Final Flashcards
(115 cards)
1
Q
U.S. Dust Bowl of 1930s
A
- plowing the short-grass prairie of Am Modwest and drought causes the U.S. Dust Bowl during the 1930s
- John Steinbeck wrote an Am realist novel on the Joads, a poor family of tenant farmers driven from Oklahoma
- Dust Bowl Refugee (Woody Guthrie)
2
Q
Soil degradation
A
- occurs when key soil attributes required for plant growth or other ecosystem services deteriorate
- when humans cut forests, graze livestock, or plant crops, the soil is managed or mismanaged
3
Q
Soil
A
- solid material of geological and biological origin (not just dirt)
- chemical, biological, and physical processes change soil
- soils are 100s of yrs old and change very slowly
4
Q
Soil characteristics
A
Soil is classified by profile, structure, and texture
- soil texture: proportions of sand, silt, and clay
- –parent material: mineral material of the soil (soil has its origin in the geological history of an area)
5
Q
weathering
A
gradual physical and chemical breakdown of parent material
6
Q
Soil texture
A
three texture classes:
- sand: particles from 2.0 to 0.063 mm (feels gritty) (largest)
- silt: particles range from 0.063 mm to 0.004 mm (feels smooth)
- clay: anything finer than 0.004 mm (feels gooey/sticky) (smallest)
sand, silt, and clay constitute the mineral part of soil - if one particle predominates, the soil is sandy, silty, or clayey
Loam: a soil with 40% sand, 40% silt, and 20% clay
Determine a soils texture by:
- feel-ribboning soil btwn thumb and index finger
- float soil in water and measure when settles (sand settles first)
- scientists classify with triangle
7
Q
Soil properties and use
A
Soil properties are influenced by its texture
- large particles have larger spaces separating them
- small particles have surfaces that collect nutrient ions and water molecules
workability or arability (to plow) - the ease with which soil can be cultivated
8
Q
Soil profiles
A
Horizons - horizontal layers of soil from soil formation (distinct)
soil profile - a vertical slice through the soil horizons (reveals the interacting factors in soil formation
Humus - decomposed dark material at the bottom of the O horizon
O horizon - topmost layer of soil
- dead organic matter (detritus) deposited by plants
- high in organic content
- primary source of energy for the soil community
9
Q
Subsurface layers
A
OAEBC
O Horizon - humus
-organic horizon - contains detritus feeders and decomposers
A Horizon - topsoil (mixture of soil and humus, permeated by fine roots)
-if there is no O in the soil profile than it is A
E Horizon - zone of leaching (less humus, minerals resistant to leaching)
B Horizon - subsoil (contains minerals leached from A, permeated by fine roots, high in iron, aluminum, calcium, clay, reddish/yellow bc oxidized metals)
C Horizon - weathered parent material (partly broken down minerals, weathered rock, glacial deposits, volcanic ash, not affected by bio or chem processes)
O INTERACTS W/ LIVING THINGS/ORGANIC THINGS THE MOST
-least likely is C
10
Q
Soil classification
A
Infinite variety of structures and textures but soils are classified by order (the most inclusive group)
Four major soil orders most important for agriculture, animal husbandry and forestry:
- Mollisols (prairie soils)
- Oxisols (tropical forest)
- Alfisols (high-nutrient)
- Aridisols (desert)
11
Q
Mollisols
A
fertile, dark soils of temperate grasslands
- PRAIRIES
- most productive soils
- worlds best agricultural soils
- midwest U.S., Ukraine, Mongolia, Argentina
- Deep A horizon - rich in humus and minerals
12
Q
Oxisols
A
soils of tropical and subtropical rain forests
- B horizon has a layer of iron and aluminum oxides
- little O horizon: rapid decomposition of vegetation
- limited agriculture: minerals are in living plant matter
- nutrient poor
- such high rainfall they get leached
13
Q
Alfisols
A
widespread, moderately weathered forest soils
- well developed O, A, B horizons
- typical of moist, temperate forests
- suitable for agriculture if they are fertilized
14
Q
Aridisols
A
soils of drylands and deserts
- unstructured bc lack of vegetation and precipitation
- thin, lightly colored
- some areas may support rangeland animal husbandry
- irrigation leads to salinization
15
Q
Soil fertility
A
the soil’s ability to support plant growth
-initially become available through rock weathering (process much too slow to support normal plant growth - breakdown and release (Recycling) of detritus provides most nutrients)
leaching - nutrients are washed from the soil by water
- decreases soil fertility
- contributes to water pollution
Farming practice that prevents nutrient leeching and creates more sustainable soil: crop rotation, no til agriculture, and eliminate irrigation and water use
16
Q
Fertilizer
A
agriculture removes nutrients from the soil - fertilizer (nutrients added to replace those that are lost)
- organic fertilizer: plant or animal wastes (manure, compost, leguminous fallow crops - alfalfa, clover) WHAT WE USE
- inorganic fertilizer: chemical formulations of nutrients (much more prone to leaching, Haber process)
17
Q
Soil-water terms
A
infiltration - water soaks into the soil
water-holding capacity - soil’s ability to hold water after it infiltrates
transpiration - water is absorbed by roots and exits as water vapor through pores (stomata) in the leaves
soil aeration - allows diffusion of oxygen into, and carbon dioxide out of the soil
18
Q
Erosion
A
the process of soil being picked up and carried away by water and wind (occurs any time soil is bared and exposed)
-vegetative cover prevents wind and water erosion (Reducing the energy of raindrops and allowing infiltration)
ONE OF THE BIG PROBLEMS WITH SOIL ENVIRONMENTALLY - nutrient loss
19
Q
Splash, sheet, and gully erosion
-sequence of erosion from rainfall = splash, sheet, gully
A
Splash erosion - begins the process of erosion
- raindrops break up the clumpy structure of topsoil or what soil is left
- dislodged particles wash btwn other aggregates
- decreases infiltration and aeration
Sheet - the result of decreased infiltration
-more water runs off, carrying away fine particles
Gully - water converges into rivulets and streams
-water’s greater volume, velocity, energy remove soil
Once started erosion is a vicious cycle (less vegetation exposes soil to more erosion)
20
Q
Reducing soil erosion
A
Contour strip cropping - plowing and cultivating at right angles to contour slopes
-shelterbelts: protective belts of trees and shrubs planted along plowed fields
The U.S. Natural resource conservation service (NRCS)
- established in response to the Dust Bowl
- regional offices provide info to farmers and others regarding soil and water conservation practices
21
Q
overcultivation
A
general loss of fertility
- if detritus is lost, soil organisms starve
- humus decomposes, breaking down the clumpy aggregate structure of glued soil particles
- -water and nutrient holding capacities, infiltration, and aeration decline
- –all that remains are the minerals (sand, silt, clay)
- –there are no more nutrients for plants to grow
22
Q
Importance of humus to topsoil
A
Loss of humus - topsoil mineralization and loss of water-holding capacity, nutrient-holding capacity, water infiltration, aeration
gain of humus - topsoil formation and gain in ^^^
23
Q
Solution: no or low-till planting
A
No-till agriculture: a tech allowing continuous cropping while minimizing erosion (practiced in U.S.)
