The Carbon cycle
The movement of carbon between
the biosphere, atmosphere, oceans,
and geosphere is described by
the carbon cycle.
Carbon is found everywhere
• In the atmosphere as CH4, CO2.
• In the bodies of all living things as
sugars, proteins, fats and DNA
• In everyday life things as fuels, plastics,
clothing, buildings (wood and concrete)
• Rocks such as limestone, marble,
diamonds and graphite
Carbon forms four strong bonds
with other elements
Carbon can share its electrons to form
CH4, methane
CO2, carbon dioxide
C6 H12 O6 glucose
C – graphite
C - diamonds
and many other compounds.
Hydrocarbons – made up of hydrogen and carbon
Methane is
part of natural
gas.
Ethane is part
of natural gas
and lab gas.
Propane and
Butane are
found in camp
ovens and
barbeques
http://www.bbc.co.uk/schools/gcsebitesize/img/gcsechem_72.gif
Hydrocarbons from crude oil
Crude oil, which comes
from under the ground
or sea bed, is a mixture
of hydrocarbons with
different chain lengths,
depending on the
number of carbons.
Crude oil is separated
into the different chain
lengths. These are then
used in many different
ways.
DNA –
lots of
carbons
http://upload.wikimedia.org/wikipedia/commons/4/4c/DNA_Structure%2BK
ey%2BLabelled.pn_NoBB.png
http://www.chemguide.co.u
k/organicprops/aminoacids
/doublehelix.gif
Methane
An important
greenhouse
gas
http://www.chm.bris.ac.uk/pt/harvey/gcse/ionic.html
Carbon dioxide
Carbon dioxide
http://en.wikipedia.org/wiki/File:Carbon-dioxide-3DvdW.svg
Carbon dioxide showing double O=C
bonds
http://en.wikipedia.org/wiki/File:Carbon_dioxide_structure.png
Dry ice
http://upload.wikimedia.org/wikipedia/commons/3/36/Dry_Ice_Pell
ets_Subliming.jpg
Atmospheric importance of CO2
CO2 is a greenhouse gas. This means that it
traps some of the Sun’s heat and keeps the
surface of Earth at a comfortable temperature.
http://nirantaradrusti.wordpress.com/2010/01/15/greenhouse-effect/
Release of carbon into atmosphere (1)
All organisms, plants, animals, fungi , bacteria
and protista respire.
This means that they break down food to gain
energy and release carbon dioxide as a waste
product into the air.
C6H12O6 + O2
glucose
CO2 + H2O + energy
Note where the carbon goes.
Release of carbon into atmosphere (2)
A big source of carbon
dioxide is the gases
from volcanic
eruptions.
This is Ngauruhoe
erupting in 1975.
Release of carbon into atmosphere (3)
Methane is released when animals burp and
give off flatulence.
CH4 methane
Note where the carbon is.
Release of carbon into atmosphere (4)
Methane can become trapped in ice and
permafrost to form methane ice. When the ice
is dug up or melts the methane escapes into
the atmosphere.
The methane in the ice can
be burnt which looks like the
water ice is burning
CH4 methane
Note where the carbon is.
Release of carbon into atmosphere (5)
When fuels burn, such as butane or petrol,
carbon dioxide is released as a waste product
into the air. E.g. combustion of
butane
C4H8 + 6O2
4CO2 + 4H2O + energy
Note:
Carbon dioxide is also released to the
atmosphere in the:
 decay of dead organic matter (methane
also)
 making of concrete
 warm oceans
Removal of carbon from the atmosphere (1)
By photosynthesis:
Plants take in carbon
dioxide from the air
and along with water
and sunlight make
simple sugars. These
sugars get made into
food.
CO2 + H2O + sunlight
O2 + C6H12O6
http://www.homestead-farm.net/art/kidsArt/photosynthesis-color.jpg
Removal of carbon from the atmosphere (1)
Phytoplankton
(marine plants) also
photosynthesize.
These are a primary
source of oxygen for
all living things.
CO2 + H2O + sunlight
O2 + C6H12O6
http://www.homestead-farm.net/art/kidsArt/photosynthesis-color.jpg
Removal of carbon from the atmosphere (2)
Absorbed by water: Carbon dioxide is also
absorbed by fresh and salt (ocean) water.
This makes a weak acid (carbonic acid). The
ocean absorbs massive amounts of CO2.
Cold water absorbs more than warm water. If
water becomes too warm some of the
absorbed carbon dioxide is released back into
the atmosphere.
Stormy cold seas absorb even more because
the wind agitates the water.
Carbon dioxide and the oceans:
This shows the exchange of carbon, or carbon flux between the
upper few metres of the ocean and lower atmosphere
http://www.niwa.co.nz/__data/assets/image/0006/49443/gas2_large.jpg
Carbon sinks or storage
A carbon sink is where carbon is stored for:
• short periods of time – from minutes to years
e.g. forests, phytoplankton, soils, permafrost,
atmosphere, all plants and animals
• long periods of time – for millions of years e.g.
the ocean, sediments, limestone, marble,
fossils, fossil fuels
Carbon sinks – the atmosphere
The atmosphere contains carbon dioxide and traces of
methane - 750 Gt (billions of metric tons).
