APES Unit I Review.ppt

APES Unit I Review

Enviro. Issues

Interconnected/rapidly growing

1. Population growth

2. Increasing resource use 3. Global climate change

4. Premature extinction of plants/animals 5. Pollution

Exponential Growth

The Earth can survive without man, man cannot survive without the Earth.

• Sun – ultimate source of energy

• Solar Capital – direct from sun, indirect – wind, biomass, hydropower

• Natural capital - air, water, soil, wildlife, forests, fisheries, minerals, natural biogeochemical

Economic Development

Improvement of living standards by economic growth

Based on per capita GNI and degree of industrialization

2 Groups

• Developed countries – US, Japan, Europe, Canada, New Zealand, Australia

Globalization

• Global social, economic, and environmental change leading to an integrated world

• Signs:

1. Economic – international trade 2. Information and communication

3. Environmental effects – infectious disease (H1N1 virus), spread of long-lived pollutants Grasshopper effect: pollutants found in the

Pollution

any addition to air, water, soil, or food that

Types of Pollution Sources

1. Point Source – identifiable source – smokestack, industrial discharge, wastewater treatment plant

2. Nonpoint Source – difficult to identify – dispersed – runoff from farms, lawns, golf courses (contains fertilizers,

pesticides), runoff from urban areas (contains oils, grease)

Basic Causes

MODELS AND BEHAVIOR OF

SYSTEMS

• Usefulness of models

– Complex systems are predicted by developing a model of its inputs, throughputs (flows), and

outputs of matter, energy and information. – Models are simplifications of “real-life”.

Systems can be affected by

1. Feedback loops 2. Time delays

1. Feedback Loops:

• Outputs of matter, energy, or information fed back into a system can cause the system to do more or less of what it was doing.

– Positive feedback loop causes a system to

change further in the same direction (e.g. money earning interest)

2. Time delays

• Time delays in a system in which the effects are not know for some time • Allows the problem to

build up slowly and then whole system changes

Ex: population growth, toxic waste leaks, forest

destruction from air pollutant

3. Synergy

• 2 or more processes combined have a

greater effect on a system than the sum of each would have.

Law of conservation of problems

“We can never do just one thing”

• Solution for a problem usually leads to other problems

Ex: addition of MTBE to gasoline to reduce air pollution, then polluted groundwater

• Must consider when we search for solutions

• Systems are interconnected

Matter: Forms, structure, quality

Important Compounds

• Chlorinated hydrocarbons: C, H, Cl

DDT, PCB’s (polychlorinated biphenyls) • Chlorofluorocarbons (CFC’s) freon

• N₂O nitrous oxide NO nitric oxide

• NO₂ nitrogen dioxide CO carbon monoxide • SO₂ sulfur dioxide NH₃ ammonia

Matter quality

• A measure of how useful a form of matter is as a resource based on availability and concentration

• High quality – concentrated, found near Earth’s surface, great potential for use Coal, Salt, Al can

• Low quality – dilute, found deep

underground or in ocean, in atmosphere with little potential for use.

ENERGY

• Energy is the ability to do work and transfer heat.

– Kinetic energy – energy in motion

• heat, electromagnetic radiation

– Potential energy – stored for possible use

Energy Quality

• High quality – concentrated/useful electricity, chem energy in coal/gasoline • Low quality – dispersed/ little ability to do

Chem/Phys Changes

“There is no away”

Can’t get rid of anything – will show up somewhere else.

Factors determining harmful effects of pollutants:

1. Chemical nature: Hg vs. Cu

2. Concentration: PPM, PPB, PPT

Categories of Persistence

1. Degradable, nonpersistent – broken down to acceptable levels by natural processes

Biodegradable – by living organisms

2. Slowly degradable, persistent – takes decades or longer DDT (

Dichloro-Diphenyl-Trichloroethane)and most plastics

Half life

• Amount of time needed for ½ of the nuclei in a radioisotope to decay to more stable isotope.

• Generally takes 10 - ½ lives for an isotope to decay to a safe state.

ENERGY LAWS

• The first law of thermodynamics: we cannot create or destroy energy.

– We can change energy from one form to another. • The second law of thermodynamics: energy

quality always decreases.

