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This lecture will help you understand: Environmental chemistry Building blocks of life Energy and energy flow Photosynthesis, respiration, chemosynthesis.

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Presentation on theme: "This lecture will help you understand: Environmental chemistry Building blocks of life Energy and energy flow Photosynthesis, respiration, chemosynthesis."— Presentation transcript:

1 This lecture will help you understand: Environmental chemistry Building blocks of life Energy and energy flow Photosynthesis, respiration, chemosynthesis Origin of life on Earth Early life

2 Central Case: Bioremediation of the Exxon Valdez Oil Spill The 1989 Alaskan spill was met with a massive cleanup. Scientists sprayed nitrogen and phosphorus on beaches to fertilize bacteria that could consume the oil. Results were mixed, but bioremediation was here to stay.

3 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Chemistry and the environment Chemistry is central to environmental science: Carbon dioxide and climate change Sulfur dioxide and acid rain Pesticides and public health Nitrogen and wastewater treatment Ozone and its atmospheric depletion

4 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Bioremediation One application of chemistry is in bioremediation, the use of plants or animals to clean up pollution. From The Science behind the Stories Rice University student Marc Burrell has researched how to get plants to take up toxic lead from contaminated soil.

5 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Atoms and elements An element is a fundamental type of chemical substance. Elements are composed of atoms. Each atom has a certain number of: protons (+ charge) electrons (– charge) neutrons (no charge)

6 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Atoms and elements 92 elements occur in nature, each with its characteristic number of protons, neutrons, and electrons.

7 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Chemical symbols Each element is abbreviated with a chemical symbol: H = hydrogen C = carbon N = nitrogen O = oxygen P = phosphorus Cl = chlorine Fe = iron

8 Most abundant elements

9 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Isotopes Isotopes are alternate versions of elements, which differ in mass by having a different number of neutrons. Carbon-14 has two extra neutrons beyond normal carbon’s 6.

10 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Using isotopes in environmental science Scientists have used isotopes to date ancient materials, reconstruct past climate, study the diet of animals, examine lifestyles of prehistoric humans, and track migrating birds and butterflies. From The Science behind the Stories

11 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Molecules, compounds, and bonds Ions = electrically charged atoms or combinations of atoms Molecules = combinations of two or more atoms Compounds = molecules consisting of multiple elements Atoms are held together by bonds: covalent bond = uncharged atoms sharing electrons (CO 2 ) ionic bond = charged atoms held together by electrical attraction (NaCl)

12 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Water is a unique compound Hydrogen bonds give water properties that make it a vital molecule for life: Is cohesive Resists temperature change Ice insulates Dissolves many chemicals

13 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Why ice floats on water Stable hydrogen bonds in ice make it less dense than water, with its unstable hydrogen bonds. ice water This allows ice to cover water bodies and protect them from freezing — a good thing for life in the water.

14 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Water, the “universal solvent” Water dissolves many chemicals. Salt (NaCl) in seawater is broken up into sodium (Na + ) and chloride (Cl – ) ions.

15 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Acidity In an aqueous solution, If H + concentration is greater than OH – concentration, then solution is acidic. If OH – is greater than H +, then solution is basic.

16 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings pH scale pH scale measures acidity and basicity. Pure water = 7 Acids < 7 Bases > 7

17 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Organic compounds Consist of carbon atoms and, generally, hydrogen atoms Joined by covalent bonds May include other elements Highly diverse; C can form many elaborate molecules Vitally important to life

18 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hydrocarbons C and H only; major type of organic compound Mixtures of hydrocarbons make up fossil fuels.

19 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Macromolecules Large molecules essential for life: Proteins Nucleic acids Carbohydrates Lipids The first three are polymers, long chains of repeated molecules.

20 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Proteins Consist of chains of amino acids; fold into complex shapes For structure, energy, immune system, hormones, enzymes

21 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Carbohydrates Complex carbohydrates consist of chains of sugars. For energy, also structural (cellulose, chitin)

22 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Lipids Do not dissolve in water Fats and oils Phospholipids Waxes Steroids

23 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Nucleic acids DNA and RNA Encode genetic information and pass it on from generation to generation DNA = double-stranded chain (double helix) RNA = single-stranded chain

24 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Nucleic acids Paired strands of nucleotides make up DNA’s double helix.

25 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Genes and heredity Genes, functional stretches of DNA, code for the synthesis of proteins.

26 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cells Basic unit of organismal organization; compartmentalize macromolecules and organelles

27 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Energy Can change position, physical composition, or temperature of matter Potential energy = energy of position (water held behind a dam) Kinetic energy = energy of movement (rushing water released from a dam)

28 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Potential and kinetic energy Potential energy stored in food is converted to kinetic energy when we exercise.

29 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Laws of thermodynamics First Law: Energy can change form, but cannot be created or lost. Second Law: Energy will tend to progress from a more- ordered state to a less-ordered state (increase in entropy).

