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2013-10-28
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Health and pollution Environmental Science Program, Iowa State University student sampling water. Water fit for human consumption is called drinking water or potable water. Water that is not potable can be made potable by filtration or distillation (heating it until it becomes water vapor, and then capturing the vapor without any of the impurities it leaves behind), or by other methods (chemical or heat treatment that kills bacteria). Sometimes the term safe water is applied to potable water of a lower quality threshold (i.e., it is used effectively for nutrition in humans that have weak access to water cleaning processes, and does more good than harm). Water that is not fit for drinking but is not harmful for humans when used for swimming or bathing is called by various names other than potable or drinking water, and is sometimes called safe water, or "safe for bathing". Chlorine is a skin and mucous membrane irritant that is used to make water safe for bathing or drinking. Its use is highly technical and is usually monitored by government regulations (typically 1 part per million (ppm) for drinking water, and 1–2 ppm of chlorine not yet reacted with impurities for bathing water).This natural resource is becoming scarcer in certain places, and its availability is a major social and economic concern. Currently, about a billion people around the world routinely drink unhealthy water. Most countries accepted the goal of halving by 2015 the number of people worldwide who do not have access to safe water and sanitation during the 2003 G8 Evian summit.[21] Even if this difficult goal is met, it will still leave more than an estimated half a billion people without access to safe drinking water and over a billion without access to adequate sanitation. Poor water quality and bad sanitation are deadly; some five million deaths a year are caused by polluted drinking water. The World Health Organization estimates that safe water could prevent 1.4 million child deaths from diarrhea each year.[22] Water, however, is not a finite resource, but rather re-circulated as potable water in precipitation in quantities many degrees of magnitude higher than human consumption. Therefore, it is the relatively small quantity of water in reserve in the earth (about 1% of our drinking water supply, which is replenished in aquifers around every 1 to 10 years), that is a non-renewable resource, and it is, rather, the distribution of potable and irrigation water which is scarce, rather than the actual amount of it that exists on the earth. Water-poor countries use importation of goods as the primary method of importing water (to leave enough for local human consumption), since the manufacturing process uses around 10 to 100 times products' masses in water.In the developing world, 90% of all wastewater still goes untreated into local rivers and streams.[23] Some 50 countries, with roughly a third of the world’s population, also suffer from medium or high water stress, and 17 of these extract more water annually than is recharged through their natural water cycles.[24] The strain not only affects surface freshwater bodies like rivers and lakes, but it also degrades groundwater resources.
2013-10-28
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As we see ,water is the source of life. But there is very limited available water resources in our world. So we shouldn't waste it. Of course, we have to use it to drink, cook, wash, clean and etc. But we must remember not to use it extravagantly. If we didn't stop such wasteful habits, we would cut off the development of the world and the human life.
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2013-10-28
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Don't Waste Water
A man is washing his clothes ,regardless of the notice above “Save the Water Please.”
As we see ,water is the source of life. But there is very limited available water resources in our world. So we shouldn't waste it. Of course, we have to use it to drink, cook, wash, clean and etc. But we must remember not to use it extravagantly. If we didn't stop such wasteful habits, we would cut off the development of the world and the human life.
A man is washing his clothes ,regardless of the notice above “Save the Water Please.”
As we see ,water is the source of life. But there is very limited available water resources in our world. So we shouldn't waste it. Of course, we have to use it to drink, cook, wash, clean and etc. But we must remember not to use it extravagantly. If we didn't stop such wasteful habits, we would cut off the development of the world and the human life.
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2013-10-28
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写不要浪费水的原因水的作用我们应该怎么做
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