Geochemical Cycles

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Geochemical Cycles
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Water Cycle
Evaporation water changing from liquid form to
gas

• Movement of water among ocean, atmosphere, and
  land.
• Enters atmosphere through evaporation and
  transpiration (plant leaves)

Transpiration plant leaves losing water to the
atmosphere
Hurricane Katrina approaches
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Geochemical Cycles

• Water Cycle
• When air is warmed up, the particles get farther
  apart (and so have lower density).
• H20 rises in columns of warm air and may remain
  in atmosphere for about 2 weeks.
• As the H20 vapor rises, it cools into droplets
  (condenses), forming clouds

Condensation water vapor transforming into
liquid water. Occurs because cooler air does not
have as much space to hold water vapor.
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Water Cycle
Runoff any water moving across the land

• Enters land through precipitation and
  condensation.
• Enters lakes or rivers through runoff
• Enters groundwater where it enters the biosphere.

Groundwater any water stored underground!
When water vapor in the air cools (usually at
night), it condenses on grass (dew) or in the air
(fog).
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SUN
WATER CYCLE
Precipitation
Precip and Conden
Movement of water vapor by wind
Mountains
Evaporation Transpiration
Run Off
Streams
LAKES
Evaporation
OCEANS
Aquifer
Groundwater
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Humans affect on water cycle

• Higher global temperature increased evaporation.
• Higher ocean temps increase evaporation
• Reduction in rainforest reduces transpiration.
• Reduction of plant life increases runoff
• Glacial melting reduces amount of reflected light

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Geochemical Cycles

• Carbon Cycle
• Early atmosphere of Earth 95 CO2. Photosynthetic
  plants removed some of the CO2 and added O2.
  Todays atmosphere is 0.04 CO2!
• Reactions of photosynthesis and cellular
  respiration couldnt take place without carbon.
  These two reactions form a continuous cycle.
• Two important sources of Carbon are the ocean
  (since CO2 dissolves easily in H20) and rocks
  (such as coal, ore and limestone formed from dead
  organisms)

Carbon is found in the atmosphere primarily as CO2
Photosynthesis Plants taking CO2 out of the
atmosphere and using it to produce sugar.
Cellular Respiration Organisms take that sugar
and in the process of burning energy release CO2
back into the atmosphere.
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And, another way to look at the carbon cycle
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Geochemical Cycles

• Nitrogen Cycle
• Organisms require Nitrogen to form amino acids
  for the building of proteins.
• Lots of N2 in our atmosphere
• Unfortunately, most organisms CANNOT use
  atmospheric nitrogen.
• Nitrogen-fixing bacteria CAN use N2 from the
  atmosphere.

Nitrogen-fixing bacteria convert atmospheric N2
into ammonia (NH4) which is a form of nitrogen
that plants CAN use.
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Nitrogen Cycle Continued

• Nitrogen-fixing bacteria live in the soil and in
  roots of legumes.
• These bacteria also form nitrites (NO2) and
  nitrates (NO3) which are compounds containing N
  and O.
• Nitrate is the most common source of N for
  plants.
• Animals get N from the proteins they eat.
• Decomposers return N to the soil in the form of
  ammonia and the cycle repeats.
• So, oftentimes, the nitrogen cycle does not
  require the N to be returned to atmospheric form!

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Nitrogen Cycle Summary

• All living organisms require nitrogen to form
  amino acids to build proteins.
• Proteins are important for locomotion,
  reproduction, defense, and structure.
• Nitrogen makes up 78 of atmosphere as N2
• Nitrogen-fixing bacteria are very important - N2
  needs to be fixed before it can be used by most
  living things.

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NITROGEN CYCLE
N2
Lightning
Fertilizer Production
Denitrification
(GAS)
Nitrogen Fixation
Crops
Legume
Nitrogen-Fixing Bacteria in soil roots
Decomposers
Ammonia Nitrates Nitrites
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