30 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Increase in entropy Burning firewood demonstrates the second law of thermodynamics.

31 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Energy from the sun Energy from the sun powers most living systems. Visible light is only part of the sun’s electromagnetic radiation.

32 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Autotrophs and photosynthesis The sun’s energy is used by autotrophic organisms, or primary producers (e.g., plants), to manufacture food. Photosynthesis turns light energy from the sun into chemical energy that organisms can use.

33 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Photosynthesis In the presence of chlorophyll and sunlight, Water and carbon dioxide are converted to sugars and oxygen.

34 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Photosynthesis 6 CO H 2 O + energy from sun ————> C 6 H 12 O 6 (sugar) + 6 O H 2 O

35 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Streamlined 6 CO H 2 O + energy from sun ————> C 6 H 12 O 6 (sugar) + 6 O 2

36 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Respiration and heterotrophs Organisms use stored energy via respiration, which splits sugar molecules to release chemical energy. This occurs in autotrophs and in the heterotrophs (animals, fungi, most microbes) that eat them.

37 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Respiration The equation for respiration is the exact opposite of the equation for photosynthesis. C 6 H 12 O 6 (sugar) + 6 O 2 ————> 6 CO H 2 O + chemical energy

38 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Energy sources besides the sun Geothermal energy comes from deep underground; radiation in Earth’s core heats the inside of the planet and rises to the surface (driving plate tectonics, volcanoes, etc.). Gravitational pull of the moon creates tidal energy. Geyser powered by geothermal energy

39 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Chemosynthesis Some organisms and communities live without sunlight and are powered by chemosynthesis. 6 CO H 2 O + chemical energy from H 2 S ————> C 6 H 12 O 6 (sugar) + 6 O 2 + sulfates (H 2 S = hydrogen sulfide)

40 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hydrothermal vent communities Such communities include those at hydrothermal vents deep in the ocean. Recently discovered; bizarre organisms.

41 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Origin of life on Earth Early Earth was a hostile place; life had a challenging start.

42 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Fossil record Fossil = imprint in rock of a dead organism The fossil record teaches us much of what we know of life on the planet over the past 3.5 billion years.

43 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Fossil record The fossil record shows that: Species today are a tiny fraction of all that ever lived. Earlier organisms evolved into later ones. The number of species has increased through time. Episodes of mass extinction have occurred. Eukaryotes are only ~600 million years old.

44 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings History of life By studying present- day organisms or their genes, we can infer relationships among organisms and decipher life’s history. Life’s complete phylogeny is the “tree of life.”

45 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings How did life originate? Several hypotheses are competing: Heterotrophic hypothesis (primordial soup): interactions in early soup of organic chemicals Extraterrestrial hypothesis (seeds from space): microbes from elsewhere arrived on meteorites Chemoautotrophic hypothesis (life from the deep): first life from deep-sea hydrothermal vents

46 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Conclusion: Carbon-based life has flourished on Earth for over 3 billion years. Scientists are trying to understand its origin. Deciphering the origins of life requires understanding energy, energy flow, and chemistry.

47 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Conclusion Energy and chemistry are tied to nearly every important process in environmental science. Chemistry can also be a tool for finding solutions to environmental problems. Knowledge of chemistry is relevant to agriculture, water resource management, energy policy, toxicology, and climate change.

48 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Review Which of the following is a heterotroph? a.Pine tree b.Photosynthetic algae c.Squid d.Hydrogen sulfide

49 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Review The second law of thermodynamics states that…? a.Energy cannot be created or destroyed b.Things tend to move toward a less-ordered state c.Matter tends to remain stable d.Potential and kinetic energy are interchangeable

50 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Review Which of these does the fossil record NOT demonstrate? a.There have been mass extinction episodes. b.Most organisms that ever lived are now extinct. c.Animals originated before plants, and plants before bacteria. d.Numbers of species have increased through time.

51 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Weighing the Issues If there was an oil spill on your campus, would you recommend bioremediation? a.Yes, because it is environmentally most desirable. b.No, because it is less tested than traditional methods. c.It depends. (on what factors…?)

52 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Interpreting Graphs and Data A molecule of the hydrocarbon ethane contains…? a. 2 carbon atoms and 6 hydrogen atoms b. 2 carbon molecules and 6 hydrogen enzymes c. Carbon and hydrogen DNA d. Eight different isotopes

53 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Interpreting Graphs and Data Which is listed from most acidic to most basic? a. Ammonia, baking soda, lemon juice b. Stomach acid, soft soap, HCl c. Acid rain, NaOH, pure water d. HCl, acid rain, ammonia

54 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings QUESTION: Viewpoints How do you think life on Earth began? a.With a mix of organic compounds in a primordial soup on Earth’s surface b.With the entrance of microbes from other planets on meteorites falling to Earth c.In deep-sea hydrothermal vents


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