Transcript Getting the balance right File

Topic 5.8
http://www.biology.ualberta.ca/facilities/multimedia/uploads/alberta/CarbonCycle.html
What carbon compounds are involved in the carbon
cycle?
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CO2
Hydrocarbons in fossil fuels
carbohydrates (glucose, sucrose, fructose, lactose,
cellulose, glycogen, starch),
protein (and amino acids of course),
lipids
DNA and RNA (composed of a ribose sugar,
phosphate group and nitrogenous Base),
ATP (sugar, base and phosphate groups),
chlorophyll
carbonates (dissolved CO2) in aquatic systems
calcium carbonates in invertebrate skeletons
a) Respiration
b) Photosynthesis
c) Death and Decomposition (decay)- which is respiration
in decomposers= bacteria and fungi
d) Death and very slow anaerobic decomposition
e) Combustion
f) Feeding (ingestion, digestion, absorption, assimilation)
g) Dissolving
h) Uptake of carbonates into aquatic invertebrates*
i) Death and sedimentation of aquatic invertebrates
(formation of sedimentary rock like limestone)*
j) Weathering of sedimentary rock*
 Q 5.51
a. Respiration:
Glucose and other organic compounds  CO2
b. Photosynthesis:
CO2  glucose (then other organic compounds)
c. Death and Decomposition:
Organic compounds in dead organisms  CO2
d. Death + slow anaerobic decomposition:
organic compounds in dead organisms  fossil
fuels
e. Combustion:
Fossil Fuels or Biomass(organic compounds) 
CO2
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Label each arrow- which processes are taking place in each case?a)-f) from above.
By drawing add processes g)-j)
Which processes are terrestial? Aquatic? Both?
◦ Carbon sink (page 64):
 Anything that absorbs more carbon than it releases◈
and stores it in organic compound for a long period
of time (net removal of CO2 from the atmosphere)
◦ Find examples on the C-cycle diagram.
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Peat and fossil fuels
Sedimentary rock like limestone (chalk is a type of limestone)
Trees
Shells
◦ Carbon source:
 Anything that releases more carbon (CO2 )than it
absorbs. Burning a C- sink or its decay represents
net addition of C02 over a short period of time.
 ◈(http://www.fern.org/campaign/carbon-trading/what-are-carbon-sinks).
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Q 1-2
Q 8a
 Which
human activities affect the
C-cycle?
Combustion of fossil fuels
increases CO2 levels
Deforestation increases CO2
levels
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Where do fossil fuels come from?
◦ Trees many years ago which decomposed
anaerobically very slowly
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Why does combustion of fossil fuels affect the Ccycle significantly?
◦ Carbon in fossil fuels (carbon sinks) has been
locked up as an organic carbon compound for
many years. Its formation by photosynthesis
occurred many years ago. It is all released as CO2
very suddenly when fossil fuels are burnt.
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What is a biofuel? Give examples.
• A renewable source of energy produced directly in
plants or indirectly in animals by recent
photosynthesis. E.g. wood, straw, vegetable oil,
methane from fermentation of human sewage or
other waste , ethanol from fermentation of sugar
Are these carbon sinks - wood from trees(biofuel) and
fossil fuels?
So why are biofuels CO2 neutral and fossil fuels are not?
• When a biofuel burns the released CO2 replaces
the CO2 which was recently absorbed by
photosynthesis and which would have been
released by the process of decomposition.
Biofuel
Any source of energy produced
directly in plants or indirectly in
animals by RECENT
photosynthesis
Fossil Fuel
Sources of energy produced directly in
plants or indirectly in animals by
photosynthesis which took place
millions of years ago. These organisms
died and produced fossil fuels by the
slow anaerobic decomposition
When a biofuel burns the released
CO2 replaces the CO2 which was
recently absorbed by
photosynthesis and which would
have been released by the
process of decomposition- carbon
neutral
When a fossil fuel burns CO2 is released
which was trapped in organic form for
millions of years. It does not replace the
CO2 which was recently absorbed by
photosynthesis. Fossil Fuels are
significant carbon sinks because carbon
is locked away for a long period of time
Definition
Carbon
dioxide
neutral?
Explain
Sustaina
ble?
Explain.
Example
s?
Sustainable energy source - can
provide energy for a long time in
the future because it will not run
out (renewable energy source)
and it will not significantly affect
the atmospheric CO2 levels
Non-renewable energy source- it will run
out. Combustion of fossil fuels do
represent pollution.
Wood, straw, vegetable oil,
biogas (methane) , ethanol
Coal,oil, natural gas
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How does deforestation affect the balance
of the C-cycle?
◦ Rate of photosynthesis drops (rate of
respiration only drops in long run because
not all animals die immediately, rather
later due to loss of habitat and possibly
lack of food) - ---less CO2 is absorbed
◦ Smaller branches, small trees and shrubs
are left to decay or are burned, more CO2
released
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New forests better CO2 absorbers than old
ones. Why?:
◦ Faster growth therefore faster rate of photosynthesis,
◦ Relatively little decay
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There is a limit to the amount of CO2 a new
forest can soak up. Why?
◦ As forests grow, more vegetation means more food
for animals, more animals and more decomposition
leads to increased rate of respiration.
◦ Limited land so eventually growth rate in plants
decreases leading to decreased rate of
photosynthesis.
◦ Increased temp  less water available in forests 
decreased rate of photosynthesis as forests decline
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Much emphasis is given on how upsetting the carbon
cycle may be causing global warming. But what effect
could global warming have on the carbon cycle? (see
page 65-67)
◦ Increased temperature and increased CO2 levels 
increased rate of photosynthesis in forests and in
aquatic systems- could explain mystery of disappearing
carbon dioxide (page 65)
◦ Increased temp  decreased dissolving of CO2 in oceans
and in soil water, however, increased CO2 levels 
increased dissolving of CO2 in oceans and in soil water
◦ Increased temp  increased rate of decomposition of
peat
◦ Increased temp  less water available in forests 
decreased rate of photosynthesis
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http://www.youtube.com/watch?v=GhUtepqB
SI0&feature=player_embedded# (watch from
1.50 to 7.40
What is an ecotron?
What does it do?
How do you build one?
What have they been used for?
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Increased volcanic activity releasing CO2
Increased rock formation balanced by
erosion/weathering
Increased acid rain- more weathering of
limestone releasing CO2