暨大生态学普生课件视频课程general ecology12

1、段舜山 2008-12-251主讲教师: 段舜山 暨南大学生命科学技术学院生态学系 生态学专业必修课普通生态学GENERAL ECOLOGY段舜山 2008-12-252第12章Human Impact on the Biosphere人类对生物圈的影响3段舜山 2008-12-25第1节 空气污染（复习）Concepts:Pollutant definition 污染物定义Pollutant types 污染物类型Pollutant disperse 污染物的扩散Thermal inversion 逆温现象Smog types 烟雾类型Photochemical smog 光化学烟雾Poll

2、utant harm 污染物的危害Ozone reduction 臭氧层减少4段舜山 2008-12-25第2节 水源短缺与水体污染（复习）Concepts:Water supply 水资源总量Disadvantages of irrigation 灌溉Water scarcity 水资源短缺Desalination 海水淡化作用Water pollution 水污染Wastewater treatment 污水处理段舜山 2008-12-255主要内容 12.3 Deforestation 12.4 Desertification 12.5 Energy sources JINAN UNIV

3、ERSITY6段舜山 2008-12-25第3节 采伐森林Concepts:Merits of recycle paperMerits of forestsDeforestationDisadvantages of deforestation7段舜山 2008-12-25Merits of recycle paper 纸张循环利用的好处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 森林的好处The worlds great forests profoundly influence the

5、 biosphere.世界大森林对生物圈具有深刻地影响.Like giant sponges, forested watersheds absorb, hold, and gradually release water.像海绵吸水并缓释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、防止河流湖泊水库淤积。9段舜山 2008

6、-12-25森林覆盖的山坡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 砍伐森林的坏处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热带森林的砍伐14段舜山 2008-12-25大范围采伐热带雨林可能对全球产生巨大影响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(反响). 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(增强) the greenhouse effect.Disadvant

11、ages of deforestation 砍伐森林的危害17段舜山 2008-12-25第4节 荒漠化Concepts:Definition of desertificationDesertification18段舜山 2008-12-25Definition of desertification 荒漠化定义Desertification refers to the conversion of large tracts of grasslands, rain-fed cropland (雨养农业), or irrigated cropland (灌溉农业) 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(造成严重的风蚀灾害) 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过度放牧和严重干旱导致沙尘暴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节 能源问题Concepts:Net energyEnergy sourcesEnergy explorationNuclear energyNuclear fuel wastesSolar energy24段舜山 2008-12-25Net energy 净能源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(减去勘察、开采、运输、储存、传输等能量) to consumers.25段舜山 2008-12-25Energy sources 能量来源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年世界能源消耗情况27段舜山 2008-12-25煤、石油和天然气等化石能的由来28段舜山 2008-12-25Energy exploration 能源开采As known oil reserves run out in accessible areas, we explore wild

17、erness areas in Alaska and other fragile environments.因易采区石油基本枯竭，不得不向边远的阿拉斯加等环境脆弱地区开采。Net energy declines as costs of extraction and transportation to and from remote areas increase. 开采运输成本大幅度增加，净能获效率下降。Environmental costs of extraction and transportation escalate.开采运输的环境代价升高。29段舜山 2008-12-25大规模开发石油

18、能源带来的溢油污染储量锐减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核能源的利与弊32段舜山 2008-12-25Nuclear fuel wastes 放射性核废料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 太阳能Solar energy is a safe and renewable resource. With serious commitment, we could expect solar cells to be supplying as much energy as