2015考研英语阅读英文原刊《经济学人》：北极海域

　　Which all sounds most promising. But many researchers think it will not continue.

　　尽管种种迹象表明在此地捕鱼致富的前景颇为乐观，然而许多学者却持不同意见。

　　First, the central Arctic is too deep for some important species, such as the polar cod.

　　首先，北冰洋中部海水过深，不利于极地鳕鱼等重要物种的生存。

　　Young polar cod are pelagic, meaning they live at or near the surface.

　　极地鳕鱼与大西洋鳕鱼同属，但前者活动范围较后者更为偏北。

　　Those one or more years old are benthic, meaning they live near the bottom.

　　此外，极地鳕鱼的幼鱼为海面鱼，这些幼鱼仅在海面附近活动;一岁及以上的极地鱼为深海鱼，这些深海鱼仅生活在类似于博福尔海域的海底。

　　In the Beaufort that bottom is 200 metres down.

　　鉴于博福尔海的深度为200米，

　　In the central Arctic it descends to about 4,000 metres, which is too deep for polar cod tosurvive.

　　而北冰洋中部深度约为4000米，因此极地鳕鱼根本无法在北极地区生存。

　　A second reason why there may be no bonanza is acidification of the ocean.

　　其次，北冰洋的酸化现象也是此地不宜鱼类生存的重要原因。

　　When water absorbs carbon dioxide, it produces carbonic acid. More CO?

　　水吸收二氧化碳后会释放出碳酸，

　　means oceans everywhere are becoming more acidic, but the phenomenon is particularlymarked at high latitudes because cold water absorbs CO? more readily than warm waterdoes.

　　因此，随着二氧化碳排放量增加，海水酸度也会随之升高。另外，因为冷水比热水更易吸收二氧化碳，所以这种现象在高纬度地区尤为明显。

　　The retreat of the ice also exposes ever more sea to do the absorbing.

　　于是，冰原面积的锐减也意味着更多的低温洋面将会暴露在空气之中，吸收大量的二氧化碳。

　　Cruises by the United States Geological Survey and the University of South Florida over thepast three years have found rising carbonic-acid levels north of Alaska.

　　在过去的三年里，美国地质调查局与南佛罗里达大学多次巡航此地进行调研，调研结果表明：阿拉斯加北部海域的碳酸值显著上升，并且该海域有机物的外壳中霰石含量不足。

　　They have also discovered that the shells of many organisms in the area are short ofaragonite, a form of calcium carbonate that gives them strength, but whose formation aciddiscourages.

　　霰石为碳酸钙的一种形式，它不仅为有机物外壳提供支撑，而且其形成过程能够降低酸性物质含量。

　　Weaker shells means fewer shelled organisms and less food for fish.

　　外壳硬度的降低则说明该海域带壳有机物及鱼类食物的数量均大大减少。

　　The most important reason, though, for thinking that global warming will not produce anArctic feeding frenzy is that it may increase ocean stratification.

　　然而，全球变暖无法为北极地区带来大量鱼类养料的真正原因在于海水分层现象的加剧。

　　This is the tendency of seawater to separate into layers, because fresh water is lighter thansalt and cold water heavier than warm.

　　由于淡水质量小于海水，而冷水质量大于热水，水温的上升会导致海水进一步分层。

　　The more stratified water is, the less nutrients in it move around.

　　同时，海水分层现越严重，则越不利于海水内部营养物质的流动。

　　Most free-swimming sea creatures are pelagic.

　　大多数海洋游泳生物均为海面生物。

　　Algae need light, so must live near the surface—as must the zooplankton and other animalsthat need the phytoplankton.

　　海藻需要阳光，因此海藻必须生活在海面附近，从而依靠海藻等浮游植物生存的浮游动物也必须在海面区域活动。

　　When they die, all these organisms sink to the bottom, where they become food for benthiccreatures.

　　这类生物死亡后，其有机体沉入海底，变为海底生物的养料。

　　Once they have been consumed their component molecules, including nutrients such asnitrates, phosphates and iron, are stuck in Davy Jones's locker.

　　当有机体的硝酸盐、磷酸盐、铁以及其他营养成分均被其他生物吸收后，他们便永远地沉在了海底。

　　For the surface to be productive, the locker must be opened and the nutrients lifted back up,so that they can feed the growth of phytoplankton.

　　因此，如果海底为一个封闭的水层，则海底营养物质将无法上升到水面，从而也无法为浮游植物等其他水面生物提供其生长所需的养料。

　　Walking the plankton

　　浮游生物的流失

　　One of the most important ways this happens is by upwellings of water from thebottom—great churning columns caused by the collision of cold and temperate waters.

　　上升流是海底营养物质上浮至水面的重要方式。

　　Two of the most important are in the Arctic: south of Greenland on the Atlantic side and southof the Bering Strait on the Pacific side.

　　北极地区具有全球最著名的几大上升流之二：大西洋侧南格陵兰上升流及太平洋侧白令海峡上升流。

　　Nitrates are abundant at the surface in both places, which is why they are among theworld's richest fishing grounds.

　　这两个海域富有硝酸盐，这便是这些地区以捕鱼业著名的原因。

　　There are few upwellings in the tropics, which are thus nutrient-poor.

　　由于热带海域则几乎没有上升流，因此这些海域通常缺乏养分。

　　Stratification threatens this recycling system by suppressing the vertical movement ofwater.

　　然而，海水分层会妨碍海水的垂直交换运动，从而威胁海洋自身的循环系统。

　　And global warming encourages stratification because it turns the ice into a layer of freshwater that sits on the surface.

　　全球变暖现象使得海面冰层融化，而融化后的淡水则只能漂浮在海面。

　　Imagine the ocean as a Tequila sunrise sitting on a warm bar.

　　这就好像是一杯放在暖气上的龙舌兰日落鸡尾酒，

　　The ice cubes at the top are melting away and the orange juice is sinking to the bottom.

　　上层的冰块在融化，而橙汁全部沉淀在杯底。

　　At the conference, a paper by Jean-éric Tremblay and Marcel Babin of Laval University, inQuebec, described the effect by reporting the density difference of water at the surface andat a depth of 100 metres in different oceans.

　　“北极边境”会上，Jean-éric Tremblay与拉瓦尔大学的Marcel Babin带来了他们的研究性论文成果。

　　This density difference is an index of ocean stratification.

　　该论文描述了不同海洋中洋面海水与100米深处海水的密度差别及其影响，而正是这一密度差别决定着海水的分层情况。

　　Parts of the Arctic seem to be getting badly stratified.

　　如图所示，北极地区部分海域已经出现了明显的分层现象。

　　In winter, there is almost no density difference in the North Atlantic and the Barents Sea—asyou would expect given the upwelling there.

　　冬季，北大西洋与巴伦支海之间几乎没有任何密度差别—即便前者本应受到上升流的影响。

　　But in summer, the northern part of the Barents Sea is even more stratified than the tropicalAtlantic and Pacific.

　　夏季，巴伦支海北部的分层现象比大西洋及太平洋热带海域更为明显。

　　And the Beaufort Sea's stratification is high in both summer and winter.

　　另外，波弗特海常年存在严重的分层现象。

　　Dr Tremblay concludes that the replenishment of nutrients is already limited by stratification,especially at high latitudes, and that global warming will make things worse.

　　Tremblay博士认为，海水分层现象已经对海洋营养物质的循环补给非常不利，全球变暖则会雪上加霜，使该现象加剧恶化。

　　For Arctic productivity, the consequences are likely to be dire.

　　就北极地区的生产力而言，其前景更是不容乐观。

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