Transcript What is Nitrogen?

Cycling of
Matter in
Ecosystems
Biogeochemical Cycles
• Matter cannot be made or destroyed.
• All water and nutrients must be produced or
obtained from chemicals already present in
the environment.
• This happens through biogeochemical cycles the movement of matter through biotic and
abiotic environment.
• Nutrients are all the chemical substances that
an organism needs to survive.
• A nutrient cycle shows how nutrients move
between organisms and the environment.
• The following cycles are especially important:
• water cycle
• carbon cycle
• nitrogen cycle
• phosphorus cycle
In general,
• producers get nutrients from the soil
• consumers get nutrients from eating producers or
other consumers
• decomposers return nutrients to the soil through
decomposition
Recycling of Atoms
• Atoms last forever.
• All the atoms found on Earth today are the same as
those that were present when Earth first formed.
• Every atom that makes up your tissues has a history!
• Every 7 years each atom in your body is replaced
Carbon
Cycle
Carbon Cycle
• The biogeochemical cycle in which carbon is cycled through
the lithosphere, atmosphere, hydrosphere, biosphere.
• Carbon is an important element, because it is the basic
building block of living things.
• Carbon is recycled in the carbon cycle through several
processes, but mostly through photosynthesis and
respiration.
• The concentration of carbon in living matter (18%)is almost
100 times greater than its concentration in the earth
(0.19%).
• So living things extract carbon from their non-living
environment.
• For life to continue, this carbon must be recycled.
What’s So Special About Carbon?
• Carbon is important for many processes
– Photosynthesis and Respiration
– Animal shells
– Getting energy (fossil fuels)
Where is all the Carbon?
• Inorganic Carbon
– The
Atmosphere
– The Ocean
– The Earth’s
Crust
• Organic Carbon
– Bodies of
Living Things
– Fossil Fuels
• Most of the carbon on earth is locked up in the
crust in limestone rocks: CaCO3
• Some is in living & dead biological tissue
(biomass)
Some is in fossil fuels:
coal, crude oil and natural
gas.
Coal = carbon
Methane = CH4
• Some is in the atmosphere as CO2
• A lot is dissolved in seawater as:
- carbonate (CO32-)
- bicarbonate (HCO3-)
- carbonic acid (H2CO3)
- carbon dioxide (CO2)
Carbon enters the biotic world through
the action of autotrophs
• Primarily photoautotrophs, like plant and algae
that use the energy of light to convert CO2 to
organic matter.
Carbon returns to the atmosphere by
• respiration (as CO2)
• burning
• Decay (producing CO2 if oxygen is present,
methane (CH4) if O2 is absent.
The uptake and return of CO2 are not in
balance.
Photosynthesis
Short
Carbon
Cycle
Cellular Respiration
Carbon
Dioxide
Bacteria
When organisms die, their
carbon molecules are returned
to the soil by decomposers and
are released to the air as carbon
dioxide.
Sometimes dead organisms are
changed over millions of years into
carbon-based fossil fuels like coal and
gas
Human Impact on the Carbon Cycle
• Humans are having a big impact on the Carbon Cycle
by:
– releasing carbon into the atmosphere faster than
would normally occur by burning fossil fuels,
returning to the atmosphere carbon that has been
locked within the earth for millions of years.
– Clearing away vegetation. In recent decades, large
amounts of Amazon rain forest have been cleared
for agriculture and cattle grazing.
• The carbon dioxide content of the atmosphere is
gradually and steadily increasing
– Since measurement of CO2 began in the late 19th
century, its concentration has risen over 20%.
The Greenhouse Effect
1. Sun’s rays enter the
Earth’s atmosphere
2. Heat is reflected
back from the
Earth’s surface
3. Heat is absorbed by
carbon dioxide
(greenhouse gas)
and as a result
becomes trapped in
the Earth’s
atmosphere
4. The Earth becomes
hotter as a result
Home Fun! 
• Page 51
– Q 3, 4, 5b
• Page 69
– Q 20
• Page 70
– Q 8, 14