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Chapter 3 Environmental Systems *Basic chapter outline and some quotes from Environmental Science for AP by Friedland and Relyea
Chapter 3
Environmental Systems
*Basic chapter outline and some quotes from
Environmental Science for AP by Friedland and Relyea
What is a system?
Definition of system:
A set of components that function and interact in
some regular and theoretically understandable
manner
Examples:
Human body, ecosystems, computer network, factory
Key Components of Systems
Inputs
(from environment)
Throughputs
(rates of flow)
Outputs
(to environment)
Human Body
(inputs may
be stored for
different lengths
of time)
Energy
Information
Matter
Heat
Ideas
and
actions Waste
and
pollution
“The Earth is a single interconnected
system”
“One basic principle of environmental science
is that we can never do just one thing. Any
action in a complex system has multiple,
unintended and often unpredictable effects.”
Miller p. 38
Example of unintended consequences
Rachel Carson’s Silent Spring is full of
examples:
In an ecosystem in Michigan in the 1950s, elm
trees were sprayed with a pesticide to kill
beetles
When it rained, the pesticide washed into the
soil under the trees and got into the
earthworms
Robins ate the earthworms and started dying
in huge numbers
No one intended to kill the birds, just the bugs,
but because they were in the same system,
the birds were affected, too
http://www.omgfactsonline.com/baby-robins-
eat-14-feet-of-earthworms-every-day/#
Human Activities Results
Population growth
Land clearing
Agriculture
Pesticides
Fertilizers
Irrigation
Fishing
Dams and water
transfers
Cities
Industrialization
Mineral extraction
Fuel consumption
Antibiotics
Unintended
Results
More food
Better nutrition
Pest control
Nutrient-rich soils
More seafood
Flood control
Shelter
Culture
Education
Mobility
Consumer goods
Better health
Decline of infectious
diseases
Longer life
Too many people in
some areas
Deforestation
Soil erosion and
degradation
Water deficits
Air pollution
Water pollution
Solid waste
Toxic waste
Loss of biodiversity
Fisheries depletion
Climate change
Ozone depletion
Genetic resistance
of pesticides
Genetic resistance
to antibiotics
“All environmental systems consist of
matter” Definition of matter: anything that has mass and takes up space
Composition of matter: Atoms
minute unit made of subatomic particles that is the basic building block of all chemical elements and thus all matter
Elements the distinctive building blocks of matter that make up every material
substance
Ions electrically charged atom or combination of atoms
Molecules combination of two or more atoms of the same or different elements held
together by chemical bonds
Compounds molecules made of two or more elements
Elements important to ES hydrogen H
carbon C
oxygen O
nitrogen N
potassium K
phosphorus P
sulfur S
chlorine Cl
fluorine F
bromine Br
sodium Na
calcium Ca
lead Pb
mercury Hg
arsenic As
uranium U
Ions Important to ES
Ions to know
Positive:
hydrogen H+
sodium Na+ ammonium NH4+
calcium Ca2+ aluminum Al3+
Negative:
chlorine Cl- sulfate SO42-
hydroxide OH- phosphate PO43-
nitrate NO-3
Compounds important to ES
Compounds to know: Sodium chloride NaCl
Carbon monoxide CO
Carbon dioxide CO2
Nitric oxide NO
Nitrogen dioxide NO2
Nitrous oxide N2O
Nitric acid HNO3
More compounds to know:
Methane CH4
Glucose C6H12O6
Water H2O
Hydrogen sulfide H2S
Sulfur dioxide SO2
Sulfuric acid H2SO4
Ammonia NH3
Which of the above compounds are organic compounds (based on carbon – not including the oxides of carbon)?
Chemical reactions
Review:
Reactants Products
Photosynthesis:
6CO2 + 6H2O C6H12O6 + 6O2
Energy is stored when chemical bonds are formed
Energy is released when chemical bonds are broken
Sunlight
• pH – measure of the H+ ions in solution
• acids – less than 7 on pH scale
• bases – greater than 7 on pH scale
• neutral – 7 on pH scale
• Note: Organisms are adapted to survive
with certain pH environments (internal
and/or external) and may die if the
environment deviates from a certain pH
range
The genes in each cell are coded by sequences of nucleotides in their DNA molecules.
Each chromosome contains a long DNA molecule in the form of a coiled double helix.
A specific pair of chromosomes contains one chromosome from each parent.
Each nucleus has an identical set of chromosomes, which are found in pairs.
There is a nucleus inside each human cell (except red blood cells).
The human body contains trillions of cells, each with an identical set of genes.
Genes are segments of DNA on chromosomes that contain instructions to make proteins—the building blocks of life.
Organization of living things:
Matter quality
High quality – concentrated, usually found
near the earth’s surface, has great potential
for use as a material resource
Low quality – dilute, often deep underground
or dispersed in the ocean or atmosphere,
little potential for use as a material resource
High Quality
Solid
Salt
Coal
Gasoline
Aluminum can
Low Quality
Gas
Solution of salt in water
Coal-fired power
plant emissions
Automobile emissions
Aluminum ore
© 2004 Brooks/Cole – Thomson Learning
Law of Conservation of Matter
Stated as: when a physical or chemical
change occurs, no atoms are created or
destroyed
“Everything we think we have thrown away
remains with us in some form.”
“Energy is a fundamental component of
environmental systems.”
Definition of energy: the capacity to do work
and transfer heat
Types:
1. Kinetic – Energy of motion
2. Potential - Stored energy
3. Electromagnetic radiation
ionizing
non-ionizing
Heat
Definition: the total kinetic energy of all the moving atoms, ions, or molecules within a given substance
Temperature – the average speed of motion of the atoms, ions or molecules in a given substance at a given moment
Three ways to transfer heat:
1. convection
2. conduction
3. radiation
Figure 3-11
Page 45
Convection Conduction Radiation
Heating water in the bottom of a pan causes some of the water vaporize into bubbles. Because they are lighter than the surrounding water, they rise. Water then sinks from the top to replace the rising bubbles. This up and down movement (convection) eventually heats all of the water.
