1. Chapter 3 Environmental Systems: Chemistry, Energy, and Ecosystems PowerPoint® Slides prepared by Jay Withgott and Heidi Marcum

2. This lecture will help you understand:
The nature of environmental systems
The fundamentals of environmental chemistry
The molecular building blocks of organisms
Energy and energy flow
Photosynthesis and respiration
Ecosystems and interactions
Fundamentals of landscape ecology
Carbon, phosphorus, nitrogen, and water cycles

3. What is a Dead Zone?

7. Its Not Just Us

9. Central Case: The Gulf of Mexico’s “Dead Zone”
Gulf of Mexico used to bring in 600 million kg/year shrimp, fish, and shellfish
Gulf “dead zone”: a region of water so depleted of oxygen that marine organisms are killed or driven away
In 2000, this zone encompassed 22,000 km2 (8,500 mi2) — an area larger than New Jersey.
Hypoxia: low concentrations of dissolved oxygen water
Caused by fertilizer, runoff, sewage
The U.S. government proposed that farmers reduce fertilizer use.

10. The Earth’s systems
System: a network of relationships among components that interact with and influence one another
Exchange of energy, matter, or information
Receives inputs of energy, matter, or information, processes these inputs, and produces outputs
Feedback loop: a system’s output serves as input to that same system
A circular process

11. Negative feedback loop
Negative feedback loop: output resulting from a system moving in one direction acts as an input that moves the system in the other direction
Input and output neutralize one another
Stabilizes the system
Example: body temperature
Most systems in nature

12. Positive feedback loop
Positive feedback loop: instead of stabilizing a system, it drives it further toward an extreme
Examples: erosion
Rare in nature
But are common in natural systems altered by humans

13. Cntd
Negative Feedback Loop: A change in which the variable being regulated brings about a response that moves the variable in the "opposite direction". for example you are inside and at normal body temperature(variable) then you go outside into the cold and your body temp begins to decrease(unintended event), your body responds by causing events that raise your temperature(intentional change) "back up to its original value"(raising your temp that was falling). this is mostly seen in homeostasis and you dont have to go outside for your body to do this because it is constantly happening all the time. Positive Feedback loop: this type of feedback loop accelerates a process and usually has no obvious means of being slowed or stopped. Think of an avalanche that started as a small snowball rolling down a steep hill. One example is child birth in mammals. A positive feedback loop occurs when a baby's head is pushed against the birth canal. the nerve signals from smooth muscle cells of the birth canal send info to the brain which then triggers a hormone release from the petuitary glands. the hormones then cause those "same smooth muscle cells" in the birth canal to contract with more force, which causes more signals to be sent to the brain and so on until the fetus is delivered

14. Environmental systems interact
Natural systems are divided into categories
Lithosphere: rock and sediment
Atmosphere: the air surrounding the planet
Hydrosphere: all water on earth
Biosphere: the planet’s living organisms
Categorizing systems allows humans to understand earth’s complexity.
Most systems overlap

15. The Gulf of Mexico: a systems perspective
Very high levels of nutrients such as nitrogen and phosphorus from a variety of sources cause the abnormally low levels of oxygen in the Gulf of Mexico.

16. Where it Begins

17. Eutrophication in the Gulf of Mexico
Nutrients (nitrogen and phosphorus) from various Midwestern sources enter the Mississippi River, which causes….
Phytoplankton (microscopic algae and bacteria) to grow, then…
Bacteria eat dead phytoplankton and wastes and deplete oxygen, causing…
Fish and other aquatic organisms to suffocate
Eutrophication: the process of nutrient overenrichment, blooms of algae, increased production of organic matter, and ecosystem degradation

18. Eutrophication

21. Activity Read article Independently and Quietly in class
AFTER everyone in class has completed the reading assignment, you can work in pairs to complete the writing assignment. We will discuss your points tomorrow in class
Look at the different projects I have created for you. You will be responsible for completing one on the due date.

