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Biogeochemical Cycles
• Biochemists are scientists who study the
type of chemical compounds that are found
in living things.
• The work of biochemists has lead to the
realization that living organisms are
composed of some of the same elements
that are found in the air, water and soil.
• There are 92 elements know to occur
naturally on Earth, however fewer than 20
elements occur in the tissues of living
things.
• Only 6 elements make up 99.2% of human
or pumpkin tissues.
• Table in notes: compares the relative abundance
(% by weight) of a few selected elements found in
the Earth's crust, human, and pumpkin.
• oxygen, carbon, hydrogen and nitrogen make up
the vast majority of living tissue.
• These four elements are recycled between living
organisms and the soil, water and atmosphere of
the Earth.
• These elements are first taken up by plants
– some oxygen is released to the atmosphere as a product
of photosynthesis, but the rest is converted into
food,and passed through the food web.
– as they pass through plants, consumers, and finally
decomposers, and then returned to the environment in a
continuous recycling of materials.
– If recycling of these materials did not occur, life could
not exist.
• Some of these elements (carbon, oxygen, sulfur, nitrogen)
are found in gaseous forms and their cycles involve the
atmosphere. As a result they have a global nature.
• elements may have a short term cycle
such as when carbon is transferred
from animals to plants in the form
of carbon dioxide
• and a long term cycle such as the transfer of carbon from a
fossil fuel to a plant following combustion.
• The elements are cycled between the living
organisms and the environment in a combination
of biological and geological processes that drives
chemical recycling.
• Biological processes include:
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respiration,
decomposition,
excretion,
photosynthesis,
and assimilation.
• Geological processes involve
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fossilization
Erosion
combustion of fossil fuels (peat, oil, coal),
weathering
formation of sedimentary rock.
Carbon Cycle
• Plants take carbon dioxide and water from
their environment.
• They use the energy they capture from the
sun to carry on a process known as
photosynthesis which converts the atoms in
the carbon dioxide and water into sugar
(glucose) and oxygen.
• 6CO2 + 6H2O + energy → C6H12O6 +
6O2
Photosynthesis
• The oxygen, released as a byproduct of
photosynthesis, generally passes into the
atmosphere.
• The sugar (known as glucose) serves a
• food for all consumers in the ecosystem.
• The consumers carry on a metabolic process
known as cellular respiration. where oxygen is
taken in from the atmosphere and used to break
down the sugar resulting in a release of energy
and the molecular products, carbon dioxide and
water.
• Respiration chemical equation
• C6H12O6 + 6O2 → 6CO2 + 6H2O + energy
• Notice: photosynthesis and respiration are
opposite reactions.
• What is made in photosynthesis is used in
respiration and what is made in respiration
is used in photosynthesis…
Carbon is the center to life..
• All living things contain carbon.
• Carbon is the link that allow plants to
transform sunlight into chemical energy.
• The sugar (glucose) produced during
photosynthesis forms the basic substance
that is transferred along food chains.
• Carbon dioxide in the atmosphere is very
small, 0.03%
• However, without the carbon cycle we
would quickly run out of carbon dioxide,
plants could not trap
sunlight, and life on earth
would cease.
Organic and inorganic
• Organic substances always contain carbon
and hydrogen, and often contain oxygen
and nitrogen.
• Important chemicals that make up your
body such as proteins, sugar and fats are
considered organic.
• Inorganic matter doesn’t contain a
combination of carbon and hydrogen.
• For example: carbon dioxide (CO2), water
(H2O) and ammonia (NH3) are inorganic.
Inorganic carbon storage
• 1. Atmosphere: a small amount in the carbon
dioxide in the air we breathe and is available for
photosynthesis.
• 2.Ocean: a large amount is found in the oceans.
This is available to algae and other water plants
for phototypesets.
• 3. Earths crust: the largest storage of inorganic
carbon is in the sedimentary rocks, such as
limestone, that have formed from the remains of
living things.
Organic Carbon Storage
• In the bodies of living organisms.
• When living things die, their bodies
decompose and the carbon is returned to the
cycle in inorganic form.
• Because there is limited oxygen in bogs,
decomposition takes thousands of years.
• Carbon may remain locked away for many year in
organic form.
• Carbon locked away in dead plants is know as
peat.
• When peat is covered in sediment for a long time
it will become coal, a carbon containing fossile
fuel.
• Other fossil flues such as
oil and gas contain organic
carbon that has been trapped
in the earth’s crust for
millions of years.
