Earth is far more alive than we previously thought, according to “deep life” studies that reveal a rich ecosystem beneath our feet that is almost twice the size of all the world's oceans. Regardless of extreme heat, no light and intense pressure, scientists estimate if has between 15 billion and 23 billion tonnes of microorganisms. “It's like finding a whole new reservior of life on Earth,” said Karen Lloyd, an associate professor at the University of Tennessee.
Results suggest 70 percent of Earth's bacteria and archaea exist in the subsurface. One organism found 2. 5 kilometers below the surface has been buried for millions of years and may not rely on all energy from the sun. Also, the methanogen (产甲烷菌) has found a way to create methane in this environment, which it may not use to reproduce or divide, but use to replace or repair broken parts. Lengths of their lives were completely different. Some microorganisms have been alive for thousands of years, barely moving except with shifts in earthquakes or eruptions. They're just active inside, with less energy than people thought possible to support life.
The team consists of 1, 200 scientists from 52 countries in disciplines ranging from geology and microbiology to chemistry and physics. The scientists say they will present their findings before the American Geophysical Union’s annual meeting opens this week, which are made possible by technical advances on drills and microscopes.
The scientists have been wondering about the point beyond which life can't exist, but the deeper they dig, the more life they find. There is a temperature maximum - currently 122 ℃ - but they believe this record will be broken if they keep exploring and developing mor advanced instruments.
Questions remain, including how the microbes interact with chemical processes, and what this might reveal about how life and Earth coevolved.
12. What do the scientists find about the underground microorganisms?
A.They can’t reproduce and divide. | B.They’re the oldest living things. |
C.Some of them consume no energy. | D.Some of them almost always keep still. |
13. What can we learn about the reseach from paragraph 3?
A.It lasts for aound one year. | B.It is conducted in 52 countries. |
C.It involves efforts from multiple fields. | D.It promotes technical development. |
14. Why do the scientists drill deep?
A.To find the depth limit of life. | B.To break their previous record. |
C.To discover more ancient microorganisms. | D.To detect the highest subsurface temperature. |
15. Which of the following is the best title for the text?
A.Earth’s Depths Are Full of Life | B.Organisms Live Better Underground |
C.Earth Is Far Beyond Human Exploration | D.Subsurface Life Differs from That on Land |