- after spraying a field with herbicide to kill weeds
- planting apparatus cuts a furrow through the mulch - rope seeds and fertilizer - closes the furrow
- the wast from the previous crop becomes detritus (so the soil is never exposed)
24
Q
CAFOS
A
In the developed world, animals are raised in confined (compartment) animal feeding operations (CAFOs)
- CAFOs hurt the env. and ppl
- manure overwhelms treatments systems and enters water (fish kills, algal growth, and pathogens)
- crowded animals allow diseases to spread
- –humans (avian flu), salmonella causes $2.5 billion lost/yr in U.S.
25
Rain forest munched
58 million acres of rain forests in Latin Am have been converted to cattle pasture
- gov policies encouraged colonization of land to produce meat for domestic use
- cattle production in the Amazon continues to expand
domestic animals wildly inefficient
26
History of overgrazing federal lands
The 1934 Taylor Grazing Act prohibits reducing grazing levels or keeps grazing fees below market level
- the U.S. Bureau of Land Management (BLM) and Forest Service leases grazing rights on 2 million km2 of land - fed land is owned by taxpayers
- the grazing fee is 10% what would be paid on private land
27
Golden rice and frankenfoods
1/2 ppl eat rice = high in energy, low in vitamins and other nutrients
- vitamin A deficiency (blindness, immune system failure) - affects 195 million children
- iron deficiency (anemia and immune system failure) - causes 100,000 maternal deaths/yr
Golden rice (GR2): genetically modified rice
- added genes allow rice to synthesize beta carotene (used to synthesize vital A) and iron
- more nutrients and more vitamin A
- golden rice has not been welcomed by all - contains genes from corn & beans
- we do not eat it bc it is a different color
Frankenfoods: foods that contain foreign genes
-transgenic plant is called frankenfoods and is diff from a hybrid plant bc it can have foreign genes from animal - bacteria and the plants are not related
28
Future of food
- genetic engineering tech may be needed to feed billions more, w/ better nutrition
- world food production doubled in the past 30 yrs, rising faster than the population
- more ppl overweight than are hungry
29
Stage I: Early agriculture
Until 150 yrs ago, most americans lived and worked on small farms - farmers used traditional approaches to pests and erosion (crop rotation, multiple crops, animals wastes as fertilizer) - ppl left the farm for city jobs
30
Stage 2: Industrial revolution and agriculture
The industrial revolution profoundly changed traditional agriculture
-increased farming efficiency (farms increased in size, farm jobs, U.S. freq produces surpluses)
-industrial revolution caused ppl to leave their farms bc there were machines
Key components of this transformation - infrastructure, machinery, fertilizers, pesticides, irrigation, and many varieties of crops
Store genetic variation for future use - source of genetic variation to improve crops
31
Stage 3: The Green Revolution
The Green revolution: genetic technologies that resulted in remarkable increases in crop production spreading throughout the world
-in 1943, Norman Borlaug and others bred dwarf hybrid wheat with a large head and thick stalk (Mexico tripled wheat production, Borlaug awarded Nobel Peace Prize 1970)
-improved tech, pesticides and fertilizers that caused food to be manufactured, produce more food than we normally could have and it allowed pop to explode
Green Revolution has done more than any other single achievement to prevent hunger and malnutrition
32
Subsistence farming
developing world farmers use labor-intensive traditional agricultural methods
- described as the "silent giant" that feeds most of the worlds poor
- subsistence farmers live on small plots of land (raise food for household, sell a small cash crop)
- much of agriculture still remains subsistence
33
Future prospects for feeding the world
Projections predict grain production to remain the same - but predict increased MEAT consumption in developing countries - developing countries will not be able to meet rising grain demands
B is high yielding bc there is more wheat and it is shorter - problem with wheat production is if wheat is blown over it gets decomposed and is useless
-thicker stalk, less seed on top: less likely to fall over, more seeds
34
Only 2 ways to increase food production
- increase crop yields
| - grow food crops on land now being used for feedback crops, biofuels, or cash crops
35
Less meat-eating lower on the food chain
Feed grain is a potential bugger against world hunger
- more ppl could eat lower on the food chain
- the trend is in the opposite direction
36
Aims of Agricultural biotechnology
- incorporate disease and pest resistance
- inc tolerance to drought, salt
- improve the nutritional quality of crops (golden rice)
- produce pharmaceutical products ("pharma crops")
37
Env benefits of bioengineered crops
- reduced pesticide use (crops are already resistant to pests)
- less erosion (no-till cropping, herbicide-resistant crops)
- less land brought into production (existing agricultural land produces more food
38
Problems of genetic engineering
Env. concerns:
- pests may become resistant to the toxin in pest-resistant transgenic crops (crop loses its advantage, resistance has been found in weeds that ingest fields "super weeds," resistant weeds can spread rapidly since pests can't hurt them)
- pollen from transgenic crops can spread to natural areas (kills beneficial insects)
Safety issues:
-transgenic crops contain proteins from other organisms (could trigger an allergic reaction in ppl)
-antiobiotic resistant genes are put into organisms (could convey resistance to pathogens, antibiotics could become ineffective)
NO EVIDENCE THESE FOODS ARE UNSAFE
-none of these concerns has become evident in the field
39
Fear vs. acceptance
controversy over genetically modified food (protests strongest in Europe)
- U.S. is far less concerned (60% of food contains genetically modified substances)
- In the U.S., the EPA, USDA, and FDA regulate genetically modified food crops
- U.S. policy does not require mandatory labeling
40
Ecology of eating
Diet determines significant portion of ecological footprint
- meat consumption increases footprint
- food miles: distance food traveled before consumption
- processing and storage
41
Eating organic
To be labeled as organic foods, products must meet strict standards
- farmers and producers follow a defined set of standards to product organic food and fiber
- Congress described general organic principles in the Organic Foods Production Act
Organic farms and processors:
- preserve natural resources and biodiversity
- support animal health and welfare (access to outdoors so animals can exercise their natural behaviors)
- only use approved materials
- do not use genetically modified ingredients
42
Choices...