•
Human Activity
•
•
People have discovered these fossil fuel deposits and have used them
to supply our energy needs.
Humans have also affected the carbon cycle by cutting down
forests. As a result of human activity, the amount of carbon dioxide
is being produced at a faster rate than nature can recycle it.
– As a result of this imbalance, the amount of carbon dioxide in the
atmosphere is increasing. As a result the earth is presently
undergoing an enhanced greenhouse effect in which the
atmosphere is gradually heating up.
• If the rise in temperature occurs too fast for organisms to
adapt, widespread extinction of plants and animals may be
the result.
What are the impacts of
deforestation on the carbon cycle
• Removing large amounts of trees will reduce the
amount of carbon dioxide that is taken out of the
atmosphere due to a decreases in photosynthesis.
• If threes are burned there will be an increase of
carbon dioxide released into the atmosphere.
• The forest acts as a carbon sink retaining carbon
for long periods of time.
•
•
•
•
Complete the Carbon cycle.
Read P. 62 –64
P. 65 Q:2, 3, 4, 5
http://www.youtube.com/watch?v=U3SZKJ
VKRxQ&feature=related
• http://www.youtube.com/watch?v=1o4OD
WMZq5U&feature=related
Nitrogen Cycle
Nitrogen
• Nitrogen is essential to living
things for the production of
proteins and DNA which are
used to pass on the hereditary
information from parent to
offspring.
• Even though the atmosphere is
about 78% nitrogen gas, plants
and animals are unable to use
nitrogen gas directly as a source
of nitrogen to make organic
nitrogen compounds.
•
• The nitrogen cycle can occur in both
terrestrial and aquatic ecosystems.
Step 1: Plants change Nitrogen
into….
Path 1: Nitrogen Fixation by Lightning
• The electrical energy of lighting causes nitrogen
gas (N2) to react with oxygen (O2) in the
atmosphere to produce nitrate ions (NO3-) which
reach the soil dissolved in precipitation.
Path 2: Nitrogen Fixation by Bacteria
• Bacteria in the soil can change nitrogen gas (N2)
into ammonia (NH3) which dissolves in water to
form ammonium ions (NH4+)
2.Nitrification
• It is a bacterial process in which
ammonium (NH4) ions are
converted into nitrate ions.
– They are first changed into nitrites
(NO2-) by bacteria, and then
converted to Nitrates (NO3-) by a
different group of bacteria.
3: Assimilation: The making
of proteins for consumer use
• Assimilation is the process by which
plants use the nitrate ions (NO3-) to
make amino acids, proteins, and DNA.
• Only plants and bacteria can carry out the process, all
other living organisms receive their nitrogen
compounds from the food they eat.
4. Ammonification
• Consumers generally produce wastes
throughout their lives. When consumers
die their body contain nitrogen
compounds such as protein and DNA.
• Ammonification is when bacteria and
some fungi break down these nitrogen
compounds to make ammonia. The
ammonia immediately dissolves in soil
water to form ammonium ions.
(NH4+)
5.Denitrification
• During this step, nitrites are
changes to Nitrogen gas (N2)
which returns to the atmosphere.
• It is basically the reverse of
nitrogen fixation and nitrification.
•
Done by bacteria!
•
Human Impact
• As a result of human activities
most ecosystems have been
either totally destroyed or have
components such as tropic
structure, energy flow and
chemical cycling disrupted.
• Most effects are local or
regional such as agriculture
effects on nutrient cycling and
introduction of toxic
compounds in food chain.
http://www.youtube.com/watch?v=ronvj5ClD3Q
How may a gardener add nitrogen to
the soil?
• Addition of fertilizer: manure, fish meal,
crushed shells, or store purchased.
• http://www.youtube.com/watch?v=ZCogeB
k92NA&feature=related
• http://www.youtube.com/watch?v=Hghru0
O7dDs
1. Which represents a major storage location for organic carbon?
a. atmosphere
b. lithosphere
c. hydrosphere
d. living things
2. Which process reduces the amount of carbon dioxide in the
atmosphere?
a. cellular respiration
b. burning of fossil fuels
c. photosynthesis
d. acid deposition
3. Which step of the nitrogen cycle returns nitrogen gas to the
atmosphere?
a. nitrogen fixation
b. ammonification
c. denitrification
d. nitrification
4. Which is the most common element in the atmosphere?
a. carbon
b. oxygen
c. hydrogen
d. nitrogen
5. Nitrogen compounds in detritus are broken
down by which bacterial process?
a. nitrogen fixation
b. ammonification
c. denitrification
d. nitrification
6. Some plants have root nodules growing on their roots.
What process do the bacteria in these root nodules carry
out?
a. nitrogen fixation
b. ammonification
c. denitrification
d. nitrification
7. Which statement is false?
a. The carbon and nitrogen cycles have an atmospheric
component.
b. The nitrogen cycle depends mainly on bacterial
processes.
c. All living things depend on the nitrogen and carbon
cycles.
d. The energy stored in materials is also recycled.
