Chapter 6
6-2 Renewable and Nonrenewable Resources
Classifying Resources
Renewable Resources – can regenerate if they are alive, or can be replenished by biochemical cycles if they are nonliving
Example: tree, water, air, solar
Nonrenewable Resources – cannot be replenished by natural processes
Once these fuels are depleted they are gone forever
Example: coal, oil, natural gas
Sustainable Development
Sustainable Development – a way of using natural resources without depleting them and causing long-term environmental harm
Forest Resources
Earth’s forests are an important resource for the products they provide and for the ecological functions they perform
Provide wood for products and fuel
Remove CO2 and produce oxygen
Store nutrients
Provide habitats and food for organisms moderate climate
Limit soil erosion
Protect freshwater supplies
Whether a forest can be considered a renewable resource depends partly on the type of forest
Temperate forests of the Northeast are renewable because they have been logged and have grown back naturally
Old-growth forests, such as those in Alaska and the Pacific Northwest, are nonrenewable because it takes centuries to produce them
Deforestation
Loss of forests, or deforestation, has several effects
Erosion can wash away nutrients in the topsoil
Grazing or plowing can permanently change local soils which prevents the regrowth of trees
Forest Management
Mature trees can be harvested selectively to promote the growth of younger trees and preserve the forest ecosystem
Tree geneticists are breeding new, faster-growing trees that produce high-quality wood
Fishery Resources
Fishes and other animals that live in water are a valuable source of food
Overfishing
Harvesting fish faster than they can reproduce
Has greatly reduced the amount of fish in parts of the world’s oceans
Fisheries seemed to be a renewable resource, but overfishing has limited that resource
U.S. National Fisheries Service has issued guidelines that specify how many fish, and of what size, can be caught
Air Resources
Smog – a mixture of chemicals that occurs as a gray-brown haze in the atmosphere
Is due to automobile exhausts and industrial emissions
Considered a pollutant because it threatens people’s health
Pollutant – a harmful material that can enter the biosphere through the land, air, or water
The burning of fossil fuels can release pollutants that cause smog and other problems in the atmosphere
Strict automobile emissions standards and clean-air regulations have improved air quality in many cities, but air pollution is still a problem
Acid Precipitation – nitrogen and sulfur compounds in the atmosphere combine with water vapor and fail to the Earth in the form of rain, snow, sleet or fog
Freshwater Resources
Although water is a renewable resource, the total supply of fresh water is limited and is threatened by pollution
Sources of freshwater pollution include:
Improperly discarded chemicals that enter streams and rivers
Wastes discarded on land that seep through soil and enter underground water supplies
Domestic sewage containing compounds that encourage growth of algae and bacteria
Sewage containing microorganisms that spread disease
Sustainable Use of Water
One way to ensure the sustainable use of water is to protect the natural systems involved in the water cycle that help purify water
Example: wetlands, forests, rock layers
Also by conserving water in:
Home
Industry
Agriculture
The Fate of Spilled Oil
According to a well-known saying that oil and water don’t mix, it might be expected that spilled oil would float around until it was washed ashore
A single gallon of oil can spread enough to cover up to four acres of water
As soon as the oil is spilled in a marine environment, may changes begin to take place
Within days, 25% of the oil is lost through evaporation
The remaining oil sinks to the bottom of the ocean
It adheres to almost all objects that it encounters
After 3 months only 15% of the original oil remains
If a substantial oil spill occurred close to shore rather than at sea, the effects would be different because there would not be sufficient time available for the process described above to affect the total amount of oil involved
Effects of Oil Spills
- Reduction of Light Transmission
Light intensity 2m below an oil slick can be reduced by 90%
Reduces the rate of photosynthesis so plants and protests die
- Reduction in Dissolved Oxygen
Oil film blocks rate of oxygen uptake by water
DO is lower in oil contaminated water
- Damage of Marine Birds
Birds covered with oil can drown
Oil causes bird feathers to mat together and reduces the birds ability to fly and float in water
Feathers lose their insulating ability
Birds die because of exposure to cold weather or inability to get food
- Toxic Effects to Marine Environment
Oil contains benzene, toluene, xylene, which are toxic to plants and animals
Methods of Oil Spill Clean-Up
Booms or Barriers
Contain oil slick
Makes it easier to skim the oil off the surface
Skimmers
Used to remove oil from the surface of the water
They are attached to ships or may be hand-held along shore
Skimming works best in calm waters
Sorbents
Materials used to soak up oil spills
Example: straw, powered clay, sawdust, chopped corn cobs, pine bark
Chemical Dispersants, Detergents, and Solvents
Used to degrade the oil
Unfortunately most of these chemicals are toxic to animals
Flames
Used to burn the oil
The black smoke contains toxic components
Bioremediation
The oil spill cleanup methods listed above only recover 10-30% of the spilled oil
The most environmentally safe prospect for the cleanup of oil spills is the use of oil-degrading microbes
Bioremediation – the use of naturally occurring microorganisms that have been genetically engineered and that can be used to degrade petroleum products
A microorganism called petrophiles are spread across an oil spill and they degrade the oil and convert it into food
The microorganisms may be mixed with nutrients such as nitrogen, phosphorus, and cottonseed protein that not only enhance the microbial growth, but also absorb the oil and provide a matrix for the microorganisms to continue to degrade the absorbed oil
The treated oil slick begins to break up and turn into a yellowish substance that eventually diminishes in size
Case Study – The Exxon Valdez
In the spring of 1989, the largest oil spill in U.S. history occurred when an oil tanker named the Exxon Valdez hit a reef in Prince William Sound off the coast of Alaska
More than 10 million gallons of crude oil spilled
The oil slick covered more than 1,000 miles of coastline
Caused an estimated 5 billion dollars in environmental damages
The Exxon Valdez disaster killed more wildlife than any other environmental disaster in our nation’s history
250,000 seabirds died
2,800 sea otters died
300 harbor seals died
250 bald eagles died
22 killer whales died
6-3 Biodiversity
The Value of Biodiversity
Biodiversity – the number of species that live in a certain area
A rain forest has the greatest amount of biodiversity
Why is biodiversity important?
