EQ1 6.2 Flashcards
What role do phytoplankton play in the carbon cycle?
Phytoplankton absorb atmospheric CO₂ through photosynthesis in the ocean’s surface, sequestering carbon as organic material.
Three types of ocean pumps
- Physical
- Carbonate
- Biological
What is the biological pump?
- Phytoplankton absorb CO2 = CO2 becomes organic matter
- Phytoplankton die - carbon in form of organic matter sinks from surface to deep ocean
What is the carbonate pump?
Marine organisms form calcium carbonate shells that sink to the ocean floor after death, storing carbon in the deep ocean or in sediments.
What is the physical pump and how does it relate to carbon sequestration?
- At poles, warm tropical water evaporates = water is colder and saltier = denser so sinks (downwelling)
- Downwelling forces water already there to move = pumps water down
- Surface winds = warm tropical water brought up to replace sunken water
How do terrestrial primary producers sequester carbon?
Through photosynthesis where they absorb CO₂ from the atmosphere and convert it into organic carbon, which is stored in their biomass
What happens to some of the carbon stored by terrestrial primary producers?
Returned to the atmosphere through respiration by consumer organisms
How is biological carbon stored in ecosystems?
Carbon is locked up in leaves, shoots, roots and bark and then transferred into soil upon decomposition by soil biota.
How do peat conditions affect carbon sequestration?
- Wet = slower anaerobic decay = LT carbon sink
- Dry = aerobic decay = releases CO2 into atmosphere
But water-logged peatlands = methane release due to decomposition
What are peatlands?
Waterlogged landscapes where the water table is significantly high.
e.g. wetlands, bogs, swamps, and marshes
What happens to vegetation in peatlands?
Due to anaerobic conditions, the vegetation partially decays = carbon stored in the dead vegetation is preserved = peatlands are a huge global store of carbon
