Activity: Nutrient Cycles in Ecosystems
While scratching your heads, dive into your knowledge centre, your brain. We hear the word "nutrient" in our lives on a regular basis. Write down your own definition of the word.
Now...how can you combine your definition to include the ecosystems that we have been discussing?
Below you will find a list of words that will be important to know. Take a moment to examine the list. How do you think they relate to Nutrient Cycles in the Ecosystem?
Now...how can you combine your definition to include the ecosystems that we have been discussing?
Below you will find a list of words that will be important to know. Take a moment to examine the list. How do you think they relate to Nutrient Cycles in the Ecosystem?
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Your predictions should be recorded in your individual Google document, Sustaining Earth's Ecosystems – Nutrient Cycles in Ecosystems.
Once you have finished your brainstorming you should move on to Time to Research portion of this activity. While you are reading the notes below and watching the videos, you should be making notes in your individual Google Document, Sustaining Earth's Ecosystems – Personal Notes, if you prefer you can record your "personal notes" on paper.
Once you have finished your brainstorming you should move on to Time to Research portion of this activity. While you are reading the notes below and watching the videos, you should be making notes in your individual Google Document, Sustaining Earth's Ecosystems – Personal Notes, if you prefer you can record your "personal notes" on paper.
Time to Research (Read, Watch, and Take Notes)
Nutrient Cycle
Nutrients are chemicals required for growth and other life processes.
- Nutrients move through the biosphere in nutrient cycles or exchanges.
- Nutrients often accumulate in areas called stores.
- Without interference, generally the amount of nutrients flowing into a store equals the amount of nutrients flowing out.
- Land clearing, agriculture, urban expansion, mining, industry, and motorized transportation can all increase the levels of nutrients more quickly than the stores can absorb them.
- Excess nutrients in the biosphere can have unexpected consequences.
- Carbon (C), hydrogen (H), oxygen (O), and nitrogen (N) cycle between living things and the atmosphere.
- Phosphorus (P) cycles in from sedimentary rock.
The Carbon Cycle
Carbon atoms are a fundamental unit in cells of all living things.
- Carbon is also an essential part of chemical processes that sustain life.
How Carbon is StoredCarbon can be stored in many different locations.
Sedimentation traps many long-term stores of carbon.
Carbon stores are also known as carbon sinks. |
How Carbon is Cycled Through the Ecosystems
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Producers release carbon dioxide back into the atmosphere in the absence of sunlight. Consumers release carbon dioxide when they exhale.
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Human Activities and the Carbon Cycle
- Since the start of the Industrial Revolution (160 years ago), CO2 levels have increased by 30 percent due to the increased burning of fossil fuels.
- The increase in CO2 levels in the previous 160 000 years was 1 - 3 percent
- Carbon is being removed from long-term storage more quickly than it naturally would as we mine coal and drill for oil and gas.
- CO2 is also a greenhouse gas, which absorbs heat in the atmosphere.
- Clearing land for agriculture and urban development reduces plants that can absorb and convert CO2.
- Farmed land does not remove as much CO2 as natural vegetation does.
The Nitrogen Cycle
Many human activities can influence the carbon cycle.
- Since the start of the Industrial Revolution (160 years ago), CO2 levels have increased by 30 percent due to the increased burning of fossil fuels.
- The increase in CO2 levels in the previous 160 000 years was 1 - 3 percent
- Carbon is being removed from long-term storage more quickly than it naturally would as we mine coal and drill for oil and gas.
- CO2 is also a greenhouse gas, which absorbs heat in the atmosphere.
- The increase in CO2 levels in the previous 160 000 years was 1 - 3 percent
- Clearing land for agriculture and urban development reduces plants that can absorb and convert CO2.
- Farmed land does not remove as much CO2 as natural vegetation does.
How Nitrogen is Cycled Through Ecosystems
Nitrogen fixation is the conversion of N2 gas into compounds containing nitrate (NO3–) and ammonium (NH4+).
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Nitrification & Uptake
Nitrification occurs when certain soil bacteria convert ammonium.
- Ammonium is converted into nitrates (NO3–) by nitrifying bacteria.
- Ammonium is converted to nitrite (NO2–), which is then converted to nitrate.
- These nitrogen compounds compose plant proteins.
- Herbivores then eat plants and use nitrogen for DNA and protein synthesis.
