雅思阅读第084套P1LakeVostok

Reading Passage 1

You should spend about 20minutes on Questions 1-13 which are based on this passage.

Lake Vostok

A

Beneath the white blanket ofAntarctica lies half a continent of virtually uncharted territory - an area so completelyhidden that scientists have little clue what riches await discovery. Recently,Russian and British glaciologists identified an immense lake - one of Earth’slargest and deepest - buried beneath 4,000 meters of ice immediately belowRussia’s Vostok Station.

B

As details have emerged, agrowing number of scientists are showing interest, with dozens of investigatorskeen to explore the feature, known as Lake Vostok. A thick layer of sediment atthe bottom of the lake could hold novel dues to the planet’s climate going backlens of millions of years. By looking at the ratio of different oxygenisotopes, scientists should be able to trace how Earth’s temperature changedover the millennia. NASA has expressed interest in Lake Vostok because of itssimilarity to Europa. This moon of Jupiter appears to have a water oceancovered by a thick ice sheet, measuring perhaps tens of kilometers in depth. Ifhydrothermal vents exist beneath the ice, chemical reactions on Europa couldhave created the molecular building blocks for life, if not life itself. Vostokwould be an ideal testing ground for technology that would eventually fly toEuropa or places even more distant, say many scientists. Though cheap comparedwith a Europan mission, any expedition to Vostok would represent a significantinvestment.

C

Vostok Station holds theuncomfortable distinction of having recorded the coldest temperature on Earth.Thermometers there measured in July 1983, and the average temperature hoversaround -55ºC. It’s the thick ice, strangely, that enables a lake to survive insuch a frozen environment. The 4 kilometers of ice acts effectively as aninsulating blanket protecting the bedrock underneath the ice from the coldtemperatures above. Geothermal heat coming from the planet’s interior keeps thelake from freezing and warms the lowest layers of ice. The tremendous weight ofthe ice sheet also plays a role in maintaining the lake. Beneath 4 kilometersof glacier, the pressure is intense enough to melt ice at a temperature of -4°C.These factors have helped lakes develop across much of the thickly blanketedEast Antarctica. More ore than 70 hidden lakes have been detected in the smallportion of the continent to date. Lake Vostok is the largest of these,stretching 280km from south to north and some 60 km from east to west. AtVostok station, which sits at the southern end of the lake, the water depthappears to be 500m according to seismic experiments carried out by Russianresearchers.

D

The first clues to LakeVostok’s existence came in the 1970s, when British, U.S., and Danishresearchers collected radar observations by flying over this region. The radarpenetrates the ice and bounces off whatever sits below. When researchers founda surface as flat as a mirror, they surmised that a lake must exist underneaththe ice. An airborne survey of the lake is being undertaken, the first steptoward eventually drilling into the water. Along with the potential rewardscome a host of challenges. Researchers must find a way to penetrate the icycovering without introducing any microorganisms or pollutants into thesealed-off water.

E

What about life in the depths?If tiny microbes do populate the lake, they may be some of the hungriestorganisms ever discovered. Lake Vostok has the potential to be one of the mostenergy-limited, or oligotrophic, environments on the planet. For the lake’sresidents, the only nutrients would come from below. Russian investigators havespeculated that the lake floor may have hot springs spewing out hydrothermal fluidsstocked with reduced metals and other sorts of chemical nutrients. Scantgeological evidence available for this region, however, indicates that thecrust is old and dead. Without a stream of nutrients seeping up from the deepEarth, the only potential source of energy lies above the lake. The ice sheetabove the water is creeping from west to east at a rate of roughly four metersper year. The lowermost layers of ice melt when they come in contact with thelake, liberating trapped gases and bits of crushed-up rock. If the glacierrecently passed over rock before reaching the lake, it could be supplyingorganic compounds useful to microorganisms. It also could be seeding the lakewith a continuous source of new residents. Bacteria, yeasts, fungi, algae andeven pollen grains have been found in the Vostok ice core samples taken down todepths of 2,750m - three quarters of the way to the bottom. At least some ofthese organisms are alive and capable of growing, according to recent reports.The results of this analysis may indirectly indicate whether anything survivesin the lightless body of water.

SECTION 1: QUESTIONS 1-13

Questions 1-4

The passage has 5 sections A-E.

Choose the most suitableheading for sections B-E from the list of headings below.

Write the appropriate numbers (i-viii).

There are more headings thansections so you will not use all of them.

List of Headings

i

Cost of exploration

ii

Location and description of the lake

iii

Potential for living organisms in the lake

iv

Challenges of exploration

v

Discovery of the lake

vi

Possible sources of nutrients to support life

vii

Types of organisms in the lake

viii

Scientific interest in Lake Vostok

Example:

Section A v

1 __________Section B

2 __________Section C

3 __________Section D

4 __________Section E

Questions 5-6

Choose the correct letter A-D.

5Which is NOT given as a reason forinterest in exploring Lake Vostok?

Ato test technology for space exploration

Bto develop anti-pollution devices

Cto investigate the history of Earth’s climate

Dto look for living organisms

6Lake Vostok does not freeze because ...

Aa thick ice cover provides insulation.

Bit is waned by heat from the earth’ssurface.

Clow pressure prevents freezing.

Dan underwater volcano erupted recently.

Questions 7-13

Do the following statementsreflect the claims of the author?

Write:

YES

if the statement agrees with the views of the writer

NO

if the statement contradicts the views of the writer

NOT GIVEN

if it is impossible to say what the writer thinks about this

7 _________________ Only one lake has been found beneath Antarctica.

8 _________________ Lake Vostok was detected by radar.

9 _________________ Exploration of Lake Vostok is coordinated by Russia.

10 _________________ Nutrients to support life have been found in the Antarctic ice.

11 _________________ The ice above the lake is moving to the east.

12 _________________ Scientists have drilled through the ice into the water of LakeVostok.

13 _________________ The water in the lake is approximately 500 in deep at thesouthern end.

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答案

雅思阅读第084套P1-Lake Vostok

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雅思阅读第084套P1:Lake Vostok