22. Chemistry is crucial for understanding…
Any environmental issue:
How gases contribute to global climate change
How pollutants cause acid rain
The effects of chemicals on the health of wildlife and people
Water pollution
Wastewater treatment
Hazardous waste
Atmospheric ozone depletion
Energy issues

23. Chemical building blocks
Matter: all material in the universe that has mass and occupies space
Can be transformed from one type of substance into others
But it cannot be destroyed or created, which is…
The law of conservation of matter
Helps us understand that the amount of matter stays constant
Recycled in nutrient cycles and ecosystems

24. Chemical building blocks
Element: a fundamental type of matter, with a given set of properties
Chemists recognize 92 elements in nature and 20 artificially created ones.
Elements abundant in nature: carbon, nitrogen, hydrogen and oxygen
Periodic table of the elements summarizes information on the elements

25. Elements are composed of atoms
Atoms: the smallest components that maintain an element’s chemical properties
The atom’s nucleus has protons (positively charged particles) and neutrons (particles lacking electric charge).
Atomic number: the atom’s number of protons
Electrons: negatively charged particles surrounding the nucleus that balance the positively charged protons
Atoms may also gain or lose electrons to become ions —electrically charged atoms.

26. The structure of an atom

27. Chemical building blocks
Isotopes: atoms with differing numbers of neutrons
Mass number: the number of protons and neutrons
Isotopes of an element behave differently.
Some isotopes are radioactive.
They decay until they become non-radioactive stable isotopes.
Emit high-energy radiation

28. Radioactive decay
Half-life: the amount of time it takes for one-half of the atoms to give off radiation and decay
Different radioscopes have different half-lives ranging from fractions of a second to billions of years.
Uranium-235, used in commercial nuclear power, has a half-life of 700 million years.

29. Molecules and compounds
Molecules: combinations of two or more atoms: Covalently Bonded
Oxygen gas: O2
Compounds: a molecule composed of atoms of two or more different elements
Water: two hydrogen atoms bonded to one oxygen atom (H20)
Carbon dioxide: one carbon atom with two oxygen atoms (CO2)
Solutions: no chemical bonding, but is a mixture of substances (i.e., blood, ocean water)

30. Hydrogen ions determine acidity
The pH scale ranges from 0 to 14 and quantifies the acidity or basicity of solutions.
Acidic solutions have a pH less than 7.
Basic solutions have a pH greater than 7.
Neutral solutions have a pH of 7 (i.e., pure water).
A substance with pH of 6 contains 10 times as many hydrogen ions as a substance with pH of 7.

31. Activity:
Outline pages 49-56

32. Organic Compounds
Organic compounds: carbon atoms joined by bonds that may include other elements
Such as nitrogen, oxygen, sulfur, and phosphorus
Hydrocarbons: contain only carbon and hydrogen
Make up fossil fuels
The simplest hydrocarbon is methane (natural gas)
Can be a gas, liquid, or solid

33. Macromolecules: life’s building blocks
Polymers: long chains of repeated molecules
The building blocks of life
Macromolecules: large-size molecules
Three types of polymers are essential to life:
Proteins
Nucleic acids
Carbohydrates
Lipids are not polymers, but are also essential.

34. Proteins
Produce tissues, provide structural support, store energy, and transport substances
Made up of chains of amino acids
Animal proteins generate skin, hair, muscles, and tendons
Some function as components of the immune system
Can serve as enzymes — molecules that promote chemical reactions

35. A special process involving proteins
Nucleic acid: directs the production of proteins
Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) carry the hereditary information of organisms.
Long chains of nucleotides that contain sugar, phosphate, and a nitrogen base
Genes: regions of DNA that code for
proteins that perform certain functions

36. Carbohydrates and lipids
Carbohydrates: atoms of carbon, hydrogen, and oxygen
Sugars: simple carbohydrates, 3-7 carbons long
Glucose: provides energy for cells
Complex carbohydrates build structures and store energy
Starch: used by plants to store energy
Animals eat plants to acquire starch.
Cellulose of plants and shells of insects
Lipids: a chemically diverse group of compounds grouped together because they don’t dissolve in water
Energy, cell membranes, structural support, and hormones

37. Cells compartmentalize macromolecules
Cell: the basic unit of life’s organization
Eukaryotes: contain a membrane-enclosed nucleus and various organelles that perform specific functions
Plants, animals, fungi, protists
Prokaryotes: single-celled organisms lacking organelles and a nucleus
Bacteria and archaea

38. Activity: Testing your comprehension questions #1-4
Seeking Solutions questions #1 and 5
Dead Zone Questions/Scenario

39. Activity: 8/31/12
After presenting Scenario 1 or 2, Work on the following:
Kinetic vs. Potential Energy
Explain how Photosynthesis works
Relate photosynthesis to Primary Productivity
Compare Photosynthesis to Cellular Respiration

40. Energy fundamentals
Energy: an intangible phenomenon that can change the position, physical composition, or temperature of matter
Potential energy: energy of position
Kinetic energy: energy of motion
Chemical energy: potential energy held in the bonds between atoms
Potential energy is changed into kinetic energy to produce motion, action, and heat.

