Chapter 2: Environmental
Systems: Connections, Cycles,
Flows, and Feedback Loops
from your text, Principles of Environmental
Science: Inquiry and Applications, 3rd ed.
William and Mary Ann Cunningham. (New York:
McGraw-Hill, 2006)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
1
Chapter Two Key Terms
McGraw-Hill Course Glossary
 Acids
 Ecosystem
 Organic compounds
 Atom
 Energy
 pH
 Bases
 First law of
thermodynamics
 Photosynthesis
 Biological community
 Biomass
 Carbon cycle
 Carnivores
 Cellular respiration
 Chemical compounds
 Conservation of matter
 Consumers
 Decomposers
 Ecology
 Food web
 Herbivores
 Ions
 Kinetic energy
 Matter
 Metabolism
 Molecules
 Population
 Potential energy
 Primary producers
 Productivity
 Second law of thermodynamics
 Species
 Tropic level
 Nitrogen cycle
 Omnivores
2
Chapter Two - Topics
•
•
•
•
•
Principles of Matter & Energy
The Building Blocks of Earth and Life
Sunlight: Energy for Life
Energy and Matter and the Environment
Biochemical Cycles and Life Processes
3
Part 1: Principles of Matter
and Energy
To understand how ecosystems function, it is
important to first know something about how
energy and matter behave - in the universe and
in living things. It is also important to
understand the basic building blocks of life,
starting with cells and organisms, and
proceeding to communities and populations.
4
Ecology
• The scientific study of relationships between
organisms and their environment
• Examines the life histories, distribution, and behavior
of individual species, as well as the structure and
function of natural systems at the level of
populations, communities, ecosystems, and
landscapes
• Encourages us to think holistically about
interconnections that make whole systems more
than just the sum of their individual parts
• Examines how and why materials cycle between the
living and nonliving parts of our environment
5
Matter and Energy
• Matter and energy are essential
constituents of both the universe and
living organisms.
• Matter - everything that takes up space
and has mass
• Energy - the capacity to do work
6
Potential vs. Kinetic Energy
• Potential energy - stored energy that is latent but
available for use
• Kinetic energy - the energy contained in moving
object
7
Energy Quality
Low Quality Energy
• Diffused, dispersed, or low in temperature
• Difficult to gather and use for productive purposes
• Example: heat stored in the oceans
High Quality Energy
• Intense, concentrated, or high in temperature
• Useful in carrying out work
• Example: high-voltage electrical energy
Many of our most common energy sources are lowquality and must be concentrated or transformed into
high-quality sources before they are useful to us.
8
Conservation of Matter
Under ordinary circumstances, matter is
neither created nor destroyed. It is recycled
endlessly.
• Matter is transformed and combined in different
ways, but it doesn't disappear. Everything goes
somewhere.
• The atoms and molecules in your body have passed
through many other organisms, over millions of
years.
9
Properties of Energy
Energy cannot be recycled. Energy is reused, but it
is constantly degraded or lost from the system.
Most energy used in ecosystems originates as
solar energy. Green plants convert some of this
energy to chemical energy, which is then converted
to heat or kinetic energy by the animal that eats the
plant.
10
Laws of Thermodynamics
First Law of Thermodynamics
Energy cannot be created or destroyed, only changed
Second Law of Thermodynamics
With each successive energy transfer or transformation in a
system, less energy is available to do work. Even though the
the total amount of energy remains the same, the energy's
intensity and usefulness deteriorate.
The second law recognizes the principle of entropy, the
tendency of all natural systems to move towards a state of
increasing disorder.
11
The Building Blocks of
Earth and Life
The basic units of matter are called “elements”,
which can’t be subdivided chemically into
smaller units. Elements make up molecules
and compounds. It is important to understand
basic chemistry in order to understand the
critical role of chemistry in Environmental
Science.
12
Atoms, Molecules, and
Compounds
• Most material substances can exist in three
interchangeable states: solid, liquid, or gas.
• Element - substance that cannot be broken down
into simpler substances by ordinary chemical
reactions
• Atom - the smallest particle that exhibits the
characteristics of an element
• Molecule - a combination of two or more atoms
• Compound - a molecule made up of two or more
kinds of atoms held together by chemical bonds
13
Fig. 2.3
14
Periodic Table of the Elements
15
16
Chemical Bonding
• Ionic Bond - Formed when one atom gives
up an electron to another atom.
• Covalent Bond - Formed when two or more
atoms share electrons.
– Energy is needed to break chemical bonds.
– Energy is released when bonds are formed.
17
Fig. 2.4
18
Acids and Bases
• Acids are compounds that readily release
hydrogen ions (H+) in water.
• Bases are substances that readily take up
hydrogen ions (H+) and release hydroxide
ions (OH-) in solution.
• Strength measured by concentration of H+.
– pH scale
• 0-14
19
Fig. 2.5
20
Water Molecule
21
Water: A Unique Compound
•
•
•
•
•
•
•
•
Sixty to 70 percent of the weight of living organisms
Medium in which all of life's chemical reactions occur
Good electrical conductor
Highest surface tension of any common, natural liquid
Liquid over a wide temperature range
Expands when it crystallizes, unlike most substances
High heat of vaporization
High specific heat
22
23
Cells: The Fundamental Units
of Life
• Microscopic organisms, such as bacteria and
protozoa, are composed of single cells.
• The human body contains several trillion cells of
about two hundred distinct types.
• Enzymes – catalysts that speed up the rate of
chemical reactions in living systems
• Metabolism - all the energy and matter exchanges
that occur within a living cell or organism
24
The Electromagnetic
Spectrum
The wavelengths of visible
light drive photosynthesis.
25
Photosynthesis
26
Light and Dark
Reactions of
Photosynthesis
27
Energy Exchange in an Ecosystem
28
Energy & Matter in the Environment
•
•
•
•
•
•
Organism (species)
Population
Biological
Community
Ecosystem
Biosphere
29
Food Web: Cross-connected Food Chains
30
31
Energy Pyramid
ADD FIG. 2.18
Most energy in most ecosystems is stored in the bodies of
primary producers. Only about 10 percent of the energy
at one energy level passes to the next highest trophic level.
32
The Water Cycle
ADD FIG. 2.19
33
The Carbon Cycle
ADD FIG. 2.20
34
The Nitrogen Cycle
ADD FIG. 2.21
35
Nitrogen
Fixation
The nodules on the roots
of this plant contain
bacteria that help convert
nitrogen in the soil to a
form the plant can utilize.
36
The Phosphorous Cycle
ADD FIG. 2.23
37
The Sulfur Cycle
ADD FIG. 2.24
38