Transcript Hydraulics - LJ Create Ltd

Nutrient Cycles
In this presentation you will:
 Identify the stages of the carbon and nitrogen cycles
 Investigate the causes of rising carbon dioxide levels
 Explore the impact of the over-use of nitrogen based fertilizers
ClassAct SRS enabled.
Nutrient Cycles
Nutrient cycles summarize the
movement of certain elements
through ecosystems.
In this presentation you will
study the carbon and nitrogen
cycles. You will identify the
different stages of these cycles
and investigate their
importance. You will also
investigate how human activity
can disturb the natural balance
of these cycles and cause
pollution.
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Nutrient Cycles
Nutrient Cycles
Nutrient cycles summarize the
movement of certain elements
through ecosystems.
Elements may be combined to
form complex organic molecules.
These later decompose to form
simpler organic and inorganic
molecules.
These simpler molecules can be
used again to become
incorporated into living things.
This is called the cycling pool.
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Nutrient Cycles
Upsetting the Balance
As well as the cycling pool of an
element, all cycles have a larger
reservoir pool. This is usually
abiotic, that is, not made up of
living things.
Exchanges between the reservoir
and the biotic cycling pools usually
happen slowly.
Human activity often speeds up the
movement of molecules through the
cycles. This may upset the natural
balance, cause build up of substances
at one point and cause pollution.
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Nutrient Cycles
Question 1
Which part of a nutrient cycle involves living organisms?
A) The cycling pool
B) The reservoir pool
C) Both the cycling and the
reservoir pool
D) Neither the cycling nor
the reservoir pool
Nutrient Cycles
The Carbon Cycle – An Overview
C = Carbon
HCO3- = Hydrogen Carbonate
Photosynthesis
CO2 in atmosphere
Respiration
Flow of carbon in
thousands of Tg/year
Tg = Terragram
1 Tg = 1 million metric tons
1 metric ton = 1000kg
Diffusion
Animals
Death
Death,
Excretion
Combustion
C in
detritus
Respiration
CO2 in water
(HCO3- ions)
Animals
Photosynthesis
Detrivores,
Decomposers
Rocks in
the Earth
C in humus
Fossil fuels eg coal, oil
Respiration by
detrivores and
decomposers
Death,
Excretion
C in algae
Death
C in detritus
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Nutrient Cycles
There are 4 large reservoirs of carbon:
the atmosphere, the oceans, limestone rocks and fossil fuels.
Photosynthesis
CO2 in atmosphere
Respiration
Flow of carbon in
thousands of Tg/year
Tg = Terragram
1 Tg = 1 million metric tons
1 metric ton = 1000kg
Diffusion
Animals
Death
Death,
Excretion
Combustion
C in
detritus
Respiration
CO22 in water
(HCO33 -- ions
ions))
Animals
Photosynthesis
Detrivores,
Decomposers
Rocks in
the Earth
C in humus
Fossil fuels eg coal, oil
Respiration by
detrivores and
decomposers
Death,
Excretion
C in algae
Death
C in detritus
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Nutrient Cycles
The processes that put carbon dioxide into the atmosphere are:
respiration, combustion and diffusion.
Photosynthesis
CO2 in atmosphere
Respiration
Flow of carbon in
thousands of Tg/year
Tg = Terragram
1 Tg = 1 million metric tons
1 metric ton = 1000kg
Diffusion
Diffusion
Animals
Death
Death,
Excretion
Combustion
Respiration
C in
detritus
Respiration
CO2 in water
(HCO3- ions)
Animals
Photosynthesis
Detrivores,
Decomposers
Rocks in
the Earth
C in humus
Fossil fuels eg coal, oil
Respiration by
detrivores and
decomposers
Death,
Excretion
C in algae
Death
C in detritus
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Nutrient Cycles
The processes that remove carbon dioxide from the atmosphere are:
photosynthesis and diffusion.
Photosynthesis
CO2 in atmosphere
Respiration
Flow of carbon in
thousands of Tg/year
TG = Terra Ton
1 Tg = 1 million metric tons
1 metric ton = 1000kg
Diffusion
Diffusion
Animals
Death
Death,
Excretion
Combustion
C in
detritus
Respiration
CO2 in water
(HCO3- ions)
Animals
Photosynthesis
Detrivores,
Decomposers
Rocks in
the Earth
C in humus
Fossil fuels eg coal, oil
Respiration by
detrivores and
decomposers
Death,
Excretion
C in algae
Death
C in detritus
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Nutrient Cycles
Question 2
Which of the following processes does not put carbon dioxide back
into the atmosphere?
A) Photosynthesis
B) Combustion
C) Respiration
D) Decomposition
Nutrient Cycles
The Carbon Dioxide Balance
There is a balance between the
carbon (in carbon dioxide)
stored in the atmosphere and the
amount of carbon (in hydrogen
carbonate ions) stored in the
sea.
There is also a fine balance
between the amount of carbon
dioxide removed from the air by
photosynthesis and the amount
replaced by respiration.
