Global Cycle Matter

Lesson 4: Cycling of Matter

Essential Question: How does matter cycle through an ecosystem?


Summary: Students will be introduced to the idea that cycles of matter are global.
They will explore the processes that comprise individual cycles (water, carbon, nitrogen, and phosphorus) and after studying each process, expand their thinking by considering the impact humans have on each cycle and analyze the consequences of disrupting these cycles.

TEKS 13.C Explain the significance of the carbon and nitrogen cycles to ecosystem stability and analyze the consequences of disrupting these cycles.

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Cycling of Matter Vocabulary

• biogeochemical cycle
• sink
• nitrogen fixation
• nitrification
• denitrification

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Global Biogeochemical Cycles 1

• The exchange of matter through the biosphere is called a

biogeochemical cycle.

• The biogeochemical cycle involves...
living organisms (bio),
geological processes (geo),
chemical processes (chemical).

• Matter in biogeochemical cycles is released from many different sources and is absorbed by sinks.

Multiple Choice

What are biogeochemical cycles?

• exchange of matter in the biosphere

• exchange of only carbon in the biosphere

• exchange of living organisms in the biosphere

• exchange of fossil fuels in the biosphere

Water Cycle

• Water moves through Earth’s systems through the water cycle.
• Energy from the sun causes water to constantly evaporate from Earth's surface

• Evaporation- liquid water is heated by the sun and changes into gaseous water vapor.

• The water vapor rises into the atmosphere.
• Water in the atmosphere then cools and forms water droplets that fall back to earth.

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Human Impacts on the Water Cycle

Human impacts on the water cycle
• Humans impact the water cycle in many ways, such as diverting

waterways for irrigation and building dams to create reservoirs.

• In many cases, these activities have disrupted the water cycle for a

given region, leading to a drastic decrease in local ecosystem stability.

• Human activities that contribute to increases in average global

temperature have also affected the water cycle.

Ask Yourself Describe how humans impact Earth’s climate and how this

affects the water cycle.

The Carbon Cycle

• Carbon cycles through Earth’s systems in different forms, often paired with oxygen.

• Photosynthesis and cellular respiration are important components of the carbon cycle.

• The carbon cycle is the biogeochemical cycle with climate change.most closely associated

Human Impacts on the Carbon Cycle

• Fossil fuels form from organic matter that is buried underground over long periods of time, forming a carbon sink.

• Burning fossil fuels releases carbon dioxide into the atmosphere, providing a carbon source for the carbon cycle.

• Humans disrupt the carbon cycle through activities such as removing fossil fuels from Earth’s crust and burning them for energy.

Ask Yourself Identify two ways that human activities disrupt the carbon cycle.

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Nitrogen Cycle

• Nitrogen in the atmosphere must undergo nitrogen fixation before it can be used by plants and animals.

• Nitrification produces nitrogen-oxygen compounds that plants use to make proteins.

• Nitrogen moves through food webs and returns to the soil through animal wastes and by decomposition.

• Denitrification converts nitrogen-oxygen compounds back into nitrogen gas, which returns to the atmosphere.

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Multiple Choice

What organism fixates nitrogen back into a useable form?

• Animals

• Plants

• Bacteria

• Algae

Human Impacts on the Nitrogen Cycle

Human impacts on the nitrogen cycle
• Many farms, businesses, and individuals use fertilizers rich in nitrogen to promote plant growth and it’s released into the nitrogen cycle by bacteria as nitrogen-containing compounds like NO3−.

• These compounds dissolve easily in water and are carried by groundwater and streams to larger waterways.

• An overabundance of nitrogen in an aquatic ecosystem can cause an overgrowth of plants and algae.

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Phosphorus Cycle

• Phosphorus, a nutrient found in all forms of life, goes through both short-term and long-term cycles.

• Phosphorus moves from the short-term cycle to the long-term cycle through precipitation and sedimentation during rock
formation

Human Impacts on the Phosphorus Cycle

• Most phosphorus is locked into its long-term cycle, either bound to other compounds in rock and soil or found in sediment at the bottom of bodies of water.

• Dead zones form when algal bloom organisms die and sink to the bottom of lakes and oceans. Decomposition of the dead algae uses up oxygen in the water, depriving other livings things from that resource.

•Humans disrupt the phosphorus cycle by moving it quickly and in large amounts from its long-term cycle to its short-term cycle, such as
through mining.

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Multiple Choice

What is a dead zone?

• when algal blooms die

• when the organisms of algal bloom die and sink to bottom

• dead organisms

Reducing Human Impacts

Driving Question Connection
• Stable matter cycles are key to healthy ecosystems.



• Ecologists are studying disruptions in the movement of carbon through the Brazilian reef ecosystem that have resulted from warmer global temperatures and increased ocean acidification.

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Open Ended

What are the 4 biogeochemical cycles we learned about?