国家地理:Killer Lakes 杀人湖

Volcanic¹ gases escape from the magma. They percolate² through the earth crust and into the atmosphere. Professional geologist³, Charles Watson, investigates the risks at Horseshoe Lake close to Mammoth⁴'s main resort. There is a quiet, silent killer⁵ that's lurking⁶ about in the trees, along the lake's edge.

In the early 1990s, trees began to die in the area north of the lake. The cause, high concentrations of carbon dioxide. Scientists have discovered that around 100 tons of the gas escapes around Horseshoe Lake each day, raising the level of carbon dioxide in the soil up to 95 times normal levels. A simple test at the lakeside shows what this means in practice. Carbon dioxide is heavier in the air, so what we've done is we dug a hole and the carbon dioxide is gonna fill that up and displace the oxygen out and extinguish this butane lighter⁷. Fire needs oxygen to burn. Starved of this, the flame dies. It won't even relight. High concentrations of carbon dioxide can kill a butane flame in seconds and it can have a deadly effect on humans.

The usual concentration of carbon dioxide in air is only 0.035 percent. At a concentration level of around one percent, it causes dizziness, headaches and hallucinations. Above 17 percent, unconsciousness and death happens in a matter of seconds.

At Mammoth Lakes, wind usually disperses⁸ the carbon dioxide safely. But in 2006 investigators⁹ confirmed that a lethally¹⁰ high concentration of the gas killed three ski patrollers who fell into a snow cave on Mammoth Mountain and there was no volcanic eruption¹¹.


magma: 【地质学】The molten rock material under the earth's crust, from which igneous¹² rock is formed by cooling. 岩浆
percolate: (v.) To drain or seep¹³ through a porous¹⁴ material or filter. 过滤
butane: 丁烷
hallucinations: (n.) False or distorted perception of objects or events with a compelling sense of their reality, usually resulting from a mental disorder¹⁵ or as a response to a drug. 幻觉

1 volcanic   

adj.火山的；象火山的；由火山引起的

参考例句：

• There have been several volcanic eruptions this year.今年火山爆发了好几次。
• Volcanic activity has created thermal springs and boiling mud pools.火山活动产生了温泉和沸腾的泥浆池。

2 percolate   

v.过滤，渗透

参考例句：

• The rain will percolate through the soil.雨水渗入土中。
• New fashions took a long time to percolate down.新时尚要很长时间才能在大众中流行起来。

3 geologist   

n.地质学家

参考例句：

• The geologist found many uncovered fossils in the valley.在那山谷里，地质学家发现了许多裸露的化石。
• He was a geologist,rated by his cronies as the best in the business.他是一位地质学家，被他的老朋友们看做是这门行当中最好的一位。

4 mammoth   

n.长毛象；adj.长毛象似的，巨大的

参考例句：

• You can only undertake mammoth changes if the finances are there.资金到位的情况下方可进行重大变革。
• Building the new railroad will be a mammoth job.修建那条新铁路将是一项巨大工程。

5 killer   

n.杀人者，杀人犯，杀手，屠杀者

参考例句：

• Heart attacks have become Britain's No.1 killer disease.心脏病已成为英国的头号致命疾病。
• The bulk of the evidence points to him as her killer.大量证据证明是他杀死她的。

6 lurking   

潜在

参考例句：

• Why are you lurking around outside my house? 你在我房子外面鬼鬼祟祟的，想干什么？
• There is a suspicious man lurking in the shadows. 有一可疑的人躲在阴暗中。 来自《现代英汉综合大词典》

7 lighter   

n.打火机，点火器；驳船；v.用驳船运送；light的比较级

参考例句：

• The portrait was touched up so as to make it lighter.这张画经过润色，色调明朗了一些。
• The lighter works off the car battery.引燃器利用汽车蓄电池打火。

8 disperses   

v.（使）分散( disperse的第三人称单数 )；疏散；驱散；散布

参考例句：

• With controlled pace and sequence of construction, excess heat disperses. 在对施工进度和程序加以控制之后，多余的热量就能散掉。 来自辞典例句
• Normally, turbulence disperses such pollutants quickly. 正常情况下，湍流将迅速驱散这类污染物。 来自辞典例句

9 investigators   

n.调查者，审查者( investigator的名词复数 )

参考例句：

• This memo could be the smoking gun that investigators have been looking for. 这份备忘录可能是调查人员一直在寻找的证据。
• The team consisted of six investigators and two secretaries. 这个团队由六个调查人员和两个秘书组成。 来自《简明英汉词典》

10 lethally   

adv.致命地；危害地；极具威胁地

参考例句：

• AMERICANS do it guiltily, Russians casually, Africans lethally and the French habitually. 通奸这种事美国人做起来满怀内疚，俄国人非常随便，非洲人相当致命，法国人习以为常。 来自互联网
• The concentration of salt in her blood was found to be lethally low. 人们发现她血液中的盐浓度很低，是致命的原因。 来自互联网

11 eruption   

n.火山爆发；（战争等）爆发；（疾病等）发作

参考例句：

• The temple was destroyed in the violent eruption of 1470 BC.庙宇在公元前1470年猛烈的火山爆发中摧毁了。
• The eruption of a volcano is spontaneous.火山的爆发是自发的。

12 igneous   

adj.火的，火绒的

参考例句：

• Igneous rocks do not contain fossils.火成岩不含化石。
• The rocks here are igneous and do not fracture along predictable lines.这儿的石头都是火成岩，石头的裂缝极不规则。

13 seep   

v.渗出，渗漏；n.渗漏，小泉，水（油）坑

参考例句：

• My anger began to seep away.我的怒火开始消下去了。
• If meteoric water does not evaporate or run overland,it may seep directly into the ground.如果雨水不从陆地蒸发和流走的话，就可能直接渗入地下。

14 porous   

adj.可渗透的，多孔的

参考例句：

• He added sand to the soil to make it more porous.他往土里掺沙子以提高渗水性能。
• The shell has to be slightly porous to enable oxygen to pass in.外壳不得不有些细小的孔以便能使氧气通过。

15 disorder   

n.紊乱，混乱；骚动，骚乱；疾病，失调

参考例句：

• When returning back,he discovered the room to be in disorder.回家后，他发现屋子里乱七八糟。
• It contained a vast number of letters in great disorder.里面七零八落地装着许多信件。