首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Lead deposits, which accumulated in soil and snow during the 1960’s and 1970’s, were primarily the result of leaded gasoline emi
Lead deposits, which accumulated in soil and snow during the 1960’s and 1970’s, were primarily the result of leaded gasoline emi
admin
2011-01-01
32
问题
Lead deposits, which accumulated in soil and snow during the 1960’s and 1970’s, were primarily the result of leaded gasoline emissions originating in the United States. In the twenty years that the Clean Air Act has mandated unleaded gas use in the United States, the lead accumulation worldwide has decreased significantly.
A study published recently in the journal Nature shows that air-borne leaded gas emissions from the United States were the leading contributor to the high concentration of lead in the snow in Greenland. The new study is a result of the continued research led by Dr. Charles Boutron, an expert on the impact of heavy metals on the environment at the National Center for Scientific Research in France. A study by Dr. Boutron published in 1991 showed that lead levels in arctic (北极的) snow were declining.
In his new study, Dr. Boutron found the ratios of the different forms of lead in the leaded gasoline used in the United States were different from the ratios of European, Asian and Canadian gasolines and thus enabled scientists to differentiate (区分) the lead sources. The dominant lead ratio found in Greenland snow matched that found in gasoline from the United States.
In a study published in the journal Ambio, scientists found that lead levels in soil in the Northeastern United States had decreased markedly since the introduction of unleaded gasoline. Many scientists had believed that the lead would stay in soil and snow for a longer period.
The authors of the Ambio study examined samples of the upper layers of soil taken from the same sites of 30 forest floors in New England, New York and Pennsylvania in 1980 and in 1990. The forest environment processed and redistributed the lead faster than the scientists had expected.
Scientists say both studies demonstrate that certain parts of the ecosystem (生态系统) respond rapidly to reductions in atmospheric pollution, but that these findings should not be used as a license to pollute.
The authors of the Ambio study have found that ______.
选项
A、forests get rid of lead pollution faster than expected
B、lead accumulations in forests are more difficult to deal with
C、lead deposits are widely distributed in the forests of the US
D、the upper layers of soil in forests are easily polluted by lead emissions
答案
A
解析
根据题干中的authors of the Ambio定位文章第五段,选项A是尾句的同义表达。
转载请注明原文地址:https://kaotiyun.com/show/lty7777K
0
大学英语四级
相关试题推荐
Ifyouweretobeginanewjobtomorrow,youwouldbring.withyousomebasicstrengthsandweaknesses.Successor【C1】______iny
Ifyouweretobeginanewjobtomorrow,youwouldbring.withyousomebasicstrengthsandweaknesses.Successor【C1】______iny
Mannersaredifferentineverycountry;buttruepolitenessiseverywherethesame.Mannersareonly【C1】______helpswhichignora
A、Gotodance.B、Gotothestudentcentre.C、Gotoaparty.D、Gotoalecture.D题目问男士周五准备做什么。女土邀请男士去跳舞,男士说很想去,但是已经准备去参加一个讲座了。可见参
Recently,astudentusedhisPersonalDigitalAssistant(PDA)tofilmafemaleteacherberating(训斥)andtearingtheworkofac
Recently,astudentusedhisPersonalDigitalAssistant(PDA)tofilmafemaleteacherberating(训斥)andtearingtheworkofac
Eachcollegeevaluatesapplicantsdifferently.Itisimportanttobeawareofthesedifferencesandtocreateastrategythatis
Eachcollegeevaluatesapplicantsdifferently.Itisimportanttobeawareofthesedifferencesandtocreateastrategythatis
Beforethe20thcenturythehorseprovideddaytodaytransportationintheUnitedStates.Trainswereusedonlyforlong-distan
Chimp(黑猩猩)ShowHallmarkofHumanCulture,StudyFindsResearchershavediscoveredthatchimpanzeesnotonlyteacheachoth
随机试题
A.新斯的明解救B.山莨菪碱C.东莨菪碱D.需和镇痛药哌替啶合用E.人工呼吸麻醉前给药常用
下列关于技术分析基本假设的说法,正确的是()。
转向轮的定位参数是_______。
对买方而言,最好的支付方式是()
在新的历史条件下,实现中华民族伟大复兴的中国梦,必须弘扬中国精神,这就是________。
横突骨折最常见于
纤维结肠镜最主要和严重的并发症是引起穿孔,穿孔发生率最高的部位是
亮亮一遇到困难就怯懦退缩,这反映的是性格的()
下列选项中不是人文主义教育的特征的是
一台交换机具有12个10/100Mbps电端口和2个1000Mbps光端口,如果所有端口都工作在全双工状态,那么交换机总带宽应为()。
最新回复
(
0
)