Environmental Science: Toward a Sustainable Future Richard T' Wright

1
Environmental Science Toward a Sustainable
Future Richard T. Wright
Chapter 3

• Ecosystems How They Work
• PPT by Terri Rogers Clark E. Adams

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Ecosystems Function Transfer Energy and Nutrients

• Matter, energy, and life
• Energy flow in ecosystems
• The cycling of matter in ecosystems
• Implications for human societies

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Matter, Energy, and Life

• Matter in living and nonliving systems
• Energy basics
• Energy changes in organisms

4
Elements of Life
Organic carbon-based molecules Examples
C6H12O6, CH4 Inorganic molecules without
carboncarbon or carbonhydrogen
bonds Examples NaCl, NH4, H2SO4
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Elements of Life
92 naturally occurring elements Elements Found
in Living Organisms N CHOPS (macronutrients) C
HOPKINS Ca Fe Mg B Mn Cu Cl Mo Zn What elements
would be harmful to living organisms?
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Atmospheric Gases
78 Nitrogen
21 Oxygen
lt0.04 Carbon Dioxide
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Match the Elements (Left) with Molecules (Right)

• Nitrogen
• Carbon
• Hydrogen
• Oxygen
• Phosphorus
• Sulfur

• Glucose
• Proteins
• Starch
• Fats
• Nucleic acids
• All of the above

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Matter and Energy

• Matter anything that occupies space and has mass
• Cannot be created or destroyed
• Can be changed from one form into another
• Can be recycled
• Can be measured where gravity is present

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Matter and Energy

• Energy anything that has the ability to move
  matter has no mass and does not occupy space
• Cannot be created or destroyed
• Can be changed from one form to another
• Cannot be recycled
• Can be measured

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Laws of Thermodynamics
First Law (CHANGE) Energy is neither created
nor destroyed but may be converted from one
form to another. NO FREE LUNCHES! Second Law
(LOSS) In any energy conversion, you will end up
with less usable energy than you started with.
YOU CANT BREAK EVEN!
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Laws of Thermodynamics
Second Law Energy is lost in the energy
conversion process, as heat. The energy value of
work performed will always be less than the fuel
it consumes.
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Entropy Energy Changes in Organisms

• Systems will go spontaneously in one direction
  only, which is toward increasing entropy..

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Ecosystems Use Sunlight As Their Source of Energy
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The First Principle of Ecosystem Sustainability
At Work
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First Principles of Ecosystem Sustainability

• Ecosystems use sunlight as their source of
  energy.
• The source of all energy is the sun.
• All elements are recycled

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The Second Principle of Ecosystem Sustainability

• Ecosystems dispose of wastes and replenish
  nutrients by recycling all elements.

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Conservation of Matter and Energy Capture
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Photosynthesis

• Natural process
• Converts atmospheric inorganic carbon
• To organic forms of carbon found in living
  systems
• Happens in plants
• Sunlight is the source of all energy
• For plants
• For other living organisms

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Energy Flow in Ecosystems

• Primary production
• Energy flow and efficiency
• Running on solar energy
• Freely available
• Nonpolluting
• Everlasting

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Energy Flow through Trophic Levels
10,000 Kcal
Producer
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Solar Energy

• Drives the following cycles
• Carbon
• Water
• Nitrogen
• Phosophorus

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The Cycling of Matter in Ecosystems

• The carbon cycle
• The phosphorus cycle
• The nitrogen cycle

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The Carbon Cycle

• How and in what form does carbon enter and leave
  the cycle?
• How is the role of autotrophs and heterotrophs
  different and the same?
• What are the human impacts on the cycle?
• Fossil fuel burning is an anthropogenic cause of
  return of carbon to the atmosphere

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The Phosphorus Cycle

• How and in what form(s) does phosphorus enter and
  leave the cycle?
• How is the role of autotrophs and heterotrophs
  different and the same?
• What are the human impacts on the cycle?
• Inadvertent fertilization of waterways
• Accumulation of phosphorus rich pollutants in the
  atmosphere
• Depletion of soil supplies by overharvesting and
  erosion

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The Nitrogen Cycle

• How and in what form(s) does nitrogen enter and
  leave the cycle?
• How is the role of autotrophs and heterotrophs
  different and the same?
• What are the human impacts on the cycle?
• The addition of fertilizer to soil contributes to
  the nitrogen cycle
• Farmers plant legumes (soybeans) to enrich the
  soil with nitrogen.
• Nitrogen fixation is the process by which
  microbes work with the legume to produce the
  nitrogen
• Converting the nitrogen gas to a chemical form
  the plant can use

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Nitrogen fixation
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Implications for Human Societies

• Ecosystem sustainability
• Value of ecosystem capital
• The future

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Ecosystem Sustainability

• Ecosystems use sunlight as their source of
  energy.
• Ecosystems dispose of wastes and replenish
  nutrients by recycling.

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The Human System

• Excessive use of fossil fuels
• Feeding largely on the third trophic level
• Use of coal or nuclear power
• Use of agricultural land to produce meats

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The Human System

• Lack of recycling
• Excessive use of fertilizers
• Destruction of tropical rain forests
• Nutrient overcharge into aquatic ecosystems
• Production and use of nonbiodegradable compounds

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Value of Ecosystem Capital

• Gas regulation
• Climate regulation
• Disturbance regulation
• Water regulation and supply
• Erosion control and sediment retention
• Soil formation
• Nutrient recycling

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Value of Ecosystem Capital

• Waste treatment
• Pollination
• Biological control
• Refugia
• Food production
• Raw materials
• Genetic resources

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Important Test Points

• Sustainability Laws
• Thermodynamics Laws
• Relationship between photosynthesis and
  respiration
• What happens when rainforests and trees are gone
• Where does all the carbon (or carbon dioxide) end
  up?
• Trophic levels
• Sun source of all energy
• Plants bottom of food chain use sun for all
  energy
• 10 energy transferred level to level
• Cycles
• Carbon, nitrogen, phosphorus
• Especially nitrogen and nitrogen fixation
• Sustainability of earth with our impacts