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
57
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
A、Beforefinishingschool.B、Afterfinishinguniversity.C、Duringheruniversitycourse.D、Betweenschoolanduniversity.D推理判断题
Asregardssocialconventions,wemustsayawordaboutthewell-knownEnglishclasssystem.Thisisanembarrassingsubjectfor
A、Toflyonefollowinganother.B、Toflywithoutstopping.C、Touselandfeaturesastheguide.D、Totakeonerouteonly.C此题的问题
SigmundFreudwasbornonMaysixth,eighteenfifty-six,inMoravia,inwhatisnowtheCzechRepublic.Earlyinhis【B1】______,
Studentswhoareshytoanswerquestionsinclasswillhavetheirembarrassmentendedinanewelectronicsystemwhichallowsth
Teachingtodaydemandsmorethanjustcaringaboutchildrenandknowingone’ssubjectwell.Teachersneedtofindoutwhat【B1】__
A、Inarestaurant.B、Inabar.C、Onajet.D、Onanoceanliner.C此题必须逐一辨析,不能急于下结沦。听到"beerandacake",也许A、B为正确选项。但接着听到的信息"theeap
A、Tosearchforthevictims.B、Todirectthetraffic.C、Toclearawaythebricks.D、Tofixthegaspipe.C事实细节题。短文第二段中提到:Twoof
A、Customerscangetthepaymentbackifthey’renotsatisfiedwiththeproducts.B、Thecompanywillredotheproductsagainand
A、Theyarebuiltinthecountryside.B、Theyarewelldecorated.C、Theyarelocatedinwarmareas.D、Theyarefinancedbythegov
随机试题
阅读《郑伯克段于鄢》中的一段话,然后回答下列小题。既而大叔命西鄙北鄙贰于己。公子吕曰:“国不堪贰,君将若之何?欲与大叔,臣请事之;若弗与,则请除之。无生民心。”公曰:“无庸,将自及。”大叔又收贰以为己邑,至于廪延。子封曰:“可矣,厚将得众。”公曰
资金的时间价值通常是通过()来反映的。
不属于高填方路基沉降病害的防治措施的是()。
套期保值效果与下列()关系最密切。
采用追溯调整法,需要做的工作有()。
职位权力的主要影响方式有()。
叉车和拖车是生产车间最常见的搬运设备,叉车多适用于非标准尺寸物料远距离的运输,拖车则可用于短距离托盘和仓储笼运输。()
智力
简述衡量国内生产总值GDP的三种计算方法(列出必要公式)。
Hardshipdidnotendwithfreedom.Therewere【C1】______regionalvariationsinboththestatusand【C2】______offreeblacksdurin
最新回复
(
0
)