can reduce environmental impacts and encourage sustainable agriculture
-eat more plants, eat local, eat fresh foods, eat seasonally, choose sustainable products, ask questions
43
Malnutrition vs. hunger
Hunger - a lack of basic food for energy and nutritional needs so the person cannot lead a normal, healthy life
Malnutrition - refers to the lack of essential nutrients and food calories
- amino acids, vitamins, minerals
- undernourishment
Overnourishment - form of malnutrition in which nutrients are oversupplied relative to the amounts required for normal growth and life
- 1/3 of Am are obese (>30 lbs overweight)
- even in developing countries
44
Extent of hunger
Accurate, reliable figures on hunger are unavailable
- 2/3s of undernourished are in Asia and Pacific (India, Pakistan, China)
- Sub-Saharan Africa: the highest percent of undernourished
- effects of hunger/malnutrition are greatest in children and women
Consequences of hunger
- sickness and death
- poor nutrition lowers resistance
- 5.5 million children die/yr in developing nations
- children rarely starve to death - they are weak, underweight, and vulnerable to disease
Root cause of hunger is poverty
-1.4 billion ppl live in poverty (income<$1.25/day)
45
Food aid
Widespread, severe hunger and famine are being prevented only bc of external assistance (food aid)
- World Food Program (WFP) of the UN coordinates global food aid (U.S., Japan, and EU donate food)
- food aid cut in half btwn 1993/1996, lowest levels in 30 yrs)
Using food aid to alleviate chronic hunger is not good
-free or cheap foreign food hurts local farmers
-they stop producing food, hurting those who sell to them
-the entire local economy deteriorates
Donating or food dumping of extremely cheap subsidized food aggravates the conditions it tries to alleviate
WE DO NOT NEED NEW SCIENCE OR TECH TO END HUNGER
-political and social action at all levels is needed
46
Desertification
Is grapes of wrath - human caused (moving plants - grazing/ranching)
- top layer of soil gets smaller and removed, bigger rocks, less nutrients and bc water is evaporating it GETS SALTIER - also easier for things to blow away
- bad bc once it happens it is hard to remediate
Wind erosion leads to the formation of desert pavement
-wind erosion, concentration of larger pebbles, desert pavement)
Prevent wind erosion and loss of moisture with a buffer zone of trees and shrubs along the edges of the crops
47
Waste
a hazardous waste disposal system: landfill, incinerator, w/ liquid waste inject it in the ground, bury it in solid containers
on site surface impoundment - oval shape, w/ lining, picture
love canal - related to on site surface impoundment, it was supposed to be like an onsite surface
who cleans up hazardous waste? - if they are still around, they have to do it, also superfund - if a site is abandoned, no one is held responsible
-superfund gives money to clean ups, especially if it is a hazard, clean up abandoned orphan sites if it is a hazard
48
Environmental justice
Social justice, low income and minorities are exposed to environmental hazards more often
- trying to get those ppl justice for being wrongfully subjected to things
- superfund pays for abandoned sites and race and income ppl living in places is environmental justice
49
White Mountains
Top removal is mining
- economical way of reaching coal seams
- has devastated parts of West Virginia, Kentucky, Tennessee, Virginia
- biggest thing affected is water, destroys streams, freshwater systems, ground water systems
In 2002, law prohibiting dumping of waste into stream valleys was changed to allow tho "fill" to be dumped
-grassroots organizations face formidable politicians and industrialists who say this mining is necessary
50
Energy sources and uses
- advancing tech civilization has been tied to energy
- in early times human muscle and livestock provided energy
- inventors in early 1700s designed machines that required energy
Average Amt of energy per person has dramatically over time
51
Types of nonrenewable energy
Coal, oil, natural gas
- by 1920, coal provided 80% of all U.S. energy for steam engines, heating, cooking
- however, smoke and fumes polluted cities and mining is hazardous and dirty
Oil is now the major energy source for the world
- more convenient and burned more cleanly
- industrial revolution changed this
U.S. also uses biofuels most - however we use oil the most naturally
- wood is non renewable and renewable - is sis also biofuel, depends how we manage it
- wood pellets used for heating your home, recycled wood = wood pellets - wood pellets are really efficient, 3x as efficient as coal, from recycled sources
Natural gas is used the least - but it is the most clean
Globally we use fossil fuels - account for nearly 80% of energy sources consumed
52
Natural gas
natural gas: found in association with oil or drilling for oil
- consists mainly of methane, which produces CO2 and water when burned
- burns more cleanly than coal or oil
- pipelines now allow it to be transported, instead of venting it into the atmosphere
- more clean, convenient, and less expensive
Most sustainable way to drive a car - electricity powered by solar, wind or any of the renewables used to get electricity
53
Fossil fuels
(Crude oil, coal, natural gas) were formed 100-500 million yrs ago in swamps and shallow seas
- anaerobic conditions slowed decomposition
- pressure and heat converted vegetation to fossil fuels
- 80% of energy sources consumed
Energy flow thru fossil fuels
- CO2 and solar energy
- photosynthesis exceeds decomposition
- accumulation of detritus
- organic material buried under sediments
- time, head, pressure
- coal, natural gas, oil
- energy, heat, CO2
Fossil fuels considered nonrenewables bc its really slow to name them, we will not get more in 50 years
54
Problems with coal, oil, natural gas
Withstanding the controversies surrounding the impact of fossil fuels on global warming, most U.S. citizens are concerned with our dependency on foreign powers for our oil
- up to 1970 the U.S. was oil independent
- in 1970, production decreased but consumption increased
- U.S. now imports 44% of oil from other nations - spent billions to restore Iraqi oil
- import from Canada, Mexico, Colombia, Russia, Nigeria - Middle East and Persian Gulf are vital
55
Three costs of U.S. dependency on foreign oil
1. cost of buying oil
2. Risk of supply disruptions (political instability in the Middle East)
