VOA标准英语2012--Russians Reach Ancient Antarctic Lake

Russians Reach Ancient Antarctic Lake

Evidence of a giant lake beneath the Antarctic ice has been gathering 1 since the 1970s.

Suspicions were first aroused after a team of Russians drilled deep into the ice to get a climate-record core sample. According to Montana State University microbiologist John Priscu, a veteran Antarctic researcher, the Russian scientists were puzzled by what their ice cores revealed.

“As they got deeper, though, they hit this funny ice, a different kind of ice that no longer had layers," Priscu says. "It didn’t have climate-record layering in the bottom. So they stopped drilling to find out what the heck they were getting into.”

What they were getting into was the vicinity of Lake Vostok, more precisely 2, the region at the bottom of the ice sheet above the lake. By 1996, scientists had gathered enough data on the structure of the ice sheet and the terrain 3 beneath it to publish an article in Nature describing the hidden lake at Vostok.

Russia quickly launched a project to drill through the four kilometers of ice and gain access to the lake. That drilling and core sampling continued every year since.

Priscu sampled some of that 400,000 year-old ice core, which, he says, contained colonies of cold-adapted micro-organisms much like those found growing near deep-ocean vents 4.

“Other ones, based on our DNA 5 data, suggested that [the bacteria] would get their energy from minerals in the water. These organisms actually can mine the minerals in the rocks and then apparently 6 they are producing new carbon to feed organisms that reduce carbon.”

Drilling into Lake Vostok without contaminating it is a complex job. Priscu says the Russians have taken extreme care to avoid introducing surface bacteria or pollutants 7 into the lake’s virgin 8 waters.

“They will put no probes into the lake or any hardware. What they will do when they penetrate 9 the lake they will back pressure their bore hole and they will let the lake water come up into the bore hole. They will not let any of their borehole fluid go into the lake. So when they penetrate only lake water will come up.”

According to plan, water will rise up through the bore hole and be left to freeze over the Antarctic winter so the scientists can go back next year and analyze 10 it. But that is water just from the lake’s surface.

While the Russians are apparently the first to tap it, teams from the United States and England already have established projects to drill into the ancient Antarctic ice.

Priscu expects that within a decade an international team will explore Lake Vostok’s deepest regions.

“I also predict that once we really start figuring these systems out, we’ll find that they play an important role in biodiversity on our planet, a role in terms of carbon sinks and sources, which is important for the atmosphere.”

Priscu expects today’s discoveries in the Antarctic will inspire a new generation of scientists to unlock the secrets of this vast and still largely unexplored world.