The Cycling of Materials

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The Cycling of Materials
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Make-up of Life

• Energy is crucial to an ecosystem
• Organisms also need water, minerals, and other
  life-sustaining compounds.
• 95 of most organisms are made of four elements
• Carbon, oxygen, nitrogen, hydrogen

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Recycling in the Biosphere

• Energy is recycled within and between ecosystems
• Biogeochemical cycles elements and other
  chemical compounds are passed from one organism
  to another, and from one part of the biosphere to
  another.

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How?

• Matter can cycle through the biosphere because
  biological systems do not use up matter, they
  transform it.
• Matter is assembled into living tissue or passed
  out of the body as waste products.

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Example Carbon atom
You are a carbon atom floating in the air in a
molecule of carbon dioxide
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Carbon Atom

• The leaf of a blueberry bush absorbs you
  through photosynthesis

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Carbon Atom

• You become part of a carbohydrate molecule in
  the form of fruit.

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Carbon Atom

• The fruit is eaten by a caribou and within a few
  hours you are passed out of the animals body.

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Carbon Atom

• You are soon swallowed by a dung beetle!

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Carbon Atom

• You are then combined with a hungry shrew.

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Carbon Atom

• The shrew is then eaten by an owl. Finally, you
  are released back into the atmosphere when the
  owl exhales!

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The Big Picture

• The same molecules are passed around again and
  again.
• Every breath you take, you inhale thousands of
  oxygen molecules that may have been exhaled by
  dinosaurs millions of years ago!

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The Carbon Cycle

• Carbon found in every living organism
• It is cycled between the atmosphere, land, water,
  and organisms.

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Short-Term Cycle

• Plants convert carbon dioxide into glucose
  (photosynthesis) and another organism eats the
  plant and gets the carbon through carbohydrates.
  Then some of this carbon gets released back into
  the air when organisms exhale carbon dioxide.

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Your Turn

• What you think would happen if all of the plants
  on the planet died. How would our atmosphere be
  changed? How would other organisms (like us) be
  affected?

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Long-Term Cycle

• Some carbon gets converted into carbonates.
• Carbonates make up the hard parts of bones and
  shells.
• Over millions of years, these carbonates form
  carbon sinks, or carbon reservoirs.

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How Humans Affect the Carbon Cycle

• When we burn fossil fuels, we release carbon into
  the air.
• Vehicles are the source of 1/3 of all carbon
  dioxide emitted in the US.

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Ways We Contribute

• Vehicles
• Power plants
• Factories
• Burning of wood

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Whats the Big Deal?

• About half of the carbon dioxide stays in the
  atmosphere and is increasing every year.
• Carbon dioxide is a green house gas.
• What happens when these gases increase?

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• GLOBAL WARMING!!!

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The Nitrogen Cycle

• Nitrogen is needed to build proteins.
• Makes up 78 of gases in atmosphere
• Most organisms cannot use nitrogen in this form.
• It must be fixed

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Nitrogen fixing bacteria

• The only organisms that can alter nitrogen so
  other organisms can use it.
• All other organisms depend on them
• Nitrogen cycle how nitrogen is cycled through
  the atmosphere, bacteria, and other organisms.

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Decomposers

• How nitrogen is returned to the atmosphere by
  bacteria.

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Your Turn

• We usually think of all bacteria as being bad
  or unhealthy. Explain, using what you just
  learned, how this is not always true. What would
  happen if there were no decomposers?

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The Phosphorous Cycle

• The movement of phosphorous from the environment,
  to organisms, and back to the environment.
• Not a gas, so does not occur in atmosphere.
• When rocks erode, phosphorous enters the soil and
  water.
• Also comes from animal excretion, and dead
  organisms.

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• Many phosphates are not soluble in water, so they
  sink to the bottom of the oceans and form
  sediment.

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Fertilizers

• Excess nitrogen and phosphorous, when in bodies
  of water, cause algae blooms.
• Causes depletion of oxygen.

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Acid Precipitation

• When we burn fuel, large amounts of nitric oxide
  is released.
• When in the atmosphere, combines with oxygen and
  water vapor and makes nitric acid.

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Last Time!!!

• Every year the LSU lakes experience an algae
  bloom followed by a fish kill. In your own words,
  explain what you think is happening. What is
  causing it? Why do the fish die? What can we do
  to prevent it?