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. 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. 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. 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. A h was produced from plants. C It was produced in oxygen-free environments. 2. To test whether plants are a sot,roe of methane,the scientists created B an environment with the same concentration of oxygen as the Earth has. D an environment filled with the greenhouse gas. A The lower the temperature,the higher the amount of methane emissions. C When exposed to sunlight,plants stop releasing methane. 4. Which of the following about methane is Not mentioned in the passage? B Plants growing in water release methane. D Microbes in plants produce methane.
北师大版英语六上《Unit 6》PPT课件4
北师大版六年级上册英语《Unit 3
北师大版六年级上册英语《Unit 1 听力》flash课件包
北师大版六年级上册英语《Unit 5 听力》flash课件包
北师大版(一起)六上《Unit 4 Choosing a gift》ppt课件1
北师大版五年级上册英语《Unit 1 Ann’s dream》flash课件包
北师大版(一起)六上《Unit 3 redrock Bay Health Club》ppt课件2
北师大版(一起)六上《Unit 4 Choosing a gift》ppt课件
北师大版五年级上册英语《Unit 1 Ann’s dream》(There be结构)ppt课件
北师大版六年级上册英语《Unit 5 The broken computer》(重点单词讲解)ppt课件
北师大版英语六上《Unit 6》PPT课件2
北师大版英语六上《Unit 6》PPT课件5
北师大版五年级上册英语《Unit 1
北师大版六年级上册英语《Unit 2 charlie’s chores》flash课件之一
北师大版(一起)六上《Unit 6 review》ppt课件4
北师大版六年级上册英语《Unit 1 meeting the BINGO Kids》flash课件包(练习)
北师大版六年级上册英语《Unit 1
北师大版(一起)六上《Unit 3 redrock Bay Health Club》ppt课件
北师大版六年级上册英语《Unit 1 meeting the BINGO Kids》flash课件
北师大版六年级上册英语《Unit 6
北师大版(一起)六上《Unit 6 review》ppt课件2
北师大版六年级上册英语《Unit 5 The broken computer》(重点难点句子讲解)ppt课件
北师大版六年级上册英语《Unit 4 Choosing a gift》ppt课件
北师大版六年级上册英语《Unit 1 meeting the BINGO Kids》flash课件包(练习一)
北师大版六年级上册英语《Unit 5 The broken computer》flash课件
北师大版六年级上册英语《Unit 5 The broken computer》ppt课件
北师大版英语六上《Unit 6》PPT课件3
北师大版(一起)六上《Unit 6 review》ppt课件3
北师大版(一起)六上《Unit 6 review》ppt课件
北师大版(一起)六上《Unit 6 review》ppt课件1
不限 |
英语教案 |
英语课件 |
英语试题 |
不限 |
不限 |
上册 |
下册 |
不限 |