1. Which represents a major storage location for organic carbon?
a. atmosphere
b. lithosphere
c. hydrosphere
d. living things
2. Which process reduces the amount of carbon dioxide in the
atmosphere?
a. cellular respiration
b. burning of fossil fuels
c. photosynthesis
d. acid deposition
3. Which step of the nitrogen cycle returns nitrogen gas to the
atmosphere?
a. nitrogen fixation
b. ammonification
c. denitrification
d. nitrification
4. Which is the most common element in the atmosphere?
a. carbon
b. oxygen
c. hydrogen
d. nitrogen
5. Nitrogen compounds in detritus are broken
down by which bacterial process?
a. nitrogen fixation
b. ammonification
c. denitrification
d. nitrification
6. Some plants have root nodules growing on their roots.
What process do the bacteria in these root nodules carry
out?
a. nitrogen fixation
b. ammonification
c. denitrification
d. nitrification
7. Which statement is false?
a. The carbon and nitrogen cycles have an atmospheric
component.
b. The nitrogen cycle depends mainly on bacterial
processes.
c. All living things depend on the nitrogen and carbon
cycles.
d. The energy stored in materials is also recycled.
Phosphorus cycle
Phosphorus cycle
Phosphorus cycle
• Phosphate is important for cell membranes, it helps release energy that
makes up DNA and calcium in bones.
• Phosphate in rocks and fossils will weather (break down into tiny
pieces).
– The inorganic phosphate dissolves in soil and rivers.
• Plants absorb phosphates and consumers receive phosphate
from eating plants.
– Organic phosphate returns to the soil when decomposition
occurs.
• Bones, teeth and waste, as well as river runoffs go to the ocean.
– Here the Phosphate is store until there is a geological uplift.
Oxygen Cycle
Nutrient Cycles
• Inorganic nutrients
(Carbon, Oxygen,
Nitrogen) are recycled
continually through
ecosystems.
• Plants and animals
build structures from
nutrients and inorganic
material.
Energy Flow vs. Nutrient
Cycling
• Energy flows through ecosystems: it enters
the ecosystem via sunlight, is stored temporarily in
complex molecules, and ultimately leaves in the
form of heat.
• Nutrients cycle within ecosystems: they are
atoms that stay within the ecosystem and are
found at different times in different pasrts of the
system.
Nutrient Cycles
• Nutrients are recycled in a living system.
• The key nutrients are carbon, hydrogen
Oxygen, Nitrogen and Phosphorus. These
constitute 95% of all living matter
Hydrogen and Oxygen (water)
cycle
Oxygen Cycle
• The complementary process of
photosynthesis and respiration ensures that
oxygen, carbon and hydrogen are repeatedly
cycled.
Oxygen
• The Earth's atmosphere contains about 21%
oxygen
– As you know from the previous lesson, oxygen gas (O2) is recycled as
part of the carbon, hydrogen, and oxygen cycles.
– Oxygen gas is cycled between the atmosphere and the living organisms of
both aquatic and terrestrial ecosystems.
– Oxygen gas from the atmosphere is absorbed by the water in aquatic
ecosystems.
– Oxygen is also produced as a byproduct of the photosynthetic organisms
that live in the aquatic ecosystems.
– Heterotrophs (consumers) living in aquatic ecosystems require oxygen for
cellular respiration but they receive their oxygen from the dissolved
oxygen in the water
Oxygen
• During winter, ponds and lakes may
freeze.
– there is little or no light and
photosynthesis ceases.
• As a result, aquatic algae and plants can no
longer produce oxygen. Therefore it is
possible that all fish within the lake or
pond will die off.
– oxygen may be a limiting factor in aquatic
ecosystems
» However Oxygen is rarely, if ever, a
limiting factor in terrestrial
ecosystems.