英语演讲稿-水污染-英文PPT.ppt

water,environment,Water 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.,Some data,water use&pollution,what can we do,71%of earths surface is covered with water,Are the water sources abundant?,less than 3%Of total water,Low layer,0.3%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,with 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,Water is considered polluted if a substance or condition is present that renders the water useless for a particular purpose,The sources of water pollutionDirect sources effluent outfalls from factories,refineries(精炼厂）,waste treatment plants.Indirect sourcescontaminants that enter the water supply from soils/groundwater systems and from the atmosphere via rain water.,Agricultural Water Use,Four common irrigation methods:Surface/FloodRequires extensive canal systemsSprayUse pumpsTrickleStrategically places openingsSub-irrigationPipes can be used for drainage as well,Excessive fertilizer use may lead to eutrophication（水体富营养化）in many aquatic habitats.Agricultural runoff from large,open expanses is major source of water pollution.,Agricultural Water Pollution,Industrial Water Use,Accounts 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 consumed.Most processes involve heat exchange.Water used to dissipate and transport waste.Toxic and overload wastes lead Stream and lake degradation.,Industrial Water Pollution,All kinds of industry generate trade waste(工业废水）Iron and steel industryFood industryComplex organic chemicals industryNuclear industryPollutants:organics,oil,metal,acidMay require special wastewater treatment.,Domestic Water Use,70%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 before release.,Domestic water pollution,Waste 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 intentional 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 Industrial3.To encourage the development of new water sources4.To strengthen legislation,severe punishment,For plants,1.To reduce water consumption2.To buy equipment of sewage treatment 3.Dont discharge sewage into water4.To use water recycling system,For individuals,1.Dont use cleaner conclude P2.Dont throw the garbage into the rivers 3.To promote awareness of preserving water resources4.To tell the persons around you to protect the water resources,World Water Day(World Day for Water),On March 22 the United Nations General Assembly（联合国大会）in 1993 aim:to arouse publics awareness of economizing water sources,and to protect itone theme per year2011:water for cities,Thank you!,