Earthlabs: Climate and the Carbon Cycle– Lab 6 http://serc.carleton.edu/eslabs/carbon/lab6.html
Name _________________________
The Oceans: Carbon Sink or Source?
PART A: The Ocean Carbon Cycle
1. Describe the physical pump's role in enabling the ocean to be a carbon sink.
Atmospheric CO2 dissolves in surface waters of seawater. Some CO2 enters the biological pump. Other dissolved CO2 moves down into deep ocean currents
(downwelling) where it stays for hundreds of years until it upwells.
2.(Powerpoint question) If phytoplankton populations decrease, you might expect:
A. the amount of CO2 in the atmosphere to decrease
B. The amount of CO2 in the atmosphere to increase
Explain why you chose your answer.
Less phytoplankton means less CO2 is absorbed for photosynthesis. Unabsorbed CO2 can make its way back to the atmosphere via diffusion.
3. (Powerpoint question) Many mountain tops contain fossils of shelled creatures that once lived in the oceans. Which of the Earth's spheres could the carbon have traveled through on its journey to these mountain tops?
A. Geosphere
B. Geosphere and biosphere
C. Geosphere, biosphere, and hydrosphere
D. Geosphere, biosphere, hydrosphere and atmosphere
4. What is the role of phytoplankton in the biological carbon pump?
When phytoplankton photosynthesize, they draw down CO2 into the biological pump food web .
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Earthlabs: The Carbon Cycle – Lab 6 http://serc.carleton.edu/eslabs/carbon /lab6.html
5. How are marine phytoplankton and forests similar in their role in the carbon cycle?
They both photosynthesize and draw down large amounts of CO2 from the atmosphere .
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Earthlabs: The Carbon Cycle – Lab 6 http://serc.carleton.edu/eslabs/carbon /lab6.html
1.
How do seasons affect the size and distribution of phytoplankton blooms?
In the Northern Hemisphere, phytoplankton reproduce rapidly in the Spring and into the Summer due to increased sunlight and mixing of nutrients.
2.
Where and when is primary production and the draw-down of carbon into the biological pump the strongest?
Areas of upwelling along coastlines where nutrients are upwelled and also run-off from land.
3.
Examine the image of chlorophyll and nitrogen(nitrate) concentration on the above right. Click to enlarge.
What evidence from these images tells you that nitrogen is a limiting factor on phytoplankton primary production? List all the evidence that you can. Note:
Nitrogen measurements are made from oceanographic ships and ocean buoys.
Chlorophyll measurements are derived mostly from satellite data.
Where nitrogen (nitrate) levels are low, chlorophyll levels are low indicating low phytoplankton population growth. Conversely, where nitrogen levels are high, chlorophyll levels are also high indicating high phytoplankton population growth.
4.
Explain why areas of upwelling and river deltas contribute to a stronger biological pump. Nitrogen and phosphorus from fertilizer run-off into rivers and are carried out to oceans. Nitrogen and other nutrients come up to surface waters from deep ocean currents in areas of upwelling.
5.
What is Trichodesmium's role in the nitrogen cycle? How does this role affect the ocean's biological pump.
Trichodesium fix nitrogen gas into ammonia which is a type of nitrogen compound phytoplankton can use. Phytoplankton use the nitrogen to build their DNA and protein molecules .
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Earthlabs: The Carbon Cycle – Lab 6 http://serc.carleton.edu/eslabs/carbon /lab6.html
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Earthlabs: The Carbon Cycle – Lab 6 http://serc.carleton.edu/eslabs/carbon /lab6.html
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