Presentation on theme: "Classifying Resources Renewable Resources – can regenerate if they are alive, or can be replenished by biochemical cycles if they are nonliving Example:"— Presentation transcript:
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
Earths forests are an important resource for the products they provide and for the ecological functions they perform. Provide wood for products and fuel. Remove carbon dioxide 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 and microclimates, 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.
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 worlds 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
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 peoples 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 fall to the Earth in the form of rain, snow, sleet, or fog Acid precipitation kills plants by damaging their cells and interfere with plant growth
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. Examples: 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 dont 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, many 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 1.Reduction of Light Transmission Light intensity 2m below an oil slick can be reduced by 90% Reduces the rate of photosynthesis so plants and protists die
2.Reduction in Dissolved Oxygen Oil film blocks rate of oxygen uptake by water DO is lower in oil contaminated water 3.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
4.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, powdered 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 nations history 250,000 seabirds died 2,800 sea otters died 300 harbor seals died 250 bald eagles died 22 killer whales died
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 species numbers become so low that extinction is possible Extinction – the disappearance of a species when the last of its members dies Since 1980s 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, cane toad, European starling, mongoose in Hawaii
Conservation Biology Conservation – 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 Examples: California condor, wolves in Yellowstone, Black-footed ferret
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 Earths surface
Early Evidence In the 1970s, scientists discovered a hole in the ozone layer over Antarctica In 1974, a research team published data showing that gases called chloroflurocarbons, or CFCs could damage the ozone layer
CFCs 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 CFCs in 1987, and eventually banned them Since the ban the level of CFCs 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 lat 19 th century, average temperatures have risen about 0.6ºC 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 that Earths 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 atmospheres 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