cycles oxygen

1. The Oxygen Cycle
Def: “The Oxygen cycle is the movement of
oxygen from the environment to orga-
nisms and then back to the environment”

2. Basic idea
Rabbit eats food,
breaks it down and
releases CO2.
Plant uses CO2
to make food.
Rabbit gives off CO2,
which is taken in by the plant.
Plant gives off O2,
which is taken in by the rabbit.
Photosynthesis:
6 CO2 + 6 H2O + light ------> C6H12O6 + 6O2
Respiration:
C6H12O6 + 6O2 ------> 6CO2 + 6H2O + energy

3. Oxygen
(atmosphere)
Respiration from plants
and animals
Respiration from
decomposers
Combustion
Carbon Dioxide
Photosynthesis by
green plants
Oxygen Cycle

4. The Carbon Cycle
Def: “The Carbon cycle is the movement of
carbon from the environment to orga-
nisms and then back to the environment”

5. Carbon in Atmosphere
Plants use
carbon to make
food
Animals eat
plants and
take in carbon
Plants and
animals die
Bodies not
decomposed —
after many
years, become
part of oil or coal
deposits
Fossil fuels are
burned; carbon
is returned to
atmosphere
Carbon slowly
released from
these substances
returns to
atmosphere
Carbon Cycle
Decomposers
break down dead
things, releasing
carbon to
atmosphere and
soil

6. Human Impact
• We keep destroying natural areas, especially forested areas
with many plants and replacing them with buildings, parking
lots, lawns, etc.
• Fewer plants mean less oxygen and more carbon dioxide.
• This disturbs the balance of the natural cycle.

7. More Human Impact
• Every time something burns (combustion), more carbon dioxide is released into
the atmosphere.
• We add more and more CO2 and destroy more and more of the plants that can
spoil the air.

8. What We Need to Do
• Stop destroying and promote regrowth of natural areas — especially
forests.
• Burn less (fossil fuels, forest fires, etc.)

9. The Nitrogen Cycle
Def: “The Nitrogen cycle is the movement of
nitrogen from the environment to orga-
nisms and then back to the environment”

10. • Nitrogen is required to make proteins and DNA which is the
genetic material found in every cell.
• Nitrogen gas composes 78% of the Earth’s atmosphere, but
in this inorganic form it can not be used by animals. In order
for nitrogen to be useful to organisms, it must be converted
to a nitrate ion (NO3
-) by the process of nitrogen fixation,
or nitrification, either by lightning or by bacteria in the soil.
Introduction

11. Atmospheric nitrogen (N2)
Plant protein
Animal protein
Death and decomposition
Ammonification (NH3)
Nitrification to nitrites (NO2
-)
Nitrification to nitrates (NO3
-)
Denitrifying bacteria
Nitrogen
fixing
bacteria
The Nitrogen Cycle
(NH3, NH4
+)

12. Nitrogen fixation - Conversion of atmospheric N2 to NH3 and NH4
+ ion
Assimilation- Conversion of inorganic NH3 and NH4
+ ion to organic nitrogen
Ammonification - Release of N from dead animals as NH3 and NH4
+
Nitrification - Conversion of NH3 and NH4
+ ion to nitrate NO3
-
Denitrification – Conversion of NO3
-, NH3 and NH4
+ to N2 and release back to the atmosphere
Process in Nitrogen Cycle
There are four major process in nitrogen cycle. These are called
Nitrogen Cycle steps.
“All these process are performed by microorganisms such as bacteria and algae.
Without these tiny species there is no multicellular organism will exist on this planet”

13. The Phosphorus Cycle
Def: “The Phosphorus cycle is the movement of
Phosphorus from the environment to orga-
nisms and then back to the environment”

14. Phosphorus Cycle
• The phosphorus cycle may also be referred to as the mineral cycle.
• Phosphorus is mainly found in water, soil and rock.
• Phosphorus is essential for life.
• Component of DNA
• Building block of our bones and teeth.
• Unlike the other cycles, phosphorus cannot be found in air in the gaseous state.
• The phosphorus cycle is the SLOWEST cycle.
• Phosphorus is most commonly found in rock formations and ocean sediments as
phosphate salts.
• Phosphate salts that are released from rocks through weathering usually dissolve in
soil water and will be absorbed by plants.
Definition ocean Sediments: Ocean sediments are unconsolidated
organic and inorganic particles that accumulate on the ocean floor
Weathering is the breaking down of rocks, soil and mineral as well as wood
and artificial materials through contact with the Earth’s atmosphere, water
and biological organisms.

15. Plant Phosphate
Decomposers
Animal Phosphate
Organic waste and remains
Phosphate in ocean sediments
Inorganic Phosphate
stored in soils and
dissolved in rivers
Run off to oceans
Weathering
Up lifting
Over time
Phosphorus Cycle
Phosphate from
fertilizers
Phosphate in
rocks and fossils

16. The Sulfur Cycle
Def: “The Sulfur cycle is the movement of Sulfur from the
environment to organisms and then back to the environment”

17. Human activities have affected the sulfur cycle primarily by releasing large
amounts of sulfur dioxide (SO2) into the atmosphere
We release sulfur to the atmosphere in three ways.
1. Burning sulfur-containing coal
2. Refining sulfur-containing oil (petroleum) to make gasoline
3. Extracting metals such as copper, lead, and zinc from their sulphide ores.

18. Sulphuric acid and sulphate
deposited as Acid rain
Decomposers
Animals
Organic waste and remains
ocean sediments
Sulfur
stored in soils, rocks
and fossil fuels
Run off to oceans
Up lifting
Over time
Phosphorus Cycle
Sulfur dioxide in
the atmosphere
Dimethyl sulfide
a bacteria byproduct
Plants
Human effects (Mining
extraction, coal burning and
refining of fossil fuels)
During oxidation

19. The Sulfur Cycle
Dimethyl sulfide- Acid rain
In the atmosphere, DMS is converted to sulfur dioxide, some of which
in turn is converted to sulfur trioxide gas (SO3) and to tiny droplets of
sulfuric acid (H2SO4)
DMS SO2
SO2
SO3
SO3
H2SO4
These droplets fall to the earth as components of acid deposition,
which along with other air pollutants can harm trees and aquatic life.
[O]
[O]
H2O