Presentation on theme: "What causes water pollution?. 97% of water on the Earth is salt water, and only 3% is fresh water of which slightly over two thirds is frozen in glaciers."— Presentation transcript:
What causes water pollution?
97% of water on the Earth is salt water, and only 3% is fresh water of which slightly over two thirds is frozen in glaciers and polar ice caps.
Earth's water distribution
Depletion of aquifers Due to the expanding human population, competition for water is growing such that many of the worlds major aquifers are becoming depleted. This is due both for direct human consumption as well as agricultural irrigation by groundwater. Millions of pumps of all sizes are currently extracting groundwater throughout the world. Irrigation in dry areas such as northern China and India is supplied by groundwater, and is being extracted at an unsustainable rate. Cities that have experienced aquifer drops between 10 to 50 meters include Mexico City, Bangkok, Manila, Beijing, Madras and Shanghai.
Pollution and water protection Water pollution is one of the main concerns of the world today. The governments of numerous countries have strived to find solutions to reduce this problem. Many pollutants threaten water supplies, but the most widespread, especially in developing countries, is the discharge of raw sewage into natural waters; this method of sewage disposal is the most common method in underdeveloped countries, but also is prevalent in quasi-developed countries such as China, India and Iran.
Oil Pollution Oceans are polluted by oil on a daily basis from oil spills, routine shipping, run-offs and dumping. Oil spills make up about 12% of the oil that enters the ocean. The rest come from shipping travel, drains and dumping. An oil spill from a tanker is a severe problem because there is such a huge quantity of oil being spilt into one place. Oil spills cause a very localised problem but can be catastrophic to local marine wildlife such as fish, birds and sea otters. Oil cannot dissolve in water and forms a thick sludge in the water. This suffocates fish, gets caught in the feathers of marine birds stopping them from flying and blocks light from photosynthetic aquatic plants.
Conclusion We are very lucky that we live in Taipei. Because we have glean water, when we turn on the faucet, the water comes out. There are a lot of people around the world dont have enough water. Save water as much as you can, and we will have enough water for years.