TOEFL Listening: ETS-TOEFL听力机经 - CQ0S14_4I1C4C152Q$

Lecture: Flotsam Science: Narrator: Listen to part of a lecture in an Earth science class. Professor: Okay, uh, before we finish class, I'd like to briefly talk about something else. Has anyone ever heard of something called flotsam science? No? Oh, I'm not surprised. It's a research method, but one of the more unusual ones out there. Now, flotsam, of course, refers to cargo or wreckage from ships that [ ... ] floating at sea or washed up on shore. Flotsam science began quite accidentally some years ago. When a shipment of plastic bath toys, shaped like frogs, ducks and turtles, fell off a cargo ship into the Pacific Ocean in stormy weather. No one thought too much of this – it happens all the time. But then these toys started to wash up on the beaches thousands of miles away. Scientists who tracked ocean currents were ecstatic, since they knew when and where the storm had occurred, they realized they could trace the routes these toys had taken as they floated through the Pacific. So flotsam science is, generally speaking, the science of floating junk. But this is a legitimate, if perhaps, unconventional discipline. In fact, thanks to flotsam science and these travelling bath toys and other harmless stuff that drops off ships, like athletic shoes, sports equipment ... you name it. Scientists now know a lot more than they used to about currents in the northern Pacific. That information in turn has allowed scientists to identify long term changes in water temperatures or salinity – the amount of salt in the water in these currents. Before flotsam science, scientists had been trying to determine this information for years by using expensive scientific devices that they would set a drift in the ocean. But there are problems with these devices. For one thing, they need to travel a great depth – as much as two kilometers down. Because if they ride on the surface of the ocean, their sensors can become obstructed by all these particles and other organisms that flied in the Sun-lit upper portion of the ocean. But if they travel way below the surface to avoid these obstructions, well, they don't tell you much about the surface movement of the water, which is what we want to know. Another problem is that the batteries don't last long enough to record sufficient data. But bath toys and athletic shoes and this sort of thing – they travel on the surface and they don't need batteries. And a lot of merchandise that falls off ships, like athletic shoes, have manufacturing codes on them that scientists use in tracing the origins of these objects and keeping track of their movements. And now scientists are using flotsam science for more than studying ocean currents. For example, some scientists are trying to use flotsam science to study glacial melt water. In the warmer summer months, ice from the top layer of the glacier melts, forming pools of melt water. So far it has been a challenge to determine just how much ice of a glacier moves each summer, or where the melt water winds up. Because it travels through [M]. A [M] is a giant crack in a glacier that meltwater drains through. And once melt water enters the [M], it's extremely difficult to track. One scientist set out to determine where melt water from a glacier in Greenland ends up. Into which neighboring body of water. So what this scientist did is he set up a special scientific instrument equipped with a tracking device down the [M] in Greenland's largest glacier. Unfortunately, his rather expensive device disappeared. Ok, so what else could be used? Now, after he realized the conditions in these [M]s are intense – it's freezing cold, plus, there's large pressure from the weight of all that ice above. So what was needed was something that was extremely durable. So he finally decided to use a yellow rubber duck – a children's bath toy. The advantage being that it is both cheap and can withstand high pressure and low temperatures. So after leaving an email address and an offer of a reward in three different languages on the duck, he dropped ninety of them down the [M] he was researching. Now, he hasn't actually had any of these ducks returning, but he remains hopeful that someone will find the duck, and return it to him.