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
32
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.
The study published in the journal Nature indicates that ______
选项
A、the Clean Air Act has not produced the desired results
B、lead deposits in arctic snow are on the increase
C、lead will stay in soil and snow longer than expected
D、the US is the major source of lead pollution in arctic snow
答案
D
解析
根据第三段中的"The dominant lead ratio found in Greenland snow matched that found in gasoline from the United States.”就可推断出极地雪地铅污染主要来自美国。
转载请注明原文地址:https://kaotiyun.com/show/9uhK777K
0
专业英语四级
相关试题推荐
PerhapsthemostheatedargumentacrosstheUnitedStatestodayisthedeathpenalty.Manyarguethatitisan【C1】______deterr
Mathematicalabilityandmusicalabilityarecloselyconnected.Mybook"Late-TalkingChildren"drovethepoint【C1】______.Thre
Psychologicallytherearetwodangerstobeguardedagainstinoldage.Oneoftheseis【C1】______absorptioninthepast.Onesh
Thescienceofgeneticsisaflourishingnewindustry,nourishedbythefederallyfundedHumanGenomeProject.Thisresearchis
Manypeoplewhoareadoptingachildexpectittobringgreatjoytotheirlife.Butwhen【C1】______parentswanttheirchildbac
Atrendamongmanycollegesanduniversitiesistooffercoursesthatareslightlyoffthebeatentrack.Manyofthesecoursesd
Americanstodaychooseamongmoreoptionsinmorepartsoflifethanhaseverbeenpossiblebefore.Toanextent,theopportunit
Mostofusspendourlivesseekingthenaturalworld.Tothis【C1】______wegofishing,sitinthegarden,drinkoutsideratherth
Thenumberofapplicantsforcivilservantshasincreasedabruptlyinrecentyears.Manypeoplebelieveitisanappealingjob,
Peoplehavebeenpaintingpicturesforatleast30,000years.Theearliestpictureswerepaintedbypeoplewhohuntedanimals.T
随机试题
核酶(ribozyme)
A.不典型增生细胞超过全层的2/3,但未累及上皮全层B.不典型增生细胞累及全层,未突破基底膜C.二者均是D.二者均不是CINⅢ是指
患者男性,46岁,出现血尿,首先应考虑
A.防风通圣散B.清暑汤C.五味消毒饮D.五神汤E.仙方活命饮合增液汤热毒蕴结型疖宜选用的内服方是
患者老年女性,间歇性无痛性血尿1年,近期又出现血尿,伴尿频、尿急、尿痛,排尿困难。应首先考虑的是
下列为防范土方开挖过程中塌方风险而采取的措施,属于风险转移对策的是()。
在计算机和手工并行阶段,应当注意()。
在《有特色的脸》一课的美术课堂上,教师引导学生观察和认识每张面孔的特点,或丰满、或清瘦、或慈祥、或甜美、或严厉……然后让学生回忆过去的自己,并将自己的成长作为一部分跨越性的想象,有趣味地学习人在不同年龄时期的体貌特征规律。运用欣赏、夸张、变形、添加等艺术手
以下说法正确的是:
Thesmallsizeofthecomponentsofcomputerchipshasprovedunstoppable.Ineachnew(1)_____,thosecomponentsaresmalleran
最新回复
(
0
)