Presentation on theme: "Ch. 25 – Earth Resources What is a natural resource?"— Presentation transcript:
1 Ch. 25 – Earth Resources What is a natural resource? A resource that Earth provides.These include rocks, minerals, nutrients, air, water, land, and all living things. - VideoSome of these natural resources can’t be replaced in reasonable amount of time – Nonrenewable.Renewable resources are natural resources that can be used without causing reduction to the available supply.What are some examples?Trees, air, soil, water, sun, etc.Video – Intro.
2 Food webs or Food chains function properly because of the balance. Living organisms are important renewable resources in order for the environment to maintain a balance.Food webs or Food chains function properly because of the balance.Humans try to manage a sustainable yields. What are sustainable yields?The replacement of renewable resources at the same rate at which they are consumed.Video - RenewableSo, what are nonrenewable resources?A resource that exists in fixed amounts throughout the Earth. They take millions of years to be replace by geological, physical, and chemical processes.Examples???Diamonds, gold, fossil fuels, etc.Video - Nonrenewable
3 Some countries with higher populations have lower standards of living. Countries with lots of natural resources have more wealth and power. The U.S. consumes approximately 30% of Earth’s crude oil, even though it has only 6% of the world’s population.Some countries with higher populations have lower standards of living.Fig 25-4 (pg. 658)Video – Other Resources
4 Land Resources 42% of the land in the U.S. is public land. Most of this is in AlaskaNational park systems are set up to preserve the land’s resources.National wildlife refuges protect habitats, breeding areas for wildlife, and some protection of endangered species.Lots of farming, logging, trapping, and fishing occurs in these areas.Topsoil accumulates at just a few centimeters every 1000 years. This topsoil can be swept away in a matter of minutes from erosion of wind and water.
5 Desertification – process by which productive land becomes desert. This can be prevented with less overgrazing and more planting of trees and shrubs.Bedrock – solid rock underneath the topsoil.Limestone, marble, granite, etc.Aggregate – mixture of gravel, sand, crushed stone that naturally accumulates on or close to Earth’s surface.Used in concrete and mortar compounds.Ore – natural resource that can be mined at a profit.They are classified by the manner at which they formed.
6 Heavier mineral like gold and silver are collected in placer deposits, where they settle out. Some ores form when the minerals in rocks are concentrated by weathering.Nickel, copper, lead, mercury, uranium.Digging or extracting these minerals can be damaging to Earth’s surface.Open-pit mines leave behind waste rock that weather and release pollutants.Gangue – is the material left after the ore is extracted and can release harmful chemicals into the ground and surface water.Example – mercury used to extract gold.
7 Air Resources 78% N, 21% O, some CO2 and water vapor. Early Earth had gases in its atmosphere from volcanic eruptions (CO2, N, & water vapor).Rains washed CO2 from the atmosphere into the oceans. Early life-forms used the CO2 during photosynthesis and released oxygen which allowed for the evolution of aerobic organisms.Geochemical cycles (carbon, nitrogen, water) are being disturbed by human activities.Carbon dioxide levels increase due to the burning of fossil fuels. The large levels of carbon dioxide may contribute to global warming.
8 Global warming effects the rainfall patterns and temperature patterns. The nitrogen cycle is being altered with the release of more fertilizers (ammonia). This causes more acid rain.Acid rain damages surface water, plants, and soil.Air pollution is due to pollutants in the air in large enough quantities to damage to the environment and to human health.The single largest air pollutant in the U.S. is motor vehicle exhaust. This is the cause of 80 to 88% of the air pollution.
9 These air pollutants can cause major health issues for humans besides the environmental issues Ex. CO, smog, radon, indoor pollutants (formaldehydes & styrene).Major cities announce on the radio whether its safe to be outside because of the pollutants.Newer homes/buildings have trouble with indoor pollutants because of the airtight seals to help with heating/cooling bills.
10 Water Resources 97% of the water on Earth is ocean. 3% freshwater. 2.997% of that freshwater is locked up in glaciers and ice caps.Only 0.003% of the freshwater is available for domestic, agricultural, and industrial use.About 71% of Earth is water.Most animals are about 50 to 65% water by weight.Water is essential for all organisms.Water’s high specific heat is an important property for distributing energy/heat.Water takes a long time to heat up and cool downVideo – Water Resource
11 Perspiring water allows us to cool as heat is drawn away from our body with the sweat. Water dissolves substances in our body for transportation processes.Turgor pressure (water) allows our cells to maintain homeostasis.Freshwater is limited in some areas of the world.Eastern U.S. received ample amounts of water for distribution, but western U.S. relies on water heavily for farming, which has produced shortages.Lack of rainfall mixed with heavy irrigation in western U.S. has produced problems with recharging the aquifers and drought stricken areas.
12 Most of the freshwater is used for irrigation (70%). The current rate of withdrawal of freshwater from both surface and groundwater sources worldwide is 5 times greater than it was 50 years ago.Fig (pg. 672)Most of the freshwater is used for irrigation (70%).Dams are used more and more for distribution purposes for water and hydroelectric power.2000 years ago Romans used aqueducts to bring water to cities and other locations.Today we use aqueducts, tunnels, and pipes to transport water .Ex. California Water Project – 75% of the annual precipitation occurs North of Sacramento. With the use of dams, pumps, and aqueducts water is transported to California’s major cities. Fig (pg. 673).
13 The lowering of the water table is known as drawdown. If too many wells are drilled in the small area the aquifer can be drawdown lower than the wells, which run dry.Desalination occurs when salt water is distilled.Most countries are using desalination more and more to access more water for drinking primarily.Will we have to use icebergs for water?Most scientists believe that we need to use water more efficiently by industrial recycling, drip irrigation, low-flow toilets, drought-resistant landscaping, etc.