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  • 海水化学

    Salt mounds in an evaporation pond, illustrating salt extraction from seawater.
     

    What do you get when you evaporate seawater?
    ::当你蒸发海水时你会得到什么?

    Salt! Human bodies need salt to live. Nowadays most of this salt comes from the oceans or saline  lakes . Some salt is mined from   that evaporated from seawater long ago.
    ::盐! 人的身体需要盐来生存。 如今,这些盐大多来自海洋或盐碱湖。 有些盐是很久以前从海水中蒸发出来的。

    Makeup of Ocean Water
    ::海洋水的构成

    You know that ocean  water  is salty. How salty is it? What is the  salinity  of seawater? Average seawater is about 3.5% salt. The amount is different if there is a nearby  source  of  freshwater . It is also different if there is a lot of  evaporation  in an area. How do you think these things affect seawater salinity? Seawater also contains other substances like sugars, acids, bases, and  organic  molecules.
    ::你知道海水是咸的,它怎么咸?海水的盐度是多少?海水的盐度是多少?海水的平均盐度是3.5%。如果附近有淡水来源,其数量也不同。如果一个区域有大量的蒸发,这些物质会如何影响海水的盐度?海水还含有糖、酸、碱和有机分子等其他物质。

    Why Is Ocean Water Salty?
    ::为什么是海水盐?

    Ocean water is salty because water dissolves   out of rocks. The  ions  enter the water. This happens whenever water flows over or through rocks. Much of this water and its minerals end up in the oceans. Minerals dissolved in water form salts. When the water evaporates, it leaves the salts behind. As a result, ocean water is much saltier than other water on Earth.
    ::海水是咸的,因为水从岩石中溶解出来,离子进入水中。当水从岩石中流过或流过时,就会发生这种情况。这些水及其矿物质中的大部分最终会进入海洋。矿物溶解成水状盐。当水蒸发时,盐就会落下。因此,海水比地球上的其他水更咸。

    How Salty Is Ocean Water?
    ::咸水是海水吗?

    Have you ever gone swimming in the ocean? If you have, then you probably tasted the salts in the water. By mass, salts make up about 3.5% of ocean water. The table below shows the most common  elements  in ocean water ( Table   ). The main components are sodium and chloride. Together they form the salt known as sodium chloride. You may know the compound as table salt or the mineral halite.
    ::你曾经在海洋中游泳吗?如果你已经游泳过,那么你也许就尝过水中的盐类。按质量计算,盐类占海洋水的3.5%左右。下表显示了海水中最常见的元素(表)。主要成分是钠和氯化物。它们共同构成盐类,称为氯化钠。你可能知道化合物是食盐或矿物质。

    Element Percent
    Oxygen 85.84
    Hydrogen 10.82
    Chloride 1.94
    Sodium 1.08
    Magnesium 0.1292
    Sulfur 0.091
    Calcium 0.04
    Potassium 0.04
    Bromine 0.0067
    Carbon 0.0028

    The amount of salts in ocean water varies from place to place. For example, near the mouth of a  river , ocean water may be less salty. That’s because river water contains less salt than ocean water. Where the ocean is warm, the water may be more salty. Can you explain why? (Hint: More water evaporates when the water is warm.)
    ::海水中的盐量因地而异。 比如,在河口附近,海水的盐量可能不那么咸。 这是因为河水中的盐量比海水少。 在海洋温暖的地方,水可能更咸。 你能解释为什么吗? (提示:当海水温暖时,水会蒸发更多)

    Density
    ::密度

    Seawater has lots of salts in it. This increases its  density  (mass per volume) over fresh water.   and pressure also affect density.
    ::海水中含有大量的盐类,这增加了淡水的密度(每体积质量),压力也影响到密度。

    Water density increases as:
    ::水密度增加如下:

    • salinity increases.
      ::盐度增加。
    • temperature decreases.
      ::温度下降。
    • pressure increases.
      ::压力增加。

    Differences in water density are responsible for deep ocean currents, as will be discussed in the concept "Deep Ocean Currents."
    ::水密度差异是造成深海洋流的原因,将在“深海洋流”概念中加以讨论。

    Summary
    ::摘要

    • Water moving through rock and soil picks up ions. Those ions end up as salts in large bodies of water.
      ::在岩石和土壤中漂流的水会吸收离子,这些离子最终成为大体水中的盐类。
    • Ocean water contains salts and other substances.
      ::海洋水含有盐类和其他物质。
    • Water density increases as salinity and pressure increase, or as temperature decreases.
      ::水密度随着盐度和压力增加或温度下降而增加。

    Review
     ::回顾

    1. Streams aren't salty, so why is the ocean salty?
      ::溪流不咸,为什么海水咸?
    1. Answer and explain the following: If evaporation is high, what happens to seawater density? If freshwater is added to a region, what happens to seawater density? If seawater gets very cold, what happens to its density?
      ::回答并解释如下:如果蒸发程度高,海水密度会怎样?如果将淡水添加到一个区域,海水密度会怎样?如果海水非常冷,其密度会怎样?
    1. What is salinity?
      ::什么是盐度?

    Explore More
    ::探索更多

    Use the resource below to answer the questions that follow. 
    ::利用以下资源回答以下问题。

     

     

    1. Why are oceans important?
      ::为什么海洋很重要?
    1. Which dissolved gases are found in the oceans?
      ::在海洋中发现了哪些溶解气体?
    1. Which dissolved salts are contained in seawater?
      ::海水中含有哪些溶解盐?
    1. What is salinity? What is the salinity of average seawater?
      ::什么是盐度?平均海水的盐度是什么?
    1. Where does the salt come from?
      ::盐从哪里来的?
    1. Why doesn't the ocean get saltier over time?
      ::海洋为什么不随着时间推移而变咸呢?
    1. What changes the salinity in different places in the oceans?
      ::是什么改变了海洋不同地方的盐度?
    1. What are the effects of salinity on water?
      ::盐碱化对水的影响如何?
    1. How does the surface temperature of ocean water vary?
      ::海水表面温度如何变化?
    1. Where is the coldest, densest ocean water?
      ::最冷、最稠密的海水在哪里?
    1. What does carbon dioxide do in the oceans?
      ::二氧化碳在海洋中做什么?
    1. How does temperature change with depth? How does pressure change with depth?
      ::温度如何随深度变化? 压力如何随深度变化?