高温天气下树木竟然会污染环境！

    高温天气下树木竟然会污染环境！
    Normally， trees are the best defence against pollution； but when it's too hot outside， the trees' own self－defence mechanism¹ may actually make things worse。
正常情况下，树木是抵御污染的最佳卫士，但是当外界温度过高时，树木自身的防御机制实际上可能会令污染状况恶化。
Trees produce natural chemicals， called isoprene and terpene， that are thought to protect their leaves from too much heat and sunlight． When the chemicals react with nitrogen oxide－－found in pollution from cars－－they form ozone²， a much bigger health threat to humans and animals。
树木分泌的天然化学物质异戊二烯和萜烯被认为可保护树叶免受过多热量和阳光的伤害。然后，当这些化学物质与氮氧化合物（存在于汽车排放的废气中）发生化学反应时，就会形成臭氧，这会对人类和动物的健康构成更大的威胁。
Dr Alastair Lewis and his team at Britain's York University noticed how the production of isoprene， and thus ozone， suddenly went up at high temperatures． "At 30℃， it's starting to become important． By 35℃， the emission³ rate has gone up by maybe an order of magnitude⁴ 10 times，" Lewis told the BBC． Lewis says that isoprene and terpene were responsible for 30 percent of the ozone in the air during the hottest part of the summer。
英国约克大学的阿拉斯泰尔·刘易斯博士及其研究小组注意到异戊二烯的分泌量及随后形成的臭氧量在高温条件下陡然上升的过程。刘易斯对英国广播公司的记者说：“30℃时数量开始增加。到35℃时，其排放速度则可能增加了一个数量级（10倍）。” 他还指出，在夏天最热的时候，空气中的臭氧有30%是由异戊二烯和萜烯生成的。
Prof．David Fowler of the Centre for Ecology and Hydrology in Edinburgh says we shouldn't blame the trees for this． "Realistically， the best way to counter this is to reduce our production of both ozone and nitrogen oxides from industrial and personal processes．"
来自爱丁堡生态学与水文学中心的戴维·富勒教授认为，我们不该因此责怪树木。他对《每日电讯报》的记者说：“现实地说，应对这一情况的最佳办法是在我们的工业生产及个人生活中减少臭氧和氮氧化合物的排放。”

1 mechanism   

n.机械装置；机构，结构

参考例句：

• The bones and muscles are parts of the mechanism of the body.骨骼和肌肉是人体的组成部件。
• The mechanism of the machine is very complicated.这台机器的结构是非常复杂的。

2 ozone   

n.臭氧，新鲜空气

参考例句：

• The ozone layer is a protective layer around the planet Earth.臭氧层是地球的保护层。
• The capacity of ozone can adjust according of requirement.臭氧的产量可根据需要或调节。

3 emission   

n.发出物，散发物；发出，散发

参考例句：

• Rigorous measures will be taken to reduce the total pollutant emission.采取严格有力措施，降低污染物排放总量。
• Finally,the way to effectively control particulate emission is pointed out.最后，指出有效降低颗粒排放的方向。

4 magnitude   

n.大小；重大；星等

参考例句：

• I want to know the magnitude of this equipment.我想知道这个设备的大小。
• I hadn't realized the magnitude of the problem.我没有认识到这个问题的重要性。