Official 32 Set 5

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The Copper Basin

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What is the lecture mainly about?
  • A. The environmental effects of heap roasting

  • B. The reforestation efforts in the Copper Basin

  • C. The process of mining and producing copper

  • D. Damages caused during an attempt to clean up industrial waste

显示答案 正确答案: A

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    NARRATOR:Listen to part of a lecture in an Earth science class. The professor is discussing an area of the United States called the Copper Basin.

    MALE PROFESSOR:Now, you may not have heard of the Copper Basin. It's in the eastern United States-in the Tennessee River Valley.It got its name because settlers discovered copper there in 1843.And soon afterwards, it supported one of the largest metal-mining operations in America.At one time, four mining companies employed twenty-five hundred workers in the Copper Basin.For that time period it was a huge operation.

    Well, this mining operation turned the Copper Basin into a desert.In the 1840s, when mining operations started, it was a dense green forest.But in the 1940s, 100 years later, it was as barren as the Moon.

    Efforts to reclaim the land and restore the basin to the fertile valley it once was [sounding discouraged, bleak]…well, actually, those efforts are still ongoing. It's been a long and tedious process.In fact, uh, it was many years before any results were seen-copper mining had gone on there for more than 90 years.The damage couldn't be reversed overnight. [An aside in a more positive tone]Although I should mention that by 1996 the water in one of the rivers flowing through the basin was clean enough that it was the site of the Olympic whitewater kayaking competition.And that river is still used now for recreation.But anyway…let's analyze the problem. [back to lecture-neutral voice]It wasn't the mining itself that caused such massive destruction.It was what happened after the copper ore was extracted from the mines.It was a process called heap roasting.

    Copper ore contains sulfur, and heap roasting was a way to burn away the sulfur in the copper-so they'd be left with something closer to pure copper.Well, in the process, large vats of raw copper ore are burned slowly-for, um, two or three months, actually-to lower the sulfur content.And this burning-well, let's look at the results: first, the mines were fairly remote, so there was no way to bring coal or other fuel to keep the fires going, so they cut down local trees for fuel.And like I said, the fires burned for months-uh, that's a lot of fires …and a lot of trees.Deforestation was occurring at a rapid rate. And it was accelerated by the smoke from the burning ore.Big clouds of sulfuric smoke-which was toxic to the trees-formed over the area.Trees that hadn't been cut for fuel were killed by the fumes.

    The sulfur also mixed with the air and created sulfur dioxide, and the sulfur dioxide settled in the clouds, fell to the land in droplets of rain, and sank into the soil.

    This is what we now call acid rain-you've probably heard of it-but no one used the term back then.Anyway, the acid rain created highly acidic soil.

    Well, soon the soil became so acidic that nothing could grow-nothing at all. Vegetation and wildlife disappeared.

    And it wasn't just the land and the air … it was the water, too.What do you think happened to the rivers?Well, there were no trees to absorb the rain, and there was a lot of rain.So, the rain eroded the soil and swept it into the rivers-this is called silting, when soil particles are washed into the rivers.And the silting continued at an alarming rate.But this was toxic soil and toxic runoff. The acid and metals in the soil made the once-clear rivers flow bright orange.

    So it was really that one step in the process of producing copper…the problems just built up and up until there was a desert where a beautiful forest used to be.OK. Now let's look at reforestation and land-reclamation efforts.

  • 旁白:听一段地球科学课堂的讲座。教授正在论述美国一个叫做阔普盆地的地方。

    教授:你可能没听说过阔普盆地,它位于美国东部的田纳西河谷。在1843年,它因殖民者在此地发现铜而得名。不久之后,它便支持美国其中一个最大的金属采矿作业。曾经,四个采矿公司在阔普盆地雇佣了2500名工人。在那段时间,它曾是一项大规模的工程。

    而这种采矿作业把阔普盆地变为了沙漠。在19世纪40年代,当采矿作业开始时,这里是一片茂密的森林。但是在100年后的20世纪40年代,这里如月球一样贫瘠。

    事实上,收回土地,并把这个盆地恢复到肥沃的山谷的努力仍在继续。这是一项冗长乏味的过程。事实上,经过多年努力,才有所成效。铜矿开采已经持续了90多年!损害不可能一夜间逆转。尽管我应该提到,到1996年,流经该盆地的一条河流的水已经足够干净了,曾成为了奥林匹克激流皮划艇比赛的场地。而且那条河至今仍用于娱乐。但是……总之,让我们分析一下问题。不是采矿本身引起了如此大的破坏性。是铜矿从矿井中提取后发生的事情。这一过程叫做堆烧法。

    铜矿含有硫磺,堆烧是烧去铜里面硫磺的一种方法,所以留下的近乎于纯铜。在这个过程中,大桶未加工的铜矿需要缓慢燃烧,事实上要两或三个月的时间减少含硫量。这种燃烧……让我们看看结果:首先,矿山的位置相当遥远,所以无法带去使火持续燃烧的煤或其他燃料,所以他们以当地砍下的树作为燃料。正如我所说,火要持续燃烧数月,需要很多火,也就需要很多树木。采伐森林以相当快的速度出现,而矿燃烧的烟雾又加剧了这一进程。大片的硫磺烟雾云笼罩着这一带,并且对树木产生毒害作用。没有被砍伐用作燃料的树木也被烟雾毒死了。

    硫磺也会与空气结合,产生二氧化硫。二氧化硫升入云里,然后变成雨滴落入地面,侵蚀土壤。

    这就是我们现在说的酸雨,你可能听说过它,但是那时候没人用到这个术语。总之,酸雨造成了高度的酸性土壤。

    很快,土壤会变成酸性,以至于无法种植任何东西,植被和野生动物消失了。

    这不仅关乎土地和空气,还会影响水资源。你认为河水会发生什么变化?没有了吸收雨水的树木,就会产生大量的雨水!所以雨水侵蚀土壤,将它冲进河里。当土壤微粒被冲进河里时,这就叫做淤泥沉积。淤泥沉积继续以惊人的速度发展。但这是有毒的土壤和径流,土壤中的酸和金属使曾经干净的河水变为橙黄色。

    所以因为铜矿生产过程的一小步导致问题不断增加,直到曾经美丽的森林变为沙漠。好,现在让我们看看重新造林和土地开垦的工作。

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    原文定位:

    But anyway… So … let’s analyze the problem. It wasn’t the mining itself that caused such massive destruction. It was what happened after the copper ore was extracted from the mines. It was a process called heap roasting.

    选项分析:

    文章开头引出讨论对象Copper basin,介绍了一系列北京,然后通过转折引出今天的重点:problem。问题。问题是什么?heap roasting。之后对heap roasting对环境的影响展开讨论。

    A项完全符合,为正确答案。其他项不是主要讨论对象

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The Copper Basin

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