1. Science, Matter, Energy, and Systems
Chapter 2

2. Core Case Study: Carrying Out a Controlled Scientific Experiment
F. Herbert Bormann, Gene Likens, et al.: Hubbard Brook Experimental Forest in NH (U.S.)
Compared the loss of water and nutrients from an uncut forest (control site) with one that had been stripped (experimental site)

3. The Effects of Deforestation on the Loss of Water and Soil Nutrients

4. Figure 2.1
Controlled field experiment to measure the effects of deforestation on the loss of water and soil nutrients from a forest. V–notched dams were built into the impenetrable bedrock at the bottoms of several forested valleys (left) so that all water and nutrients flowing from each valley could be collected and measured for volume and mineral content. These measurements were recorded for the forested valley (left), which acted as the control site. Then all the trees in another valley (the experimental site) were cut (right) and the flows of water and soil nutrients from this experimental valley were measured for 3 years.
Stepped Art
Fig. 2-1, p. 28

5. 2-1 What Is Science?
Concept 2-1 Scientists collect data and develop theories, models, and laws about how nature works.

6. Science Is a Search for Order in Nature (1)
Identify a problem
Find out what is known about the problem
Ask a question to be investigated
Gather data
Hypothesize
Make testable predictions
Keep testing and making observations
Accept or reject the hypothesis

7. Science Is a Search for Order in Nature (2)
Important features of the scientific process
Curiosity
Skepticism
Peer review
Reproducibility
Openness to new ideas

8. The Scientific Process

9. Identify a problem
Find out what is known
about the problem
(literature search)
Ask a question to be
investigated
Perform an experiment
to answer the question
and collect data
Analyze data
(check for patterns)
Scientific law
Well-accepted
pattern in data
Propose an hypothesis
to explain data
Use hypothesis to make
testable predictions
Figure 2.2
What scientists do. The essence of science is this process for testing ideas about how nature works. Scientists do not necessarily follow the exact order of steps shown here. For example, sometimes a scientist might start by formulating a hypothesis to answer the initial question and then run experiments to test the hypothesis.
Perform an experiment
to test predictions
Accept
hypothesis
Revise
hypothesis
Make testable
predictions
Test
predictions
Scientific theory
Well-tested and
widely accepted
hypothesis
Fig. 2-2, p. 30

10. Science Focus: Easter Island: Revisions to a Popular Environmental Story
Some revisions in a popular environmental story
Polynesians arrived about 800 years ago
Population may have reached 3000
Used trees in an unsustainable manner, but rats may have multiplied and eaten the seeds of the trees

11. Scientists Use Reasoning, Imagination, and Creativity to Learn How Nature Works
Important scientific tools
Inductive reasoning-bottom up
Deductive reasoning-top down
Scientists also use
Intuition
Imagination
Creativity

12. Scientific Theories and Laws Are the Most Important Results of Science
Scientific theory
Widely tested
Supported by extensive evidence
Accepted by most scientists in a particular area
Scientific law, law of nature
Paradigm shift

13. Science Focus: The Scientific Consensus over Global Warming
How much has the earth’s atmosphere warmed during the last 50 years?
How much of this warming is due to human activity?
How much is the atmosphere likely to warm in the future?
Will this affect climate?
1988: Intergovernmental Panel on Climate Change (IPCC)

14. The Results of Science Can Be Tentative, Reliable, or Unreliable
Tentative science, frontier science
Reliable science
Unreliable science

15. Environmental Science Has Some Limitations
Particular hypotheses, theories, or laws have a high probability of being true while not being absolute
Bias can be minimized by scientists
Statistical methods may be used to estimate very large or very small numbers
Environmental phenomena involve interacting variables and complex interactions
Scientific process is limited to the natural world

16. Science Focus: Statistics and Probability
Collect, organize, and interpret numerical data
Probability
The chance that something will happen or be valid

17. Animation: pH scale

18. Video: ABC News: Easter Island

19. 2-2 What Is Matter?
Concept 2-2 Matter consists of elements and compounds, which are in turn made up of atoms, ions, or molecules.

