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 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.

【2016届湖南长沙市高考英语二轮阅读理解训练（35）（含答案）】相关文章：

★ 【课堂新坐标】2017届高考英语（通用版）二轮复习书面表达专题训练：Ⅱ卷强化增分练 训练2（含解析）

★ 湖南省汝城二中2014届高考英语一轮复习阅读训练 (66)

★ 2014高考英语（新人教版）一轮基础训练（4）A、B卷（附答案或解析）

★ 湖南省汝城二中2014届高考英语一轮复习阅读训练 (63)

★ 2017高考四川省广安市英语阅读理解一轮系列训练：4（含解析）

★ 湖南省汝城二中2014届高考英语一轮复习阅读训练 (24)

★ 四川省广安市2014高考英语一轮基础训练题（1）及答案

★ 浙江省湖州市2014高考英语完形填空一轮（暑假）精炼（13）含答案

★ 四川省广安市2014高考英语一轮基础训练题（10）及答案

★ 【课堂新坐标】2017届高考英语（通用版）二轮复习短文改错专题训练：训练2 短文改错（Ⅱ）（含解析）