3. Ultimate resource limitations
- in 2,000 the U.S. paid $300 billion in oil imports
- since 2000, imports increased 24% and oils price rose fivefold
- U.S. spends more money globally to import oil
- gap btwn oil production and consumption is getting bigger
- U.S. has been involved in a couple wars in the past decades for oil
56
2. Oil spills and drills
With millions of gallons of oil in constant transit, it is inevitable that spills occur
57
3. Env. impacts: hydraulic fracturing
- hydraulic fracturing is a process used in 9/10 natural gas wells in the US, where millions of gallons of water, sand, and chemicals are pumped underground to break apart the rock and release the gas
- scientists are worried that the chem used in fracturing may pose a threat either in groundwater/aquafier or when waste fluids are handled and sometimes spilled on the surface
58
3. Env. impacts: oil shales
oil shale is a sedimentary rock that contains solid bituminous materials known as kerogen
- green river formation: Utah, Colorado, and Wyoming
- when the rock is heated to very high temp. it releases kerogen that can be stabilized, upgraded, and processed into fuel
- developing oil shale is energy-intensive and env. destructive that is not yet commercially viable
59
3. Env. impacts: acid mine drainage
- sulfides leaches from coal mine tailings pollute waters
| - mediated by bacteria
60
keystone pipeline
Diff. env. groups, citizens, and politicians have raised concerns about the potential negative impacts of the keystone XL project
-the main issues are the risk of oil spills along the pipeline, which would traverse highly sensitive terrain and 17% higher greenhouse gas emissions from the extractions of oil sands compared to extraction of conventional oil
61
Fukushima Daiichi nuclear disaster
On March 11, 2011 a series of equipment failures, nuclear meltdowns and releases of radioactive materials at the Fukishima Nuclear Power Plant
-due to the Tohoku earthquake and tsunami
Nuclear energy
- an energy future based on fossil fuels is not an option (non fossil fuel sources must be developed)
- nuclear power has few emissions and there is enough uranium for years of nuclear power
62
Why were nuclear power plants cancelled?
Due to Russia and PA
- increasing safety standards for construction and operation
- costs increased at least fivefold
- withdrawn gov. subsidies
- public protests delayed construction and startup
Objective of nuclear power: to control nuclear reactions
- energy released as heat
- heat used to boil water to steam
- steam turns a conventional turbogenerator
Nuclear plants use fission (splitting) of uranium - uranium occurs naturally in the earth's crust
- two forms (isotopes): contain diff numbers of neutrons but same number of protons and electrons
- mass # = protons + neutrons
- diff mass # come from diff numbers of neutrons
63
uranium extraction and processing
Uranium ore is mined from underground and processing
- uranium crushed into fine powder and processed into yellowcake
- yellowcake converted to gas and centrifuged to produce uranium pellets
- pellets packed into rods
- tech diff prevent less developed countries from advancing their nuclear programs
Nuclear bomb
- when U is highly enriched, spontaneous fission triggers a chain reaction
- nuclear weapons have small amounts of pure U235 but the entire mass undergoes fission in a fraction of a second
64
Disposal of radioactive wastes
Development of nuclear power went ahead without solving the issue of waste disposal
- assumed geologic burial: burring solidified wastes
- in 10 yrs, fission wastes lose 97% of radioactivity
- long term containment: the EPA recommends a 10,000 yr min
Yucca Mountain, Nevada nuclear waste storage facility
-for past 25 yrs, U.S. department of energy has been working on tech and protocols to place over 70,000 metric tons of spent fuel in the geolic strata of Yucca Mountain
France derives 75% of its electricity from nuclear energy
-about 17% of France's electricity is from recycled nuclear fuel
65
Nuclear power beneficial
In comparison with coal, nuclear power is beneficial bc it does not produce sulfur dioxide or CO2
-coal is bad bc pollution, specifically sulfur dioxide
In past 30 yrs, nuclear power usage has stayed about the same
Safest place to store nuclear waste is deep underground in strong containers
66
China and solar power
23 gigawatts of solar power installed, twice as much as US
| -Germany first place for successful energy
67
Renewable energy
Source that are continuously replenished
- falling water, wind, sunlight, Earth's heat, ocean tides and waves, biomass
- sunlight and wind are abundant but are not concentrated in forms that are easy to access
Challenges in transitioning to renewable energy
-renewable diffuse and intermittent, insufficient tech to harvest, and lacking infrastructure
Benefits
-far fewer env impacts and infinite energy source
U.S. biggest renewable energy source is BIOMASS energy - over 50% - biofuels (wood)
-then hydropower, wind, geothermal, solar
68
renewable energy 2
we are using more renewable energy bc we are running out of fossil fuels and it is becoming cheaper
-solar energy is considered non-polluting and we are not worried about nuclear bc the nuclear waste is at the sun, nuclear waste is produced at the sun so we do not worry about it being here - solar energy is not pollution bc all radioactive components are produced at the sun
in comparison to fossil fuels, wind energy is great bc it is clean, no pollutants
69
Hydropower
hydroelectric dams use water under high pressure to drive turbogenerators
- in US it generates 6% of electrical power (dams)
- worldwide dams generate 19% of electrical power (most common form of renewable energy)
Benefits of dams:
- they eliminate the cost and env. impacts of fossil fuels and nuclear power
- provide flood control and water
- relatively pollution free
- reservoirs provide recreational and tourist opportunities
Disadvantages
- loss of lands-reservoirs drown farmland, wildlife habitats, towns (historical, cultural value)
- dams impede or prevent migration of fish
- dams wreak havoc downstream (decreased sediment reaches river's mouth)
- messes with fish pop and floods areas
Dams are good for biodiversity for about 5 years and then plates or drops biodiversity
Dams influence seasonal flows
70
Wind power
Horse Hollow Wing energy center in Texas (worlds largest wind farm)
- U.S. is world leader in wind energy
- economically comp.
