Transcript How Does Nature Recycle Nutrients?

How Does Nature
Recycle Nutrients?
What is the Nitrogen Cycle?
► Facts:
Nitrogen (N) is an essential constituent of
protein, DNA, RNA, and chlorophyll.
► Nitrogen is the most abundant gas in the
atmosphere (78%), but it must be fixed or
converted into a usable form.
►
How is Nitrogen Fixed?
►
Nitrogen Fixation Methods:
►
High energy fixation- a small amount of atmospheric
nitrogen is fixed by lightening. The high energy combines
N and H2O resulting in ammonia (NH3) and nitrates (NO3).
These forms are carried to Earth in precipitation.
►
Biological fixation: achieves 90% of the nitrogen
fixation. Atmospheric nitrogen (N2) is split and combined
with hydrogen (H) atoms to eventually form ammonia
(NH3).
Who Performs Nitrogen Fixation?
Symbiotic bacteria (eg. Rhizobium spp.) living in
association with leguminous (plants in the pea/bean
family).
- free-living anaerobic bacteria
- blue-green algae (cyanobacteria)
 Ammonification: Once NH3 is in the soil it combines with
H+ ions to form ammonium ion (NH4), or without it to form
NO3. NH4+ and NO3 are readily absorbed by plants.
 Nitrification: is the biological oxidation of ammonia with
oxygen into nitrite followed by the oxidation of these
nitrites into nitrates (bacteria)
 Denitrification: Bacteria reduces nitrates and nitrites back
into gaseous nitrogen (N2)

The Nitrogen Cycle
What is the Carbon Cycle?
► All life is based on the element carbon.
► Carbon is the major chemical constituent
of most
organic matter, from fossil fuels to the complex
molecules (DNA and RNA) that control genetic
reproduction in organisms.
► Yet by weight, carbon is not one of the most
abundant elements within the Earth's crust. In
fact, the lithosphere is only 0.032 % carbon by
weight.
► In comparison, oxygen and silicon respectively
make up 45.2 % and 29.4 % of the Earth's
surface rocks.
The Carbon Cycle
Where is Carbon Stored
► Living
Organisms (organic molecules)
► Sedimentary Rock (limestone, dolomite)
► Shells of marine organisms (calcium
carbonate)
► Fossil Fuels
► Carbon Dioxide in our atmosphere
► Organic matter in our soils
What is the Phosphorus Cycle?
►
Component of DNA, RNA, ATP, proteins and enzymes
►
Cycles in a sedimentary cycle
- A good example of how a mineral element becomes part of an
organism.
►
The source of Phosphorus (P) is rock.
►
It is released into the cycle through erosion or mining.
►
It is soluble in H2O as phosphate (PO4)
►
It is taken up by plant roots, then travels through food chains.
►
It is returned to sediment
The Phosphorus Cycle
What is the Oxygen Cycle?