Food
Medicines
Industrial products
Threats to Biodiversity
Human activity can reduce biodiversity by:
Altering habitats
Hunting species to extinction
Introducing toxic compounds into food webs
Introducing foreign species to new environments
Threatened Species – when the population of a species begins declining rapidly
Endangered Species – when its numbers become so low that extinction is possible
Extinction – the disappearance of a species when the last of its members dies
Since 1980’s almost 40 species of plants and animals living in the United States have become extinct
Although extinction can occur as a result of natural processes, humans have been responsible for the extinction of many species
Habitat Alteration
Habitat loss is the biggest threat to biodiversity
Habitat Fragmentation – the separation of wilderness areas from other wilderness areas
Presents problems for organisms that need large areas to gather food
Habitat Degradation – the damage to a habitat by pollution
Introduced Species
Another threat to biodiversity comes from plants and animals that humans transport around the world either accidentally or intentionally
Exotic (Invasive) Species – organisms that are not native to a particular area
Reproduce rapidly because their new habitat lacks the predators that would control their population
Example: zebra mussels, amur honeysuckle, kudzu
Conservation Biology
Conservation Biology – the management of natural resources including the preservation of habitats and wildlife
Many species are in danger due to the actions of humans, so working with people is an important part of conservation biology
Strategies for Conservation
Many conservation efforts are aimed at managing individual species to keep them from becoming extinct
U.S. Endangered Species Act – this law made it illegal to harm any species on the endangered or threatened species lists
Create more natural preserves
Reintroduction Programs – release organisms into an area where their species once lived
6-4 Charting a Course for the Future
Ozone Depletion
Ozone Layer – atmospheric layer in which ozone gas is relatively concentrated
The ozone layer absorbs a good deal of harmful ultraviolet or UV radiation from sunlight before it reaches Earth’s surface
Early Evidence
In the 1970’s scientists discovered a hole in the ozone layer
In 1974, a research team published data showing that gases called chlorofluorocarbons, or CFC’s could damage the ozone layer
CFC’s were once widely used:
As propellants in aerosol cans
As coolant in refrigerators, freezers, and air conditioners
In the production of plastic foams
The U.S. and other nations began reducing the use of CFC’s in 1987, and eventually banned them
Since the ban the level of CFC’s in the atmosphere had decreased, indicating that the ban will have positive long-term effects on the global environment
Current data predict that the ozone holes should shrink and disappear within 50 years.
