Chapter 2: Energy Flow and
Nutrient Cycles Support Life in
Ecosystems
Today
 Virtual lab
http://www.mhhe.com/biosci/genbio/virtual_labs/BL_03
/BL_03.html
Diagram page 76 textbook
Nutrient cycling (CARBON)
 Stores
 6 main processes C is cycled
 Anthropogenic effects
 Workbook pages
A 54-year
old
sealed
terrarium
(planted
in 1960)
no fresh
air or
water
2.2 Nutrient Cycles in
Ecosystems
2.2 Nutrient Cycles in
Ecosystems
Human activities can upset the natural balance of
nutrient cycles:
- land clearing
- agriculture
- industry
- motorized transportation
Nutrient Cycling
• Nutrients: chemicals that are needed for plant and animal
growth and other life processes.
• Are accumulated in atmosphere, oceans, and land masses
• Stores: location of nutrient accumulation
Nutrient Cycling
• Nutrient Cycling: movement in and out of stores
• Caused by biotic and abiotic processes
• Cycles are near balance (input = output)
You need to know about C, N, & P cycles
But O and H are also needed for life
Carbon Cycle
Carbon Stores
• All living things contain carbon in their cells
How carbon is stored:
1. Short term stores
- vegetation on land, in oceans
- animals and decaying OM in soil
- atmosphere as CO2
- top layers of ocean
Carbon Stores
2. Long-term stores:
- intermediate and deep oceans
- coal deposits
- marine deposits and sedimentary rock
Carbon Stores
Store
Marine sediments and
sedimentary rock
Oceans (intermediate/deep)
Coal Deposits
Soil and organic matter
Atmosphere
Terrestrial Vegetation
Oil and Gas Deposits
Amount of C /Gigatonnes
68 000 000 to 100 000 000
Where is most carbon stored?
38 000 to 40 000
3 000
1 500 to 1 600
750
540 to 610
300
Carbon Stores
• Sedimentation:
– Traps many long-term carbon stores
– Layers of soil/decomposing OM get buried
– turn into rock/coal/oil/gas by SLOW geological
processes
Carbon Stores
• Limestone (CaCO3 ) forms from shell deposits on
ocean floor
• Long-term carbon stores
are aka carbon sinks
Carbon Cycle
Carbon is cycled through
ecosystems by:
1. Photosynthesis
2. Cellular respiration
3. Decomposition
#1) Photosynthesis
chemical reaction in plants and
cyanobacteria where sunlight
(solar energy) is used to make
glucose (chemical energy)
Sun + 6H20 + 6CO2 → C6H12O6 + 6O2
(sun + water + carbon dioxide → sugar + oxygen)
#1) Photosynthesis
• recycles carbon and oxygen through ecosystems
By eating plants,
consumers obtain
energy and take carbon
into their cells.
#2) Cellular Respiration
• Opposite of photosynthesis
• chemical reaction in mitochondria of cells where
oxygen is used to liberate energy from glucose.
6O2 + C6H12O6 -> 6CO2 + 6H2O + energy
#3) Decomposition
• the breaking down of dead organic matter
• Decomposers (bacteria + fungi) convert organic
molecules (carbohydrates) back into carbon dioxide.
Today
 Nutrient cycling (CARBON)
 Review 6 main
processes C is cycled
 What are YOU doing?
 PHosphorUs and Nitrogen
(Phun with a P-H!)
You’re the next contestant!
•
http://www.bcscience10.com/docs/puzzles/section02_1_puzzle/index.html
• One lucky volunteer gets to click the link and
be the host while I check WB 24-26
• You have 10 minutes…
Other ways carbon is cycled
#4) Ocean processes (CO32-) sediments, marine organisms
remember CaCO3! We made some in a lab.
#5) Volcanic eruptions release CO2
#6) CO2 is rapidly released during forest fires (slowly for
decomposing trees)
Human activities and the
carbon cycle
• Industry, motorized transportation, land clearing
• Industrial revolution (160 yrs ago) CO2 levels increased by
30% from increase of fossil fuel burning
• Increase in CO2 in the previous 160 000 ya was 1-3%
• We release C from long-term
stores FAST (coal, oil, gas)
Anthropogenic effects
• Burning fossil fuel reintroduces C to
the cycle that was removed in a long term
store
• CO2, a greenhouse gas, is the most common form of carbon
absorbs heat in atm.
• Contributes to global climate change
Anthropogenic effects?
• Clearing land reduces amount of carbon taken from
atmosphere by plants during photosynthesis
• Farm plants remove CO2, but less than natural vegetation
Agriculture: cows are carbon culprits
• Our obsession with
cows is causing almost
10% of global warming
emissions http://qz.com/128662/ourobsession-with-cows-is-causing-almost-10-of-globalwarming-emissions/#/h/15425,1/
• Cows release methane
from digestion (23x
stronger than CO2)
• Feed is not
environmentally
friendly
•
Breaking
down
the
carbon
cycle
http://www.bcscience10.com/media/EP_carbon_cycle.swf
Carbon cycle
• http://www.bcscience10.com/protect/flash_u1_carbon_cycle.html
Today
 Nutrient cycling (CARBON)
 Review 6 main
processes C is cycled
 What are YOU doing?
 PHosphorUs and Nitrogen
(Phun with a P-H!)
 BONUS CHALLENGE… tell me what you learned
about nutrient cycling from THE link that was NOT
covered in class (5 marks maximum, handed in at
beginning of next class)
www.kssscience.weebly.com