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CHAPTER 1CHAPTER 1 Nutrient Cycles and Energy Flow
Nutrient Cycles and Energy Flow
In this chapter, you will:• explain that life depends on recycled matter• describe the processes of photosynthesis and cellular respiration• explain how humans can affect the cycles of matter and energy flow in ecosystems• assess the impact of fertilizers on aquatic ecosystems• observe the chemistry of photosynthesis• model acid precipitation• determine the impact of excess fertilizers on plants
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Abiotic Characteristics of an EcosystemAbiotic Characteristics of an Ecosystem(Page 12)
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Abiotic Characteristics of an Ecosystem
Abiotic Characteristics of an Ecosystem
(Page 12)
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Cycling of Matter and Earth’s Spheres
Cycling of Matter and Earth’s SpheresEcological processes move matter from the biotic and abiotic parts of
an ecosystem and back again in continuous cycles.
•The lithosphere is the hard part of Earth’s surface.
•The hydrosphere is all of the water found on Earth (lakes, oceans, and ground water).
•The atmosphere is the layers of gas above Earth’s surface.
•The biosphere is the regions of Earth where living organisms exist.
(Page 13)
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Nutrient Cycles: Water Nutrient Cycles: Water
Nutrients are chemicals that are needed by living things and are continually cycled through ecosystems.
The water cycle moves water through the hydrosphere, atmosphere, and lithosphere. This occurs by way of evaporation, condensation, and precipitation.
(Page 14)
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Nutrient Cycles: CarbonNutrient Cycles: Carbon
The carbon cycle moves carbon through all of Earth’s spheres. Carbon exists as a gas—carbon dioxide (CO2)—in the atmosphere. This gas is used by plants to make sugars. Sugars are broken down by organisms to release energy and CO2. Carbon is stored in fossil fuels buried within Earth and in carbonate (CO3) rock found in the lithosphere.
(Page 15)
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Nutrient Cycles: NitrogenNutrient Cycles: Nitrogen
The nitrogen cycle moves nitrogen through Earth’s spheres. Nitrogen gas (N2) from the air is converted into ammonium (NH4) and into nitrates (NO3) by bacteria and cyanobacteria.
In terrestrial (land based) ecosystems, ammonium (NH4) is produced by soil bacteria. In aquatic (water based) ecosystems, NH4 is produced by cyanobacteria. Nitrates (NO3) are produced from ammonium.
(Page 16)
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Nutrient Cycles: PhosphorusNutrient Cycles: PhosphorusThe phosphorus cycle moves phosphorus from the lithosphere, where it is stored in rocks as phosphate (PO4
3-), to the hydrosphere by the processes of leaching and run-off. Plants then use the phosphorus.
The phosphates in plants and animals are released back into the soil by bacterial decomposition.
(Page 17)
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Nutrient Cycle ReviewNutrient Cycle ReviewClick the “Start” buttons to review the various nutrient cycles.
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Human Activities and Nutrient CyclesHuman Activities and Nutrient Cycles
Aquatic ecosystems suffer when run-off contains high amounts of agricultural fertilizers (which are high in nitrates and phosphates). The added nutrients can lead to the eutrophication of bodies of water.
Eutrophication is a process in which nutrient levels in aquatic ecosystems increase, leading to an increase in the populations of primary producers, such as algae.
Eutrophication eventually leads to a reduction in the oxygen content of the water.
(Page 18)
Copyright © 2010 McGraw-Hill Ryerson Ltd.
Cycling of Matter and Earth’s Spheres
Cycling of Matter and Earth’s Spheres
(Page 19)
Learning Check 2
5. What is eutrophication?
6. Which nutrient was found to be the main cause of eutrophication in northern Ontario lakes?
7. What is one possible source of excess phosphorus in aquatic ecosystems?
8. Suppose that you have a small fishpond in your backyard. You work hard to get your lawn looking thick and green. By the end of the summer, your lawn looks great, but the water in your fishpond is green and the fish are dead. What might have happened?