20. Matter Consists of Elements and Compounds
Has mass and takes up space
Elements
Unique properties
Cannot be broken down chemically into other substances
Compounds
Two or more different elements bonded together in fixed proportions

21. Elements Important to the Study of Environmental Science

22. Atoms, Ions, and Molecules Are the Building Blocks of Matter (1)
Atomic theory
Subatomic particles
Protons (p) with positive charge and neutrons (0) with no charge in nucleus
Negatively charged electrons (e) orbit the nucleus
Mass number
Protons plus neutrons
Isotopes-different mass numbers

23. Atoms, Ions, and Molecules Are the Building Blocks of Matter (2)
Gain or lose electrons
Form ionic compounds pH
Measure of acidity
H+ and OH-

24. Atoms, Ions, and Molecules Are the Building Blocks of Matter (3)
Two or more atoms of the same or different elements held together by chemical bonds
Chemical formula

25. Model of a Carbon-12 Atom

26. 6 protons 6 neutrons 6 electrons Figure 2.3
Greatly simplified model of a carbon-12 atom. It consists of a nucleus containing six positively charge protons and six neutral neutrons. There are six negatively charged electrons found outside its nucleus. We cannot determine the exact locations of the electrons. Instead, we can estimate the probability that they will be found at various locations outside the nucleus—sometimes called an electron probability cloud. This is somewhat like saying that there are six airplanes flying around inside a cloud. We don’t know their exact location, but the cloud represents an area where we can probably find them.
Fig. 2-3, p. 36

27. Ions Important to the Study of Environmental Science

28. Loss of NO3− from a Deforested Watershed

29. Nitrate (NO3– ) concentration (milligrams per liter)60 40
Nitrate (NO3– ) concentration
(milligrams per liter)
Undisturbed
(control)
watershed
Disturbed
(experimental)
watershed 20
Figure 2.4
Loss of nitrate ions (NO3−) from a deforested watershed in the Hubbard Brook Experimental Forest in New Hampshire (Figure 2-1, right). The average concentration of nitrate ions in runoff from the deforested experimental watershed was 60 times greater than in a nearby unlogged watershed used as a control (Figure 2-1, left). (Data from F. H. Bormann and Gene Likens)
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
Year
Fig. 2-4, p. 37

30. Compounds Important to the Study of Environmental Science

31. Organic Compounds Are the Chemicals of Life
Inorganic compounds
Organic compounds
Hydrocarbons and chlorinated hydrocarbons
Simple carbohydrates
Macromolecules: complex organic molecules
Complex carbohydrates
Proteins
Nucleic acids
Lipids

32. Matter Comes to Life through Genes, Chromosomes, and Cells
Cells: fundamental units of life
Genes: sequences of nucleotides within the DNA
Chromosomes: composed of many genes

33. Cells, Nuclei, Chromosomes, DNA, and Genes

34. A human body contains trillions of cells, each with an identical set
of genes.
Each human cell (except for red
blood cells) contains a nucleus.
Each cell nucleus has an identical set
of chromosomes, which are found in
pairs.
A specific pair of chromosomes
contains one chromosome from each
parent.
Figure 2.5
Relationships among cells, nuclei, chromosomes, DNA, and genes.
Each chromosome contains a long
DNA molecule in the form of a coiled
double helix.
Genes are segments of DNA on
chromosomes that contain instructions
to make proteins—the building blocks
of life.
Fig. 2-5, p. 38

35. A human body contains trillions of cells, each with an identical set
of genes.
Each human cell (except for red
blood cells) contains a nucleus.
Each cell nucleus has an identical set
of chromosomes, which are found in
pairs.
A specific pair of chromosomes
contains one chromosome from each
parent.
Each chromosome contains a long
DNA molecule in the form of a coiled
double helix.
Figure 2.5
Relationships among cells, nuclei, chromosomes, DNA, and genes.
Genes are segments of DNA on
chromosomes that contain instructions
to make proteins—the building blocks
of life.
Stepped Art
Fig. 2-5, p. 38

36. Matter Occurs in Various Physical Forms
Solid
Liquid
Gas

37. Some Forms of Matter Are More Useful than Others
High-quality matter
Low-quality matter

38. Examples of Differences in Matter Quality

39. Coal-fired power plant emissions
High Quality
Low Quality
Solid
Gas
Salt
Solution of salt in water
Coal
Coal-fired power
plant emissions
Figure 2.6
Examples of differences in matter quality. High-quality matter (left column) is fairly easy to extract and is highly concentrated; low-quality matter (right column) is not highly concentrated and is more difficult to extract than high-quality matter.
Gasoline
Automobile emissions
Aluminum can
Aluminum ore
Fig. 2-6, p. 39