Heat from a stove burner causes atoms or molecules in the pan’s bottom to vibrate faster. The vibrating atoms or molecules then collide with nearby atoms or molecules, causing them to vibrate faster. Eventually, molecules or atoms in the pan’s handles are vibrating so fast it becomes too hot to touch.
As the water boils, heat from the hot stove burner and pan radiate into the surrounding air, even though air conducts very little heat.
Sun
High energy, short wavelength
Low energy, long wavelength
Ionizing radiation Nonionizing radiation
Cosmic rays
Gamma rays
X rays Far ultraviolet
waves
Near ultraviolet
waves
Visiblewaves
Near infrared waves
Far infrared waves
Microwaves TV waves
Radio waves
Wavelength in meters (not to scale)
10-14 10-12 10-8 10-7 10-6 10-5 10-3 10-2 10-1 1
Figure 3-9
Page 44
Energy Quality
High quality energy – concentrated, can
perform much work
Low quality energy – dispersed, has little
ability to do useful work
Electricity
Very–high-temperature
heat (greater than 2,500°C)
Nuclear fission (uranium)
Nuclear fusion (deuterium)
Concentrated sunlight
High-velocity wind
High-temperature heat
(1,000–2,500°C)
Hydrogen gas
Natural gas
Gasoline
Coal
Food
Normal sunlight
Moderate-velocity wind
High-velocity water flow
Concentrated
geothermal energy
Moderate-temperature heat
(100–1,000°C)
Wood and crop wastes
Dispersed geothermal energy
Low-temperature heat
(100°C or lower)
Very high
High
Moderate
Low
Source of Energy Relative Energy Quality
(usefulness)
Energy Tasks
Very–high-temperature heat
(greater than 2,500°C)
for industrial processes
and producing electricity to
run electrical devices
(lights, motors)
Mechanical motion (to move
vehicles and other things)
High-temperature heat
(1,000–2,500°C) for
industrial processes and
producing electricity
Moderate-temperature heat
(100–1,000°C) for industrial
processes, cooking,
producing steam,
electricity, and hot water
Low-temperature heat
(100°C or less) for
space heating
© 2
004 B
roo
ks/C
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– T
ho
mso
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earn
ing
“Energy conversions underlie all
ecological processes.”
Energy can be converted from one form to
another, but not at 100% efficiency
First Law of Thermodynamics
In a physical or chemical change, we can
change energy from one form to another but
we can never create or destroy any of the
energy involved.
Also called Law of Conservation of Energy
energy input = energy output
Second Law of Thermodynamics
Whenever energy is changed from one form to
another we always end up with less usable
energy than we started with.
Some of the energy is degraded to lower
quality, more dispersed or less useful energy.
Energy efficiency
Definition: measure of how much useful work is accomplished by a particular input of energy into a system
Examples:
A car only converts about 25% of the chemical energy in the fuel to mechanical energy
Standard light bulbs produce 5% useful light, and 95% heat
Process of photosynthesis is about 1% efficient
In living systems, solar energy converted into chemical energy in food, then into mechanical energy, energy degrades with every step (remember the 10% rule?)
Solar energy
Waste heat
Chemical energy
(photosynthesis)
Waste heat
Waste heat
Waste heat
Chemical energy (food)
Mechanical energy (moving, thinking,
living)
“Systems analysis shows how matter and
energy flow in the environment.”
Two possibilities: open and closed systems
For the earth:
Energy flows from sun constantly into our system – open system
Matter is recycled – earth is a closed system for matter
www.geozoo.org
Systems analysis
If input = output the
system is in a steady
state
Ex: water cycle has been in a
steady state but with
climate change, this may
not be balanced any more
because evaporation
speeds up at higher
temperatures
www.env.gov.bc.ca
Feedback loops can help a system
maintain a steady state or drive it out of
balance
Definition: when an output of matter, energy,
or information is fed back into the system as
input and leads to changes in that system
Positive feedback loop – causes system to
continue in same direction
Negative or corrective feedback loop –
causes system to reverse
Positive or Negative Feedback?
Every time a dog tries to cross an electric
fence, he gets a shock. Soon he doesn’t try
to cross it at all.
Training a rat to get food by pressing a lever:
positive or negative feedback?
Positive or Negative Feedback?
“Natural systems change across space and
over time.” May change as a result of a feedback loop
(Ex: Arctic ice melting, permafrost melting – both
increase the warming of the earth)
May change as a result of an external change, such as
climate change or community change (ecological
succession)
coppellprairie.wikispaces.com
Matter and Energy Laws
and Environmental Problems
High Through-put Economy of most developed
countries – converts a lot of energy and
matter into waste, pollution and low-quality
heat
This is a throwaway economy
Inputs
(from environment)
High-quality energy
Matter
System
Throughputs
Output
(intro environment)
Unsustainable
high-waste
economy
Low-quality energy (heat)
Waste matter and pollution
High-Throughput Economy: Straight Line
Low throughput economies –
better for the environment
includes some cycling (not all linear)
reduces what goes into the economic system
by conservation and prevention at the front
end, thus reducing waste and pollution as
output
Energy
Matter
Energy Feedback
Energy
conservation
Waste and
pollution
prevention
Sustainable
low-waste
economy
Matter
Feedback
Recycle
and
reuse
Pollution
control
Waste
and
pollution
Low-quality
energy
(heat)
Low-Throughput Economy: Go in Circles
