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
Scientists have long believed one way to stop the Earth’s atmosphere from warming is by planting more trees. The idea is that mo
Scientists have long believed one way to stop the Earth’s atmosphere from warming is by planting more trees. The idea is that mo
admin
2010-01-10
68
问题
Scientists have long believed one way to stop the Earth’s atmosphere from warming is by planting more trees. The idea is that more trees will take in or absorb some of the carbon dioxide in the atmosphere. Carbon dioxide is a gas released by cars, factories and other human activities. The gas traps heat in the Earth’s atmosphere, which warms the planet. However, two new studies have found that trees may not be as helpful in reducing carbon dioxide as had been thought.
The first study was done at Duke University in Durham, North Carolina. Researchers pumped extra carbon dioxide into a test area where pine trees were growing. The trees grew thirty-four percent faster during the first three years. However, in time, the trees slowed to about their normal growth rate. The scientists say this is because trees need other nutrients, such as nitrogen.
In the second study, researchers from Duke and Bowdoin College in Brunswick, Maine examined the soil around trees. They discovered that as the leaves broke down into the soil, all the carbon was not trapped in the soil. Much of it was released into the atmosphere as carbon dioxide.
The findings of the two studies were published last month in Nature magazine. They suggest there is limited value in planting trees to reduce the carbon dioxide pollution in the atmosphere.
Forest planting has been a part of negotiations on a world agreement to reduce greenhouse gases that scientists believe cause global warming. The United States, Canada, Japan and some other industrial countries have supported the idea. But this new research suggests the idea is not as effective as environmental activists had thought. Scientist Ram Oren of Duke University led the study on tree growth. He says that earlier estimates on the ability of forests to absorb carbon dioxide were overly hopeful.
Some scientists not involved in the studies say the research provides some of the first evidence on how trees react to carbon dioxide. Other scientists say the research disputes a belief among some coal and power companies. The companies say that rising levels of carbon dioxide in the atmosphere will not create harmful global warming. Instead, they say it will increase forests and other plants.
Why researchers put trees in extra carbon dioxide in the first study?
选项
A、To learn whether trees can still absorb carbon dioxide under extreme conditions.
B、To get more oxygen from these trees.
C、To evaluate the maximum carbon dioxide that trees can absorb.
D、To see the growth rate of these trees.
答案
D
解析
关键语句:The trees grew thirty—four percent faster during the first three years.However,in time,the trees slowed to about their normal growth rate.The scientists say this is because trees need other nutrients,such as nitrogen.可以看出是研究生长规律。A,B,C均和本文无关。
转载请注明原文地址:https://kaotiyun.com/show/4c6K777K
0
专业英语四级
相关试题推荐
读书的状态大致分为三种:一是为别人而读,二是为有用而读,三是为兴趣而读。处在第一种状态是最痛苦的,自己本不想读,但迫于外界压力却不得不读。好多中小学生就属于这种情形。在这样的状态下,读书真是苦不堪言。有不少学生曾咬牙切齿地发誓:毕业考试一结束,一
Duringthepastdecade,talentshowshavebeenquitepopularamongChineseaudience.Despitethephenomenalresponsefromthegr
(1)AsIponderwhomitmightbethatIwouldconsiderarolemodel,IrealizedthattherearealotofpeopleIknowpersonally
(1)Consideringitisabusinessthathasprovokedwarsincenturiespast,scantattentionispaidtothemodernslavetrade.But
(1)Sometimesthebiggestchangesinsocietyarethehardesttospotpreciselybecausetheyarehidinginplainsight.Itcouldw
ThePressConferenceI.AdvantagesofthePressConference—theeventitselfhaving【T1】________
IfNajibullahZaziiseverythingtheFBIsaysheis,thentheAfghan-bornDenverairport-shuttle-busdriverrepresentsanewk
PassageTwo(1)Britain’seconomywilllosemomentumthisyearamidsqueezedlivingstandardsanduncertaintyoverBrexita
AlejandroToledo,aformershoe-shineboyturnedeconomist,isnowPeru’sPresident-elect,followinghisvictorySundayinarun
Tolearnwithsuccessisnotaverydifficulttaskofsomefundamentalprinciples【C1】______tobeitsbases.【C2】______discussi
随机试题
急性消化道大出血时,下列描述错误的是
患者,女,46岁。劳累后出现尿频、尿急、尿痛、血尿3天,伴发热、寒战、全身关节酸痛、腰痛、乏力。既往有糖尿病史15年,曾有尿路感染史。查体:体温39.2℃,脉搏106次/分,血压150/90mmHg;心率106次/分,律规整,双肺正常,腹部无异常,双下肢轻
为减轻肾小球的高灌注、高滤过、高压状态,其饮食疗法应选择
在票据的记载事项中,可以更改的事项是( )。
下列社会保险不需要劳动者缴费的是()。
下列图中,哪个是长江海事局2018年5月签发的各类海船船员证书结构示意图?()
下列选项不属于泰勒主张的教育目标的来源的是()。
Advertisingispaid,nonpersonalcommunicationthatisdesignedtocommunicateinacreativemanner,throughtheuseofmassor
A、Itisnotstable.B、Shemeetstoomanypeople.C、Shehatestobealawyer.D、Ithaslongworkinghours.D对话中男士说他听说女士要辞职,女士说是的,
A、Adriver’slicense.B、Apassport.C、Aninternationalcreditcard.D、Adeposit.B
最新回复
(
0
)