42. Energy is conserved...but changes in quality
First law of thermodynamics: energy can change forms, but cannot be created or destroyed
Second law of thermodynamics: the nature of energy changes from a more-ordered to a less-ordered state if no force counteracts this tendency
Entropy: an increasing state of disorder
For example, burning a log of firewood transforms the log from a highly organized product into light and heat energy, gases, smoke, and carbon ash.

43. The sun’s energy powers life
The energy that powers Earth’s ecological systems originates mainly from the sun.
The sun releases radiation from the electromagnetic spectrum.
Some is visible light

44. Photosynthesis
Autotrophs (producers): produce their own food from the sun’s energy
Green plants, algae, and cyanobacteria
Photosynthesis: the process of turning light energy from the sun into chemical energy
Carbon dioxide + water + sun’s energy is converted into sugars and high-quality energy.
Low-quality energy is turned into high-quality energy.

45. Photosynthesis produces food
Chloroplasts: organelles where photosynthesis occurs
Contain chlorophyll: a light-absorbing pigment
Light reaction: solar energy is used to split water to form oxygen and a small, high-energy molecule that fuels the….
Calvin cycle: links carbon atoms from carbon dioxide into sugar (glucose)
6CO2 + 6H20 + the sun’s energy C6H12O6 + 6O2

46. Cellular respiration releases chemical energy
Organisms can use chemical energy created by photosynthesis through cellular respiration.
Oxygen is used to convert glucose into water + carbon dioxide + energy.
Only 2/3 of the original energy input per glucose molecule is gained in respiration.
Occurs in autotrophs and organisms that feed on others
Heterotrophs (consumers): organisms that gain energy by feeding on others
Animals, fungi, microbes
C6H12O6 + 6O CO2 + 6H20 + energy

47. Energy and matter in ecosystems
Ecosystem: all organisms and non-living entities occurring and interacting in a particular area
Animals, plants, water, soil, nutrients, etc.
Energy from the sun flows in one direction through ecosystems.
Energy is processed and transformed.
Matter is recycled within ecosystems.
Outputs: heat, water flow, and waste 47

48. Energy is converted to biomass
Primary production: conversion of solar energy to chemical energy by autotrophs
Gross primary production: assimilation of energy by autotrophs
Net primary production (NPP): energy remaining after respiration, used to generate biomass
Available for heterotrophs
Productivity: rate at which autotrophs convert energy to biomass 48

49. Net primary productivity of ecosystems
High net primary productivity: ecosystems whose plants rapidly convert solar energy to biomass

50. A global map of NPP
NPP increases with temperature and precipitation on land, and with light and nutrients in aquatic ecosystems.

51. Nutrients can limit productivity
Nutrients: elements and compounds that organisms consume and require for survival
Stimulate plant production
Lack of nutrients can limit production.
Nitrogen and phosphorus are important for plant and algal growth.
Oceanic primary productivity is highest in water near shore.
Over 200 dead zones now exist due to nutrient pollution. 51

52. Nutrient runoff devastates aquatic systems
Aquatic dead zones result from nutrient pollution from farms, cities, and industry.
Most dead zones are located near Europe and the eastern U.S.
Scientists are investigating innovative and economical ways to reduce nutrient runoff.
Phytoplankton blooms off the Louisiana coast.

53. Ecosystems come in different sizes
Ecosystems vary greatly in size.
The term “ecosystem” is most often applied to self-contained systems of moderate geographic extent.
Adjacent ecosystems may interact extensively.
Ecotones: transitional zones between two ecosystems in which elements of each ecosystem mix 53

54. Landscape ecology
Landscape ecology: the study of how landscape structure affects the abundance, distribution, and interaction of organisms
Helpful for sustainable regional development
Useful for studying migrating birds, fish, mammals
Patches: ecosystems, communities, or habitat form the landscape and are distributed in complex patterns (a mosaic)
This landscape consists of a mosaic of patches of 5 ecosystems. 54