The ocean is a huge carbon sink. CO2 is absorbed from
the atmosphere and is carried to the depths of the ocean
by currents such as the thermohaline current. Organic
matter such as dead phytoplankton also carry carbon to
the bottom of the ocean
Carbon sinks – the ocean
Absorption of
CO2 by the
ocean water
(40 000 Gt)
Cold oceans absorb much more carbon dioxide than
warm oceans. Rough water absorbs more than still
water. The Southern Ocean is a very important sink
because it is very cold and very stormy.
Carbon sinks – phytoplankton
Phytoplankton use carbon dioxide to make the delicate
platelets that can be seen in this photograph. When
they die the platelets fall to the ocean floor and become
part of the sediment that gradually forms limestone.
Carbon sinks on land
Carbon is stored short term in forests (as wood), soils
and land animals and plants. Any body is a short term
storage of carbon.
http://www.earthtimes.org/newsimage/forests-sucking-carbon_14711.jpg
Carbon sinks on land
Carbon in the form of organic material and methane is
also stored in permafrost (frozen ground) for longer
periods of time (1000s of years).
http://www.earthtimes.org/newsimage/forests-sucking-carbon_14711.jpg
Carbon sinks – landfills (rubbish dumps)
Landfills store
carbon in the
form of
rubbish,
organic and
inorganic e.g.
plastics, food,
cardboard and
paper
Long term storage of carbon in rocks such as
limestone (100 000 000 Gt)
The Pancake rocks and the limestone in caves were once on the
bottom of the ocean floor. The sediment containing
phytoplankton shells became layered and compressed,
eventually forming limestone rock.
Carbon sinks – sedimentary rocks
Sediments, which contain
both inorganic and organic
matter, build up in layers on
the bottom of the ocean.
The oldest layers are on
the bottom.
These layers get
compressed by the weight
of sediments accumulating
above, until rock is formed.
This rock may become
buried deeply.
Storage of carbon –fossils
Fossils are made when plants
and animals become
compressed under layers of
sediment. The fossils and the
sediment eventually get
changed to rock.
Carbon – fossil fuels (10 000 Gt)
Coal is fossilized carbon from
dead plants that have built up
and become compressed
over millions of years. Oil is
plants and animals
compressed on the bottom of
the ocean between layers of
sedimentary rock The
organic matter is changed to
hard coal or a layer of thick
liquid that is crude oil.
Yellow numbers are
natural movement of
carbon
Red are human
contributions in billions
of tons of carbon per
year.
White numbers indicate
stored carbon.
Biological sub-cycle (days to years)
carbon dioxide in the atmosphere
carbon removed
carbon released into atmosphere
Respiration in
photosynthesis in
animals (consumers in plants (producers)
herbivores, carnivores
Carbon stored
and omnivores)
short term in
forests
death
of animals
decomposers e.g.
bacteria and fungi
Death of plants
Yellow numbers are
natural movement of
carbon
Red are human
contributions in billions
of tons of carbon per
year.
White numbers indicate
stored carbon.
The rock sub-cycle
http://www.vtaide.com/png/images/carbonCycle2.jpg
Subduction and the Taupo volcanoes
http://www.teara.govt.nz/en/volcanoes/2/2
The rock sub-cycle
http://www.newscientist.com/data/images/archive/2675/26751901.jpg
The global carbon cycle involves the earth's atmosphere, fossil fuels, the oceans, and
the vegetation and soils of the earth's terrestrial ecosystems [Figure 2].
The Oceans & The Carbon Cycle:
http://www.topnews.in/usa/why-tectonic-plates-move-way-they-do-24873
Tectonic plate boundary through NZ
http://www.teara.govt.nz/en/geology-overview/1/1
http://www.vtaide.com/png/images/carbonCycle2.jpg
In the geological carbon cycle, carbon moves
between rocks and minerals, seawater, and the
atmosphere. Carbon dioxide in the atmosphere reacts
with some minerals to form the mineral calcium
carbonate (limestone). This mineral is then dissolved
by rainwater and carried to the oceans. Once there, it
can precipitate out of the ocean water, forming layers
of sediment on the sea floor. As the Earth’s plates
move, through the processes of plate tectonics, these
sediments are subducted underneath the continents.
Under the great heat and pressure far below the
Earth’s surface, the limestone melts and reacts with
other minerals, releasing carbon dioxide. The carbon
dioxide is then re-emitted into the atmosphere
through volcanic eruptions.
Rock sub-cycle (millions of years)
Ocean sub-cycle 10 – 100s years
carbon dioxide in the atmosphere
Photosynthesis
Warm surface ocean 2000 Gt
Mixing brings C back to surface
CO2 in warm ocean evaporates
back to atmosphere.
Absorbed / dissolved in ocean
forming weak carbonic acid
Respiration and
decomposition
sedimentation
C carried to bottom of ocean by deep
currents, stays for 100’s years.
Cold deep ocean contains 38 000 Gt