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雷暴会造成汞污染

来源: 英语作文网 时间: 2016-09-03 阅读:
In the southern United States, an afternoon thunderstorm is part of a regular summer day. But new research shows those storms might be doing more than bringing some scary thunder and lightning. In fact, these storms are moving significant amounts of mercury1 to the ground. In a new study published in the journal Environmental Science and Technology, Assistant Professor of Meteorology Christopher Holmes writes that thunderstorms have 50 percent higher concentrations of mercury than other rain events.
 
"The mercury is being transported into our region by winds, and tall thunderstorms are bringing it down to the earth," Holmes said.
 
Holmes and a team of researchers collected rain in a variety of locations in Florida, as well as Vermont, Georgia and Wisconsin. They then matched it to weather data that told them whether it was from a thunderstorm or just rain. They also used radar2 and satellite data to examine storm clouds.
 
In a regular rainstorm, clouds are only a few kilometers thick. In a thunderstorm, they reach about 15 kilometers thick. Researchers found that more mercury was in rain from the clouds that reached the highest altitudes.
 
"The highest concentrations occurred during thunderstorms and the lowest during a regular rainstorm," Holmes said.
 
For the last 20 years, the Mercury Deposition3 Network has recorded mercury content of precipitation across the United States. During this period, the states bordering the Gulf4 of Mexico have consistently5 seen the highest mercury deposition in the eastern U.S., typically double that of the northeast states.
 
Typically, the Southeast sees a high number of thunderstorms in the summer months. Holmes and his colleagues believe that this is the reason the Southeast has higher levels of mercury in rain.



  
1 mercury     
n.汞,水银,水银柱
参考例句:
  • The liquid we can see in thermometers is mercury.我们看到的温度计里的液体是水银。
  • Mercury has a much greater density than water.水银的密度比水大得多。


  • 2 radar     
    n.雷达,无线电探测器
    参考例句:
  • They are following the flight of an aircraft by radar.他们正在用雷达追踪一架飞机的飞行。
  • Enemy ships were detected on the radar.敌舰的影像已显现在雷达上。


  • 3 deposition     
    n.免职,罢官;作证;沉淀;沉淀物
    参考例句:
  • It was this issue which led to the deposition of the king.正是这件事导致了国王被废黜。
  • This leads to calcium deposition in the blood-vessels.这导致钙在血管中沉积。


  • 4 gulf     
    n.海湾;深渊,鸿沟;分歧,隔阂
    参考例句:
  • The gulf between the two leaders cannot be bridged.两位领导人之间的鸿沟难以跨越。
  • There is a gulf between the two cities.这两座城市间有个海湾。


  • 5 consistently     
    ad.一贯地,一直
    参考例句:
  • The Ministry of Finance consistently overestimated its budget deficits. 财政部一贯高估预算赤字。
  • The minister has consistently opposed any relaxation in the law. 部长一向反对法律上的任何放宽。



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