Chapter 2

1. Chapter 2 Science Review

2. Bell Work • A hectare (ha) is a land measurement equal to 10,000 square meters. 1 acre=.40 ha • A web search of environmental organizations yielded a range of estimates of the amount of forest clearing that is occurring worldwide: • Estimate 1: 1 acre per second • Estimate 2: 80,000 acres per day • Estimate 32,000 ha per day • How can we convert these figures so that we can compare them?

3. Objectives • Explain the fundamentals of Environmental Chemistry and apply them to real world situations • Differentiate between the types of energy and explain energy flow

4. Explain the fundamentals of Environmental Chemistry and apply them to real world situations • Understanding Chemistry provides a powerful tool for understanding environmental science and developing solutions to environmental problems • Atoms can form molecules and compounds, and changes at the atomic level can result in alternate forms of elements, such as ions and isotopes • Water facilitates the chemistry of life • Living things depend on organic compounds, which are carbon-based

5. Reasons to understand Chemistry for APES • Chemistry is crucial for understanding • How gases contribute to global climate change • How pollutants cause acid rain • The effects on health of wildlife and people • Water pollution • Wastewater treatment • Atmospheric ozone depletion • Energy Issues • Etc

6. pH and Solutions

7. What is pH? • pH stands for “Potential/Power of Hydrogen” • The negative logarithm of the concentration of hydrogen ions in a solution • A high number = a very small concentration of H+ ions in solution • A low number = a very high concentration of H+ ions in solution • Logarithmic scale = each number on the scale represents 10x more or less H+

8. Elements Important to the Study of Environmental Science

9. Ions Important to the Study of Environmental Science

10. Matter is conserved • Law of conservation of matter • Matter can be transformed from one type of substance into others, but it can neither be created nor destroyed • Because the amount of matter stays constant • It is recycled in nutrient cycles and ecosystems • We need to consider the results of our actions, especially in terms of pollution

11. Energy & Matter • Fixed amounts of each in the universe • Can be converted interchangeably (e = mc2) • Earth is an “open system” regarding energy • Earth is a “closed system” regarding matter • Energy & Mass Laws • 1: Energy/Matter cannot be created or destroyed • 2: Energy is always converted to “lower quality” forms whenever work is done

12. Atomic Structure • The nucleus is tiny and very dense • The volume is almost entirely the electron cloud

13. Isotopes • Atoms with the same number of protons, but different numbers of neutrons. • Atoms of the same element (same atomic number) with different mass numbers • Isotopes of chlorine • 35Cl 37Cl • 1717 • chlorine - 35 chlorine - 37 LecturePLUS Timberlake

14. Types of Isotopes • Stable: the nucleus contains enough neutrons to block the repulsive forces of the protons. This keeps the isotope from breaking down over time. • 2. Unstable: the nucleus of the atom does not have right amount of neutrons to block the repulsive forces of the protons; this makes the isotope radioactive!

15. Radioactive Isotopes Radioactive isotopes have unstable nuclei and undergo nuclear decay (breakdown) 2. Nuclear decay involves the emission of energy and/or particles from the nucleus in an attempt to become more stable. The energy/particles emitted from the nucleus are termed radiation and can be alpha or beta particles and gamma rays. Isotopes disintegrate at predictable rates

16. RadioactiveIsotopes Radioactive elements are unstable. They decay, and change into different elements over time. Not all elements are radioactive. Those that are listed below are the most useful for geologic dating of fossils are: U-238 Half-life = 4.5 Billion Years K-40 Half-life = 1.25 Billion Years C-14 Half-life = 5, 730 Years

17. Radioactive Decay and Half Life The half-life of an element is the time it takes for half of the material you started with to decay. Each element has it’s own half-life Each element decays into a new element C14 decays into N14 while U238 decays into Pb206 (lead), etc. The half-life of each element is constant. It’s like a clock keeping perfect time.

18. Nuclear Chemistry Review • Three types of radiation • Alpha (He nucleus) • Beta (electrons) • Gamma (EMR wave) • Differences in penetration • Alpha (sheet of paper) • Beta (block of wood) • Gamma (concrete wall)

19. Fission 1 nucleus splits into fragments (chain reaction) Ex. Nuclear reactor Fusion 2 or more nuclei fuse together Ex. The Sun Fission and Fusion

20. First Law Energy cannot be created or destroyed, only transformed or converted between different forms Ex. Solar energy to chemical energy during Photosynthesis During work, energy “in” ALWAYS equals energy “out” “You cannot get something for nothing” Second Law During work, some energy is degraded into lower quality forms High Quality (ex. Electricity, Nuclear Fission) Medium Quality (ex. Normal sunlight) Low Quality (ex. Geothermal heat) You always end up with less useable energy than you start with “You cannot break even” Energy Laws

21. The Second Law of Thermodynamics in Living Systems

22. Electromagnetic Spectrum

23. Environmental “Science” • Some areas of ES research are experimental and lab-based • Most research is field-based, involving the study of highly complex FEEDBACK LOOPS • ES research is characterized by • A focus on CONNECTIONS & INTERACTIONS • LONG time periods • SYNERGISTIC connections

25. Types of Pollution • Degradable • Ex. Human sewage, organic matter • Persistent • Ex. DDT, certain plastics, laminates • Non-degradable • Ex. heavy metals, lead & mercury

26. Through-Put Economies • High Through-Put Economy • High consumption of both matter and energy • Matter Recycling Economy • Reduced matter consumption • Still very high energy consumption • Low Through-Put Economy • Reduced matter and energy consumption • Is this possible to achieve?

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

28. Problem Question to be answered Hypothesis Scientifically testable statement Independent or Manipulated Variable The one(s) being tested or changed Dependent or Responding Variable The one(s) being measured Control Group No M.V. (for comparison) Constants All other variables influencing the outcome Experimental Design

29. Precision vs. Accuracy • Accuracy • The nearness of a measurement to an agreed standard (ex. how close to 1kg is a 1kg standard weight on a particular balance?) • Precision • The degree of reproducibility and consistency of a measuring device throughout multiple measurements

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

31. 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)

32. 60 40 Nitrate (NO3– ) concentration (milligrams per liter) Undisturbed (control) watershed Disturbed (experimental) watershed 20 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 Year Fig. 2-4, p. 37