(小学节约用水主题班会课件.ppt

水的分类 水可以分为两大类：淡水，海水（咸水）。 水在自然界占的比例是：海洋水占96.53%，大气水占0.001%，陆地水占3.5%。 人类可用的淡水资源占的比例很小，而人类目前比较容易利用的淡水资源比例更小，主要是河流水、淡水湖泊水以及浅层地下水。 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 此物真稀奇， 越洗越有泥。 不洗可以吃， 洗了吃不得。  （打一液体） Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 饮用 浇灌 生产 水有哪些用途？ Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 人类的生存和发 展都离不开水！ Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 海水和淡水 如果把地球的总水量平均分成100份，海水大约占97份，在不足3份的淡水中，冰又占了2份，可供利用的淡水还不到1份。请将海水、冰和可供利用的淡水的份数在下图中用不同的颜色表示出来。 海水 冰 可供利用的淡水 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 科学在线 淡水的缺乏越来越严重地限制了农业生产、工业生产和人民生活。 虽然我国淡水资源比较丰富，但是由于人口众多，每人平均占有的淡水资源是世界人均水平的百分之二十五，全国大多数地区都面临着淡水资源紧张的问题。我国300多个大城市中有188个供水紧张，40多个严重缺水。同时，我国的水资源利用率极低，污染和浪费十分严重。 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client P