40. Animation: Subatomic particles

41. Animation: Carbon bonds

42. Animation: Ionic bonds

43. Animation: Atomic number, mass number

44. Some Important Chemical Reactions in Environmental Science
6 CO H2O + sunlight = C6H12O O2
Photosynthesis
Producers, autotrophs
C6H12O O2 = 6 CO H2O + energy
Aerobic respiration

45. Nitrogen Reactions in Soil
N2 + 8 H+ -> 2 NH3 (Ammonia) + H2
Nitrogen Fixation
2 NH3 + 3 O2 → 2 NO H2O + 2 H+
2 NO O2 → 2 NO3-
Nitrification
SO2 + H2O + ½O2 = H2SO4
Formation of Sulfuric Acid in Atmosphere

46. 2-3 How Can Matter Change?
Concept 2-3 When matter undergoes a physical or chemical change, no atoms are created or destroyed (the law of conservation of matter).

47. Matter Undergoes Physical, Chemical, and Nuclear Changes
Physical change
Chemical change, chemical reaction
Nuclear change
Natural radioactive decay
Radioisotopes: unstable
Nuclear fission
Nuclear fusion

48. Types of Nuclear Changes

49. Figure 2.7
Types of nuclear changes: natural radioactive decay (top), nuclear fission (middle), and nuclear fusion (bottom).
Fig. 2-7a, p. 41

50. Radioactive decay Alpha particle (helium-4 nucleus)
Radioactive isotope
Gamma rays
Figure 2.7
Types of nuclear changes: natural radioactive decay (top), nuclear fission (middle), and nuclear fusion (bottom).
Beta particle (electron)
Fig. 2-7a, p. 41

51. Figure 2.7
Types of nuclear changes: natural radioactive decay (top), nuclear fission (middle), and nuclear fusion (bottom).
Fig. 2-7b, p. 41

52. Nuclear fission Uranium-235 Fission fragment Energy n n Neutron n n
Figure 2.7
Types of nuclear changes: natural radioactive decay (top), nuclear fission (middle), and nuclear fusion (bottom).
Energy
Fig. 2-7b, p. 41

53. Figure 2.7
Types of nuclear changes: natural radioactive decay (top), nuclear fission (middle), and nuclear fusion (bottom).
Fig. 2-7c, p. 41

54. Nuclear fusion Reaction conditions Fuel Products Proton Neutron
Helium-4 nucleus
Hydrogen-2
(deuterium nucleus)
100
million °C
Energy
Figure 2.7
Types of nuclear changes: natural radioactive decay (top), nuclear fission (middle), and nuclear fusion (bottom).
Hydrogen-3
(tritium nucleus)
Neutron
Fig. 2-7c, p. 41

55. Beta particle (electron) Radioactive decay
Radioactive isotope
Alpha particle
(helium-4 nucleus)
Gamma rays
Nuclear fission
Uranium-235
Energy
Fission
fragment
Neutron n
Nuclear fusion
Fuel
Proton
Neutron
Hydrogen-2
(deuterium nucleus)
Hydrogen-3
(tritium nucleus)
Reaction
conditions
100
million °C
Products
Helium-4 nucleus
Energy
Figure 2.7
Types of nuclear changes: natural radioactive decay (top), nuclear fission (middle), and nuclear fusion (bottom).
Stepped Art
Fig. 2-7, p. 41

56. We Cannot Create or Destroy Matter
Law of conservation of matter
Matter consumption
Matter is converted from one form to another

57. Animation: Total energy remains constant

58. Animation: Half-life

59. Animation: Isotopes

60. Animation: Positron-emission tomography (PET)

61. Video: Nuclear energy

62. 2-4 What is Energy and How Can It Be Changed?
Concept 2-4A When energy is converted from one form to another in a physical or chemical change, no energy is created or destroyed (first law of thermodynamics).
Concept 2-4B Whenever energy is changed from one form to another, we end up with lower- quality or less usable energy than we started with (second law of thermodynamics).

