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 mid 7O’s, were primarily the result of leaded gasoline emiss
Lead deposits, which accumulated in soil and snow during the 1960’s mid 7O’s, were primarily the result of leaded gasoline emiss
admin
2013-02-05
67
问题
Lead deposits, which accumulated in soil and snow during the 1960’s mid 7O’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 airborne 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 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 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 North-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 Am/do study examined samples of the upper layers of soft 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 respond rapidly to reductions in atmospheric pollution, but that these findings should not be used as a license to pollute.
How did scientists discover the source of lead pollution in Greenland?
选项
A、By analyzing the data published in journals like Nature and Ambio.
B、By observing the lead accumulations in different parts of the arctic area.
C、By studying the chemical dements of soil and snow in Northeastern America.
D、By comparing the chemical compositions of leaded gasoline used in various countries.
答案
D
解析
文章第三段指出,欧洲、亚洲、加拿大和美国的含铅汽油的成分不一样,因此可以据此找出铅污染源。这就是说,可以通过分析各国含铅汽油的化学成分来确定格陵兰岛铅污染的来源。
转载请注明原文地址:https://kaotiyun.com/show/6uhK777K
0
专业英语四级
相关试题推荐
Youshouldhaveputthemilkintotherefrigerator,Iexpectit______badbynow.
PerhapsthemostheatedargumentacrosstheUnitedStatestodayisthedeathpenalty.Manyarguethatitisan【C1】______deterr
Criticsofearlyschoolingciteresearchthatquestionswhether4-year-oldchildrenarereadytotakeonformallearning.Educat
Inasurprisinginteractionatsea,hugewhalesharksfollowfishingnetsneartheislandofNewGuinea—andfishermendistribute
ScientistshadthoughtpeoplebeganmanipulatingfiretocreatetoolsinEuropeabout25,000yearsago.Butthenewfindssugge
Atrendamongmanycollegesanduniversitiesistooffercoursesthatareslightlyoffthebeatentrack.Manyofthesecoursesd
Atrendamongmanycollegesanduniversitiesistooffercoursesthatareslightlyoffthebeatentrack.Manyofthesecoursesd
Mostofusspendourlivesseekingthenaturalworld.Tothis【C1】______wegofishing,sitinthegarden,drinkoutsideratherth
Allparentspushtheirkidsatleastalittle.Wepressureourkidstobepolite,learntoeat【C1】______andbeobedient.So,pre
Inanysociety,nomatterhow【C1】______,someindividualshaveauthority【C2】______others,atleastwithinalimitedsphere.Obed
随机试题
推进自主创新,人才是关键,要广纳人才,要放手使用人才,要完善促进人才脱颖而出的机制。()
A.西咪替丁B.法莫替丁C.雷尼替丁D.奥美拉唑E.胶体次枸橼酸铋作用最强的H2-受体拮抗剂是()
A、风邪B、寒邪C、湿邪D、燥邪E、暑邪导致出现头重如裹,周身困重,四肢酸懒沉重的邪气是()
2007年7月,赖某在与孙某等人赌博中输给孙某5000元,赖某怀疑孙某在赌博中作弊,即回到家中取来砍刀,要求孙某退回输掉的5000元,遭到孙某的拒绝。赖某遂连砍孙某数刀,孙某被迫交出5000元。赖某得款后逃离现场。经鉴定,孙某构成轻伤。赖某的行为构成何罪?
市场比较法是以()为理论基础,因此具有现实性和富有说服力。
某施工企业在2017年2月1日办理了安全生产许可证,则其向原发证机关办理延期手续的期间为()。
下列选项中,属于法人的是()。
尚书台
简述新中国成立时的国内外形势。
国际收支弹性论主要探讨()。
最新回复
(
0
)