- through a system of shafts and gears, the propellers of a wind turbine turn a generator to produce electricity
Drawbacks
- wind is intermittent, so backup or batteries are needed
- wind farms are visually unappealing
- turbines can be hazardous to birds
- offshore wind farms use dependable, strong winds (have less of a visual impact, land does not need to be bought)
Western mountains and central plains
71
Solar energy
- amt of sunlight reaching earth is unbelievable (sun delivers 10,000 times the energy used by humans)
- solar energy is abundant but diffuse (varies w/ season, latitude, atmospheric conditions)
- using solar energy requires turning a diffuse, intermittent source into a form (fuel, electricity)
Solar heating of water
- flat plat collector (thin broad box)
- black bottom absorbs sunlight and heats up
- water in tubes absorbs heat
- glass top prevents heat loss
Solar production of electricity
- Photovoltaic (PV) cells: a wafer of material
- one wire attached to top and one at bottom, sunlight striking wafer puts out 1 watt of power, 40 linked PV cells produce enough energy to light a lightbulb
- PV cells are highly sophisticated
- light hitting wafer causes an electron to go from lower layer to upper layer
Solar cells do not wear out
- no moving parts and last about 20 yrs
- Silicon, one of most abundant elements, is main material in solar cells
- becoming cheaper-cell's cost lies mostly in its design and construction
- cells used in calculators, watches, toys, rural homes, pumps, traffic signals, transmitters, lighthouses, satellites
low rainfall and limited cloud cover make SW US an ideal region for solar power use
72
Biomass energy
Energy derived from present day photosynthesis
- burning firewood for heat: oldest from of energy ("utilizing biomass energy")
- leads hydropower in US renewable energy - most is used for heat
- produced by burning wood or municipal waste, generating charcoal and methane, or producing ethanol and biodiesel
73
Biogas
anaerobic digestion of sewage sludge to produce methane (nutrient rich sludge for fertilizer)
-animal manure can also be digested
METHANE FROM WASTE AND MANURE
digesters: undergound fermentation chambers with a dome on top to store gas
- fermented agricultural wastes
- biogas is used for cooking, heating, lighting
- residual slurry used for fertilizer
- developing world - india and china provide subsidies for home biogas plants
74
Renewable energy for transportation
the most critical need for a sustainable future: a new way to fuel vehicles
biofuels: complex organic matter (plant and animal waste) - ethanol and biodiesel
- biofuels produce 1% of global transportation fuels - but expanding rapidly
Ethanol - produced by fermentation of starches or sugar (using corn, sugarcane, beets, grains)
-production costs make it more expensive than oi
Gasohol - 10% ethanol, 90% gasoline
- widely used in US Midwest
- provides another corn market to help local economies
Production of ethanol from corn uses lots of nonrenewable energy, including gasoline used to run machinery and the fossil fuels used to manufacture fertilizer
Tropical forests in Asia cleared for plantations of oil palm - source of biodiesel
75
Farm production
advantages: carbon neutral and less pollutants
Disadvantages: impacts on food supply and land clearing
- 25% of US corn dedicated to ethanol
- demand for corn ethanol caused prices to increase - bc corn used in food and livestock feed, food prices also increased
76
Second-generation biofuel and biodiesel
Made from cellulosic plants or algae - crop residues, grasses, logging residues, fast-growing trees, fuelwood
Miscanthus - a giant perennial grass
Cellulosic tech uses enzymes to break cellulose (cheaper and more energy efficient)
Biodiesel: made largely from soybean oil (can come from any natural oil or fat - recycled vegetable oil from frying) - 1% of US diesel fuel transportation use
77
Geothermal energy
Around world springs yield hot, boiling water (areas have natural steam vents and thermal features)
-features occur when the hot molten rock or Earth's interior is close enough to heat groundwater (near volcanic regions)
geothermal energy: using naturally heated water or steam to heat buildings or produce electricity
Advantages - inexpensive and pollution free
disadvantages - start-up costs high and regional
78
Tidal and wave power
Advantages: pollution free, predictable, abundant
Tidal Barrage: a dam is built across the mouth of a bay
- incoming and outgoing tides turn turbines
- In North Am: Bay of Fundy
Adverse env. impacts:
-traps sediments, impedes fish migration, prevents navigation, changes water circulation patterns
teach is in research and development stage to harness energy in ocean waves
-once operational, tidal turbine in N Ireland will generate renewable energy
79
Energy conservation
Help meet growing energy demands
- lighting and appliance efficiency (incandescent vs. compact fluorescent lights)
- automobile efficiency (fuel efficiency: gasoline electric hybrid and plugin hybrid automobiles)
Appliances that meet "EPA energy star" standards display average annual energy and cheaper
Conventional cars can be adapted to run on hydrogen gas
- hydrogen not a fuel but an energy carrier (like electricity) - must be generated using another form of energy
- only major by-product of burning H2 is water
- there is almost no hydrogen gas on earth (soil bacteria produces it)
- hydrogen can be extracted from water by electrolysis
- hydrogen can be derived from hydrocarbon fuels (methane, petroleum, oil, methyl, alcohol)
Fuel cells are being used - 45-60% efficient
- along with a hydrogen storage device, a cooling system, and a device to force oxygen into the fuel cell
- fuel cells power buses
- all major car manufacturers are developing concept cars
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Hydrogen for cars
In our natural atmosphere hydrogen is most abundant when it is combined with oxygen-H20
-Hydrogen most abundant when combined w/ oxygen, more oxygen in atmosphere than mat hen or anything else
hydrogen in automobiles generates electricity
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DDT
DDT is a pesticide
- Chemist Paul Muller studied DDT in 1930s
- as a pesticide it was extremely successful
GOOD
- extremely toxic to insects
- not harmful to humans/mammals
- cheap and effective against any insect pests
- Used to control insect disease carriers
- During WW2 it was used to control body lice, which carried typhus fever
- fight malaria bc killed mosquitos carrying it
- DDT saved millions lives
BAD (killed birds, bioaccumulates, affects birds eggs)
- DDT used widely 1940-60
- in 1950s-60s many bird species declined drastically
- They were top of food chain (eagle, osprey)
- DDE (ethylene) resulted in thin-shelled eggs
- higher doses of DDT and DDE accumulate up the food chain
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Bioaccumulation and biomagnification
Bioaccumulation: many synthetic organic chemicals are soluble in lipids (Fats)
-small amts accumulate over time to toxic levels
Biomagnification: the multiplying effect of bioaccumultation through the food chain (DDT)
- organisms in the chain have more concentrated amts of chemicals in their bodies
- predators and eat smaller things it builds up in their system
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Rachel Carson and Silent Spring
Silent Spring (1962) documented the effects of the uncontrolled use of insecticides in U.S.
