Chapter 2

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

2. Video: Easter Island • By what name did the early settlers refer to Easter Island? • Which individuals are believed to be the first inhabitants of Easter Island? • In 1722, which Dutch Admiral landed on Easter Island? • What is believed to be the cause of the fall of the civilization and population of Easter Island? • What is the name of the giant statues on Easter Island? PLAY VIDEO • From ABC News, Environmental Science in the Headlines, 2005 DVD.

3. Core Case Study: Environmental Lesson from Easter Island • Thriving society • 15,000 people by 1400. • Used resources faster than could be renewed • By 1600 only a few trees remained. • Civilization collapsed • By 1722 only several hundred people left. Figure 2-1

4. THE NATURE OF SCIENCE • What do scientists do? • Collect data. • Form hypotheses. • Develop theories, models and laws about how nature works. Figure 2-2

5. Ask a question Do experiments and collect data Interpret data Well-tested and accepted patterns In data become scientific laws Formulate hypothesis to explain data Do more experiments to test hypothesis Revise hypothesis if necessary Well-tested and accepted hypotheses become scientific theories Stepped Art Fig. 2-3, p. 30

6. Scientific Theories and Laws: The Most Important Results of Science • Scientific Theory • Widely tested and accepted hypothesis. • Scientific Law • What we find happening over and over again in nature. Figure 2-3

7. Testing Hypotheses • Scientists test hypotheses using controlled experiments and constructing mathematical models. • Variables or factors • influence natural processes • Single-variable experiments involve a control and an experimental group. • Most environmental phenomena are multivariable and are hard to control in an experiment. • Models are used to analyze interactions of variables.

8. Scientific Reasoning and Creativity • Inductive reasoning • Involves using specific observations and measurements to arrive at a general conclusion or hypothesis. • Bottom-up reasoning going from specific to general. • Deductive reasoning • Uses logic to arrive at a specific conclusion. • Top-down approach that goes from general to specific.

9. Frontier Science, Sound Science, and Junk Science • Frontier science • has not been widely tested (starting point of peer-review). • Sound science • consists of data, theories and laws that are widely accepted by experts. • Junk science • presented as sound science without going through the rigors of peer-review.

10. Limitations of Environmental Science • Inadequate data and scientific understanding can limit and make some results controversial. • Scientific testing is based on disproving rather than proving a hypothesis. • Based on statistical probabilities.

11. Does the fact that science can never prove anything absolutely mean that it is not valid or useful? • Yes • No

12. 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”. • Models can be used to predict if-then scenarios.

13. Feedback Loops: How Systems Respond to Change • 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. erosion • Negative (corrective) feedback loop • causes a system to change in the opposite direction • e.g. seeking shade from sun to reduce stress

14. Feedback Loops: • Negative feedback can take so long that a system reaches a threshold and changes. • Prolonged delays may prevent a negative feedback loop from occurring. • Processes and feedbacks in a system can (synergistically) interact to amplify the results. • E.g. smoking exacerbates the effect of asbestos exposure on lung cancer.

15. TYPES AND STRUCTURE OF MATTER • Elements and Compounds • Elements • represented on the periodic table • distinctive building blocks of matter • Can be found in atomic or molecular forms • Compounds • two or more different elements held together in fixed proportions by chemical bonds

16. Atoms Figure 2-4

17. Ions • Ion • atom or group of atoms with one or more net positive or negative electrical charges • Cations (+) • Anions (-) • Hydrogen ions (H+), Hydroxide ions (OH-) • Sodium ions (Na+), Chloride ions (Cl-)

18. The pH (potential of Hydrogen) is the concentration of hydrogen ions in one liter of solution. Figure 2-5

19. Organic Compounds: Carbon Rules • Organic compounds • Must contain carbon and hydrogen • May also contain oxygen, nitrogen, phosphorus, sulphur, chlorine • Most contain at least 2 carbon atoms • Methane (CH4) is the only exception • All other compounds are inorganic.

20. Organic Compounds: Carbon Rules • Hydrocarbons: • compounds of carbon and hydrogen atoms • e.g. methane (CH4) • Chlorinated hydrocarbons: • compounds of carbon, hydrogen, and chlorine atoms • e.g. DDT (C14H9Cl5) • Simple carbohydrates: • certain types of compounds of carbon, hydrogen, and oxygen • Usually in a 1:2:1 ratio • e.g. glucose (C6H12O6)

21. Cells: The Fundamental Units of Life • Cells • basic structural and functional units of all forms of life. • Prokaryotic cells • bacteria • lack a distinct nucleus and membrane bound organelles • Eukaryotic cells • Fungi, plants and animals • distinct nucleus and organelles Figure 2-6

22. (a) Prokaryotic Cell DNA(information storage, no nucleus) Cell membrane (transport of raw materials and finished products) Protein construction and energy conversion occur without specialized internal structures Fig. 2-6a, p. 37

23. (b) Eukaryotic Cell Nucleus (information storage) Energy conversion Protein construction Cell membrane (transport of raw materials and finished products) Packaging Fig. 2-6b, p. 37

24. Animation: Prokaryotic and Eukaryotic Cells

25. Macromolecules, DNA, Genes and Chromosomes • complex organic molecules (macromolecules) make up the basic molecular units found in living organisms • Complex carbohydrates • Ex. starch, glycogen, cellulose, chitin • Proteins • Ex. hemoglobin, pepsin • Nucleic acids • Ex. DNA, RNA • Lipids • Ex. fats, oils, waxes, pigments Figure 2-7

26. A human body contains trillions of cells, each with an identical set of genes. There is a nucleus inside each human cell (except red blood cells). 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. Genes are segments of DNA on chromosomes that contain instructions to make proteins—the building blocks of life. The genes in each cell are coded by sequences of nucleotides in their DNA molecules. Stepped Art Fig. 2-7, p. 38

27. States of Matter • Physical states • Solid • Liquid • Gaseous • Plasma • a high energy mixture of positively charged ions and negatively charged electrons • The sun and stars consist mostly of plasma. • Scientists have made artificial plasma (used in TV screens, gas discharge lasers, florescent light).

