozone highest at poles and lowest at equator. Mainly producedat equator, but circulates to poles.

8. Polar stratospheric clouds are observed at 20km. Glow.

(a) Form during polar winter: Antarctic air mass isolated and circlesabout pole�polar vortex.

(b) Vortex cools, condenses, descends (no sun to warm up).

(c) Type I (190�195 K): H2SO4 particles freeze; seed for HNO3.

(d) Type II (< 190 K): water vapor condenses around Type I particles.Mother-of-pearl color.

(e) HNO3 settle out. Cl sink ClONO2 cannot be formed. Can destroy70% O3 in weeks.

(f) Arctic clouds are not as severe, but ClO can dissipate southwards.

9. Tropical, mid-latitude depletion also hypothesized. Polar stratosphericclouds migrate; volcanic explosions (SO2 may gentrify).

10. E�ects

(a) Reduce ocean productivity: Antarctic waters decreased primary pro-ductivity 6�12% associated with ozone depletion.

i. Plankton are CO2 sink → exacerbate global warming.

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(b) Disrupt food production.

(c) Cancer predicted to increase until 2060 when ozone layer begins torecover.

(d) Reduce immune function.

(e) Cataracts.

11. Strategies for reducing ozone depletion

(a) Estimated to return to pre-1980 by 2050. Already growth reduced.

(b) Recover discarded CFCs. 1.2 kg CFC per refrigerator (50 M world-wide).

(c) Hydro�urocarbons: F reacts similarly to Cl, but 1,000 less e�-cient. Possible to make it not deplete.

(d) Hydrochloro�urocarbons can be broken down in lower atmosphere.But if it gets into upper atmosphere, still deplete. Transition; phaseout 2030.

12. Relevant laws and treaties

(a) 1987 Montreal Protocol�27 original, 119 later.

i. Reduce CFCs to 50% of 1986 levels. Eliminate by 1999.

ii. Developed stopped by 1995; deadline for developing, 2005.

iii. China, India are not parties.

iv. Requires technology and money for developing countries.

v. Black market for CFCs.

(b) 1990 London

(c) 1992 Copenhagen

7.2 Global Warming

1. Climate change refers to �uctuation of annual mean temperature ofearth by several ◦C over the past million years.

(a) Temperatures dropped in 1940 but began dramatically increasingstarting in 1970s.

(b) Milankovitch cycles: earth's unstable orbit produces 100,000 yearcycles, which correlates with major (inter)glacial periods. 40,000 and20,000 year changes are result of earth's wobble. Insu�cient�seenas one mechanism among many.

2. Mean surface temperature expected to increase by 1.5◦C to 4.5◦C by 2100.

3. Surface temperature determine by:

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(a) Sunlight received and re�ected.

(b) Heat re�ected by atmosphere.

(c) Evaporation and condensation of water vapor.

4. Greenhouse gases re-emits radiation to earth's surface, warming earth.

(a) Water vapor responsible for 85% and water aerosol 12%.

(b) Atmospheric window is the 8�12 µm wavelength where natural green-house gases do not absorb well. But CFCs do!

(c) Lower atmosphere kept 33◦C warmer than otherwise and moderateday/night temperature ∆.

(d) CO2: 50�60% of anthropogenic greenhouse e�ect.

i. Exponential growth for 150 years; r = 0.5% per year.

ii. By 2050, 1.5× pre-industrial level.

(e) CH4 12�20%; more than doubled in past 200 years. Human sources:land�lls, burning biomass, coal and natural gas, agriculture: rice(anaerobes release CH4,), raising cattle.

i. Naturally, methane releases may have ended glacial periods andquickly increased temperatures. As ocean levels dropped, so didpressure on methane hydrates, causing them to be released intothe atmosphere. Waters also warmed at the beginning of inter-glacial periods, further favoring release of methane.

(f) CFCs: inert compounds used at aerosol propellants up to 1978 inU.S. Tremendously more potent than CO2.

(g) N2O 5%. Fertilizer application and fossil fuels. Long residence timein atmosphere.

5. Forcing is any process that changes global temperatures.

6. Hypothesized negative feedback:

(a) Global warming increases algae, which consume CO2.

(b) Greater [CO2] stimulates forest growth, removing CO2.

(c) Polar regions receive more precipitation from warmer air carryingmore moisture; deposited snow re�ects heat.

(d) Warmer temperature evaporates more water from oceans, formingmore clouds, which re�ect heat.

7. Hypothesized positive feedback:

(a) Increase oceanic evaporation increases water vapor�increase warm-ing.

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(b) Melting of permafrost releases methane.

(c) Reducing summer snowpack reduces re�ection.

(d) People use additional air conditioning, burning more fossil fuels.

