情字白头human-induced climate change.
Beaulieu and colleagues measured nitrous oxide production rates in 72 streams. When summed across the globe, 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,” 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 the source of nitrogen?
A. Fertilizer use.
B. Sewage discharges.
C. Fossil fuel combustion.
D. Climate change.
3. Nitrous oxide is a powerful greenhouse gas because
A. it can protect us from the sun’s harmful ultraviolet radiation
B. it is to blame for most of human-induced climate change
C. it is a far more common greenhouse gas
