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  3. On 28 March, scientists got a whiff of something strange in the air off a pier in San Diego, California. The atmosphere had sudd

On 28 March, scientists got a whiff of something strange in the air off a pier in San Diego, California. The atmosphere had sudd

admin2015-03-25  21
问题     On 28 March, scientists got a whiff of something strange in the air off a pier in San Diego, California. The atmosphere had suddenly become flush with radioactive sulfur(a light-yellow non-metallic solid)atoms. That sulfur, it turns out, had traveled across the Pacific from a nuclear power plant in Fukushima, Japan, that was shaken by the 11 March earthquake and the tsunami and aftershocks that followed. Now the same team has studied those radioactive winds to come up with the first estimate of damage to the plant’s cores at the height of the disaster.
    To cool fuel rods and spent fuel while stanching a total meltdown, responders pumped several hundred tons of seawater into three reactors at the Fukushima Dai-ichi nuclear power plant. The white-hot rods fizzled off steam, which had to go somewhere. So workers vented it into the air.
    Meanwhile, across the Pacific, atmospheric scientist Antra Priyadarshi of the University of California, San Diego(UCSD), remembered a study she had read a while back: Following underwater nuclear bomb tests in the 1950s and 60s, physicists noticed that a heavy form of sulfur—sulfur-35—had mushroomed. Nuclear reactions spit out lots of fast and therefore "hot" particles called neutrons, which can then bang into abundant chloride ions in saltwater, converting them to sulfur-35. Priyadarshi and her colleagues were already tracking tiny traces of radioactive sulfur to study how layers of air mix in the atmosphere, so all they had to do was wait.
    They didn’t have to wait long. The sulfur was already swirling over Fukushima, where it had combined with oxygen to form sulfur dioxide gases and fine particles of sulfates called aerosols. Soon, strong winds pushed them west. Sulfur-35 does occur naturally—cosmic rays zap argon atoms in the upper atmosphere, or stratosphere, to make radioactive sulfur. But little of it makes its way down to the lowest slice of atmosphere, called the marine boundary layer. On a normal day, Priyadarshi sees between 180 and 475 sulfur-35 atoms as sulfates per cubic meter of air, but on the 28th, her team recorded about 1500. "No one has ever seen such a high percentage of the stratospheric air coming into the marine-bound layer," she says.
    The UCSD team ran a computer simulation to trace the path of the gases and aerosols from Fukushima to the West Coast. Most sulfur -35 atoms likely dispersed or rained down into the sea before hitting San Diego, but Priyadarshi estimates that about 0.7% completed the trip, too few to become harmful. Based on the simulation, about 365 times the normal levels of radioactive sulfates had gathered over Fukushima during the disaster.
    Now that Fukushima’s reactors have cooled back down, the biggest challenge facing scientists will be to contain radioactive elements that escaped during the disaster. Mark Thiemens, the study co-author, an atmospheric scientist who is also at UCSD, will be working with Japanese researchers to follow sulfur-35’s path through soil and streams near Fukushima to find where even more harmful elements may have hidden.
It can be inferred from Priyadarshi that surfur-35 detected in America
选项 A、was produced because of the seawater infused into the reactors in Fukushima.
B、was similar to that grew from the underwater nuclear test in the 1950s and 60s.
C、will mushroom as that derived from the underwater nuclear test half a century ago.
D、will spread widely and mix with air in different layers of atmosphere.
答案A
解析 推理判断题。根据题干关键词Priyadarshi定位到第二段第一句和第三段第二句。第三段第二句指出，Priyadarshi了解到20世纪50年代和60年代水下核试验后，硫-35大量出现的原因是核反应堆释放出大量因快速移动而很“热”的物质，被称为中子，中子能够进入到盐水中丰富的氯离子中，将它们转化为硫一35。由第二段第一句可知，为了冷却燃料棒及止住燃料棒溶化时消耗燃料，应急泵曾将几百吨的海水注人福岛第一核电站的三个反应堆。因此可推测这些海水进入核反应堆后产生了硫一35，之后硫一35漂洋过海到了美国。[A]与原文意思相符，是正确答案。
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