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
考研
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
2010-01-13
101
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 world-wide 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 North-eastern 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 study published in the journal Nature indicates that______.
选项
A、lead deposits in arctic snow are on the increase
B、the Clean Air Act has not produced the desired results
C、the US is the major source of lead pollution in arctic snow
D、lead will stay in soil and snow longer than expected
答案
C
解析
细节理解题。由第二段第一句可知,“美国排放的含铅气体是格陵兰雪地中高含铅量的主要贡献者”。故选C项。
转载请注明原文地址:https://kaotiyun.com/show/pMmi777K
0
在职申硕(同等学力)英语
相关试题推荐
Themediacanimpactcurrentevents.AsagraduatestudentatBerkeleyinthe1960s,Irememberexperiencingtheeventsrelated
Learningdisabilitiesareverycommon.Theyaffectperhaps10percentofallchildren.Fourtimesasmanyboysasgirlshavelea
TheNetherlandsplanstostartbuildingfloatingcommunitiesonwaterbecause______Byciting"Everyoneaskswhydidn’twedo
Andreahadneverseenanoldladyhitchhiking(搭车)before.However,theweatherandthecomingdarknessmadeherfeelsorryfor
Someinternationalstudents(use)acassetterecorder(tomake)tapesoftheirclasses(sothat)theycanrepeatthelectures(a
Sincetheearly19~0s,Swissbankshadpridedthemselves______theirsystemofbankingsecrecyandnumberedaccounts.
TheCommitteepronouncedfourmembersexpelledforfailuretoprovideinformationinthe______ofinvestigations.
Accordingtoasurvey,whichwasbasedontheresponsesofover188,000students,today’straditional-agecollegefreshmenare"
Man:We’rehavingahardtimedecidingwheretogoskiingoverbreak.Wherewouldyouprefertogothisyear?Women:IguessIdi
Sometimesthemessagesareconveyedthroughdeliberate’consciousgestures’,othertimes,ourbodiestalkwithoutourevenknowi
随机试题
我国现行的环境与资源保护法体系构成部分有【】
某框架结构柱基础.由上部结构传至该柱基的荷载标准值为:Fk=6600kN,Mkx=Mky=900kN.m,柱基础独立承台下采用400×400钢筋混凝土预制桩,桩的平面布置及承台尺寸如图5-14所示。承台底面埋深3.0m,柱截面尺寸700×700,居承台中心
企业从投资人或其他外部来源取得的由所有者享有但不属于企业注册资本范围的资本是()。
商业银行通常仅接受()。
根据支付结算法律制度的规定,下列有关预付卡的表述中,正确的是()。
外同合营者的下列出资方式中,符介巾外合资经营企业法律制度规定的是()。
某大学学生会换届选举,张华和其他四个竞选者报名竞选学生会主席一职。其他四个竞选者都没有同时具备张华所有的优点。从以上断定能合乎逻辑地得出以下哪项结论?()
[A]Nodisciplineshaveseizedonprofessionalismwithasmuchenthusiasmasthehumanities.Youcan,MrMenandpointsout,beca
WhichofthefollowingisTRUEaboutthegeneralmanagerandhisassistants?
A、AnIndiansummerbringswarmdaysandnights.B、AnIndiansummeroccursonlyinOctober.C、AnIndiansummerisanannualpheno
最新回复
(
0
)