55. Conservation biology
If a habitat is distributed in patches, organisms face danger in traveling from one patch to another.
Patches spaced too far apart prevent travel
Conservation biologists: study the loss, protection, and restoration of biodiversity
Humans are dividing habitat into small, isolated patches.
Corridors of habitat can link patches.
Geographic information systems (GIS): computer software that layers multiple types of satellite data to create a complete picture of a landscape
Geology, vegetation, animal species, and human development

56. Activity: Testing Your Comprehension Questions #5-7
Calculating Ecological Footprints
HW: Complete the “Testing Your Comprehension” Questions, 8-10 after reading pages 63-69; Biogeochemical Cycles

57. Nutrients circulate through ecosystems
Physical matter is circulated continually in an ecosystem.
Nutrient (biogeochemical) cycle: the movement of nutrients through ecosystems
Pools (reservoirs): where nutrients remain for varying amounts of time
Flux: movement of nutrients among pools
Can change over time 57

58. The carbon cycle
Carbon cycle: describes the routes that carbon atoms take through the environment
Through photosynthesis, producers move carbon from the air and water to organisms.
Respiration returns carbon to the air and oceans.
Decomposition returns carbon to the sediment, the largest reservoir of carbon.
Ultimately, it may be converted into fossil fuels.
The world’s oceans are the second largest reservoir.
Obtain carbon from the air and organisms 58

59. The carbon cycle

60. Humans affect the carbon cycle
Burning fossil fuels moves carbon from the ground to the air.
Cutting forests and burning fields moves carbon from organisms to the air.
Today’s atmospheric carbon dioxide reservoir is the largest in the past 800,000 years.
The driving force behind climate change

61. The phosphorus cycle
Phosphorus cycle: describes the routes that phosphorus atoms take through the environment
No significant atmospheric component
Most phosphorus is within rocks and is released by weathering.
With naturally low environmental concentrations, phosphorus is a limiting factor for plant growth.
Phosphorus is a key component of cell membranes, DNA, RNA, and other biochemical compounds.

62. The phosphorus cycle

63. Humans affect the phosphorus cycle
Mining rocks for fertilizer moves phosphorus from the soil to water systems.
Wastewater discharge also releases phosphorus, which boosts algal growth and causes eutrophication.
May be present in detergents
Consumers should purchase phosphate-free detergents.

64. The nitrogen cycle
Nitrogen comprises 78% of our atmosphere and is contained in proteins, DNA, and RNA.
Nitrogen cycle: describes the routes that nitrogen atoms take through the environment
Nitrogen gas is inert and cannot be used by organisms.
Needs lightning, bacteria, or human intervention
Nitrogen fixation: Nitrogen gas is combined (fixed) with hydrogen by nitrogen-fixing bacteria or lightning to become ammonium
Can be used by plants
Nitrogen-fixing bacteria live in legumes (i.e., soybeans)

65. Nitrification and denitrification
Nitrification: bacteria that convert ammonium ions first into nitrite ions then into nitrate ions
Plants can take up these ions
Animals obtain nitrogen by eating plants or other animals.
Denitrifying bacteria: convert nitrates in soil or water to gaseous nitrogen, releasing it back into the atmosphere

66. The nitrogen cycle

67. Humans affect nitrogen cycle
Excess nitrogen leads to hypoxia in coastal areas.
Synthetic fertilizers doubled the rate of Earth’s nitrogen fixation.
Burning forests and fossil fuels leads to acid precipitation.
Wetland destruction and increased planting of legumes has increased nitrogen-rich compounds on land and in water.
Increased emissions of nitrogen-containing greenhouse gases
Calcium and potassium in soil are washed out by fertilizers.
Reduced biodiversity of plants adapted to low-nitrogen soils.
Changed estuaries and coastal ecosystems and fisheries

68. Human inputs of nitrogen into the environment
Fully half of nitrogen entering the environment is of human origin.

69. A law addressing hypoxia in the Gulf
The Harmful Algal Bloom and Hypoxia Research and Control Act (1998) called for an assessment of hypoxia in the Gulf and to:
Reduce nitrogen fertilizer use in Midwestern farms
Change timing of fertilizer applications to minimize runoff
Use alternative crops
Manage livestock manure
Restore wetlands and create artificial ones
Improve sewage-treatment technologies
Evaluate these approaches
This Act has worked, and was reauthorized in 2003.

