How Does Nature How Does Nature Recycle Nutrients?Recycle Nutrients?

What is the Nitrogen Cycle?What is the Nitrogen Cycle?

►Facts:Facts: ► Nitrogen (N) is an essential Nitrogen (N) is an essential

constituent of protein, DNA, RNA, and constituent of protein, DNA, RNA, and chlorophyll.chlorophyll.

► Nitrogen is the most abundant gas in Nitrogen is the most abundant gas in the atmosphere (78%), but it must be the atmosphere (78%), but it must be fixed or converted into a usable form. fixed or converted into a usable form.

                      

How is Nitrogen Fixed?How is Nitrogen Fixed?

► Nitrogen Fixation Methods:Nitrogen Fixation Methods:

► High energy fixation-High energy fixation- a small amount of a small amount of atmospheric atmospheric  nitrogen is fixed by lightening. The high energy  nitrogen is fixed by lightening. The high energy combines N and Hcombines N and H22O resulting in ammonia (NHO resulting in ammonia (NH33) and ) and nitrates (NOnitrates (NO33). These forms are carried to Earth in ). These forms are carried to Earth in precipitation. precipitation.

► Biological fixationBiological fixation: achieves 90% of the nitrogen : achieves 90% of the nitrogen fixation. Atmospheric nitrogen (Nfixation. Atmospheric nitrogen (N22) is split and ) is split and combined with hydrogen (H) atoms to eventually combined with hydrogen (H) atoms to eventually form ammonia (NHform ammonia (NH33). ).

Who Performs Nitrogen Who Performs Nitrogen Fixation?Fixation?

Symbiotic bacteriaSymbiotic bacteria (eg. Rhizobium spp.) living in (eg. Rhizobium spp.) living in association with leguminous (plants in the pea/bean association with leguminous (plants in the pea/bean family).family).                                    - free-living anaerobic bacteria   - free-living anaerobic bacteria                    - blue-green algae (cyanobacteria                   - blue-green algae (cyanobacteria) )

AmmonificationAmmonification: Once NH: Once NH33 is in the soil it combines is in the soil it combines with H+ ions to form ammonium ion (NHwith H+ ions to form ammonium ion (NH44), or ), or without it to form NOwithout it to form NO33. NH. NH44

++ and NO and NO33 are readily are readily absorbed by plants. absorbed by plants.

NitrificationNitrification: is the biological oxidation of ammonia : is the biological oxidation of ammonia with oxygen into nitrite followed by the oxidation of with oxygen into nitrite followed by the oxidation of these nitrites into nitrates (bacteria)these nitrites into nitrates (bacteria)

DenitrificationDenitrification: Bacteria reduces nitrates and : Bacteria reduces nitrates and nitrites back into gaseous nitrogen (Nnitrites back into gaseous nitrogen (N22))

The Nitrogen CycleThe Nitrogen Cycle

What is the Carbon Cycle?What is the Carbon Cycle?

► All life is based on the element All life is based on the element carboncarbon..► Carbon is the major chemical constituent of Carbon is the major chemical constituent of

most organic matter, from fossil fuels to the most organic matter, from fossil fuels to the complex molecules (DNA and RNA) that complex molecules (DNA and RNA) that control genetic reproduction in organisms. control genetic reproduction in organisms.

► Yet by weight, carbon is not one of the most Yet by weight, carbon is not one of the most abundant elements within the Earth's crust. abundant elements within the Earth's crust. In fact, the lithosphere is only 0.032 % In fact, the lithosphere is only 0.032 % carbon by weight. carbon by weight.

► In comparison, oxygen and silicon In comparison, oxygen and silicon respectively make up 45.2 % and 29.4 % of respectively make up 45.2 % and 29.4 % of the Earth's surface rocks.the Earth's surface rocks.

The Carbon CycleThe Carbon Cycle

Where is Carbon StoredWhere is Carbon Stored

►Living Organisms (organic molecules)Living Organisms (organic molecules)►Sedimentary Rock (limestone, Sedimentary Rock (limestone,

dolomite)dolomite)►Shells of marine organisms (calcium Shells of marine organisms (calcium

carbonate)carbonate)►Fossil FuelsFossil Fuels►Carbon Dioxide in our atmosphereCarbon Dioxide in our atmosphere►Organic matter in our soilsOrganic matter in our soils

What is the Phosphorus What is the Phosphorus Cycle?Cycle?

► Component of DNA, RNA, ATP, proteins and enzymesComponent of DNA, RNA, ATP, proteins and enzymes

► Cycles in a sedimentary cycleCycles in a sedimentary cycle         - A good example of how a mineral element becomes         - A good example of how a mineral element becomes part of an organism.part of an organism.

► The source of Phosphorus (P) is rock.The source of Phosphorus (P) is rock.

► It is released into the cycle through erosion or mining.It is released into the cycle through erosion or mining.

► It is soluble in HIt is soluble in H22O as phosphate (POO as phosphate (PO44))

► It is taken up by plant roots, then travels through food It is taken up by plant roots, then travels through food chains.chains.

► It is returned to sedimentIt is returned to sediment

The Phosphorus CycleThe Phosphorus Cycle

What is the Oxygen Cycle?What is the Oxygen Cycle?