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  3. The warming of the Arctic is releasing a new wave of banned toxic chemicals that had been trapped in the ice and cold water, sci

The warming of the Arctic is releasing a new wave of banned toxic chemicals that had been trapped in the ice and cold water, sci

admin2012-05-17  51
问题     The warming of the Arctic is releasing a new wave of banned toxic chemicals that had been trapped in the ice and cold water, scientists have discovered.
    The researchers warn that the amount of the poisons stored in the polar region is unknown and their release could "undermine global efforts to reduce environmental and human exposure to them."
    The chemicals leaking out as temperatures rise include DDT, lindane, chlordane, PCBs and HCBs. All of these persistent organic pollutants (Pops) are banned under the 2004 Stockholm Convention.
    Pops can cause cancers and birth defects and take a very long time to degrade (降解), meaning they can be transported for long distances and accumulate over time.
    Over past decades, the low temperatures in the Arctic trapped volatile (易挥发的) Pops in ice and cold water. But scientists in Canada and Norway have now discovered that global warming is freeing the Pops once again.
    They examined measurements of Pops in the air between 1993 and 2009 at the Zeppelin research station in Svalbaard and Alert weather station in northern Canada. After allowing for the decline in global emissions of Pops, the team showed that the toxic chemicals are being remobilised by rising temperatures and the retreat of the sea ice, which exposes more water to the Sun. For example, air concentrations of PCBs and HCBs have shown a rising trend from about 2004 onwards.
    Hayley Hung, a member of Environment Canada and of the team, said its work provided the first evidence of the releasing of Pops in the Arctic. "But this is the beginning of a story," she said. "The next step is to find out how much is in the Arctic, how much will leak out and how quickly." With the exception of lindane, there was little existing knowledge of the scale of the Pops stored in high latitude (纬度) regions.
    The fate of the frozen Pops depends on the speed of warming in the Arctic — it is currently heating up much more quickly than lower latitudes — as well as how the chemicals interact with snow and rain. Pops accumulate in fats and are therefore concentrated up the food chain, but Hung cautions that food chains themselves in the Arctic may be altered by climate change.
According to Hayley Hung, the scientists need to figure out______.
选项 A、the harm the Pops will do to human beings
B、why the Pops have been trapped in the ice
C、the scale of the Pops stored in the Arctic
D、how to eliminate the banned toxic chemicals
答案C
解析 根据题干中的Hayley Hung和figure out将本题出处定位到第7段第3句。该句提到Hayley Hung对如何应对释放的Pops的看法：下一步是要弄清这些物质在北极圈有多少，会释放出来多少，释放速度有多快。[C]the scale of the Pops stored in the Arctic正是对Hayley Hung提到的how much is in the Arctic的同义转述，故为答案。[A]、[B]和[D]均不是Hayley Hung的看法，故排除。
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