1977年8月联合国水资源大会就向全世界发出警告：“水不久将成为一场深刻的社会危机。”水，这种覆盖地球达71％的物质，也许正是由于它存在的太普遍了，才使许多人未加重视，显得并不太珍贵。然而你可曾知道全球淡水仅占总水量的2．5％，可淡水中又有约70％在南北两极和雪山冰川 In August 1977, the UN Water Conference issued a warning to the world: “The water will soon become a profound social crisis.” Water, a substance that covers 71% of the earth, may precisely because of its existence too It is commonplace to make many people unimpressed and not too precious. However, you have known that global fresh water accounts for only 2.5% of the total amount of freshwater and about 70% of freshwater can be found in the northern and southern poles and snow-capped mountains and glaciers