Plant Gas
Scientists have been studying natural sources of methane for decades but hadnt regarded plants as a producer,notes Frank Keppler,a geochem[st at the Max Planck Institute for Nuclear Physics in Heidelberg,Germany1.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,microbes2 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 Earths atmosphere and contributeto global warming.
In its experiments,Kepplers 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 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. 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.
Beeause there was plenty of oxygen available,its unlikely that the types of bacteria that normally make methane were involved. Experiments on plants that weregrown 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.King,a biogeochemist at the University of Minnesota in St.Paul3.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 plants influence,she notes.
词汇:
methane/5meWein/n.甲烷,沼气 emission/i5miFEn/n.散发,发射
geochemist n.地球化学家 triple/5tripl/v.增加三倍;adj.三倍的
Celsius n..adj.摄氏 bacteria/bAk5tiEriE/n.细菌
microbe/5maIkrEJb/n.微生物 nanogram n.微克
biogeochemist n.生物地球化学家 chamber/5tFeimbE/n.室,房间;腔
注释:
1. the Max Planck Institute for Nuclear Physics in Heidelberg,Germany:马克思普朗克核物理研究所,位于德国海德堡。海德堡系德国西南部城市,在巴登一符腾堡州的内卡河畔。海德堡大学是德国历史最悠久的大学。
2. microbe:细菌,意义同bacterium。但microbe不用作专门术语。
3. St.Paul:圣保罗,美国明尼苏达州首府。
练习:
1. What was scientists understanding of methane?
A h 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.
2. To test whether plants are a sot,roe of methane,the scientists created
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.
3. Which statement is true of the methane emissions of plants in the experiment?
A The lower the temperature,the higher the amount of methane emissions.
B I.iving plants release less methane than dried plants at the same temperature.
C When exposed to sunlight,plants stop releasing methane.
D The higher the temperature,the greater the amount of methane emissions.
4. Which of the following about methane is Not mentioned in the passage?
A Plants growing in soil release methane.
B Plants growing in water release methane.
C Soil microbes consume methane.
D Microbes in plants produce methane.
5. What is the beneficial point of some microbes consuming plant-produced methane?
A Methane becomes less poisonous.
B Methane is turned into a fertilizer.
C Less methane reaches the atmosphere.
D Air becomes cleaner.
雅思考试词汇每日累积自行车的结构
雅思考试每日词汇累积表示生气的词汇及词组
雅思考试词汇每日累积千变万化的性格
雅思考试每日词汇累积美味健康的蔬菜
雅思考试备考词汇记忆中国各大银行的名称
雅思考试每日词汇累积大树的各个部分
雅思考试每日词汇累积各种各样的舞蹈
雅思考试每日词汇累积入住酒店必知的词汇
雅思考试每日词汇累积不同笑法的英文
雅思考试每日词汇累积树的种类
雅思考试备考词汇累积动物的孩子都叫什么
雅思考试每日词汇累积吃东西的方式
雅思考试备考词汇累积最美的英文单词
雅思考试词汇每日累积千变万化的红色
雅思考试词汇每日累积烹饪大法
雅思考试备考词汇记忆幸福婚姻的开始婚礼
雅思考试每日词汇累积与酒有关的表达
雅思考试每日词汇累积我们应该珍惜的那些时光
雅思考试备考词汇记忆服装的分类
雅思考试每日词汇累积离婚相关词汇
雅思考试每日词汇累积照亮生命的光
雅思考试词汇每日累积恋爱与婚姻
雅思考试每日词汇累积交通运输系统铁路
雅思考试词汇每日累积道路的种类
雅思考试每日词汇累积各种事故accidents
雅思考试备考词汇记忆奥斯卡颁奖典礼电影类型
雅思考试每日词汇累积眼中的词汇
雅思考试每日词汇累积中国传统建筑
雅思考试每日词汇累积指尖的动作
雅思考试每日词汇累积犯罪词汇
不限 |
英语教案 |
英语课件 |
英语试题 |
不限 |
不限 |
上册 |
下册 |
不限 |