1. Ecology II - Cycles of Matter
Photo Credit: ©Bruce Coleman, LTD/Natural Selection
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2. Recycling in the Biosphere
Recycling in the Biosphere Energy and matter move through the biosphere very differently.
Unlike the one-way flow of energy, matter is recycled within and between ecosystems.
The biosphere, speaking generically, is all the living things -- plants and animals -- in the world.
The biosphere is the global ecosystem, the sum of all the planet's ecosystems. This includes the atmosphere (several kilometers), and the land (at least 3000 meters below ground to the depth of several kilometers). It is often referred to as the "zone of life", where all of earths organisms live.
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The Water Cycle
Water moves between the ocean, atmosphere, and land.
This diagram shows the main processes involved in the water cycle. Scientists estimate that it can take a single water molecule as long as 4000 years to complete one cycle.
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Nutrient Cycles
The Carbon Cycle
Carbon is a key ingredient of living tissue.
Biological processes, such as photosynthesis, respiration, and decomposition, take up and release carbon and oxygen.
Geochemical processes, such as erosion and volcanic activity, release carbon dioxide to the atmosphere and oceans.
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Nutrient Cycles
CO2 in Atmosphere
Photosynthesis
Volcanic activity
feeding
Respiration
Erosion
Human activity
Respiration
Decomposition
CO2 in Ocean
Uplift
Carbon is found in several large reservoirs in the biosphere. In the atmosphere, it is found as carbon dioxide gas; in the oceans as dissolved carbon dioxide; on land in organisms, rocks, and soil; and underground as coal, petroleum, and calcium carbonate rock. 
Deposition
Photosynthesis
feeding
Fossil fuel
Deposition
Carbonate Rocks
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Nutrient Cycles
The Nitrogen Cycle
All organisms require nitrogen to make proteins.
Although nitrogen gas (N2) is the most abundant form of nitrogen on Earth, only certain types of bacteria can use this form directly.
Such bacteria live in the soil and on the roots of plants called legumes. They convert nitrogen gas into ammonia in a process known as nitrogen fixation.
Other bacteria in the soil convert ammonia into nitrates and nitrites.
Nitrogen fixation is the natural process, either biological or abiotic, by which nitrogen (N2) in the atmosphere is converted into ammonia.
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Nutrient Cycles
Once these products are available, producers can use them to make proteins.
Consumers then eat the producers and reuse the nitrogen to make their own proteins.
FYI: Ammonia is a compound of nitrogen and hydrogen with the formula NH3.
(It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. )
The nitrate ion is a polyatomic ion with the molecular formula NO−3 and a molecular mass
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8. NH3 N2 in Atmosphere NO3 and NO2 Nutrient Cycles
Synthetic fertilizer manufacturer
Atmospheric nitrogen fixation
Decomposition
Uptake by producers
Reuse by consumers
Uptake by producers
Reuse by consumers
The atmosphere is the main reservoir of nitrogen in the biosphere. Nitrogen also cycles through the soil and through the tissues of living organisms. 
Decomposition excretion
Decomposition excretion
Bacterial nitrogen fixation
NO3 and NO2
NH3
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Nutrient Cycles
When organisms die, decomposers return nitrogen to the soil as ammonia.
The ammonia may be taken up again by producers.
Other soil bacteria convert nitrates into nitrogen gas in a process called denitrification.
This process releases nitrogen into the atmosphere once again.
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Nutrient Cycles
The Phosphorus Cycle
Phosphorus is essential to organisms because it helps forms important molecules like DNA and RNA.
Most phosphorus exists in the form of inorganic phosphate, a salt.
Inorganic phosphate is released into the soil and water as sediments wear down.
Eventually the phosphates will enter the ocean, where it is used by marine organisms.
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Why it phosphorus is a concern: In water, phosphorus behaves as a fertilizer, accelerating plant and algae growth. When plants and algae die, bacteria consume oxygen that is dissolved in the water. When this happens, less oxygen is available for fish and aquatic life that need oxygen to survive. Excess phosphorus in drinking water is difficult to remove, and also can require an increase in treatment chemicals which adds cost.
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Nutrient Cycles
Organic phosphate moves through the food web and to the rest of the ecosystem.
Organisms
Phosphorus in the biosphere cycles among the land, ocean sediments, and living organisms.
Land
Ocean
Sediments
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Nutrient Limitation
Nutrient Limitation
The primary productivity of an ecosystem is the rate at which organic matter is created by producers.
One factor that controls the primary productivity of an ecosystem is the amount of available nutrients.
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Nutrient Limitation
If a nutrient is in short supply, it will limit an organism's growth.
When an ecosystem is limited by a single nutrient that is scarce or cycles very slowly, this substance is called a limiting nutrient.
When an aquatic ecosystem receives a large input of a limiting nutrient—such as runoff from heavily fertilized fields—the result is often an immediate increase in the amount of algae and other producers.
Why?
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Nutrient Limitation
When an aquatic ecosystem receives a large input of a limiting nutrient—such as runoff from heavily fertilized fields—the result is often an immediate increase in the amount of algae and other producers.
This result is called an algal bloom.
Algal blooms can disrupt the equilibrium of an ecosystem.
Why is that?
See, Article
Sabah, Malaysia (Red Algae bloom; where is?)
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3–3
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Transpiration is part of the
water cycle.
carbon cycle.
nitrogen cycle.
phosphorus cycle.
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Carbon is found in the atmosphere in the form of
carbohydrates.
carbon dioxide.
calcium carbonate.
ammonia.
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Biologists describe nutrients as moving through cycles because the substances
start as simple organic forms that plants need.
provide “building blocks” and energy that organisms need.
are passed between organisms and the environment and then back to organisms.
are needed by organisms to carry out life processes.
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The only organisms that can convert nitrogen in the atmosphere into a form useful to living things are nitrogen-fixing
plants.
bacteria.
detritivores.
animals.
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When an aquatic ecosystem receives a large input of a limiting nutrient, the result is
runoff.
algal death.
algal bloom.
less primary productivity.
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Resources:
Pearson Prentice Hall DVD
Holt Modern Biology
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23. END OF SECTION References: Pearson Prentice Hall DVD
Text Book: Holt, Biology 1999