1、1高效精读策略专项练习李仕才Rivers may be a significant source of the greenhouse gas nitrous oxide (一氧化二氮), scientists now find.Their calculation suggests that across the globe the waterways contribute three times the amount of nitrous oxide to the atmosphere as had been estimated by the International Panel on Cl
2、imate Change (IPCC), the United Nations scientific body charged with reviewing climate change research. They found that the amount of nitrous oxide produced in streams is related to human activities that release nitrogen (氮) into the environment, such as fertilizer use and sewage discharges. “Human
3、activities, including fossil fuel combustion and intensive agriculture, have increased the availability of nitrogen in the environment,” said Jake Beaulieu of the University of Notre Dame and the U.S. Environmental Protection Agency in Cincinnati, Ohio, and lead author of the paper published this we
4、ek in the journal Proceedings of the National Academy of Sciences. “Much of this nitrogen is transported into river and stream networks,” Beaulieu said. There, microbes (微生物) convert the nitrogen into nitrous oxide (also called laughing gas) and an inert gas called dinitrogen (二氮). The finding is im
5、portant, the researchers say, because nitrous oxide is a powerful greenhouse gas that contributes to climate change and destruction of the stratospheres ozone layer, which protects us from the suns harmful ultraviolet (紫外线) radiation. Compared with carbon dioxide, nitrous oxide is 300-fold more powe
6、rful in terms of its warming potential, though carbon dioxide is a far more common greenhouse gas. Scientists estimate nitrous oxide accounts for about 6 percent of human-induced climate change. Beaulieu and colleagues measured nitrous oxide production rates in 72 streams. When summed across the glo
7、be, the results showed rivers and streams are the source of at least 10 percent of human-caused nitrous oxide emissions to the atmosphere. “Changes in agricultural and land-use practices that result in less nitrogen being delivered to streams would reduce nitrous oxide emissions from river networks,
8、 Beaulieu said. 1. From the second paragraph we can learn . A. actually rivers give off much more nitrous oxide than expected B. scientists calculation is totally wrong C. human activities release nitrous oxide in to the rivers D. there is no nitrogen in fertilizer 2. Which of the following is NOT
9、the source of nitrogen? A. Fertilizer use. B. Sewage discharges. C. Fossil fuel combustion. 2D. Climate change. 3. Nitrous oxide is a powerful greenhouse gas because_. A. it can protect us from the suns harmful ultraviolet radiation B. it is to blame for most of human-induced climate change C. it is
10、 a far more common greenhouse gas D. it has much more warming potential than carbon dioxide 4. What does the passage mainly tells us? A. Rivers may be a source of the greenhouse gas nitrous oxide. B. Its human activities that release nitrogen into the environment. C. How to reduce nitrous oxide emissions from river networks D. What to do with the climate change caused by nitrous oxide.参考答案1. A 2. D 3. D 4. A