- if use continued as usual there might be a spring with no birds
- DDT banned in U.S. 1970s
As a result we stopped using DDT and it was the birth of the env. movement
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Need for pest control
| -pest, weeds, exotic species
Pest: general term for an organism that is noxious, destructive, or troublesome
-creature you don't like
agricultural pests: feed on crops (insects, fungi, viruses, worms, snails, rats, mice, birds)
Weeds: plants that compete with crops, forests, grasses
-plant you don't want
Pests destroy 37% of U.S. agricultural production/ys
- herbicides: chemicals that kill plants/weeds
- pesticides: chemicals that kill animals and insects
We are dependent on pesticides
- danger in using pesticides a lot: they can grow immune and become resistant
- best way to control resistance and reduce amt. of insects: switch up pesticides, use biological controls, and crop rotation
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Exotic (fallen) species
| invasive species
Exotic (fallen) species: one that is introduced into an area from somewhere else
-most don't survive or don't become pests
Invasive species are pests but not usually associated with agriculture: thrives, spreads, and can eliminate native species by predation/competition
- brown tree snake in Guam, it is an invasive species bc didn't exist there before
- Hawaii didn't have mosquitos before mosquitos came - if brown tree snake went to Hawaii it would explode there too and eat everything, all the birds - if it spread to Hawaii we would expect a massive decrease in biodiversity
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Problems of chemical pesticides
Resurgence: occurs after a pest has almost been eliminated
-pop recovers and explodes
Secondary pest outbreak: small pops of insects that were originally of no concern explode
-pesticides often kill more predators of pests than the pests
CYCLE
pest problems - use of chemical pesticides - increased resistance, resurgence, secondary outbreaks - pest problems...
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Parasitic relationship
Wasp lays on a leg: it is a form of natural enemies control
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4 Types of natural enemies
Predators, parasitoids, pathogens, plant-eaters
Import aliens as a last resort
- effective natural enemies are not always available - we imported pests, but their enemies
- natural enemies are found in their native region - must be carefully tested before being released
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Integrated Pest Management (IPM)
IPM aims to minimize use of synthetic organic pesticides
-crops and pests are seen as parts of a dynamic system
GOAL is not pest eradication, but keeping crop damage below the economic threshold
4 approaches
- Set action thresholds: identify the point where conditions indicate that some control is needed
- monitor and identify pests: experts determine if pests exceed economic threshold (field scouts trained in identifying and monitoring pests)
- prevent pests: through cultural and biological controls (Crop rotation, predators, fertilizing)
- control pests: selected brands of pesticides are used (do the least damage to natural enemies of pest)
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Species introduction
Accidental introduced
- Bromus Tectorum - grass from Europe caught on cattle and has replaced most grass of West US
- Brown tree snake entered Guam on cargo ships - in 50 yrs kills 9/12 bird species
Deliberately introduced
- Saltcedar in SW US to control erosion
- house cat kills birds and mammals
Everything now has the change to move everywhere
-species without borders will cause extinction and create a boring Earth
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Biological wealth and cultivar
Biota: natural species
Biological wealth: biota plus their ecosystems (makes up most ecosystem capital that sustains humans)
Biodiversity: richness of living species
Human growth and culture development have killed 631 N Am species btwn 1642 and 2001
Cultivar (cultivated variety): a highly selected strain of the original species
- has minimal genetic variation
- produces outstanding yields in specific conditions
- wild pop have traits for comp, resistance to parasites, tolerance to adverse conditions
- plant breeders combine wild pop or related species for desired traits
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Genetic bank
Genetic bank: living things are a bank of the gene pools of all living species
- wild relatives of cultivated crops are being preserved (England and Norway hold seeds for backup for other seed banks)
- Zoos act as genetic banks for animals
- --United Kingdom's Frozen Ark projects collects cells and DNA ftp, species likely to go extinct
Genetic banks is a storage of all the genes of all the living things, referred to as every living thing on earth
Eco tourism: a place that attracts tourists based on its ecosystems
- tourists visit a place to observe wild species or unique ecological sites
- it is the largest foreign exchange generating enterprise for many developing countries
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Plant species use
Out of all plant species we only use about 7,000
-three most important species for food (wheat, maize, rice)
Species for medicine
-Rosy periwinkle from Madagascar - used to treat cancer, leukemia and Hodgkin's disease
Ethnobotany: studies relationships btwn plants and animals - this field studies plants for potential human use for medicine
-bioprospecting: studies indigenous people's use of plants
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Biodiversity
Biodiversity in the world is decreasing
Two measures to calculate
- the # of species (richness)
- more importantly how "even" the species are distributed
- ---habitat has low biodiversity if it is dominated by 1 species with few members of other species
- ---high if dominance of any one species is low
Greatest biodiversity would be an ecosystem with same number of species as other ecosystems but has NO DOMINANT SPECIES
current global extinction rate = 100-1,000 times greater than past rates
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Reasons for biodiversity decline (HIPPO)
Past: climate change, plate tectonics, asteroid impacts
Current: HIPPO
Habitat destruction!!
---greatest source of biodiversity loss (36%)
---conversion: most common form, natural areas converted to farms, housing, malls, industrial centers (species adapted to habitats so when habitat changes, species goes with it)
-fragmentation: fragments of habitat support small numbers and pops of species (patches of diff habitats/land bordering each other) - see it in airplanes
Invasive species
Pollution
Population (human)
Overexploitation!!!
