情字白头“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 important, the researchers say, because nitrous oxide is a powerful greenhouse gas that contributes to climate change and destruction of the stratosphere’s ozone layer, which protects us from the sun’s harmful ultraviolet (紫外线) radiation. Compared with carbon dioxide, nitrous oxide is 300-fold more powerful 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
