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The warming of the Arctic is releasing a new wave of banned toxic chemicals

游客2023-07-20  32
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. [br] What have the researchers discovered in the Arctic?
选项 A、The ice and cold water in the region contain banned toxic chemicals.
B、Poisons stored in the region are leaking out due to global warming.
C、The amount of toxic chemicals in the region could destroy all mankind.
D、The ecosystem in the region has been changed by rising temperatures.
答案 B
解析 根据题干中的discovered和the Arctic将本题出处定位到首段。该段提到，科学家已经发现，北极地区温度的升高，使得新一波被禁用的有毒化学物质被释放出来，这些物质之前一直被困在冰层和冰冷的海水中。[B]中的Poisons stored in the region对应toxic chemicals．．．trapped in the ice and cold water，leaking out对应releasing，global warming对应The warming of the Arctic对应，故答案为[B]。科学家发现的是被困在冰层和冰冷的海水中的有毒化学物质被释放出来，并不是发现冰层和冰冷的海水中包含有毒化学物质，故排除[A]。文中提到冻结在这个极地的毒素数量不明，而且，这些毒素的释放会“破坏人们在保护环境和人类免受这些毒素伤害方面所做的全球努力”，并未提及毒素数量能毁灭全人类，故排除[C]。文中提到北极地区温度升高，但未提及这一区域的生态系统因此改变，故排除[D]。
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