How Nitrogen is Returned to the Atmosphere
Nitrogen is returned to the atmosphere via denitrification.
- Nitrates are converted back to N2 by denitrifying bacteria.
- N2 is also returned to the atmosphere through volcanic eruptions.
How Nitrogen is Removed from the EcosystemExcess nitrogen dissolves in water, enters the waterways, and washes into lakes and oceans.
The nitrogen compounds eventually become trapped in sedimentary rocks and will not be released again until the rocks undergo hundreds of years of weathering. |
Human Activities and the Nitrogen Cycle
Human activities can also affect the nitrogen cycle.
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The Phosphorus Cycle
Phosphorus is essential for life processes in plants and animals.
- Phosphorus is a part of the molecule that carries energy in living cells.
- Phosphorus promotes root growth, stem strength, and seed production.
- In animals, phosphorous and calcium are important for strong bones.
How Phosphorus is Stored
Phosphorus is not stored in the atmosphere.
- Instead, it is trapped in phosphates (PO43–, HPO42–, H2PO4–) found in rocks and in the sediments on the ocean floor.
How Phosphorus is Cycled Through Ecosystems
Weathering releases these phosphates from rocks.
- Chemical weathering, via acid precipitation or lichens, releases phosphates.
- Physical weathering, including wind, water and freezing, releases phosphates.
- Phosphates are then absorbed by plants, which are then eaten by animals.
- Weathering does not occur until there is geologic uplift, exposing the rock to chemical and physical weathering.
Human Activities and the Phosphorus Cycle
Humans add excess phosphorus to the environment through mining for fertilizer components.
Humans can also reduce phosphorus supplies.
- Extra phosphorus, often along with potassium, then enters the ecosystems faster than methods can replenish the natural stores.
Humans can also reduce phosphorus supplies.
- Slash-and-burning of forests removes phosphorus from trees, and it then is deposited as ash in waterways.
How Changes in Nutrient Cycles Affect Biodiversity
Any significant changes to any of these nutrients (C, H, O, N, or P) can greatly affect biodiversity.
- Carbon: The carbon cycle changes contribute to climate change and global warming.
- Slight temperature fluctuations and changes in water levels can drastically change ecosystems.
- Changes influence other organism in the food webs.
- Nitrogen: Increased levels of nitrogen can allow certain plant species to outcompete other species, decreasing resources for every species in the food webs.
- Phosphorus: Decreased levels of phosphorus can inhibit the growth of algae that are very important producers in many food chains.
Videos
- The Global Carbon Cycle - Crash Course Chemistry #46 - by CrashCourse
- What Is The Carbon Cycle - Part 1 | Chemistry for All | FuseSchool - by FuseSchool Global Education
- The Nitrogen Cycle | Chemistry for All | FuseSchool - by FuseSchool
- What Is Photosynthesis? | Biology for All | FuseSchool - by FuseSchool
- Photosynthesis - by Bozeman Science
- 3 Amazing Photosynthetic Animals - by SciShow - Talk about adaptations!
- Forest Floor - In the Ecosystem - by Virtual Soil Science Learning Resources
Check-In - To Be Completed Before Moving On
Let's have a check in. Take the time to answer the following questions; record your answers in Sustaining Earth's Ecosystem - Nutrient Cycles in Ecosystems. (You should be able to answer the following questions without having to refer to your notes).
Write down questions you still have about Nutrient Cycles. Or write 1, or more, explanations you have that may better explain an idea discussed on this page.
Finally, take a moment to think about what the Big Idea is of Nutrient Cycles in Ecosystems. Put everything you learned into a 1-2 sentence summary of your own words. Take this, and share it on the second Padlet Wall above.
- What is a nutrient store? And Provide one example.
- Name a biotic and an abiotic process that allow nutrients to flow in and out.
- Photosynthesis is an important process in which carbon and oxygen are cycled through the ecosystems. Describe this process.
- How is decomposition related to the carbon cycle?
- What is nitrogen fixation?
- What is denitrification?
- How have human activities impacted the carbon cycle? The nitrogen cycle? The phosphorus cycle?
Write down questions you still have about Nutrient Cycles. Or write 1, or more, explanations you have that may better explain an idea discussed on this page.
Finally, take a moment to think about what the Big Idea is of Nutrient Cycles in Ecosystems. Put everything you learned into a 1-2 sentence summary of your own words. Take this, and share it on the second Padlet Wall above.