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

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“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