Lecture 6 Flashcards
carbon cycle
Carbon
- 4th most abundant element
- organic (reduced and reactive) or inorganic (oxidized and less reactive, CO2)
organic carbon _______s to create _______
oxidizes, inorganic carbon
cellular respiration, opposite for photosynthesis
3 species of carbon in the ocean
co2 (acidic), HCO3 bicarbonate (neutral), CO3 carbonate (basic)
residence time
average length of time a molecule will cycle through a reservoir in a steady state
residence time of carbon shortest to longest
CO2, mixe dlayer of ocean, land/bio, deep
characteristic response time
how long it takes for a reservoir to react once it falls out of a steady state
CO2 fertilization
Photosynthesis rates increase to compensate for increasing CO2 in order to return to steady state
residence time = characteristic response time
short term carbon cycle
- Photosynthesis move inorganic carbon into organic carbon system
- Anaerobic respiration occurs in absence of O2 (methanogenesis)
- Aerobic respiration of decomposers
- methane oxidation
- respiration of plants and animals
primary productivity
○ Autotrophs
○ Amount of organic material produced by photosynthesis in a unit area over a unit of time (kg/m2/yr)
○ Most of biomass in terrestrial landscapes is stored in tree trunks and roots (big forests)
the biological pump
the ocean
taking carbon from mixed layer/surface and transport to deep layer
- through phytoplankton and zooplankton
what happens to upper ocean in the biological pump
depleted of nutrients and dissolved carbon but rich in oxygen and photosynthesis
deep oceans in the bio pump and carbon cycle
nutrient rich as organic matter settles and use O2 to decompose and CO2 is liberated
- CO2 rich and colder
where does most productivity occur
along the coasts
- more mixing going on so more stuff available and more mixing towards poles due to reduced thermal gradient
carbon sinks vs sources
carbon sinks - coastal and cold water
sources - coastal and warm waters
what happens when co2 enters ocean
dissolves in water, reacts into carbonic acid, liberates hydrogen and bicarbonate ion, and further into hydrogen and carbonate
ocean acidification process
- Adding CO2 slowly decreases ph because it is using up carbonate
- Decreases buffering capacity of seawater and drives system to the left
Leaks
Organics sequestered into sediments
- carbons that survive dissolution leak into rock cycle for long term sequestration
carbon compensation depth
depth in the ocean at which CaCO3 cannot exist
long term carbon cycle
carbonate rock formation, storage in rocks, weathering,
carbonate rock formation
areas above CCD will form carbonate rocks, eventually buried by ocean conveyor belt past the CCD
carbon stored in what kinds of rocks
limestone, sed rocks, fossil fuels, soils, sediments
in that order of most to least
types of weathering
organic in sedimentary rocks - oxidization
chemical weathering of carbonates and silicate rocks - when CO2 in rain reacts
Tectonic forcing
moving continents change climate on long time scales
- alters distribution of land masses and climate patterns
- more uplift means more weathering and more CO2 drawdown
- Carbon isotopes tell us
○ Changes in carbon cycle
○ Estimate oxygen concentrations
- Rough estimates of partial pressure of CO2
Three main isotopes of carbon
○ Carbon 12 - stable, light - 99% of naturally abundant carbon
○ Carbon 13 - stable - 1%, heavier means more C13 than the standard, positive values
- Carbon 14 - radioisotope - super small
Plants prefer C__ resulting in negative delta C__
12, 13
carbon 13 ___ in summer and ___ in winter
increases, decreases, because C12 gets used by plants more in summer
buried organic carbon is ____ light/heavy
light, so the left over in atmosphere and oceans is heavy
the faster organic carbon is buried, the heavier the carbonates will be
