Lecture 12- Carbon cycles and elevated CO2 Flashcards
How many gigatons of Carbon are there in the deep ocean?
-38 100 -by far the most
How many gigatons of Carbon are there in the vegetation on land and in the marine biota? What does this mean for photosynthesis?
-610 in land vegetation -3 in marine biota -almost as much photosynthesis takes place in the sea as on land, means the photosynthetic life in the sea turns over quickly and is more efficient
How many gigatons of Carbon are released by humans into the atmosphere via fossil fuel burning etc?
-4000 -significant amount
What does the ocean carbon cycle look like?
-

What is the equation for the ocean carbon cycle?
-

What is H2CO3?
-carbonic acid
What is HCO3-?
-bicarbonate
What is CO3 2-?
-carbonate
What is the most abundant form of carbon in the sea?
HCO3- = bicarbonate, 98% -CO2=around 1% -CO3 2-= around 1%
What are the two things carbon can do when it gets into the sea?
- can either sink (100 gigatonnes)
- or exchange with the atmosphere (about 92 gigatonnes do that)

How much of dissolved organic carbon is there in the sea?
-700 gigatonnes
What are the two processes that drive C into the deep ocean?
1) Solubility Pump 2) Biological Pump
How does the solubility pump work?
- CO2 is more soluble in cold water and cold water is deeper, CO2 follows the solubility gradient
- moves passively

How does the biological pump work? (2)
- -all living organisms have lot of C, they due and their remains/shells sink deeper into the ocean
- -lot of predators hide at night in the deep sea, come out during the day to feed, eat other organisms and retreat back, taking the C with them

How much C of the biological pump is coccolith sedimentation responsible for?
-Coccolith sedimentation ~25% of C transport to deep ocean
How much of the ocean floor is covered by calcareous ooze?
-Calcareous ooze covers 48% of oceans sea floor -comes from Calcium carbonate so driven by haptophytes
How much of the ocean floor is covered by siliceous ooze?
-Siliceous ooze covers 15% of oceans sea floor
What are the current levels of atmospheric CO2?
-Atmospheric CO2 has fluctuated over geological time, however we are entering unprecedented high levels (>100ppm higher than ever before)
What may happen as more C is deposited in the ocean (solubility pump)?
-as temperatures rise -the solubility gradient may be disrupted -more C on top
How can the biological pump be affected by the increased atmospheric CO2?
-not clear, need to consider: 1.-What factors increase primary productivity? a) available nutrients (upwellings/mixing/dust),storms 2.What factors decrease primary productivity? a) nutrient deprivation (water column stratification)
Can increased C in the sea increase productivity?
-it can -but it is not usually limiting, mostly P, Ni and Fe are needed
Has primary production increased or decreased since 1998-2006?
- 1998-2000 increased - 2000-2006 decreased
How have the Arctic phytoplankton blooms been affected by the elevated CO2?
-some occur up to 50 days earlier -may last only 14 days -some delayed -potential impacts for down-stream food chain as very seasonal life in the Arctic
What will happen to the ocean pH as the CO2 increases?
-it will acidify (decrease)