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Nutrient Cycles
Upsetting the CO2 Balance
Despite the fact that these
processes maintain a natural
balance, the level of carbon
dioxide in the atmosphere is
still rising.
This is because the burning
of fossil fuels and wood
releases carbon dioxide into
the atmosphere.
In addition to this, deforestation
removes large areas of trees that
would have absorbed large
quantities of carbon dioxide for
photosynthesis.
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Nutrient Cycles
Question 3
Why does deforestation result in increased carbon dioxide levels in
the atmosphere?
A) It results in fewer trees taking
up nutrients from the soil
B) It results in fewer trees
being burnt
C) It results in fewer trees
respiring
D) It results in fewer trees
photosynthesizing
Nutrient Cycles
Around 1850, the atmosphere
contained about 270ppm (parts
per million) of carbon dioxide. In
2004, it contained around 360
ppm, and is rising at a rate of
1 to 2 ppm per year.
The worst possible long term effect
of increasing carbon dioxide levels
in the atmosphere is the
'greenhouse effect', which in turn
leads to global warming.
Atmospheric CO2 levels (ppm)
The Greenhouse Effect and Global Warming
Time (Years)
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Nutrient Cycles
The Nitrogen Cycle – An Overview
The atmosphere is made up of
79% nitrogen. A shortage of
nitrogen based compounds in
ecosystems can reduce plant
growth, and animal growth.
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Nutrient Cycles
The abiotic outer cycle consists of nitrogen from the air being 'fixed' by:
lightning and the Haber-Bosch process.
Nitrogen fixation
fixation by
by lightning
lightning
Nitrogen
Nitrogen gases in
atmosphere
Denitrification: denitrifying bacteria
Feeding
Nitrogen in animals
e.g. Protein
Nitrogen in plants
e.g. protein
Uptake of nitrates
and ammonium
Nitrification = oxidation
of ammonium to nitrate
NH4+
NO3Bacteria
NO2-
Fertilizer
Fertilizer manufacture
manufacture
(Nitrogen
(Nitrogen fixation
fixation by
by
Haber-Bosch
Haber-Bosch process)
process)
Death and
excretion
Nitrogen in detritus
and humus
e.g. as protein
Invertebrates
Nitrogen Fixation
Free-living
bacteria
Bacteria
in legume
root nodules
Microorganisms:
Bacteria and fungi
NO3-, NH4+
toxic
Leaching to ground water
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Nutrient Cycles
Nitrogen can also be fixed by bacteria in the root nodules of legumes and by
bacteria living freely in the soil.
Nitrogen fixation by lightning
Nitrogen gases in
atmosphere
Denitrification: denitrifying bacteria
Feeding
Nitrogen in animals
e.g. Protein
Nitrogen in plants
e.g. protein
Uptake of nitrates
and ammonium
Nitrification = oxidation
of ammonium to nitrate
NH4+
NO3Bacteria
NO2-
Fertilizer manufacture
(Nitrogen fixation by
Haber-Bosch process)
Death and
excretion
Nitrogen in detritus
and humus
e.g. as protein
Invertebrates
Nitrogen Fixation
Free-living
bacteria
Bacteria
in legume
root nodules
Microorganisms:
Bacteria and fungi
NO3-, NH4+
toxic
Leaching to ground water
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Nutrient Cycles
Leguminous Plants
Leguminous plants are plants
that produce peas or beans.
They contain nodules on their
roots that are full of nitrogen
fixing bacteria.
Farmers often rotate crop
plants with leguminous (pea or
bean) plants. This is because
crop plants take nitrogen from
the soil and leguminous plants
put nitrogen back into the soil.
Root nodule
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Nutrient Cycles
Rhizobium
One of the most common
bacteria that produce nodules
on legumes is Rhizobium.
The relationship between the
bacterium and the plant is
mutualistic, that is, both
organisms benefit.
The plant obtains some nitrogen
from the bacterium and the
bacterium obtains other nutrients,
in particular, sugars, made by
the plant.
Rhizobium bacterium
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Nutrient Cycles
In the central cycle, plants absorb nitrates or ammonium ions from the soil.
The nitrogen forms amino acids and proteins.
Nitrogen fixation by lightning
Nitrogen gases in
atmosphere
Denitrification: denitrifying bacteria
Feeding
Nitrogen in animals
e.g. Protein
Nitrogen
Nitrogen in
in plants
plants
e.g.
e.g. protein
protein
Uptake
Uptake of
of nitrates
nitrates
and
and ammonium
ammonium
Nitrification = oxidation
of ammonium to nitrate
NH4+
NO3Bacteria
NO2-
Fertilizer manufacture
(Nitrogen fixation by
Haber-Bosch process)
Death and
excretion
Nitrogen in detritus
and humus
e.g. as protein
Invertebrates
Nitrogen Fixation
Free-living
bacteria
Bacteria
in legume
root nodules
Microorganisms:
Bacteria and fungi
NO3-, NH4+
toxic
Leaching to ground water
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Nutrient Cycles
These compounds may or may not be eaten by animals.
