Plant Gas
Scientists have been studying natural sources of methane for decades but hadnt regarded plants as a producernotes Frank Kepplera geochemist at the Max Planck Institute for Nuclear Physics in HeldelbergGermany.Now Keppler and his colleagues find that plantsfrom grasses to treesmay also be sources of the greenhouse gas.This is really surprisingbecause most scientists assumed that methane production requires an oxygen-free environment.
Previouslyresearchers had thought that it was impossible for plants to make significant amounts of the gas.They had assumed that microbes2 need to be in environments without oxygen to produce methane.Methane is a greenhouse gaslike carbon dioxide.Gases such as methane and carbon dioxide trap heat in Earths atmosphere and contribute to global warming.
In its experimentsKepplers team used sealed chambers that contained the same concentration of oxygen that Earths atmosphere has.They measured the amounts of methane that were released by both living plants and dried plant materialsuch as fallen leaves.
With the dried plantsthe researchers took measurement at temperatures ranging from 30 degrees Celsius to 70 degrees C.At 30 degrees Cthey founda 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 temperaturethe 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 availables 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.Thats another strong sign that the gas came from the plants and not soil microbes.
The new finding is an interesting observation, says Jennifer Y.Kinga biogeochemist at the University of Minnesota in St.Paul3.Because some types of soil microbes consume methanethey may prevent plant-produced methane from reaching the atmosphere.Field tests will be needed to assess the plants influenceshe notes.(367 words)
《神探夏洛克》,本季可能是终结
科学家研发出电脑法官 断案准确率达79%
Refugee camps are a breeding ground for disease
《霍比特人3》电影精讲
Can social media improve voter turnout?
Apollo's final missions: The last footsteps on the moon
When it comes to beer, variety rules in USA
“百慕大三角之谜”已解开?
词法翻译之转性翻译
European farmers work to boost global grain supplies
English settlers establish colonies In the New World
After long fight, DC wins right to a statue in the Capitol Building
让你更时髦的5样明星单品
吴恳大使在禁化武组织第83届执理会上的发言
Protests spread over anti-Islam video
Despite recession, blow-dry bars heat up
富人“眼中无人”是有科学依据的?!
Marylanders recall bloodiest day in US history
Officials say New Orleans is better protected(视频)
懒癌患者的福音 十款快捷美味的早餐
跟熊在一起生活是何体验
CPJ: Journalists need new ways to stay safe
王群司长在第71届联大一委一般性辩论中的发言
科学证实 富人总是“目中无人”?
Scientists seek HIV vaccine using monkey model
US beefs up security after embassy attacks(视频)
US drought renews debate on biofuel
unlucky的十种表达方法
Dire warnings issued on diminishing Arctic ice(视频)
你见过最奇葩的密码是什么?