人類在地幔中找燃料
DIGGING in dirt and rock is big business. If you dig deep enough, with luck, you will strike oil or gas, which are used as our main sources of fuel and energy.
Until now, we have only explored the Earth's outer layer, the crust. Oil and gas wells normally go no deeper than about six kilometres. But as these stocks rapidly decrease a new study has shown that natural gas, mainly methane, could be found deeper, within the Earth in the mantle. This means that new sources of energy could lie at depths of 100 kilometres or more.
Oil and gas found near the earth's surface are often described as fossil fuels. Most scientists believe that these fuels were formed by the breakdown of ancient plants and animals. But, the recent research shows that methane gas can form in the crust where there are no living creatures.
Researchers from Indiana University, in the US, wondered if this could also happen deeper down in the earth. They did an experiment to simulate the effects of extreme heat and pressure in the mantle on the materials found there.
The experiment produced tiny bubbles of methane gas, the scientists reported. But, no one knows yet how much methane, if any, is actually present in the mantle. If it is present, it could seep into the crust and escape through the ocean floor.
The research could provide important clues as to how life began on the Earth. Some bacteria feed on methane. If methane were present in the mantle, it could support populations of microbes, allowing them to survive in such an extreme environment. Stores of methane on Mars and other planets could show the possibility of life there too.
參考譯文：
在泥土和巖石構筑的地表中進行挖掘工作，有時是收益頗豐的。如果你挖得夠深，就可能挖到石油或者天然氣。這些東西都是人類的主要燃料和能源。
迄今為止，人類的探測范圍也只是局限在地球的表層，也就是地殼。一般來說，石油、天然氣蘊藏在地下六千米之內(nèi)。隨著這些能源的儲量迅速地枯竭，人們開始把目光投向地球更深處。一項研究表明，天然氣（主要成分是甲烷）有可能存在于地球深處的地幔之中。換句話說，地下100公里的地方有可能存在天然氣。
在地表附近獲取的油氣資源通常被稱為化石燃料。大多數(shù)科學家認為，化石燃料是大量遠古動植物遺體被分解而形成的。不過，最近的研究成果表明，在沒有生物存在的地殼中的某些區(qū)域里，也能找到甲烷。
美國印第安娜大學的研究者推測，能否可以在地球更深處找到甲烷。為了驗證其推測，他們做了一個實驗，模擬了一個極端高溫高壓的類地幔環(huán)境。
結果出來了，科學家們說，在實驗中產(chǎn)生了甲烷小氣泡。然而，無人知曉，如果地幔中存在甲烷的話，究竟其儲量有多少。如果真的存在的話，那么，甲烷就可能滲出地殼，通過海底逸出。
這項研究可能為解開生命開始之迷提供重要線索。因為，一些細菌就是以甲烷衛(wèi)生。如果地幔中真的存在甲烷的話，那兒說不定生活著無數(shù)的微生物。而且，火星和其它星球上也具有了生命存在的可能性。因為，這些星球上存在著大量的甲烷。
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