– When energy changes from one form to another, it is always degraded to a more dispersed form. – Usually takes the form of heat given off at lower

Energy Efficiency

• A measure of how much useful work is accomplished by a particular input of energy into a system

• Only about 16% of the energy used in the US ends up performing useful work.

• Wasted through the 2nd law or

How does 2

Law affect life?

• Use high quality energy to maintain

molecules & biochemical processes, and then give off low quality heat to your

surroundings

Best solution is low-throughput economy

resources

• Use renewable resources sustainably • Efficient use of matter/energy resources • Reduce unnecessary consumption

• Emphasize pollution prevention and waste reduction

Chapter 4

Ecosystems:

Components, Energy

Flow and Matter

I. Levels of organization

• Biosphere

• Ecosystem

• Community

• Population

A. Organism – 1

level

• Cell – basic unit of life

Classify cells as (according to cellular structure)

1. Eukaryotic –Surrounded by membrane, membrane bound nucleus, internal

structures – organelles

2. Prokaryotic – cell membrane, but no organized nucleus or organelles. BacT Eukaryotes cannot exist without

Species

• Groups of organisms that resemble one another in appearance, behavior, chemistry and genetic makeup

• In organisms utilizing sexual reproduction – organisms that can breed with one another to produce fertile offspring

B. Population -2

level

• Group of interacting individuals of the same species that occupy the same area at the same time

Ex: all white oak trees in a forest

Populations change in response to

environment:

1. Size

2. Age distribution 3. Density

Population Terms

• Habitat – place a population lives address

• Niche – general term for the role of a

C. Community – 3

level

• Populations of different species living in the same place at the same time – all the plants, animal, and microorganisms

D. Ecosystem – 4th Level

• Community and its nonliving environment of matter and energy

Biosphere – 5

Level

Atmosphere

1. Troposphere – inner layer , 11 miles high 78% N₂ 21% O₂ others, H₂ He

2. Stratosphere – 11-30 miles contains ozone layer (filters harmful UV radiation)

Hydrosphere

1. Liquid water – surface and groundwater 2. Ice – polar ice, icebergs, permafrost

Lithosphere

• Earth’s crust and upper mantle

What Happens to Solar Energy

Reaching the Earth?

• Solar energy

Ecosystems: Concepts and Components

• Biome: terrestrial region of the biosphere that has a distinct climate & specific life forms

adapted to it.

• Climate: long term pattern of weather • Aquatic life zones:

Ex: freshwater – lakes, streams, rivers

Ecosystems Boundaries

Abiotic : Limiting Factors

• Too much or too little of any abiotic factor can

limit or prevent growth of a population, even if all other factors are optimum.

• Limiting factors on land: precipitation, soil nutrients

Range of Tolerance

Biotic: Producers (autotrophs)

• Make own food through chemosynthesis or photosynthesis

6CO₂ + 6H₂O + solar energy  C₆H₁₂O₆ + 6O₂

Chemosynthesis

• Instead of sunlight organisms use chemical energy. • Deep ocean – H₂S from hydrothermal vents used by

Consumers (heterotrophs)

• Get energy and nutrients from other organisms or their remains

Herbivores

• Primary consumers

Carnivore

• Eat meat, feed on other consumers

• Those feeding on primary consumers are called secondary consumers

Omnivore

Scavengers

Detritivores

(detritus feeders and decomposers)

• Feed on detritus – parts of dead organisms and waste of living organisms

- detritus feeders: crabs, termites, earthworms extract nutrients from partially decomposed organic matter

Aerobic Respiration

• Both producers and consumers undergo aerobic respiration reverse of photosynthesis

• Uses glucose and oxygen to produce energy,CO₂, and H₂O

Anaerobic Respiration/Fermentation

• Some organisms use – no oxygen present

• End products are still energy, but instead of CO₂ and water, you might get CH₄, ethyl alcohol,

Biomass

• Each trophic level contains a certain amount of biomass

• Dry weight of all organic matter in the organisms at that level.

• Chemical energy is stored and transferred through biomass from one trophic level to another.

