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An unexpected source of methane just keeps poppingup
　　
　　一个意想不到的甲烷来源突然出现
　　
　　NEARLY two millennia a, Pliny the Elder, a Romanchronicler of natural history, spotted flames seeping from bare rock at a sitethat is probably Yanartas, in modern Turkey. It was an extraordinary find,though not for reasons that Pliny could have guessed. The gas that fuelled theflames, and fuels them still today, comes from a source that geologists wouldonce have decried as implausible, if not altogether impossible. But that sourceis turning out to be a significant one.
　　
　　大约两千年前，一位罗马自然历史的年代记录者——老普林尼，在现今的土耳其一个叫做火石的地方发现有火焰从光秃秃的石头中冒出来。然而，这项发现的伟大之处并不在于普林尼将这种现象所归为的原因。那是因为石头表面有天然气，天然气可以燃烧，至今我们仍然会发现这种现象，至于天然气的来源，有一种来源，地质学家一度谴责为是毫无根据的，即便他们没说完全不可能之类的话。但是，这种来源认为是天然气的重要来源。
　　
　　The overwhelming majority of the methane extractedcommercially and 90% of what is in the air is biotic—that is to say, it comes from the decomposition of thestuff of life. However, natural gas can also form abiotically, as a result ofchemical reactions in a kind of volcanic rock called peridotite. Add to suchrock the heat and pressures of depth, throw in a splash of water, andeventually out comes methane.
　　
　　绝大多数的甲烷都是商业提取，空气中存在的甲烷90%是来源于生物。也就是说，甲烷来自于生命体的腐烂。然而，天然气也可以无机产生产生，由于一种叫做橄榄岩的火山岩发生的化学反应的结果。将橄榄岩放入高温、高气压的环境下，和水混合后，便就能产生甲烷。
　　
　　But it is not just explaining away fires on Earththat is of interest; serpentinization, as this process is called, was invokedto account for plumes of methane spotted by orbiters around Mars that mightotherwise have been indicative of life (such methane plumes are now in doubt).Well-understood as the phenomenon is, however, such "seeps" ofabiotic methane were until recently believed to be an exceptionally rare thing:between Pliny's observations in 77AD and 2012, only three more were discovered.
　　
　　然而有趣的是，这不仅仅能解释地球上发生的这一类火；蛇纹岩化的过程用来解释在火星轨道上的人造卫星发现的的甲烷羽状流，原本甲烷羽状流可能暗示着在火星上有生命存在（甲烷羽状流至今还是谜）。然而，虽然我们很了解这类现象，但这类现象在以前认为是极为罕见的：自公元77年老普林尼发现至2012年，只发现过三起。
　　
　　That view is now changing. In 2013 and so far in2014, a further five abiotic gas seeps have been reported—in Portugal, Greece, Italy, Japan and another inTurkey. The man behind many of these finds is Giuseppe Etiope of the ItalianNational Institute of Geophysics and Volcanology, in Rome. Together withcolleagues in Canada and Spain, Dr Etiope has discovered two more abiotic seepsthat the team will report in December, at the annual meeting of the AmericanGeophysical Union.
　　
　　这种情形正在改变。从2013年到2014年现在，已经报道了5起这类甲烷的“渗漏”现象，发生在葡萄牙、希腊、意大利、日本和土耳其的另一处地方。其中，就职于位于罗马的意大利国家地质和地球物理研究所的古斯旁爱提欧皮（Giuseppe Etiope）目睹了其中许多次。跟他一起的还有加拿大和西班牙的同事，Etiope博士已经发现了另外两起该现象，该团队将在12月每年一度的美国地球物理联合会的会议上作出报告。
　　
　　With the addition of these two sites, in Spain andthe UAE, the number of known abiotic seeps has more than doubled since thebeginning of 2013. Six more, from Europe to North and Central America to theSouth Pacific, are currently being analysed for suspected abiotic origins. Itis not that the world is springing an abiotic methane leak, however. The recentspate of discoveries can be ascribed in part to advances in technology—a new generation of sensors in wide use can measure theflow of methane on diverse sites—and to growingscientific interest in the details of serpentinization.
　　
　　加上在西班牙和阿拉伯联合酋长国发生的这两起，光是已知的这类非生物来源的甲烷“渗漏”现象自2013起，数量增加了一倍还多。从欧洲到美国的中、北部再到南太平洋，就发生了六次，这六次现在用来分析还存在疑问的这类甲烷的起源。然而，这些渗漏出来的甲烷并不是从地球中释放出来的。最近的大量发现要部分归因于科技的进步——新一代的传感器可以广泛用于测量在不同地方的甲烷的流动的情况，和日渐浓厚的关于蛇纹岩化的众多细节的科学兴趣。
　　
　　What started as geochemistry curiosity could yethave economic implications as the number of abiotic seeps—which have never been commercially exploited—rises further. Based on geological similarities with existing sites,Dr Etiope strongly suspects that there may be more in Cyprus and Bosnia. Asimilar hunch prompted the search for the seeps that were discovered in Spainand the UAE.
　　
　　起初是源于对地球化学的好奇，随着无机甲烷“渗漏”频繁发生，其可能存在经济意义，无机甲烷还从来没被商业开采过。基于与已发生过的地点在地质方面存在许多相似点，Etiope博士坚定地认为在塞浦路斯和波斯尼亚可能发生这种现象的次数更多。同样是出于好奇心促使他们研究曾在西班牙和阿拉伯联合酋长国发现的无机甲烷。
　　
　　Dr Etiope has received research funding fromPetrobras, Brazil's state-owned oil giant, to formulate an estimate for theworldwide abiotic methane reserve. He reckons that it will take at least a yearto arrive at even a rough guess. But Pliny may finally be of some help here.Given the well-dated observation of the fires at Yanartas and a od estimateof how much methane is required to keep them ing, Dr Etiope believes the seephas expelled some 400m cubic metres since then—comparable to the output of some conventional gas fields. That islikely to be an underestimate; presumably, it had been ing for a while beforePliny showed up.
　　
　　Etiope博士已经拿到了来自巴西国家石油公司——巴西的国有的石油巨头——的研究经费，旨在估计出全世界的这类甲烷的存储量。他认为至少要一年的时间才能得到一个大致的估算。但是，老普林尼或许可以提供一些帮助。鉴于之前在火石的观察和对有多少甲烷才能使甲烷不断“渗漏”的准确估计，Etiope博士认为自那时开始已经“渗漏”了4亿立方米的甲烷——跟一般的天然气工厂的输出量相当。这也可能会低估了其存储量；也可能在老普林尼发现的那次之前，就已经开始一段时间了。
　　
　　As a newly appreciated potential source of gas, itwill take some time to understand just how many abiotic seeps there are, andhow much methane each might produce. The general view of hydrocarbons such asoil and gas is one of dwindling reserves. But there is still some exploring tobe done.
　　
　　作为一种新地重要的天然气的潜在来源，要弄清现存多少这类甲烷，能产生多少这类甲烷，还需要花些时间。一般认为像石油和天然气这类碳氢化合物的储存量只会越来越少。但是这些探索仍然需要做。

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