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  • 地球上的水分布

    View of Earth from space showing land and oceans, highlighting water distribution.
     

    Where is Earth's Water?
    ::地球的水在哪里?

    Here's a photo of Earth from space again. It's pretty easy to see where most of Earth's  water  is. It's in the oceans. Nearly all of Earth's water is in the seas. Although it's extremely useful for ocean  ecosystems , it's not very useful for people. So where is the water that we can use?
    ::这是从太空再次拍摄的地球照片。 很容易看到大部分地球的水在海洋中。 几乎所有的地球水都在海洋中。 虽然这对海洋生态系统非常有用, 但对于人类来说并不十分有用。 因此, 我们能使用的水在哪里?

    Where Is Earth’s Freshwater?
    ::地球淡水在哪里?

    Most of Earth’s water is salt water in the oceans. As seen below, only 3 percent of Earth’s water is fresh ( Figure   ).  Freshwater  is water that contains little or no dissolved salt. Most freshwater is frozen in ice caps and  . Glaciers cover the peaks of some tall  mountains . For example, the Cascades Mountains in North America and the Alps Mountains in Europe are capped with ice. Ice caps cover vast areas of Antarctica and Greenland. Chunks of ice frequently break off ice caps. They form icebergs that float in the oceans.
    ::地球的水大部分是海洋中的盐水。如下文所示,地球水中只有3%是淡水(图 ) 。淡水是很少或没有溶解盐的水。淡水大多被冰盖冻结,冰川覆盖一些高山峰。例如,北美的喀斯喀底山脉和欧洲的阿尔卑斯山脉被冰封住了。冰盖覆盖了南极洲和格陵兰的大片地区。冰块经常断裂冰盖。它们形成浮在海洋中的冰山。

    Infographic showing Earth's water distribution: 97% salt water, 3% freshwater sources breakdown.
     
    What percentage of Earth’s surface freshwater is water vapor in the air?

    Only a tiny fraction of Earth’s freshwater is liquid at the surface. Most liquid freshwater is under the ground in layers of  . Of freshwater on the surface, the majority occurs in  lakes  and  soil . What percentage of freshwater on the surface is found in living things?
    ::地球淡水中只有一小部分是地表液体,大部分液体淡水在地下层层。 在地表淡水中,大部分是在湖泊和土壤中。 地表淡水在生物中所占的百分比是多少?

    Water can remain in a particular   for a long time. This is known as a  reservoir . Reservoirs for water include oceans, glaciers,  ponds , or even the  atmosphere . A water  molecule  may pass through a reservoir very quickly or may remain for much longer. The amount of time a molecule stays in a reservoir is known as its  residence time . The residence time of water in the ocean is 3,200 years. Of course, not every molecule stays that long. That number is an average for all molecules.
    ::水可以长期留在某个特定地方。 这被称为水库。 水库包括海洋、 冰川、 池塘, 甚至大气。 水分子可以通过水库快速通过, 或者可以停留更长的时间 。 分子在水库中停留的时间称为停留时间 。 海洋中水的停留时间是3 200年 。 当然, 并不是每个分子都停留那么长。 这个数字是所有分子的平均数量 。

    Summary
    ::摘要

    • Of Earth's water, 97% is in the oceans.
      ::地球水的97%在海洋中
    • Of the remaining 3%, much is trapped in ice and glaciers.
      ::在剩下的3%中,大部分被困在冰和冰川中。
    • A substance is stored in a reservoir. The amount of time it stays in that reservoir is its residence time.
      ::物质储存在储油层中,在储油层中停留的时间是其停留时间。

    Review
    ::回顾

    1. Earth has a tremendous amount of water. So why is water sometimes a scarce resource?
      ::地球有巨大的水量。为什么水有时是稀缺的资源?
    1. What are the reservoirs for water?
      ::水库是什么?
    1. What is residence time? What does it mean to say the residence time of water in the atmosphere is nine days?
      ::空气中的水的停留时间是9天,这是什么意思?

    Explore More
    ::探索更多

    Use this resource to answer the questions that follow.
    ::使用此资源回答下面的问题 。

     

     

     

    1. How much of Earth's surface is covered with water? What is most of this water in?
      ::地球表面有多少水覆盖?
    1. What percent of Earth's water is salty? How much is fresh water?
      ::地球上有多少水是咸的?淡水是多少?
    1. Of all of the fresh water, what percentage is ice, what is shallow groundwater, what is deep groundwater, what is in lakes and rivers and what is in the atmosphere as water vapor?
      ::在所有淡水中,冰占多大比例,浅地下水占多大比例,深地下水占多大比例,湖泊和河流中有哪些水,大气中哪些是水蒸发物?
    1. How much of Earth's fresh water is available for human consumption?
      ::地球有多少淡水可供人类消费?