• Only about 10% of energy entering a trophic level is available to the next trophic level

Ecological efficiency

• Amount of usable energy transferred as biomass from one trophic level to another • Dependent upon the species

• Ranges from 5-20%

• The more trophic levels in a food chain or web, the greater the cumulative loss of

energy

Productivity of Producers:

The Rate Is Crucial

• Gross primary production

(GPP)

Net Primary Production (NPP)

• NPP = GPP – R

– Rate at which producers use

photosynthesis to store energy minus the rate at which they use some of this

NPP – available for use as food by

consumers

• Most productive: estuaries, swamps and marshes, tropical rain forests

MATTER CYCLING IN

ECOSYSTEMS

• Nutrient Cycles: Global Recycling

– Global Cycles recycle nutrients through the earth’s air, land, water, and living organisms.

– Nutrients are the elements and compounds that organisms need to live, grow, and reproduce.

– Biogeochemical cycles move these substances through air, water, soil, rock and living

Effects of Human Activities

on Water Cycle

• We alter the water cycle by:

– Withdrawing large amounts of freshwater. – Clearing vegetation and eroding soils.

Effects of Human Activities

on Carbon Cycle

• We alter the

carbon cycle by

adding excess CO₂ to the atmosphere through:

– Burning fossil fuels. – Clearing vegetation

faster than it is replaced.

Figure 3-28

Nitrogen Cycle

• N₂ Composes 78% of earth’s atmosphere • Cannot be used by multicellular plants and

animals

Nitrogen Fixation

• N₂ is converted to ammonia (NH₃) and then to ammonium (NH₄+)

• natural processes

Lightening (ammonium enters soil through precipitation)

Cyanobacteria in soil and water

Anthropogenic Nitrogen Fixation

• Industrial fixation of nitrogen in manufacturing fertilizer

Nitrification

• NH₄+ is converted to nitrites (NO

2-) and

then to nitrates (NO₃-) by nitrifying bacteria

• Nitrites are harmful to plants

Assimilation

• Plants absorb the ammonia and nitrates and make nitrogen containing organic molecules

Ammonification

• Organic matter is converted back into NH₃ and NH₄+ by decomposers

• Occurs when plant and animals die or when animals emit wastes

Dinitrification

• Specialized bacteria convert NH₃ and NH₄+ back into NO₂- and NO

3

-• NO₂- and NO

3- are then converted by

Effects of Human Activities

on the Nitrogen Cycle

• We alter the nitrogen cycle by:

– Adding gases that contribute to acid rain.

– Adding nitrous oxide to the atmosphere through farming practices which can warm the atmosphere and deplete ozone.

– Contaminating ground water from nitrate ions in inorganic fertilizers.

Phosphorus Cycle

• Phosphorus exists as PO₄

3-• Found as phosphate salts in terrestrial rock formations and ocean bottom

sediments

• Only in atmosphere as small particles of dust

• Often the limiting factor for plant growth – very little in soil

• Also limits growth of producer populations in freshwater streams and lakes – only

Effects of Human Activities

on the Phosphorous Cycle

• We remove large amounts of phosphate from the earth to make fertilizer.

• We reduce phosphorous in tropical soils by clearing forests.

• We add excess phosphates to aquatic

Sulfur Cycle

• Most sulfur is stored underground in rocks and minerals

• Sulfur can enter the atmosphere as H₂S and SO₂ from active volcanoes, and H₂S from the

breakdown of organic matter (through anaerobic decomposers).

• Sulfate salts enter the atmosphere from sea spray

Sulfur cycle continued

• SO₂ reacts with O₂ in the atmosphere to produce SO₃

• SO₃ reacts with water vapor to produce H₂SO_4. • Results in acid deposition

• Plants absorb sulfur when dissolved in water • Animals obtain sulfur by consuming plants

Effects of Human Activities

on the Sulfur Cycle

• We add sulfur dioxide to the atmosphere by:

– Burning coal and oil

– Refining sulfur containing petroleum.

The Gaia Hypothesis:

Is the Earth Alive?

• Some have proposed that the earth’s various forms of life control or at least influence its chemical cycles and other earth-sustaining processes.

– The strong Gaia hypothesis: life controls the earth’s life-sustaining processes.