8. Both negative and positive occur spontaneously, but evidence points topositive being favored. Role of water vapor is critical and not well under-stood.

9. Global dimming is the reduction of solar radiation by re�ection o� par-ticles and their interaction with water vapor. SO2 and volcanic aerosolso�set some global greenhouse e�ect because they at as seeds for clouds. Insome areas pollutants o�set 50% of expected warming due to greenhousegases.

10. Potential consequences:

(a) Polar ampli�cation is positive feedback of ice melting, thus re�ect-ing less heat.

(b) Climate change could damage agricultural productivity because op-timal climate is not longer paired with optimal soil.

i. Runo� may be much faster because snow pack is reduced, leadingto less runo� for more downstream regions.

ii. Could increase occurrence or magnitude of violent storms be-cause warmer ocean water puts more energy into storms. Pasthurricanes show average magnitude has increased (but occur-rence has not).

(c) Rising sea levels�half the people on earth live near the coast! Causedby (1) thermal expansion of water, (2) melting of glacial ice.

i. Already 1�2mm/yr. Estimated 45�55cm by 2100.

ii. Increase coastal erosion, loss of wetlands, saltwater intrusion.

(d) Glaciers melt, but Antarctic ice cap grows. Consistent with models.

(e) Changes in biosphere: evidence of many animals adapting.

i. Some species cannot adapt quickly enough, particular plants,

ii. Wild relatives of crops used for hybridization may die.

iii. ↑ range of mosquitoes carrying malaria, dengue fever.iv. Possibly responsible for spread of West Nile Virus to New York

City.

11. Simply learning to live with global warming may not be the best ideabecause the rapid rise may bring many nasty surprises. If reduced tobelow 2.0◦C over the next century, then very likely to be able to adapt.

12. Reducing climate change:

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(a) California (itself 12th largest greenhouse gasser) passed legislation toreduce emissions by 25% by 2020.

(b) Conserve; use nuclear and renewables; use natural gas instead ofother fuels.

(c) Minimize burning of forests; reforest.

(d) Geologic sequestration: capture CO2 and inject into reservoirs. De-pleted oil �elds or saltwater aquifer. Need to sequester 2 GtC/yr tobe e�ective.

i. Norway sequester CO2 from natural gas production facility undernatural gas �eld in North Sea. Expensive, but so is paying carbontax.

13. Laws and Treaties

(a) 1987Montreal Protocol signed by 24 states to reduce and eliminateCFC use and develop alternatives. Nearly phased out by 2000.

7.3 Loss of Biodiversity

7.3.1 Habitat loss; overuse; pollution; introduced species; endan-gered and extinct species

1. Species introduced to di�erent biotic provinces (regardless of biome) likelyto cause trouble because the introduced and local species have not evolvedwith each other.

(a) Ubiquitous species can be found anywhere.

(b) Cosmopolitan species can be found almost anywhere within suit-able conditions.

(c) Endemic species can be found naturally in only one place.

(d) Exotic species are species introduced into an area where it has notevolved.

2. International Union for the Conservation of Nature's Red List of Threat-ened Species

(a) 20% known species of mammals, 12% birds, 4% reptiles, 31% am-phibian, 3% �sh, 3% vascular plants.

3. Endangered species means �any species which is in danger of extinctionthroughout all or a signi�cant portion of its range� [except insect pests].

4. Threatened species means �any species which is likely to become anendangered species within the foreseeable future throughout all or a sig-ni�cant portion of its range.�

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5. Causes of Extinction

(a) Population risk: random variations in birth and death rates result inmany individuals unable to �nd mates.

(b) Environmental risk: non-catastrophic changes kill species. Some-times can be very isolated, for example, speci�c pollinator/�owerrelationship: if plants die, so do pollinators.

(c) Natural catastrophe.

(d) Genetic risk: (not including environmental damage) genetic drift,widespread mutation.

7.3.2 Maintenance Through Conservation

1. Goals: two approaches:

(a) To some pretechnological number. Complex, inaccurate.

(b) Seek some determinable number: minimum viable, optimal popula-tion, etc.

i. Minimal viable population is smallest estimated populationto maintain itself and its genetic variability inde�nitely.

ii. Optimum sustainable population is the largest estimatedpopulation to sustain itself without detriment to ecosystem.

2. Sometimes protection works too well: sea lions, mountain lions have be-come problems for human life and property.

3. Spatial relationships�looking at each specie's habitat�can allow for preser-vation of certain species without compromising other species.

7.3.3 Laws and Treaties

1. Endangered Species

(a) 1973 U.S. Endangered Species Act listed endangered, threatenedspecies and was the most wide-ranging piece of environmental legis-lation in the 1970s. As of 2007, 41 species have been de-listed

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