However, they are all eventually turned into detritus (rotting organic matter).
Nitrogen fixation by lightning
Nitrogen gases in
atmosphere
Denitrification: denitrifying bacteria
Feeding
Nitrogen in animals
e.g. Protein
Nitrogen in plants
e.g. protein
Uptake of nitrates
and ammonium
Nitrification = oxidation
of ammonium to nitrate
NH4+
NO3Bacteria
NO2-
Fertilizer manufacture
(Nitrogen fixation by
Haber-Bosch process)
Death and
excretion
Nitrogen
Nitrogen in
in detritus
detritus
and
humus
and humus
e.g.
e.g. as
as protein
protein
Invertebrates
Nitrogen Fixation
Free-living
bacteria
Bacteria
in legume
root nodules
Microorganisms:
Bacteria and fungi
NO3-, NH4+
toxic
Leaching to ground water
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Nutrient Cycles
Detritus is attacked by detrivores and decomposers.
The nitrogen is released as ammonium ions that are converted to nitrates.
Nitrogen fixation by lightning
Nitrogen gases in
atmosphere
Denitrification: denitrifying bacteria
Feeding
Nitrogen in animals
e.g. Protein
Nitrogen in plants
e.g. protein
Uptake of nitrates
and ammonium
Nitrification = oxidation
of ammonium to nitrate
+
NH44+
NO
NO33-Bacteria
NO22--
Fertilizer manufacture
(Nitrogen fixation by
Haber-Bosch process)
Death and
excretion
Nitrogen in detritus
and humus
e.g. as protein
Invertebrates
Nitrogen Fixation
Free-living
bacteria
Bacteria
in legume
root nodules
Microorganisms:
Bacteria and fungi
NO3-, NH4+
toxic
Leaching to ground water
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Nutrient Cycles
Nitrification
The conversion of ammonium ions
to nitrites and then to nitrates is
known as nitrification.
Nitrification = oxidation
of ammonium to nitrate
NO3-
The bacteria that carry out
nitrification are called nitrifying
bacteria. They are
chemoautotrophic, that is, they
obtain their energy from oxidation
of inorganic ions.
NH4+
Bacteria
NO2toxic
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Nutrient Cycles
Question 4
Nitrogen fixing bacteria put nitrogen back into the soil.
Answer True or False.
Nutrient Cycles
Question 5
Nitrification is:
A) The conversion of
ammonium to nitrite
B) The conversion of nitrate
to nitrite
C) The conversion of
ammonium to nitrate
D) The conversion of nitrite
to nitrate
Nutrient Cycles
Upsetting the Nitrogen Balance
Most nitrogen-based fertilizers are
made by the Haber-Bosch process.
This accounts for about one third of
the total nitrogen fixation each year.
Normally, natural nitrogen fixation
would be balanced by denitrification.
This is the process whereby
bacteria take up inorganic nitrogen
compounds and release nitrogen
gas into the atmosphere.
However, because there is more
nitrogen being put into the soil than
put back into the atmosphere, by
the use of fertilizers, the balance is
being disrupted.
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Nutrient Cycles
Question 6
Which of the following does not put nitrogen back into the ground?
A) Lightning
B) Denitrification
C) Nitrification
D) The Haber-Bosch process
Nutrient Cycles
Question 7
Which of the following is the most harmful way of putting nitrogen
back into ecosystems?
A) Lightning
B) The Haber-Bosch process
C) Nitrogen fixing bacteria
D) Death and excretion
Nutrient Cycles
Eutrophication
Nitrogen-based fertilizers lead to
a type of pollution called
eutrophication. The nitrates are
washed by rainfall into ground
water streams. Water supplies
become enriched with nitrates.
As a result of eutrophication, the
algae at the water's edge grow
rapidly. They prevent light from
reaching aquatic plants.
These plants, and the invertebrates
that feed on them, then die.
The algae also block water supplies,
including drinking water.
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Nutrient Cycles
Hypoxia
When the algae die, plants and
invertebrates die and they are
decomposed by bacteria. These
bacteria deoxygenate, that is,
remove oxygen from, the water.
This is known as hypoxia.
The bacteria also produce
hydrogen sulphide gas, which is toxic.
The fish and invertebrates that
require high levels of oxygen die.
This affects food webs and
subsequently the entire ecosystem.
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Nutrient Cycles
Question 8
Which of the following is likely to be the best long-term solution for
the problem of eutrophication?
A) Re-stocking water systems
with fish and invertebrates
B) Removing pond weed and
algae from water systems
C) Supplying people with free
bottled water
D) Reducing the use of artificial
fertilizers
Nutrient Cycles
Summary
After completing this presentation you should be able to:
 Identify the stages of the carbon cycle
 Identify the stages of the nitrogen cycle
 Show knowledge of the causes of
increasing carbon dioxide levels
 Show knowledge and understanding
of the consequences of the over-use
of nitrogen based fertilizers
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