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
Plant Gas Scientists have been studying natural sources of methane for decades but hadn’t regarded plants as a producer, notes F
Plant Gas Scientists have been studying natural sources of methane for decades but hadn’t regarded plants as a producer, notes F
admin
2009-06-15
105
问题
Plant Gas
Scientists have been studying natural sources of methane for decades but hadn’t regarded plants as a producer, notes Frank Keppler, a geochemist at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany. Now Keppler and his colleagues find that plants, from grasses to trees, may also be sources of the greenhouse gas. This is really surprising, because most scientists assumed that methane production requires an oxygen-free environment.
Previously, researchers had thought that it was impossible for plants to make significant mounts of the gas. They had assumed that microbes need to be in environments without oxygen to produce methane. Methane is a greenhouse gas, like carbon dioxide. Gases such as methane and carbon dioxide trap heat in Earth’s atmosphere and contribute to global warming.
In its experiments, Keppler’s team used sealed chambers that contained the same concentration of oxygen that Earth’s atmosphere has. They measured the amounts of methane that were released by both living plants and dried plant material, such as fallen leaves.
With the dried plants, the researchers took measurement at temperatures ranging from 30 degrees Celsius to 70 degrees C. At 30 degrees C, they found, a gram of dried plant material released up to 3 nanograms of methane per hour. ( One nanogram is a billionth of a gram. ) With every 10-degree rise in temperature, the amount of methane released each hour roughly doubled.
Living plants growing at their normal temperatures released as much as 370 nanograms of methane per gram of plant tissue per hour. Methane emissions tripled when living and dead plant was exposed to sunlight.
Because there was plenty of oxygen available, it’s unlikely that the types of bacteria that normally make methane were involved. Experiments on plants that were grown in water rather than soil also resulted in methane emissions. That’s another strong sign that the gas came from the plants and not soil microbes.
The new finding is an "interesting observation," says Jennifer Y. King, a biogeochemist at the University of Minnesota in St. Paul. Because some types of soil microbes consume methane, they may prevent plant-produced methane from reaching the atmosphere. Field tests will be needed to assess the plant’s influence, she notes.
选项
A、It was produced from plants.
B、It was not a greenhouse gas.
C、It was produced in oxygen-free environments.
D、It traps more heat than any other greenhouse gas.
答案
C
解析
短文的第一和第二段都讲到,科学家过去曾经认为,沼气必须在无氧的环境中才能产生。注意,作者用的是过去式:Most scientists assumed that...,They had assumed that...”
转载请注明原文地址:https://kaotiyun.com/show/OWhd777K
本试题收录于:
职称英语理工类基础题库职称英语分类
0
职称英语理工类基础
职称英语
相关试题推荐
Theresultsofthenewstudyareunexpected.Allthosepeoplewhotookpartinthestudyreceivedvitaminsandminerals.
BetterControlofTBSeenIfaFasterCureIsFoundTheWorldHealthOrganizationestimatesthataboutone-thirdofallpeoplea
Accordingtothepassage,someengineersaretryingtoimprovethehandlebarsbecauseInparagraph2,theauthormentionsastu
Itisestimatedthatthereare______peoplesufferingfromobesityintheworld.Whichofthefollowingismostoftenaccompan
WhydidJeanSibeliusfeelalone?Whatwashisproblemwhenhebegantocomposesymphonies?
WhichofthefollowingstatementswouldBowlbysupport?WhichofthefollowingstatementsisNOTanargumentagainstBowlby’st
Thisisespeciallytrueintoday’sextremelyharsheconomicclimate.
DrugAbuse1Theterm"drugabuse"mostoftenreferstotheuseofadrugwithsuchfrequencythatitcausesphysicalormental
DrugAbuse1Theterm"drugabuse"mostoftenreferstotheuseofadrugwithsuchfrequencythatitcausesphysicalormental
随机试题
从某小学随机抽取100名同学,将他们的身高(单位:厘米)数据绘制成频率分布直方图如下图所示:要求计算:(1)a的取值。(2)若要从身高在[120,130),[130,140),[140,150]三组内的学生中,用分层抽样的方法选取18人参加一项活动
某工程单代号网络计划如下图所示,工作E的最早开始时间是()。
下列各项中,属于应当编制简式权益变动报告书的情形是()。
联合行文时,必须做好会签工作,使各机关或部门领导人均履行签发手续。()
价格调整方程
中共中央政治局2015年5月29日就健全公共安全体系进行第二十三次集体学习。中共中央总书记习近平在主持学习时强调,公共安全连着千家万户,确保公共安全事关人民群众生命财产安全,事关改革发展稳定大局。要切实抓好社会治安综合治理,坚持的总体思路是()
Intheidealizedversionofhowscienceisdone,factsabouttheworldarewaitingtobeobservedandcollectedbyobjectiveres
Ifthereisanyendeavorwhosefruitsshouldbefreelyavailable,thatendeavorissurelypubliclyfinancedscience.Morally,ta
Twowaysofowningabook:-payingforit,whichisthe【D1】______topossession-【D2】______theideas3kindsofbookowners:-h
Adisheartenedyounglawstudentonce【S1】______me.Hehadfailedthe"bar(法律)examination"forthesecondtime,wasoutofmo
最新回复
(
0
)