盐渍土能吸收空气中的水分
文章来源:未知 文章作者:enread 发布时间:2012-02-28 05:21 字体: [ ]  进入论坛
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The frigid1 McMurdo Dry Valleys in Antarctica are a cold, polar desert, yet the sandy soils there are frequently dotted with moist patches in the spring despite a lack of snowmelt and no possibility of rain. A new study, led by an Oregon State University geologist2, has found that that the salty soils in the region actually suck moisture out of the atmosphere, raising the possibility that such a process could take place on Mars or on other planets.

The study, which was supported by the National Science Foundation, has been published online this week in the journal Geophysical Research Letters, and will appear in a forthcoming printed edition.

Joseph Levy3, a post-doctoral researcher in OSU's College of Earth, Ocean, and Atmospheric4 Sciences, said it takes a combination of the right kinds of salts and sufficient humidity to make the process work. But those ingredients(材料) are present on Mars and, in fact, in many desert areas on Earth, he pointed5 out.

"The soils in the area have a fair amount of salt from sea spray and from ancient fjords(峡湾,海湾) that flooded the region," said Levy, who earned his doctorate6(博士学位) at Brown University. "Salts from snowflakes also settle into the valleys and can form areas of very salty soil. With the right kinds of salts, and enough humidity, those salty soils suck the water right out of the air.

"If you have sodium7 chloride, or table salt, you may need a day with 75 percent humidity to make it work," he added. "But if you have calcium8 chloride, even on a frigid day, you only need a humidity level above 35 percent to trigger the response."

Once a brine(卤水,盐水) forms by sucking water vapor9 out of the air, Levy said, the brine will keep collecting water vapor until it equalizes with the atmosphere.

"It's kind of like a siphon(虹吸管) made from salt."

Levy and his colleagues, from Portland State University and Ohio State University, found that the wet soils created by this phenomenon were 3-5 times more water-rich than surrounding soils -- and they were also full of organic matter, including microbes, enhancing the potential for life on Mars. The elevated salt content also depresses the freezing temperature of the groundwater, which continues to draw moisture out of the air when other wet areas in the valleys begin to freeze in the winter.

Though Mars, in general, has lower humidity than most places on Earth, studies have shown that it is sufficient to reach the thresholds that Levy and his colleagues have documented. The salty soils also are present on the Red Planet, which makes the upcoming landing of the Mars Science Laboratory this summer even more tantalizing10(撩人的,挑逗性的) .

Levy said the science team discovered the process as part of "walking around geology" -- a result of observing the mysterious patches of wet soil in Antarctica, and then exploring their causes. Through soil excavations11 and other studies, they eliminated the possibility of groundwater, snow melt, and glacial runoff(径流) . Then they began investigating the salty properties of the soil, and discovered that the McMurdo Dry Valleys weather stations had reported several days of high humidity earlier in the spring, leading them to their discovery of the vapor transfer.



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1 frigid TfBzl     
adj.寒冷的,凛冽的;冷淡的;拘禁的
参考例句:
  • The water was too frigid to allow him to remain submerged for long.水冰冷彻骨,他在下面呆不了太长时间。
  • She returned his smile with a frigid glance.对他的微笑她报以冷冷的一瞥。
2 geologist ygIx7     
n.地质学家
参考例句:
  • The geologist found many uncovered fossils in the valley.在那山谷里,地质学家发现了许多裸露的化石。
  • He was a geologist,rated by his cronies as the best in the business.他是一位地质学家,被他的老朋友们看做是这门行当中最好的一位。
3 levy Z9fzR     
n.征收税或其他款项,征收额
参考例句:
  • They levy a tax on him.他们向他征税。
  • A direct food levy was imposed by the local government.地方政府征收了食品税。
4 atmospheric 6eayR     
adj.大气的,空气的;大气层的;大气所引起的
参考例句:
  • Sea surface temperatures and atmospheric circulation are strongly coupled.海洋表面温度与大气环流是密切相关的。
  • Clouds return radiant energy to the surface primarily via the atmospheric window.云主要通过大气窗区向地表辐射能量。
5 pointed Il8zB4     
adj.尖的,直截了当的
参考例句:
  • He gave me a very sharp pointed pencil.他给我一支削得非常尖的铅笔。
  • She wished to show Mrs.John Dashwood by this pointed invitation to her brother.她想通过对达茨伍德夫人提出直截了当的邀请向她的哥哥表示出来。
6 doctorate fkEzt     
n.(大学授予的)博士学位
参考例句:
  • He hasn't enough credits to get his doctorate.他的学分不够取得博士学位。
  • Where did she do her doctorate?她在哪里攻读博士?
7 sodium Hrpyc     
n.(化)钠
参考例句:
  • Out over the town the sodium lights were lit.在外面,全城的钠光灯都亮了。
  • Common salt is a compound of sodium and chlorine.食盐是钠和氯的复合物。
8 calcium sNdzY     
n.钙(化学符号Ca)
参考例句:
  • We need calcium to make bones.我们需要钙来壮骨。
  • Calcium is found most abundantly in milk.奶含钙最丰富。
9 vapor DHJy2     
n.蒸汽,雾气
参考例句:
  • The cold wind condenses vapor into rain.冷风使水蒸气凝结成雨。
  • This new machine sometimes transpires a lot of hot vapor.这部机器有时排出大量的热气。
10 tantalizing 3gnzn9     
adj.逗人的;惹弄人的;撩人的;煽情的v.逗弄,引诱,折磨( tantalize的现在分词 )
参考例句:
  • This was my first tantalizing glimpse of the islands. 这是我第一眼看见的这些岛屿的动人美景。 来自《简明英汉词典》
  • We have only vague and tantalizing glimpses of his power. 我们只能隐隐约约地领略他的威力,的确有一种可望不可及的感觉。 来自英汉非文学 - 历史
11 excavations 185c90d3198bc18760370b8a86c53f51     
n.挖掘( excavation的名词复数 );开凿;开凿的洞穴(或山路等);(发掘出来的)古迹
参考例句:
  • The excavations are open to the public. 发掘现场对公众开放。
  • This year's excavations may reveal ancient artifacts. 今年的挖掘可能会发现史前古器物。 来自辞典例句
TAG标签: water salty soils
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