28. Matter Quality • Matter can be classified as having high or low quality depending on how useful it is to us as a resource. • High quality matter • Concentrated • easily extracted • low quality matter • more widely dispersed • more difficult to extract Figure 2-8

29. High Quality Low Quality Solid Gas Solution of salt in water Salt Coal Coal-fired power plant emissions Gasoline Automobile emissions Aluminum can Aluminum ore Fig. 2-8, p. 39

30. CHANGES IN MATTER • Physical change • maintains original chemical composition. • Chemical change • involves a chemical reaction which changes the arrangement of the elements or compounds involved • Often oxidation or explosive • When a physical or chemical change occurs, no atoms are created or destroyed. • Law of conservation of matter.

31. Reactant(s) Product(s) energy carbon dioxide carbon + oxygen + energy + O2 C CO2 + energy + + black solid colorless gas colorless gas p. 39

32. Types of Pollutants • Factors that determine the severity of a pollutant’s effects: chemical nature, concentration, and persistence. • Pollutants are classified based on their persistence: • Degradable pollutants • Biodegradable pollutants • Slowly degradable pollutants • Nondegradable pollutants

33. Nuclear Changes: Radioactive Decay • Natural radioactive decay: • unstable isotopes spontaneously emit: • fast moving chunks of matter (alphaorbeta particles) • high-energy radiation (gamma rays) • or both at a fixed rate • Radiation is commonly used in energy production and medical applications • The rate of decay is expressed as a half-life (the time needed for one-half of the nuclei to decay to form a different isotope)

35. Nuclear Changes: Fission • Nuclear fission: nuclei of certain isotopes with large mass numbers are split apart into lighter nuclei when struck by neutrons Figure 2-9

36. Nuclear Changes: Fusion • Nuclear fusion: • two isotopes of light elements are forced together at extremely high temperatures until they fuse to form a heavier nucleus Figure 2-10

37. Video: Nuclear Energy • What type of cancer is linked with exposure to radiation? • How many deaths resulted from the Three Mile Island accident in 1979? • What percentage of the total energy used in the US does nuclear energy represent? What percentage does nuclear energy represent in France? • How many nuclear reactors does China plan on building over the next two decades? • Discuss some ideas or ways to protect the public from further exposure to radiation from nuclear fallout. PLAY VIDEO • From ABC News, Environmental Science in the Headlines, 2005 DVD.

38. 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 • batteries, glucose molecules

39. Sun Ionizing radiation Nonionizing radiation Near infrared waves Far infrared waves Near ultra- violet waves Far ultra- violet waves Cosmic rays Gamma Rays Visible Waves TV waves Radio Waves X rays Micro- waves High energy, short Wavelength Wavelength in meters (not to scale) Low energy, long Wavelength Fig. 2-11, p. 43

40. Electromagnetic Spectrum • Organisms vary in their ability to sense different parts of the spectrum. Figure 2-12

41. Relative Energy Quality (usefulness) Source of Energy Energy Tasks Electricity Very high temperature heat (greater than 2,500°C) Nuclear fission (uranium) Nuclear fusion (deuterium) Concentrated sunlight High-velocity wind Very high-temperature heat (greater than 2,500°C) for industrial processes and producing electricity to run electrical devices (lights, motors) High-temperature heat (1,000–2,500°C) Hydrogen gas Natural gas Gasoline Coal Food Mechanical motion to move vehicles and other things) High-temperature heat (1,000–2,500°C) for industrial processes and producing electricity Normal sunlight Moderate-velocity wind High-velocity water flow Concentrated geothermal energy Moderate-temperature heat (100–1,000°C) Wood and crop wastes Moderate-temperature heat (100–1,000°C) for industrial processes, cooking, producing steam, electricity, and hot water Dispersed geothermal energy Low-temperature heat (100°C or lower) Low-temperature heat (100°C or less) for space heating Fig. 2-13, p. 44

42. ENERGY LAWS: TWO RULES WE CANNOT BREAK • 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. • Energy is often lost in the form of heat • Energy efficiency is a measure of how much useful work is accomplished before it changes to its next form.

43. Mechanicalenergy(moving,thinking,living) Chemical energy (photosynthesis) Chemical energy (food) Solar energy Waste Heat Waste Heat Waste Heat Waste Heat Fig. 2-14, p. 45

44. SUSTAINABILITY AND MATTER AND ENERGY LAWS • Unsustainable High-Throughput Economies: Working in Straight Lines • Converts resources to goods in a manner that promotes waste and pollution. Figure 2-15

45. Sustainable Low-Throughput Economies: Learning from Nature • Matter-Recycling-and-Reuse Economies: Working in Circles • Mimics nature by recycling and reusing, thus reducing pollutants and waste. • It is not sustainable for growing populations.

46. Inputs (from environment) System Throughputs Outputs (into environment) Energy conservation Low-quality Energy (heat) Energy Sustainable low-waste economy Waste and pollution Waste and pollution Pollution control Matter Recycle and reuse Matter Feedback Energy Feedback Fig. 2-16, p. 47