Human Impact. Chapter 5

Transcription

1 Human Impact Chapter 5

2 Loss of Biodiversity Biodiversity - variety of life in an area Tropical regions contain two-thirds of all land species Number of mammals, for example: Canada U.S Mexico Importance of biodiversity food webs and ecosystem balance 0 2 for humans diverse diets, clothing and building materials medicines

3 Endangered Species in GA Purple pitcher plant Sarracenia purpurea Loggerhead Sea Turtle Caretta caretta

4 Endangered Species in GA Black right whale Eubalaena glacialis Red-cockaded woodpecker Picoides borealis

5 Loss of Biodiversity Possible causes Habitat loss Habitat fragmentation Habitat degradation (by pollution) Solutions Habitat Preservation through National and State Parks W.M.A (Wildlife Management Areas)

6 Biomagnification Biomagnification toxins become more concentrated as it moves up the trophic levels Example is DDT insecticide Dichloro-diphenyl-trichloroethane Collects in fatty (adipose) tissues of animals

7 Biomagnification

8 History of DDT Developed and used during WWII small tins given to soldiers to combat lice & malaria Heavily used in U.S. from 1940s to 1970s even sprayed in public areas to kill mosquitoes Banned from U.S. in 1972, but continues to be used in other countries

9 History of DDT

10 Rachel Carson DDT a serious problem decline in bird (top of food chain) populations (thin egg shells) Silent Spring written by Carson helped to bring about formation of EPA and banning of DDT Bird populations showed dramatic recovery Even today, traces of DDT have been found in every organism tested - even in human breast milk throughout world

11 Land Resource Depletion What happening? Plowing removes the roots that hold the soil in place, increasing the rate of soil erosion. SOIL EROSION is the wearing away of surface soil by water and wind. Desertification the process of turning once productive areas into deserts from a combination of farming, overgrazing, and drought.

12 Land Resources Why is it a problem? Soil is a renewable resource, however it can be permanently damaged if mismanaged What is being done? Contour plowing- fields plowed across the slope of the land Leaving stems and roots of the previous year s crops in place to hold soil. Planting trees

13 Land Resource Depletion Deforestation - loss of forest which leads to severe erosion

14 Water Resources What is happening? Pollution such as OIL SPILLS threatens our water supply. Improperly discarded chemicals can enter streams and rivers. Domestic sewage entering our water ways can cause an increase in bacteria growth. Overfishing - fish stocks in many fisheries are being harvested faster than they reproduce.

15 Water Resources Why is this a problem? Fresh water is used daily for everything from drinking and washing to watering crops and making steel. Although water is a renewable resource, the total supply of fresh water is limited. What is being done? Conservation by: drip irrigation and consumer awareness of conservation

16 Water Resources (Oceans) What is happening? Overfishing - fish stocks in many fisheries are being harvested faster than they reproduce. o Why is this a problem? o o o People depend on the ocean as a major source of protein, both from finfish and from shellfish. With the amount of fish caught each year increasing, the fish cannot reproduce fast enough to keep up. Disrupts ecosystem (food web)

17 Water Resources What is being done? Limiting the catch of fish Certain fishing grounds have been temporarily closed Aquaculture - farming of aquatic organisms

18 Air Resources What is happening? Smog a mixture of chemicals that occurs as a gray-brown haze in the atmosphere This is due primarily to automobile exhausts and industrial emissions. Pollutant - a harmful material that can enter the biosphere through air, land, or water The burning of fossil fuels can release pollutants that cause smog and other problems in the atmosphere.

19 What is Acid Rain and What Causes It? "Acid rain" is a broad term used to describe several ways that acids fall out of the atmosphere. A more precise term is acid deposition, which has two parts: wet and dry. Wet deposition refers to acidic rain, fog, and snow. As this acidic water flows over and through the ground; it affects a variety of plants and animals. Dry deposition refers to acidic gases and particles. About half of the acidity in the atmosphere falls back to earth through dry deposition. The wind blows these acidic particles and gases onto buildings, cars, homes, and trees. Dry deposited gases and particles can also be washed from trees and other surfaces by rainstorms.

20 What is Acid Rain and What Causes It? Prevailing winds blow the compounds that cause both wet and dry acid deposition across state and national borders, and sometimes over hundreds of miles. Scientists discovered, and have confirmed, that sulfur dioxide (SO 2 ) and nitrogen oxides (NOx) are the primary causes of acid rain. In the U.S., about 2/3 of all SO 2 and 1/4 of all NOx come from electric power generation that relies on burning fossil fuels like coal. Acid rain occurs when these gases react in the atmosphere with water, oxygen, and other chemicals to form various acidic compounds. Sunlight increases the rate of most of these reactions. The result is a mild solution of sulfuric acid and nitric acid.

21 Air Resource Depletion

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23 Air Resources Why is it a problem? This leads to toxins that enter the mouth, nose and lungs causing health problems over the long term. Gases released from the burning of fossil fuels combine with water vapor to form ACID RAIN Acid rain kills plants and changes the chemistry of soils What is being done? Technology to control emissions from factory smokestacks Strict automobile emission standards and clean air regulations

24 Global Warming

25 Global Warming Some warming is good if not for the ozone and atmosphere, Earth would be -18 C Warming is due to greenhouse gases in the atmosphere trapping in heat Estimated increase of 2 C by end of 21 st century Even 1.3 C affects polar ice cap melting Sea levels could rise 100 m, gradually going in 150 km or more

26 Green House Effect Natural situation in which heat is retained in the earth s atmosphere by green house gasses Examples: carbon dioxide, methane, water vapor, and other gasses

27 Global Warming

28 Global Warming Why is this a problem? Polar ice caps will continue to melt and could rise enough to flood some low lying coastal areas. Storms and other weather disturbances could become more frequent and severe. Heat favors rodents, weeds, and insects that reproduce and spread quickly.

29 Ozone Depletion Ozone layer is composed of 0 3 in lower stratosphere. Stratospheric Ozone The stratosphere, or "good" ozone layer extends upward from about 6 to 30 miles and protects life on Earth from the sun's harmful ultraviolet (UV) rays This natural shield has been gradually depleted by man-made chemicals like chlorofluorocarbons (CFCs). A depleted ozone shield allows more UV from the sun to reach the ground, leading to more cases of skin cancer, cataracts, and other health problems.

30 Ozone Depletion

31 Ozone Depletion

32 Ozone Depletion Why is this a problem? The ozone layer absorbs a great deal of harmful UV rays before it reaches the earth s surface. As the ozone layer is depleted, UV exposure can cause sunburns, cancer, eye damage and decreases an organism s resistance to disease.

33 Ozone Depletion Solutions Reduce the amount of CFC s use. Most CFC s are banned 1987 The Montreal Treaty reduction of CFC s and eventual ban the CFC production.