RECYCLING IN THE BIOSPHERE

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RECYCLING IN THE BIOSPHERE

• Biogeochemical Cycles
• 1. water cycle
• 2. carbon cycle
• 3. nitrogen cycle
• 4. phosphorus

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The Carbon Cycle
http//earthobservatory.nasa.gov/Library/CarbonCyc
le/carbon_cycle4.html
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Movement of carbon into plants for photosynthesis

• Stomata openings on the underside of leaves,
  guard cells control opening
• What comes in through stomata that the plant
  needs?
• What goes out through the stomata that the plant
  needs?

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GtC gigatons of carbon
Four main types of processes that move carbon
through the carbon cycle 1. biological
processes PS, CR, decomposition 2. geochemical
processes erosion, volcanic activity 3. mixed
biogeochemical processes burial and
decomposition of dead organisms? fossil
fuels 4. human activities burning fossil
fuels, cutting/burning forests
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World map of photosynthetic activity

• Interpret the map
• What areas of the world have the highest rate of
  photosynthetic activity in December? Explain
  what environmental factors cause this pattern.
• What would the map look like in June?

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Atmospheric carbon dioxide varies over time

• The long-term record of atmospheric carbon
  dioxide obtained from Antarctic ice cores shows
  huge fluctuations over the past 150,000 years.
  Periods of low carbon dioxide concentration
  correspond to ice ages, while higher carbon
  dioxide concentrations are linked to warmer
  periods. The last ice age ended 10,000 to 20,000
  years ago, as carbon dioxide levels rose from
  below 200 parts per million to about 280 parts
  per million. Current atmospheric carbon dioxide
  levels are above 370 parts per million because of
  the burning of fossil fuels. This has raised
  concern in the scientific community that average
  global temperatures may rise as a result. (Graph
  by Robert Simmon, based on data from Lorius, C.,
  J. Jouzel, C. Ritz, L. Merlivat, N.I. Barkov,
  Y.S. Korotkevitch, and V.M. Kotlyakov. 1995. A
  150,000-year climatic record from Antarctic ice.
  Nature 316591-596

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Atmospheric carbon dioxide levels 1960-2000

• Graph interpretation
• What is happening to the level of carbon dioxide
  in the atmosphere?
• Carbon dioxide contributes to the greenhouse
  effect. How does a rise in atmospheric carbon
  dioxide effect our climate?

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Global Warming?

• This graph shows annual mean global temperature
  anomalies over the period 1880-2001. The zero
  line represents the long term mean temperature
  from 1880-2001, and the red and blue bars are
  showing annual departures from that mean. As is
  evident in the graph, 2001 was second only to
  1998 in terms of global temperature, and the
  trend has been toward increasing temperatures at
  least since the beginning of the 20th century.
  Land temperatures have greater anomalies than the
  ocean, which is to be expected since land heats
  up and cools down faster than water.

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The Nitrogen Cycle

• Living organisms use nitrogen to make DNA, RNA,
  proteins
• Definitions
• N2 is nitrogen gas (atmosphere)
• Forms plants can use
• ammonia (NH3) nitrate (NO3-) nitrite
  (NO2-)
• Nitrogen fixation when bacteria take up N2 and
  convert it into the forms plants can use
• Denitrification when bacteria convert nitrates
  into N2
• Eutrophication process in which bodies of water
  receive excess nutrients (such as nitrates from
  fertilizers) that stimulate aquatic plant growth
  (if algae, then it is called an algal bloom)
  when these plants die and decompose, oxygen in
  the water is used up, which can hurt fish and
  other animals

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The Nitrogen Cycle
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The Phosphorus Cycle

• Phosphorus is used by living organisms in DNA,
  RNA, ATP
• Phosphorus is not common in the biosphere and
  therefore, is a limiting factor in ecosystems
• Unlike CO2 and N2, phosphorus does not go into
  the atmosphere
• Phosphorus in fertilizers and livestock waste can
  lead to eutrophication of aquatic ecosystems

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Phosphorus Cycle
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Eutrophication

• Too much fertilizer (nitrogen or phosphorus) in
  the ecosystem leads to overproduction of algae
  and other aquatic plants

Satellite image of eutrophication of the northern
Caspian Sea
Algal bloom
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Review of Biogeochemical Cycling

• What are the major cycles that occur in our
  biosphere?
• How does the atmosphere play a role in each?
• What are global warming and eutrophication and
  how have humans contributed to both?
• Which of the cycles, if thrown off balance, would
  have the most immediate catastrophic affect to
  the biosphere? Can you pick ONE or all they all
  important and intertwined?