63. Energy Comes in Many Forms
Kinetic energy
Heat
Transferred by radiation, conduction, or convection
Electromagnetic radiation
Potential energy
Stored energy
Can be changed into kinetic energy

64. The Spectrum of Electromagnetic Radiation

65. Energy emitted from sun (kcal/cm2/min)15 10
Energy emitted from sun (kcal/cm2/min) 5
Visible
Figure 2.8
Solar capital: the spectrum of electromagnetic radiation released by the sun consists mostly of visible light. See an animation based on this figure at CengageNOW.
Infrared
Ultraviolet
0.25 1 2
2.5 3
Wavelength (micrometers)
Fig. 2-8, p. 42

66. The Second Law of Thermodynamics in Living Systems

67. Mechanical energy (moving, thinking, living) Chemical energy
(photosynthesis)
Chemical
energy
(food)
Solar
energy
Waste
heat
Waste
heat
Waste
heat
Waste
heat
Figure 2.9
The second law of thermodynamics in action in living systems. Each time energy changes from one form to another, some of the initial input of high-quality energy is degraded, usually to low-quality heat that is dispersed into the environment. See an animation based on this figure at CengageNOW. Question: What are three things that you did during the past hour that degraded high-quality energy?
Fig. 2-9, p. 43

68. Some Types of Energy Are More Useful Than Others
High-quality energy
Low-quality energy

69. Energy Changes Are Governed by Two Scientific Laws
First Law of Thermodynamics
Energy input always equals energy output
Second Law of Thermodynamics
Energy always goes from a more useful to a less useful form when it changes from one form to another
Energy efficiency or productivity

70. Active Figure: Energy flow

71. Active Figure: Visible light

72. Animation: Martian doing mechanical work

73. 2-5 What Are Systems and How Do They Respond to Change?
Concept 2-5A Systems have inputs, flows, and outputs of matter and energy, and their behavior can be affected by feedback.
Concept 2-5B Life, human systems, and the earth’s life support systems must conform to the law of conservation of matter and the two laws of thermodynamics.

74. Systems Have Inputs, Flows, and Outputs
Inputs from the environment
Flows, throughputs
Outputs

75. Inputs, Throughput, and Outputs of an Economic System

76. Energy Inputs Throughputs Outputs Energy resources Heat Matter
Waste and
pollution
Economy
Figure 2.10
Inputs, throughput, and outputs of an economic system. Such systems depend on inputs of matter and energy resources and outputs of waste and heat to the environment. Such a system can become unsustainable if the throughput of matter and energy resources exceeds the ability of the earth’s natural capital to provide the required resource inputs or the ability of the environment to assimilate or dilute the resulting heat, pollution, and environmental degradation.
Goods and
services
Information
Fig. 2-10, p. 44

77. Systems Respond to Change through Feedback Loops
Positive feedback loop
Negative, or corrective, feedback loop

78. Positive Feedback Loop

79. Decreasing vegetation...
...which causes
more vegetation
to die.
...leads to
erosion and
nutrient loss...
Figure 2.11
Positive feedback loop. Decreasing vegetation in a valley causes increasing erosion and nutrient losses, which in turn causes more vegetation to die, which allows for more erosion and nutrient losses. The system receives feedback that continues the process of deforestation.
Fig. 2-11, p. 45

80. Negative Feedback Loop

81. Temperature reaches desired setting and furnace goes off
House warms
Temperature reaches desired setting
and furnace goes off
Furnace on
Figure 2.12
Negative feedback loop. When a house being heated by a furnace gets to a certain temperature, its thermostat is set to turn off the furnace, and the house begins to cool instead of continuing to get warmer. When the house temperature drops below the set point, this information is fed back, and the furnace is turned on and runs until the desired temperature is reached. The system receives feedback that reverses the process of heating or cooling.
House cools
Temperature drops below desired setting
and furnace goes on
Fig. 2-12, p. 45

82. Time Delays Can Allow a System to Reach a Tipping Point
Time delays vary
Between the input of a feedback stimulus and the response to it
Tipping point, threshold level
Causes a shift in the behavior of a system

83. System Effects Can Be Amplified through Synergy
Synergistic interaction, synergy
Helpful
Harmful
E.g., Smoking and inhaling asbestos particles

84. Human Activities Can Have Unintended Harmful Results
Deforested areas turning to desert
Coral reefs dying
Glaciers melting
Sea levels rising

85. Animation: Economic types

86. Animation: Feedback control of temperature