Chapter 2 Science, Systems, Matter, and Energy

Video: Easter Island  From ABC News, Environmental Science in the Headlines, 2005 DVD. PLAY VIDEO 1.By what name did the early settlers refer to Easter Island? 2.Which individuals are believed to be the first inhabitants of Easter Island? 3.In 1722, which Dutch Admiral landed on Easter Island? 4.What is believed to be the cause of the fall of the civilization and population of Easter Island? 5.What is the name of the giant statues on Easter Island?

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

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

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

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

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

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

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

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. Scientific testing is based on disproving rather than proving a hypothesis. Based on statistical probabilities.Based on statistical probabilities.

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

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. 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 are simplifications of “real-life”. Models can be used to predict if-then scenarios. Models can be used to predict if-then scenarios.

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 Positive feedback loop causes a system to change further in the same directioncauses a system to change further in the same direction e.g. erosion e.g. erosion Negative (corrective) feedback loop Negative (corrective) feedback loop causes a system to change in the opposite directioncauses a system to change in the opposite direction e.g. seeking shade from sun to reduce stress e.g. seeking shade from sun to reduce stress

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. 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. E.g. smoking exacerbates the effect of asbestos exposure on lung cancer.

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

Atoms Figure 2-4

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

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

Organic Compounds: Carbon Rules  Organic compounds Must contain carbon and hydrogen Must contain carbon and hydrogen May also contain oxygen, nitrogen, phosphorus, sulphur, chlorine May also contain oxygen, nitrogen, phosphorus, sulphur, chlorine  Most contain at least 2 carbon atoms Methane (CH 4 ) is the only exception Methane (CH 4 ) is the only exception All other compounds are inorganic. All other compounds are inorganic.

Organic Compounds: Carbon Rules  Hydrocarbons: compounds of carbon and hydrogen atoms compounds of carbon and hydrogen atoms e.g. methane (CH 4 )e.g. methane (CH 4 )  Chlorinated hydrocarbons: compounds of carbon, hydrogen, and chlorine atoms compounds of carbon, hydrogen, and chlorine atoms e.g. DDT (C 14 H 9 Cl 5 )e.g. DDT (C 14 H 9 Cl 5 )  Simple carbohydrates: certain types of compounds of carbon, hydrogen, and oxygen certain types of compounds of carbon, hydrogen, and oxygen Usually in a 1:2:1 ratio Usually in a 1:2:1 ratio e.g. glucose (C 6 H 12 O 6 )e.g. glucose (C 6 H 12 O 6 )

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

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

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

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

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

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 High quality matter ConcentratedConcentrated easily extractedeasily extracted low quality matter low quality matter more widely dispersedmore widely dispersed more difficult to extractmore difficult to extract Figure 2-8

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

p. 39 Reactant(s)Product(s) carbon +oxygen carbon dioxide + energy C +O2O2 CO 2 energy + + black solidcolorless gas +

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 Degradable pollutants Biodegradable pollutants Biodegradable pollutants Slowly degradable pollutants Slowly degradable pollutants Nondegradable pollutants Nondegradable pollutants

Nuclear Changes: Radioactive Decay  Natural radioactive decay: unstable isotopes spontaneously emit: unstable isotopes spontaneously emit: fast moving chunks of matter (alpha or beta particles)fast moving chunks of matter (alpha or beta particles) high-energy radiation (gamma rays)high-energy radiation (gamma rays) or both at a fixed rateor both at a fixed rate Radiation is commonly used in energy production and medical applications 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) 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)

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

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 two isotopes of light elements are forced together at extremely high temperatures until they fuse to form a heavier nucleus Figure 2-10

Video: Nuclear Energy  From ABC News, Environmental Science in the Headlines, 2005 DVD. PLAY VIDEO 1.What type of cancer is linked with exposure to radiation? 2.How many deaths resulted from the Three Mile Island accident in 1979? 3.What percentage of the total energy used in the US does nuclear energy represent? What percentage does nuclear energy represent in France? 4.How many nuclear reactors does China plan on building over the next two decades? 5.Discuss some ideas or ways to protect the public from further exposure to radiation from nuclear fallout.

ENERGY  Energy is the ability to do work and transfer heat. Kinetic energy – energy in motion Kinetic energy – energy in motion heat, electromagnetic radiationheat, electromagnetic radiation Potential energy – stored for possible use Potential energy – stored for possible use batteries, glucose moleculesbatteries, glucose molecules

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

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

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

ENERGY LAWS: TWO RULES WE CANNOT BREAK  The first law of thermodynamics: we cannot create or destroy energy we cannot create or destroy energy We can change energy from one form to another.We can change energy from one form to another.  The second law of thermodynamics: energy quality always decreases energy quality always decreases When energy changes from one form to another, it is always degraded to a more dispersed form.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 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.Energy efficiency is a measure of how much useful work is accomplished before it changes to its next form.

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

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. Converts resources to goods in a manner that promotes waste and pollution. Figure 2-15

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. Mimics nature by recycling and reusing, thus reducing pollutants and waste. It is not sustainable for growing populations. It is not sustainable for growing populations.

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