英语演讲稿-水污染_英文PPT

1、waterenvironmentenvironmentWater is the source of all things Its the only water, but its the liquid wonder that makes our world possible. Water is able to dissolve more substances than any other liquid. Its takes a lot of water to keep life going.123Some data water use& pollution what can we do 71%

2、of earths surface is covered with waterAre the water sources abundant? less than 3%Of total waterLow layer0.3% of fresh water China water resource rank fourth in the world. China isnt rich in water resources . Obviously, the prospect of Chinese water resources isnt optimistic.Water Issues in China w

3、ith water resources per capita being2200m3 or so, only 1/4 of that of the world. water resources per capita South:population 53% waterresource:78%North: population:47% water resource:22%Uneven distribution of water resources n Water is considered polluted if a substance or condition is present that

4、renders the water useless for a particular purposenThe sources of water pollutionnDirect sources neffluent outfalls from factories, refineries( 精炼厂）, waste treatment plants .nIndirect sourcesncontaminants that enter the water supply from soils/groundwater systems and from the atmosphere via rain wat

5、er.Agricultural Water UseFour common irrigation methods:Surface / FloodRequires extensive canal systemsSprayUse pumpsTrickleStrategically places openingsSub-irrigationPipes can be used for drainage as wellnExcessive fertilizer use may lead to eutrophication（水体富营养化） in many aquatic habitats.nAgricult

6、ural runoff from large, open expanses is major source of water pollution.Agricultural Water PollutionIndustrial Water UseAccounts for nearly 50% of all water withdrawal in U.S., and 23% worldwide.90% of water used by industry is for cooling, and is returned to the source.Very little actually consume

7、d.Most processes involve heat exchange.Water used to dissipate and transport waste.Toxic and overload wastes lead Stream and lake degradation.Industrial Water PollutionAll kinds of industry generate trade waste (工业废水）Iron and steel industryFood industryComplex organic chemicals industryNuclear indus

8、tryPollutants: organics, oil, metal, acidMay require special wastewater treatment. Domestic Water Use70% used as solvent to carry wastes.30% used for lawn and garden.Very small fraction used for drinking.Natural purification processes cannot cope with highly concentrated urban wastes.Must be treated

9、 before release.Domestic water pollutionWaste water from Bathing, dishes, toiletsNo toxic substance, abundant in nutrients with nitrogen (N，氮）and phosphorus (P，磷）Eutrophication （水体富营养化）Trash or garbage (e.g. paper, plastic, or food waste) discarded by people on the ground, along with accidental or i

10、ntentional dumping of rubbish, that are washed by rainfall into storm drains and eventually discharged into surface waters .For governments 1.To establish urban sewage treatment system(城市污水处理系统) 2.To restructure Industrial 3.To encourage the development of new water sources 4.To strengthen legislati

11、on, severe punishmentFor plants 1.To reduce water consumption 2.To buy equipment of sewage treatment 3.Dont discharge sewage into water 4.To use water recycling systemFor individuals 1 .Dont use cleaner conclude P 2. Dont throw the garbage into the rivers 3. To promote awareness of preserving water resources 4. To tell the persons around you to protect the water resourcesWorld Water Day (World Day for Water) On March 22 the United