Ecosystems and Their Interactions Chapter 6 Lesson 6.2.
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Transcript of Ecosystems and Their Interactions Chapter 6 Lesson 6.2.
Ecosystems and Their Ecosystems and Their InteractionsInteractions
Chapter 6 Chapter 6
Lesson 6.2Lesson 6.2
PA Academic Standards for PA Academic Standards for Environment & EcologyEnvironment & Ecology
Standard 4.6.10.BStandard 4.6.10.B• Explain how cycles affect the balance in an Explain how cycles affect the balance in an
ecosystem.ecosystem.• Describe an element cycle and its role in an Describe an element cycle and its role in an
ecosystem.ecosystem.• Explain the consequences of interrupting Explain the consequences of interrupting
natural cycles.natural cycles.
Learning ObjectivesLearning Objectives
• Students will describe an element cycle and its role Students will describe an element cycle and its role in an ecosystem.in an ecosystem.
• Students will explain the consequences of Students will explain the consequences of interrupting natural cycles.interrupting natural cycles.
Theme OutlineTheme Outline
Lesson 6.2Lesson 6.2• Cycles in an EcosystemCycles in an Ecosystem• The Water CycleThe Water Cycle• The Carbon CycleThe Carbon Cycle• The Nitrogen CycleThe Nitrogen Cycle
Cycles in an Ecosystem• Earth is a closed system• Matter continuously cycles throughout different
parts of an ecosystem
Major Cycles
Three major cycles• Water Cycle• Carbon Cycle• Nitrogen Cycle
Major Cycles
Three major cycles• Water Cycle• Carbon Cycle• Nitrogen Cycle
The Water CycleThe Water Cycle
Worldwide Water Supply
Water water everywhere but…
• Covers 70% of the Earth’s surface.Covers 70% of the Earth’s surface.• Most living things are primarily water.Most living things are primarily water.
• Humans are ~65% water.Humans are ~65% water. … the Earth’s water supply is
finite• Finite – – a fixed amount.
Which means … The same amount of water that was on Earth when
the dinosaurs were around, still exists today!!!
The Water Cycle
Processes at work…Processes at work…• Evaporation
• Liquid water to water vapor• Condensation
• Water vapor cools and condenses into clouds as water droplets
• Precipitation• Water droplets fall to the Earth as rain, sleet, hail, Water droplets fall to the Earth as rain, sleet, hail,
or snowor snow• Runoff
• Water runs off into nearby streams, rivers, lakes, Water runs off into nearby streams, rivers, lakes, or enters the groundwateror enters the groundwater
• Infiltration/Percolation
Why is water such an important substance?
• There is less than 1% of freshwater available on the surface of the Earth for drinking, bathing, and cooking.
• Human activities have greatly impacted quality of freshwater supplies.Example: pollution from chemical spills, poor wastewater
treatment, agricultural runoff, and septic tank failure
Water Quality Concerns • Agricultural runoff contains a host of potentially
harmful chemicals and sediments that can easily enter waterways.
• In Pennsylvania, access to potable drinking water is not an issue for most.
• However, in other parts of the world, limited access to safe potable water is a major concern for populations living along many waterways.
Major Cycles
Three major cycles• Water CycleWater Cycle• Carbon CycleCarbon Cycle• NitrogenNitrogen
The Carbon CycleThe Carbon Cycle
Why is carbon important anyway?
• Carbon is the building block for life.• Carbon is the basis for all organic life.• Carbon is essential for making … DNADNA
ProteinsProteins FatsFats CarbohydratesCarbohydrates
Where else is carbon found?
• Carbon Dioxide (CO2)
• This greenhouse gas helps maintain heat in the This greenhouse gas helps maintain heat in the Earth’s upper atmosphere.Earth’s upper atmosphere.
• Carbon reservoirs• Oceans• Atmosphere• Rocks
The Carbon Cycle… simplified
The Carbon Cycle: Rock and Fossil Fuel Formation
Organic matterOrganic matterMarine Marine shellsshells
Rocks Minerals
pre
ssur
e
Wetland Wetland MaterialMaterialOrganic Organic MatterMatter
Fossil Fuels
pressure
Major Cycles
Three major cycles• Water CycleWater Cycle• Carbon CycleCarbon Cycle• NitrogenNitrogen
The Nitrogen Cycle
Nitrogen• Composes ~79% of the atmosphereComposes ~79% of the atmosphere• The atmosphere is a major nitrogen reservoir.The atmosphere is a major nitrogen reservoir.• However, most of the nitrogen in the atmosphere However, most of the nitrogen in the atmosphere
is not in a usable form so it can not be used by is not in a usable form so it can not be used by plants and animals.plants and animals.
Nitrogen is necessary for making…
• DNADNA• ProteinsProteins• Amino AcidsAmino Acids• ChlorophyllChlorophyll
The Big 3…
N2
Atmosphere
NO3
Nitrates
NO2
Nitrites
Four major processes…
1) Nitrogen fixation
2) Decay
3) Nitrification
4) Denitrification
Types of Nitrogen Fixation
Atmospheric fixationLightning in the atmosphere breaks up nitrogen
molecules and when combine with oxygen they form nitrates.
NN22 NO NO33Atmospheric Nitrogen Nitrates
Industrial fixation Combines nitrogen in the
atmosphere with hydrogen to form ammonia
Occurs under pressure and high temperatures (~600oC)
Product used as fertilizer in agriculture
N2 NH3
Atmospheric Nitrogen Ammonia
Fertilizer Labels
Biological fixation Plants and bacteria convert atmospheric
nitrogen into ammonia
NN22 NH NH33
Atmospheric Nitrogen Atmospheric Nitrogen Ammonia Ammonia
Soybeans/Legumes - Soybeans/Legumes - Nitrogen fixing Nitrogen fixing
bacteriabacteria
Decay• Nitrogen cycles through food chains like other
elements.• Nitrogen is found in excreted wastes from
animals.• Microorganisms break down excretions and dead
animals to form ammonia.
Nitrification A process that converts nitrogen, in various forms,
into more usable forms of nitrogen that can be taken up through the roots of plants.
Convert organic nitrogen into nitrites and nitrates.
NHNH33 NO NO33Ammonia Ammonia Nitrates Nitrates
Denitrification A process preformed by bacteria that live deep in
soils and aquatic sediments under anaerobic conditions.
What does it mean when we say anaerobic?
NONO33 N N22
Nitrates Nitrates Atmospheric Nitrogen Atmospheric Nitrogen
The Nitrogen Cycle
Changes to Ecosystems
• Occur more frequently in some ecosystems than Occur more frequently in some ecosystems than othersothers
• Cycles and processes continue to cycle materials Cycles and processes continue to cycle materials through ecosystems, even after disturbancesthrough ecosystems, even after disturbances
• Ecosystems change in order to meet the conditions Ecosystems change in order to meet the conditions presentpresentExample: regrowth of a forest after forest fires destroy Example: regrowth of a forest after forest fires destroy
forest floor (organic matter)forest floor (organic matter)