地球上究竟有多少水呢?当代一些水文学家认为地球上共有21亿立方公里水体;其中地表水占14亿立方公里,尚有7亿立方公里的水保存于地壳中。在14亿立方公里的地表水中,海洋中水为13.7亿立方公里,河湖中水为75万立方公里,冰川水占2260万立方公里。保存于地壳中的水,部分参加到矿物结晶格架中,如美国地球化学家鲁比认为在结晶岩中有水 How much water on earth does it have? Some contemporary hydrologists think there are 2.1 billion cubic kilometers of water on the earth; surface water accounts for 1.4 billion cubic kilometers and about 700 million cubic kilometers of water remains in the crust. In 1.4 billion cubic kilometers of surface water, the ocean water is 1.37 billion cubic kilometers, the water of rivers and lakes is 750,000 cubic kilometers, and the glacial water accounts for 22.6 million cubic kilometers. Some of the water preserved in the earth’s crust is partly incorporated into the mineral crystalline framework, as the American geochemist Rubi describes as having water in the crystalline rocks