- overharvest of a particular species (removing individuals faster than they can reproduce) - greed, ignorance, desperation
- illegal trade of exotics generates $12 billion/yr - 3rd largest source
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Who is at most biodiversity risk?
K-strategists - many declining species
- long-living, large, older at first reproduction, high parental care
- vulnerable to rapid env. change (mammals)
r-strategists are less likely to be harmed by humans
-widely distributed, small, rapid reproduction, ability to migrate (Bacteria, insects)
Loss of biodiversity will do what to prevent types of species that are alive: increase pests, cockroaches, mosquitos, flies
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Endangered species Act
Endangered species: in imminent danger of becoming extinct if it is not protected
threatened species: in jeopardy but not yet endangered
Endangered Species Act (1973)
-protects to bring pops back up and preserve or restore historical habitat, want species to live where they historically live as well
Elements:
-listing of species: by appropriate agency, individuals, groups, state agencies (based on best available info)
-critical habitat: areas where a species is or could spread as it recovers (includes privately held lands)
-recovery plans: designed to allow listed species to survive and thrive
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Future legislation - endangered species
Many political and commercial groups want to weaken the Endangered Species Act
-6,000 scientists signed letter to Senate to maintain
Endangered Species Act recognizes importance of preserving species
- regardless of their economic importance
- species have legal rights to protection
CITES (Convention on international trade in endangered species of wild Fauna and Flora)
- established 1970s
- international agreement focusing on trade and wildlife
Highest level of vulnerability: species threatened with extinction
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Sustainable communities
New Zealand city: Waitakere - a sustainable city that decided to all be env stewards
- suffered urban sprawl: moving out of the city
- has become an ecocity
URBANIZATION - the concentration of human pops in densely populated cities
-env is drastically diff along the urban-suburbs-rural gradients
Excerb: where we all want to live, in btwn suburbs and city
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Urban environments
Urban heat island effect (Warmer and less humid)
-4 characteristics drive this: less vegetation, impervious surface cover (ISC), sources of heat, structures trapping heat
ISC: concrete, asphalt, rooftops
-reduces drainage and filtration, increases runoff, and diminished water quality
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Urban sprawl
Areas with low-density residential areas, shopping malls, industrial parks, and other facilities
-moving out of the city
Sprawl: city perimeters are continuously extended into the countryside
- little planning
- no notion of where it will stop
- farms and natural areas are destroyed, highways are built, and old roads are expanded
Origins of urban sprawl
- until end of WW2, ppl didn't own cars
- cities developed so ppl could walk most places, ppl used public transportation to go "downtown"
- outer ends of the city ended at farms that provided food and natural areas
- end of WW2 cities became less desirable as more ppl wanted the American Dream - THEIR OWN HOME
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Suburbs
to meet demand after WW2, suburbs were build and ppl bought cars - veterans and baby boom increased housing demand
- mushrooming development around cities lacked any plan - it happened wherever developers got land
- no governing bodies existed to devise or enforce plans
Cost of suburbs
- new highways fostered development of open land
- more fuel is required which generates more money for roads from taxes which builds more roads
- gov. policy promotes urban sprawl
Stereotypically who lives I'm suburbs: upper middle class white people
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Env. impacts of cars
energy resources: care use of petroleum has tripled
Air pollution: many cities don't meet air quality standards (cars cause 80% of air pollution)
Water: pavement increases runoff, flooding, erosion
Loss of agricultural land
Loss of landscapes and wildlife
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Urban blight
In developing world, urban blight (decay) results from ppl moving to the city (beyond capacity of cities)
- in developed world, urban blight results from affluent ppl moving from the cities "white flight" - excluding poor, elderly, minorities, disabled
- wealthy ppl moving to suburbs or exurbs starts a vicious cycle of exurban migration and urban blight
- affluent ppl increase the tax base of suburbs but decreased the tax base in cities
- lower demands = lower property values = lower tax revenues (city abandons properties)
- services are paid by property taxes determined by value of home (decrease services and facilities)
- poor immigrants settle in cities, requiring public help
1/3 of ppl in developing world cities live in slums (no water, sewer, land ownership - crime, disease)
-can't afford rent for housing, continue growth due to pop and immigration
URBAN BLIGHT: big effects economically, educationally, socially - lower tax base so you can't have better schools, don't attract businesses, food, lack of access to fresh produce
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Smart/ sustainable growth
Smart growth: the key to controlling sprawl is to provide quality of life benefits without incurring serious env and social costs
- create a range of housing pop and mix land uses
- create walkable neighborhoods
- foster distinctive, attractive neighborhoods
- conserve open space, farmland, natural beauty, critical areas
- provide a variety of transportation choices
In livable cities, space is designed for ppl not cars (2/3 of land in cities for moving, parking, servicing cars)
-worlds most livable cities reduce sprawl and improve movement by foot, bike, or mass transportation
LEED (leadership in energy and env design) drives green building industry
According to what we have learned in class, a successful urban plan - designs space for green space, green space increases wellness, ppl have a place to interact with each other easily and enjoy the space together, city that accommodates ppl to interact with each other easily
Linear metabolism - compared to natural ecosystems, the flow of materials and energy in urban ecosystems is generally linear
circular metabolism (recycle and reuse to convert energy)
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Three types of hazards
Physical hazards
- geological, weather, fire
- earthquakes (West coast of Am, Asia, Middle East)
- tsunami, hurricane, typhoon, suburban wildfire in S Cali
Chemical hazards
- toxin transport and fate
- persistence, volatility, solubility in water
- persistent organic pollutants (POPs)
Biological hazards
-infections diseases
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Chemical hazards - POPs
- Arctic fish, birds, and mammals of POPs in their bodies (DDT, toxaphene, dioxins)
- --POPs reach Arctic bc carried in the air - bioaccumulate and biomagnify (condense in snow pack and enter water during spring thaw, plankton pick up chemicals and pass them up food chain, birds pick up)
The dose (level of exposure is multiplied by the length of time of exposure) is linked with the response (effects)
- human exposure to a hazard is a vital part of risk characterization
