lec 12 carbon cycle pt 1

carbon useful to form molecules because

can form 4 strong bonds with other elements and enter ring formations

to break carbon bonds

energy is required, stable at room temperature

exothermic because

more energy is released by a broken carbon bond than is needed to break the bond

in presence of oxygen, the reaction of carbon bond breaking is

combustion

large carbon molecules are reservoirs of

stable, stored energy e.g. sugars and fats for life, fossil fuels

we can only have a stable temperature and liquid water because of

presence of carbon in the atmosphere

carbon cycle is

the movement of carbon through abiotic and biotic reservoirs

carbon source

a reservoir releasing more carbon than received

carbon sink

a reservoir receiving more carbon than released

Gt

billion tons

aspects within the carbon cycle grouped based on

timescale and whether organic or inorganic reservoirs

inorganic carbon cycle

cycling of carbon between only the ocean, rocks, and atmosphere on millions of years timescale

reservoirs of inorganic C cycle

oceans, atmosphere, and rock

linkages of inorganic C cycle

precipitation, chemical weathering, solubility pump, deposition, volcanism, and mountain building

precipitation

water moving from atmosphere to terrestrial reservoirs

rain is naturally acidic because

atmospheric CO2 naturally reacts with water vapor in atmosphere to form carbonic acid

when carbonic acid rainwater hits oceans

carbon moving directly from atmopshere to ocean in slightly acidic water

when carbonic acid rainwater hits land

it interacts with minerals in chemical weathering

chemical weathering

chemical breakdown of larger minerals, which releases elements, ions, and molecules

carbonic acid reacts with exposed rock to release

calcium ions and bicarbonate ions, eventually washed into the ocean with surface runoff

solubility pump

direct exchange of carbon between atmosphere and ocean because of reservible reaction involving carbonic acid formation/decomposition

movement of CO2 into ocean relies on

random movement of molecules in gaseous atmosphere and then coming into contact with the ocean surface

deposition

chemical transformation from ocean reservoir to sedimentary rock reservoir through depositing of sediment

deposition steps

calcium and carbonate ions combine in solution to form calcium carbonate, which deposits on the ocean floor over time to form mineral deposit rocks

volcanism

melting of rocks and gases rise towards surface, ultimately emerging into atmosphere

subduction

often causes volcanism, tectonic plate is pushed under another

volcanism byproducts differ depending on

chemical composition of rocks, CO2 released by carbonate rocks along with melted minerals

new rock produced by volcanism exposed to

chemical weathering, with greater amounts of minerals

mountain-building events

formation of elevated rock regions due to continental drift or volcanism, ends up exposing new rock to chemical weathering

over long term, inorganic aspects of C cycle are

self-regulating, in a negative feedback loop

snowball earth may have emerged from a

positive feedback loop due to increased rainfall weathering, sequestration of CO2 in rocks, lowering of temperature, higher albedo from continents, further lowering of temperature, ice formation and further albedo and temperature lowering

we got out of snowball earth because

volcanism continued, low precip in the cold so less CO2 removed, greenhouse effect eventually warmed it up again