暨大生態(tài)學(xué)普生課件視頻課程general ecology12

1、段舜山 2008-12-251主講教師: 段舜山 暨南大學(xué)生命科學(xué)技術(shù)學(xué)院生態(tài)學(xué)系 生態(tài)學(xué)專業(yè)必修課普通生態(tài)學(xué)GENERAL ECOLOGY段舜山 2008-12-252第12章Human Impact on the Biosphere人類對生物圈的影響3段舜山 2008-12-25第1節(jié) 空氣污染（復(fù)習(xí)）Concepts:Pollutant definition 污染物定義Pollutant types 污染物類型Pollutant disperse 污染物的擴(kuò)散Thermal inversion 逆溫現(xiàn)象Smog types 煙霧類型Photochemical smog 光化學(xué)煙霧Poll

2、utant harm 污染物的危害Ozone reduction 臭氧層減少4段舜山 2008-12-25第2節(jié) 水源短缺與水體污染（復(fù)習(xí)）Concepts:Water supply 水資源總量Disadvantages of irrigation 灌溉Water scarcity 水資源短缺Desalination 海水淡化作用Water pollution 水污染W(wǎng)astewater treatment 污水處理段舜山 2008-12-255主要內(nèi)容 12.3 Deforestation 12.4 Desertification 12.5 Energy sources JINAN UNIV

3、ERSITY6段舜山 2008-12-25第3節(jié) 采伐森林Concepts:Merits of recycle paperMerits of forestsDeforestationDisadvantages of deforestation7段舜山 2008-12-25Merits of recycle paper 紙張循環(huán)利用的好處It takes more than 500,000 trees to supply a Sunday newspaper to Americans.Every week if everyone recycled even one out of ten news

4、papers, 25 million trees a year could be left standing.Also, recycling paper reduces by 95 percent the air pollutants released during paper manufacture.And recycling takes less energy than manufacturing new paper.8段舜山 2008-12-25Merits of forests 森林的好處The worlds great forests profoundly influence the

5、 biosphere.世界大森林對生物圈具有深刻地影響.Like giant sponges, forested watersheds absorb, hold, and gradually release water.像海綿吸水并緩釋By intervening in the downstream flow of water, forests help control soil erosion, flooding, and sediment buildup in rivers, lakes, and reservoirs.森林有助于控制水土流失、防洪、防止河流湖泊水庫淤積。9段舜山 2008

6、-12-25森林覆蓋的山坡10段舜山 2008-12-25失去森林的山坡11段舜山 2008-12-25Deforestation 采伐森林Deforestation is the removal of all trees from large tracts of land for logging, agricultural, or grazing operations.The loss of vegetation cover exposes the soil, and this promotes leaching of nutrients and erosion, especially on

7、 steep slopes.12段舜山 2008-12-25Disadvantages of deforestation 砍伐森林的壞處In the tropics, clearing forests for agriculture leads to a long-term loss in productivity.Shifting cultivation (slash-and-burn agriculture) disrupts the forest ecosystem. People cut and burn trees, then till the ashes into the soil

8、. The nutrient-rich ashes sustain crops for one to several seasons. Then, as a result of leaching, the cleared plots e infertile and are abandoned.13段舜山 2008-12-25熱帶森林的砍伐14段舜山 2008-12-25大范圍采伐熱帶雨林可能對全球產(chǎn)生巨大影響15段舜山 2008-12-25Deforestation may disrupt regional patterns of rainfall. Without trees, annual

9、 precipitation declines.Rain rapidly runs off the bare soil. As the region gets hotter and drier, soil fertility and moisture decline even more.Disadvantages of deforestation 砍伐森林的危害16段舜山 2008-12-25Widespread tropical forest destruction may have global repercussions(反響). These forests absorb much of

10、 the sunlight reaching the equatorial regions.When the forests are cleared, the land reflects more ing energy back into space. Also, when trees are burned, carbon stored in their biomass is released to the atmosphere in the form of carbon dioxide. This may amplify(增強(qiáng)) the greenhouse effect.Disadvant

11、ages of deforestation 砍伐森林的危害17段舜山 2008-12-25第4節(jié) 荒漠化Concepts:Definition of desertificationDesertification18段舜山 2008-12-25Definition of desertification 荒漠化定義Desertification refers to the conversion of large tracts of grasslands, rain-fed cropland (雨養(yǎng)農(nóng)業(yè)), or irrigated cropland (灌溉農(nóng)業(yè)) to a more desertl

12、ike state, with a 10 percent or greater drop in agricultural productivity.19段舜山 2008-12-25Desertification 荒漠化In the past fifty years, 9 million square kilometers worldwide have e desertified.Prolonged drought(久旱) can accelerate the process.In the 1930s, a combination of extreme drought and poor cons

13、ervation practices led to severe wind erosion of the topsoil(造成嚴(yán)重的風(fēng)蝕災(zāi)害) in the Great Plains of the United States. About 3.6 million hectares (9million acres) of cropland were affected.Today, desertification of at least 200,000 square kilometers occurs annually.20段舜山 2008-12-25過度放牧和嚴(yán)重干旱導(dǎo)致沙塵暴21段舜山 200

14、8-12-25干旱和和半干旱土地的荒漠化22段舜山 2008-12-25西部非洲的荒漠化23段舜山 2008-12-25第5節(jié) 能源問題Concepts:Net energyEnergy sourcesEnergy explorationNuclear energyNuclear fuel wastesSolar energy24段舜山 2008-12-25Net energy 凈能源It takes energy to make energy. There is a huge difference between the total energy and the net energy amo

15、unts available.Net energy is that left over after subtracting the energy used to locate, extract, transport, store, and deliver energy(減去勘察、開采、運輸、儲存、傳輸?shù)饶芰? to consumers.25段舜山 2008-12-25Energy sources 能量來源Some energy sources, such as direct solar energy, are renewable. Others, such as coal and petrol

16、eum, are not.The most widely used energy source is fossil fuels. These fuels are remains of forests that existed millions of years ago.26段舜山 2008-12-251991年世界能源消耗情況27段舜山 2008-12-25煤、石油和天然氣等化石能的由來28段舜山 2008-12-25Energy exploration 能源開采As known oil reserves run out in accessible areas, we explore wild

17、erness areas in Alaska and other fragile environments.因易采區(qū)石油基本枯竭，不得不向邊遠(yuǎn)的阿拉斯加等環(huán)境脆弱地區(qū)開采。Net energy declines as costs of extraction and transportation to and from remote areas increase. 開采運輸成本大幅度增加，凈能獲效率下降。Environmental costs of extraction and transportation escalate.開采運輸?shù)沫h(huán)境代價升高。29段舜山 2008-12-25大規(guī)模開發(fā)石油

18、能源帶來的溢油污染儲量銳減30段舜山 2008-12-25Nuclear energy 核能源What about nuclear energy? Many energy-poor industrialized nations, France included, now depend heavily on nuclear power.Yet nuclear power plants have been delayed or canceled in most other countries. Questions surround nuclear energys costs, efficiency

19、, safety record, and environmental impact.31段舜山 2008-12-25核能源的利與弊32段舜山 2008-12-25Nuclear fuel wastes 放射性核廢料Unlike coal, nuclear fuel cannot be burned to harmless ashes. The wastes are radioactive and dangerous.After nearly fifty years of research, scientists still cannot agree on the best way to store high-level radioactive wastes.33段舜山 2008-12-25Solar energy 太陽能Solar energy is a safe and renewable resource. With serious commitment, we could expect solar cells to be supplying as much energy as