首页
登录
职称英语
Lead deposits, which accumulated in soil and snow during the 1960’s and 1970
Lead deposits, which accumulated in soil and snow during the 1960’s and 1970
游客
2024-02-22
48
管理
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. [br] 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Nature查找到第二段首句,选项D是该句的同义概括。
转载请注明原文地址:https://tihaiku.com/zcyy/3472837.html
相关试题推荐
Leaddeposits,whichaccumulatedinsoilandsnowduringthe1960’sand1970
A、Hewasknockedoutduringonecontest.B、Helostthefinalchancetowinacha
Therewasa______growthofthelightindustriesduringthewar.A、considerableB
Duringthepressconference,thereporters______someofthepresident’sstatem
Duringtheirfirstteacher-trainingyear,thestudentsoftenvisitedlocalschoo
Duringthefamine,manypeopleweretobeggingfoodandmoneyfarawayfromthei
Theyhadapleasantchat______acupofcoffee.A、forB、withC、duringD、overD介词辨
[originaltext]Duringthepastdecade,therehasbeenamultifoldincreasei
[originaltext]Duringthepastdecade,therehasbeenamultifoldincreasei
[originaltext]Duringthepastdecade,therehasbeenamultifoldincreasei
随机试题
Choosethecorrectletter,A,B,orC.[br]Leadersmustdevelop[originaltext]S
Didyounoticeanybody(take)______myumbrella?take句子意为:你注意到有人拿了我的伞吗?在复合宾语中,宾语
Whatdoestheconversationsayaboutthetermpaper?[br][originaltext]W:List
Eyecontactisanonverbal(非语言的)techniquethathelpsthespeakers"sell"
仲裁是劳动争议案件处理必经的法律程序。
下列选项中,其各项指标的指数同比上升的是( )。A、2013年创新投入领域
2004年全国主要机械产品产量统计表 下面哪项陈述可以从上表中得出?()
保险合同的当事人包括()。A.投保人 B.保证人 C.保险人 D.被保险人
在一个乳腺癌与产次关系的病例对照研究中,研究结果表明100例乳腺癌患者有25人未
A.正确处理同行关系 B.不仅关心病人的躯体,而且关心病人的心理 C.注意克
最新回复
(
0
)