Biological processes sequestering carbon Flashcards
What is carbon sequestration?
Carbon sequestration is the process by which carbon dioxide is removed from the atmosphere and held in solid or liquid form.
It is the process that facilitates the capture and storage of carbon.
Compared with its geological counter part, does biological sequestering operate on longer or shorter time scales?
Shorter
The oceanic store of carbon is larger how many times that of the atmosphere?
50
In what is the most of the oceanic carbon stored in?
Marine algae, plants and coral.
What are carbon pumps?
Carbon pumps are the processes operating in the oceans that circulate and store carbon.
What are the three types of oceanic carbon pumps?
Biological pump
Physical pump
Carbonate pump
What is the biological pump?
Biological pumps move carbon dioxide from the ocean surface to marine plants (phytoplankton) by a process known as photosynthesis.
This effectively converts carbon dioxide into food for zooplankton (microscopic animals) and their predators. Most of the carbon dioxide taken up by phytoplankton is recycled near the surface. About 30% sinks into deeper waters before being converted back into carbon dioxide by marine bacteria.
What is the physical pump?
Physical pumps move carbon compounds to different parts of the ocean in downwelling and upwelling currents. Downwelling occurs in those parts of the oceans where cold, denser water sinks. These currents bring dissolved carbon dioxide down to the deep ocean. Once there, it moves in slow-moving deep ocean currents, staying there for hundreds of years.
Eventually, these deep ocean currents, part of the thermohaline circulation, return to the surface by upwelling.
The cold deep ocean water warms as it rises towards the ocean surface and some of the dissolved carbon dioxide is released back into the atmosphere.
What is the carbonate pump?
Carbonate pumps form sediments from dead organisms that fall to the ocean floor.
Particularly significant here are the hard outer shells and skeletons of crustaceans, fish and corals.
All are rich in calcium carbonate.
What does phytoplankton consist of?
Phytoplankton consists of the microscopic plants and plant-like organisms drifting ot floating in the sea (or freshwater) along with diatoms, protozoa and small crustaceans.
What is photosynthesis?
Photosynthesis is the process by which green plants and some other organisms use sunlight to synthesise (extract) nutrients from carbon dioxide and water.
What is the thermohaline circulation?
The thermohaline circulation is the global system of surface and deep ocean currents driven by temperature (thermo) and salinity (haline) differences between different parts of the oceans.
Process of terrestrial sequestering
Plants sequester carbon out of the atmosphere during photosynthesis. In this way, carbon enters the food chains and nutrient cycles of terrestrial ecosystems.
When animals eat plants, carbon sequestered in the plant becomes part of their fat and protein.
Respiration, particularly by animals, returns some of the carbon back to the atmosphere. Waste from animals is eaten by micro-organisms (bacteria and fungi) and detritus feeders (e.g. beetles).
As a consequence, carbon becomes part of these creatures. When plants and animals die and their remains fall to the ground, carbon is released into the soil.
Carbon fluxes within ecosystems vary on which two timescales?
Diurnally: during the day, fluxes are positive - that is, from the atmosphere into the ecosystem; at night the reverse situation applies.
Seasonally: during winter, carbon dioxide concentrations increase because of the levels of plant growth. However, as soon as spring arrives and all plants grow again, those concentrations begin to decrease until the onset of autumn.
By weight, how much of the human body is carbon as a percentage?
18%
