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, not
Plant Gas Scientists have been studying natural sources of methane for decades but hadn’t regarded plants as a producer, not
admin
2013-09-25
108
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 amounts 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 ℃ elsius to 70 degrees℃. At 30 degrees ℃ , 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.
To test whether plants are a sot, roe of methane, the scientists created
选项
A、a oxygen-free environment.
B、an environment with the same concentration of oxygen as the Earth has.
C、a carbon dioxide-free environment.
D、an environment filled with the greenhouse gas.
答案
B
解析
转载请注明原文地址:https://kaotiyun.com/show/yN1d777K
本试题收录于:
职称英语卫生类C级题库职称英语分类
0
职称英语卫生类C级
职称英语
相关试题推荐
Imagineaworldwithoutbrands.【R1】______Noraucousadvertising,nouglybillboards,andnoMcDonald’s.Yet,givenachanceand
Somepeoplebelievethatinternationalsportcreatesgoodwillbetweenthenationsandthatifcountriesplaygamestogetherthey
ItiscommonforAmericanstohavedifferent"circlesoffriends"suchaschurchfriends,workfriends,orsportsfriends.【R1】__
ItiscommonforAmericanstohavedifferent"circlesoffriends"suchaschurchfriends,workfriends,orsportsfriends.【R1】__
Facialexpressionscarrymeaning,determinedbycontextsandrelationships.【R1】______Awoman’ssmileatapolicemanwhoisabou
Whenwespeakofabasichumanneed,wemeansomethingwhichisnecessarytolife,somethingthatwecannotpossiblydowithout.
1.Mostyoungpeopleenjoysomeformsofphysicalactivity.Itmaybewalking,cyclingorswimming,orinwinter,skatingorski
1.Theprivatecarisassumedtohavewidenedourhorizonsandincreasedourmobility.Whenweconsiderourchildren’smobility,
THETRAINJOURNEY0YouknowIwasgoingdowntoLondontostaywithmyfriend00Aliceduringtheholidays.Well,thetr
Ifaperformancebeginsat8p.m.,theGoddingtonTheatreTicketOfficere-opensat7:30thatevening.Youneedtodriveawayq
随机试题
TheInternetisquicklychangingpeople’sideasontheverythings________areaccepted.
一座城市要想发展好会展产业,就需要“筑巢引凤”——先具备软硬件基础,再吸引会展活动。拥有完备的会展设施和理想的交通条件,只是说明一座城市具备了发展会展产业的硬件基础,要想吸引足够数量的高质量会展活动,还需要提高公共服务水平、构建良好的营商环境,从而加强软实
我国实行民族区域自治制度的基本依据有()。
乳牙早失引起间隙改变,下列各项中错误的是
简述不可抗力、意外事件、情事变更的区别。
信息标准化是建立全国建设工程造价信息系统的基础性工作,其具体建设工作内容不包括()。【2012年真题】
我国西南某新建机场为高填方机场,在施工前和施工过程中发生了以下事件:事件一:在机场高填方工程大面积施工前,施工单位在适宜地段开展了高填方试验工作。事件二:为了追赶工期,在土石方施工完成2个月后,施工单位提出了立刻开始摊铺基层与面层施工的申请。事件三:
股份有限公司召开股东大会年会时应当提前将财务会计报告置备于公司。根据公司法律制度的规定,该提前的日期是()。
下列对VLAN的描述中,错误的是()。
Thefirstthingforyoutodobeforeyoubuyclothesistoreadthelablesinsidetheclothes.Ifyouwanttosavemoney,youc
最新回复
(
0
)