Transcript Review of Carbon, Nitrogen and Phosphorus Cycles

Review of Carbon, Nitrogen and
Phosphorus Cycles
The Carbon Cycle
Carbon Moves From:
• Atmosphere to plants
(C02 pulled from air to use
in photosynthesis)
• Plants to animals
(animals eat plants or other
animals)
• Plants and animals to
soils
(decaying bodies release
carbon into the soil)
• Living things to
atmosphere
(as you exhale, release CO2)
Concerns for Humans
• CO2 is a greenhouse gas that traps heat in the
atmosphere.
• Burning fossil fuels has added 5.5 billion tons
per year of carbon to the atmosphere (a 30%
increase over the past 150 years)
• The increased Carbon is causing the planet to
become warmer.
The Nitrogen Cycle
• 80% of Nitrogen is in the
atomosphere
(it is not in a form that
humans can use: needs
to be broken down by
lightning, fire or bacteria)
• Animals get nitrogen to
make amino acids by
eating plants
(when animals/plants die,
decompose and return
nitrogen to soil)
Concerns for Humans
• The use of nitrogen rich fertilizers, causes too
much nitrogen to be added to waterways via
runoff.
• Animal wastes associated with farming add
more nitrogen to soil and water.
• Burning fossil fuels fixes nitrogen from the air.
• High concentrations of nitrogen in the water
causes “algae blooms”: toxic to fish and
shellfish.
The Phosphorus Cycle
• No atmosphere
connection. Phosphorus
added by animal waste,
runoff and rock erosion.
(Plants hydrolyze the
phosphorus; animals
eat the plants. Decaying
plants and animals and
animal wastes return
phosphorus to the soil.)
Concerns for Humans
• Phosphorus run off leads to eutrophication
• Eutrophication: a process whereby water
bodies, such as lakes, estuaries, or slowmoving streams receive excess nutrients that
stimulate excessive plant growth (algae and
nuisance plants weeds). This enhanced plant
growth reduces dissolved oxygen in the water
when dead plant material decomposes and
can cause other organisms to die.