- usually a threshold level in the dose-response relationship
Threshold level: the level below which there are no ill effects (can deal with some level of substance w/o suffering)
- effects above this level depend on concentration and duration of exposure
- below threshold level nothing bad will happen to you
Dirty Dozen: worst POPs (persistent organic pollutants), POPs are among the most troublesome chemical hazards to human health
- 10/12 produced to kill fungi/insects
- Halogenated hydrocarbons: synthetic organics that contain halogens (chlorine, bromine, fluorine, iodine)
- Chlorinated hydrocarbons: the most common halogenated hydrocarbons (plastics, pesticides (DDT), solvents, insulation)
- most Dirty Dozen POPs are halogenated hydrocarbons (all are toxic and cause cancer) - banned or restricted by 2004 Stockholm Convention
PCDS - not many regulations
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Sources of hazardous chemicals
Toxic chemicals in U.S. have decreased
Total product life cycle: encompasses all steps in a material's life from raw materials to disposal
-chemical wastes and by-products are inevitable - they enter the env at every stage
All toxic chemicals are hazards that threaten humans
-many are broken down in the env
Two classes that do not readily break down: heavy metals and synthetic organics
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Heavy metals (lead, mercury, arsenic, tin, chromium, zinc, copper)
-used in industry, batteries, electronics
once used in paint, lead paint poisoned U.S. children ad it was banned in 1978
-heavy metals are extremely toxic - small amts can cause mental retardation, insanity, birth defects
-worst case was Minamata disease in Japan 1970s where a chemical company near village discharged mercury into a river which entered the bay, mercury bioaccumulated and biomagnified, humans eating fish affected their nervous system
-heavy metals affect nervous system
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Synthetic organic compounds
- petroleum: derived and synthetic organics are the basis for plastics, fibers, synthetic rubber, pesticides
- resistence to degradation makes them useful and dangerous
- are readily absorbed and interact with enzymes
Chemical industry is heavily regulated to handle and dispose of chemicals to minimize risks
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Current chemical regulations
Chemical industry is heavily regulated to handle and dispose of chemicals to minimize risks
Early land disposal was not regulated - deep wells injected wastes into groundwater, abandoned quarries used as landfills - created waste disposal
-midnight dumping: disreputable businesses pocketed fees, then illegally dumped wastes in abandoned warehouses, vacant lots, or landfills - individuals responsible could not be found - problem only found when ppl got sick
Love Canal, NY - on edge of Niagara Falls suffered worst toxic disaster in US history
- toxic waste from Hooker Chemical seeped into neighborhoods and school yard - 800 families relocated and reimbursed for their homes
- public realized that anyone of them could have lived in Love Canal or Times Beach
- they were being exposed to a legacy of unfettered toxic waste abuse and toxic tragedies
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Managing hazardous waste
Problems of toxic chemical wastes occur in 3 areas:
- cleaning up messes already created
- regulating disposal of wastes being produced
- reducing the quantity of hazardous waste produced
Cleaning up mess
-contaminated drinking water: a major public health threat (first priority is ensuring ppl have safe water - second, clean up or isolate pollution's source to prevent further contamination)
Safe Drinking Water Act (1974) - EPA set national standards to protect public health
- Max contaminant levels (MCLs) - if contaminants exceed this level, the water source is closed
- groundwater remediation: a developing tech used if toxic materials have contaminated groundwater (tech. = drilling wells, pumping out contaminated water, purifying it, re-injecting it)
- deep well injection: wastes in deep wells react with natural material leaving them less hazardous (wells can keep toxic wastes from contaminating water)
Surface impoundments
-ponds: excavated depressions into which liquid wastes are drained and held - least expensive most widely used way to dispose of large amts of water carrying small amts of waste (solid wastes settle and water evaporates)
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Cleaning up: Superfund
Only 23 landfills in N Am receive off-site hazardous wastes
-secure landfill: a reasonably safe landfill that is lined
Most monumental task we face is cleaning up toxic sites
- Superfund - a trust fund that uses money from taxes on chemical raw materials
- based on the "polluter pays" principle
Resource Conservation and Recovery Act
-designed to prevent unsafe or illegal disposal of solid wastes on land - all disposal facilities (landfills) must have permits
"Cradle to grave"-
-fill out form to EPA detailing what kinds and amounts of waste - ensures that generators deal only with responsible parties and curtails midnight dumping
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Environmental justice
It is the fair treatment and involvement of all people - equal enforcement of env laws, regulations, and policies
- no group of ppl should beat a disproportionate share of negative env consequences
- hazardous facilities more likely to be located in non-white/poor - rich generate wastes but don't want them close
pollution control: uses tech to prevent pollutants from entering env. - solutions to dispose and control
pollution prevention: involves changing production, materials, or both so pollutants won't be released at all
-substitution to avoid pollution
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Biological hazards
Infectious disease
- pathogens
- Anthroponosis: disease only in humans
- Zoonosis - disease shared by animals and humans
Diarrheal diseases - poor sanitation and polluted water are responsible for most diseases infecting stomach and intestines
-pathogens including viruses, bacteria that inflame lining of stomach and small intestine
Asthma - increasing prevalence of asthma in U.S. is a consequence of increasing urbanization of the pop and diminishing air quality in many regions
Common allergen: microscopic dust mites, common in carpets - allergic reactions in ppl
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The Commons
Seeking to maximize personal gain - overgrazing by all
-each person is locked into a system that compels them to increase their herd without limit - in a world that is limited
Lifestyles
- env problems are human, not scientific or technical (we know enough to act, our decisions bring about change)
- making stewardly appropriate decisions is not easy - but business as usual solves very few problems
The common good: to improve human welfare and protect the natural world
- compassion for less fortunate
- concern for justice
- honesty: keeping laws
- sufficiency: simple lives
- humility: share with others
- neighborliness: concern for others and helping them
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Sustainability
a property whereby a process can be continued indefinitely without depleting the energy or material resources on which it depends
- ppl must be willing to grapple with scientific evidence to respect scientific consensus
- sustainability must be economically feasible, socially desirable and economically viable
- we are all involved whether we recognize it or not
