Lecture 2 Flashcards
(42 cards)
Why is carbon cycle important?
Sustaining biosphere.
Why is carbon important?
Fixing solar energy for entire ecosystem (photosynthesis)
How is carbon cycled and exchanged?
Photosynthesis, decomposition, respiration, and mineralisation.
What are heterotrophs?
Other feeders, cannot make their own food.
Oxidising organic molecules consumed from other organisms.
What are the heterotrophs processes?
Fermantation: anoxic environment, ferment carbohydrates to produce ethanol and other compounds.
Anaerobic respiration: some microorganisms use nitrate, sulphates and CO2 as electron acceptors in absence of oxygen.
Aerobic respiration: organic material completely oxidised to CO2+H2O
What are autotrophes?
Self feeders, use external source of energy, such as sunlight or chemically reduced matter
Where to autotrophic organisms derive carbon from?
Photosynthesis .
Oxygenic
CO2 + H2O -> (CH2O)n + O2
Anoxygenic
CO2 + H2S -> (CH2O)n + So
what are fast fluxes of carbon?
removal of CO2 from environment due to photosynthesis.
How is CO2 returned to environment?
Byproduct of respiration.
What is organic decomposition?
fungi and bacteria obtain organic material from dead sources.
produces CO2 and H2O, consumes O2.
What are primary factors determining terrestrial carbon?
Rain water and snow melt water.
What accounts for 90% of carbon flux between land and water?
Bicarbonate. (controls pH of natural waters)
Four forms of oceanic carbon.
DOC, DIC, POC, and marine biota itself.
Main mechanism of carbon removal in oceans?
Burial in sediments. Does not approach intake. 10000 year residence time.
Why does adding CO2 to atmosphere take hundreds of years to recalibrate?
Ability of carbon cycle to transport excess carbon away from atmosphere takes a long time.
What happens to CO2 from atmosphere?
Reduced by autotrophic organisms. Formula is: CO2 + H2O -> (CH2O)n + O2
What is gross primary production?
Total rate of photosynthesis consumed by respiration.
What is primary net production?
Rate of storage of organic matter in excess of respiration.
Largest reservoir of carbon.
Lithosphere. Very long turnover times.
How is carbon released from lithosphere?
Erosion (resides in ocean for 10^5 years).
Resides in lithosphere for 10^8 years.
Oxidation of reduced carbon?
C0(s) + O2 -> CO2
Dissolution of carbonates?
CaCO3 (s) + CO2 (g) + H2O -. Ca2+ (aq) + 2HCO3-(aq)
Impacts of human activity for carbon cycle.
Increased atmospheric CO2 by 50% since 1960 to today.
produce an excess 1000 metric tonnes of CO2 moved to atmosphere and hydrosphere.
Fossil fuels are carbon, and CO2 is released when burned. Removed from lithosphere moved to atmosphere. CO2 in atmosphere aborbs heat and re emits (greenhouse effect).
Deforestation and land-use changes also affect carbon cycle.
Increasing CO2 causes ocean acidification and temperature increases.
O2 is also consumed during combustion, concern for biodiversity.
Why is Nitrogen important?
Essential element of protein (growth and energy)