Global Climate Change
Since the late 19th century, average temperatures have risen between 0.2 and 0.3ºC
Global Warming – the increase in the average temperature of the biosphere
One sign of global warming is melting polar ice
Evidence of Global Warming
The geological record shows the Earth’s climate has changed repeatedly during its history
Researchers must determine whether the current warming trend is part of a larger, natural cycle of climate change or whether it is caused by human activity
A widely accepted hypothesis is that current warming is related, in part, to human activities that add carbon dioxide and other greenhouse gases to the atmosphere
Data show that concentrations of carbon dioxide in the atmosphere have been rising for 200 years
As a result the atmosphere’s natural greenhouse effect is intensified, causing the atmosphere to retain more heat
Possible Effects of Global Warming
Most recent computer models suggest that average global surface temperatures will increase by 1 to 2ºC by the year 2050
Sea levels may rise enough to flood coastal areas affecting coastal ecosystems as well as human communities
Parts of North America may experience more droughts during the summer growing season
New organisms may be able to live in places where they once could not
Other organisms may become threatened or extinct in areas where they once thrived
Chapter 6
6-2 Renewable and Nonrenewable Resources
Classifying Resources
Environmental goods and services may be classified as either renewable or nonrenewable
Renewable Resources –
Example:
Nonrenewable Resources –
Once these fuels are depleted they are gone forever
Example:
Sustainable Development
Sustainable Development –
Forest Resources
Earth’s forests are an important resource for the products they provide and for the ecological functions they perform
Remove ______and produce oxygen
Provide habitats and food for organisms moderate climate
Whether a forest can be considered a renewable resource depends partly on the type of forest
Temperate forests of the Northeast are renewable because they have been logged and have grown back naturally
Old-growth forests, such as those in Alaska and the Pacific Northwest, are nonrenewable because it takes centuries to produce them
Deforestation
Loss of forests, or deforestation, has several effects
______or ______can permanently change local soils which prevents the regrowth of trees
Forest Management
Mature trees can be harvested selectively to promote the growth of younger trees and preserve the forest ecosystem
Tree geneticists are breeding new, faster-growing trees that produce high-quality wood
Fishery Resources
Fishes and other animals that live in water are a valuable source of food
Overfishing
Harvesting fish faster than they can ______
Has greatly reduced the amount of fish in parts of the world’s oceans
Fisheries seemed to be a ______resource, but overfishing has limited that resource
U.S. National Fisheries Service has issued guidelines that specify how many fish, and of what size, can be caught
Air Resources
Smog –
Is due to automobile exhausts and industrial emissions
Considered a pollutant because it threatens people’s ______
Pollutant –
The burning of fossil fuels can release pollutants that cause ______and other problems in the atmosphere
Strict automobile emissions standards and clean-air regulations have improved air quality in many cities, but air pollution is still a problem
Acid Precipitation –
Acid precipitation kills plants by damaging their ______and interferes with plant growth
Freshwater Resources
Although water is a ______resource, the total supply of fresh water is limited and is threatened by pollution
Sources of freshwater pollution include:
Wastes discarded on land that seep through soil and enter underground water supplies
Domestic sewage containing compounds that encourage growth of ______and ______
Sustainable Use of Water
One way to ensure the sustainable use of water is to protect the natural systems involved in the water cycle that help purify water
Example:
Also by conserving water in:
The Fate of Spilled Oil
According to a well-known saying that oil and water don’t mix, it might be expected that spilled oil would float around until it was washed ashore
A single gallon of oil can spread enough to cover up to ______acres of water
As soon as the oil is spilled in a marine environment, many changes begin to take place
Within days, ______of the oil is lost through evaporation
It adheres to almost all objects that it encounters
After 3 months only ______of the original oil remains
If a substantial oil spill occurred close to shore rather than at sea, the effects would be different because there would not be sufficient time available for the process described above to affect the total amount of oil involved
Effects of Oil Spills
- Reduction of Light Transmission
Light intensity 2m below an oil slick can be reduced by ______
Reduces the rate of photosynthesis so plants and protests die
- Reduction in Dissolved Oxygen
Oil film blocks rate of ______uptake by water
- Damage of Marine Birds
Oil causes bird feathers to mat together and reduces the birds ability to fly and float in water
Birds die because of exposure to cold weather or inability to get food
- Toxic Effects to Marine Environment
Oil contains ______, ______, ______, which are toxic to plants and animals
Methods of Oil Spill Clean-Up
Booms or Barriers
Skimmers
They are attached to ships or may be hand-held along shore
Skimming works best in ______waters
Sorbents
Example:
Chemical Dispersants, Detergents, and Solvents
Unfortunately most of these chemicals are toxic to animals
Flames
The black smoke contains toxic components
Bioremediation
The oil spill cleanup methods listed above only recover 10-30% of the spilled oil
The most environmentally safe prospect for the cleanup of oil spills is the use of oil-degrading ______
Bioremediation –
A microorganism called ______are spread across an oil spill and they degrade the oil and convert it into food
The microorganisms may be mixed with nutrients such as nitrogen, phosphorus, and cottonseed protein that not only enhance the microbial growth, but also absorb the oil and provide a matrix for the microorganisms to continue to degrade the absorbed oil
The treated oil slick begins to break up and turn into a ______substance that eventually diminishes in size
Case Study – The Exxon Valdez
In the spring of 1989, the largest oil spill in U.S. history occurred when an oil tanker named the Exxon Valdez hit a reef in Prince William Sound off the coast of Alaska
More than 10 million gallons of crude oil spilled
The oil slick covered more than 1,000 miles of coastline
Caused an estimated 5 billion dollars in environmental damages
The Exxon Valdez disaster killed more wildlife than any other environmental disaster in our nation’s history
______seabirds died
______sea otters died
______harbor seals died
______bald eagles died
______killer whales died
6-3 Biodiversity
The Value of Biodiversity
Biodiversity –
A rain forest has a greater amount of ______than a cornfield
Why is biodiversity important?
Biodiversity is one of Earth’s greatest natural resources
Species of many kinds have provided us with:
Threats to Biodiversity
What are the current threats to biodiversity?
Human activity can reduce biodiversity by:
Introducing toxic compounds into ______
Introducing foreign species to new environments
Threatened Species –
Endangered Species –
Extinction –
Since 1980’s almost 40 species of plants and animals living in the United States have become extinct
Although extinction can occur as a result of natural processes, humans have been responsible for the extinction of many species