70. The hydrologic cycle
Water is essential for biochemical reactions and is involved in nearly every environmental system.
Hydrologic cycle: summarizes how liquid, gaseous, and solid water flows through the environment
Oceans are the main reservoir.
Less than 1% is available as fresh water.
Evaporation: water moves from aquatic and land systems to air
Transpiration: release of water vapor by plants
Precipitation: condensation of water vapor as rain or snow returns water from the air to Earth’s surface

71. Groundwater
Aquifers: underground reservoirs of spongelike regions of rock and soil that hold …
Groundwater: water found underground beneath layers of soil
Water table: the upper limit of groundwater held in an aquifer
Water may be ancient (thousands of years old).

72. The hydrologic cycle

73. Human impacts on hydrologic cycle
Damming rivers increases evaporation and infiltration into aquifers.
Altering the surface and vegetation increases runoff and erosion.
Spreading water on agricultural fields depletes rivers, lakes, and streams and increases evaporation.
Overdrawing groundwater for drinking, irrigation, and industrial uses depletes groundwater resources.
Removing forests and vegetation reduces transpiration and lowers water tables.
Emitting pollutants changes the nature of precipitation. 73

74. Activity: 9/4/12 Carbon Cycle- 2 Phosphorus- 2 Nitrogen- 4
Nitrification
Denitrificaiton
Hydrologic- 3
Create brochure, pamphlet, etc. explaining each in detail.

75. Conclusion
Life interacts with its abiotic environment in ecosystems through which energy flows and materials are recycled.
Understanding biogeochemical cycles is crucial.
Humans are causing significant changes in the ways those cycles function.
Understanding energy, energy flow, and chemistry increases our understanding of organisms, their environment, and how environmental systems function.
Thinking in terms of systems can teach us how to avoid disrupting Earth’s processes and how to mitigate any disruptions we cause. 75

76. QUESTION: Review
Which of the following part of an atom has a positive charge?
a) Proton
b) Neutron
c) Electron
d) Hydrogen
e) Neutreno
Answer: a

77. QUESTION: Review
Which of the following consists of a chemically diverse group of compounds that don’t dissolve in water?
a) Nucleic acids
b) Proteins
c) Carbohydrates
d) Lipids
e) Polymers
Answer: d

78. QUESTION: Review Sugars, starches, and glucose are all: a) Lipids
b) Proteins
c) Carbohydrates
d) Nucleic acids
e) Synthetic molecules
Answer: c

79. QUESTION: Review According to the first law of thermodynamics:
Energy cannot be created or destroyed
Things tend to move toward a more disorderly state
Matter can be created, but not energy
Kinetic energy is the most efficient source of energy
Energy is constantly recycled
Answer: a

80. QUESTION: Review Which of the following organisms is an autotroph?
Deep-sea tubeworm
Horse
Pine tree
Human
None of these
Answer: c

81. QUESTION: Review A transitional zone between two ecosystems is a(n):
a) Conservation zone
b) Corridor
c) Reservoir
d) Ecotone
e) Patch
Answer: d

82. QUESTION: Review
Humans have affected the nitrogen cycle in all of the following ways EXCEPT:
a) Doubling the rate of nitrogen fixation
b) Increasing emissions of greenhouse gases
c) Lowering water tables
d) Changing estuaries and coastal ecosystems
e) Reducing diversity of plants adapted to nitrogen-poor soils
Answer: c

83. QUESTION: Weighing the Issues
Who should be responsible for reducing nitrogen pollution and eutrophication off coastal waters?
a) Fishermen, since they reap the benefits of fishing
b) Farmers, since they are causing much of the problem
c) Taxpayers, since they are getting both fish and food
d) The federal government, since it’s job is to protect American citizens and the environment
Answer: any

84. QUESTION: Interpreting Graphs and Data
A molecule of the hydrocarbon ethane contains:
a) 10 carbon atoms and 8 hydrogen atoms
b) 8 carbon molecules and 10 hydrogen enzymes
c) 2 carbon atoms and 6 hydrogen atoms
d) 2 different ions
Answer: c

85. QUESTION: Interpreting Graphs and Data
Which is the most basic material?
a) Lemon juice
b) Acid rain
c) Rainwater
d) Seawater
e) Soft soap
Answer: e

86. QUESTION: Interpreting Graphs and Data
According to this graph, which ecosystem has the lowest amount of biomass?
a) Temperate grassland
b) Boreal forest
c) Savanna
d) Tropical rainforest
Answer: a