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碳足迹外,关注您的氮足迹

所属:听力板块 来源:voa 阅读:3765 次 评论:0 条 [我要评论]  [+我要收藏]

小编摘要:碳足迹(也称为碳耗用量)是指人类活动产生的二氧化碳污染量。一些人关注气候变化,因此试图减少碳足迹。如今,研究人员为人们提供了一种衡量个人产生的氮污染量的办法--氮足迹。

Next Step After Carbon: Knowing Your Nitrogen Footprint

 

 A carbon footprint is the amount of carbon dioxide pollution that we produce as a result of our activities. Some people try to reduce their carbon footprint because they are concerned about climate change. Now, researchers have a way for people to measure how much nitrogen pollution they produce -- their nitrogen footprint.

All plants and animals need nitrogen. Nitrogen is a major element in the proteins in our bodies. The atmosphere is mostly nitrogen.

In the early twentieth century, scientists learned how to take nitrogen out of the air and make it into a form that plants could use. University of Virginia professor Jim Galloway calls synthetic nitrogen fertilizer a "wonderful invention" because it increased food production. But he says many parts of the world use too much nitrogen fertilizer, and that harms the environment.

JIM GALLOWAY: "It contributes to smog, acid rain, loss of biodiversity, dead zones along the coast, global warming, stratospheric ozone depletion. The list is quite long."

So Professor Galloway and other researchers have developed a nitrogen footprint calculator. This Web-based tool asks people about the foods they eat and questions like how much they fly and drive and how big a house they live in.

Researchers say the average American produces forty-two kilograms of nitrogen pollution a year. Some of that comes from fossil fuels like oil and coal. But more than seventy percent involves food.

University of Virginia researcher Allison Leach says Americans eat almost twice as much protein as the government recommends. She says eating only the recommended levels could reduce nitrogen footprints by almost half.

Professor Galloway says animal protein plays a big part. He points to the example of cattle that are given feed grown with nitrogen fertilizer.

JIM GALLOWAY: "For large animals like beef, a very large fraction of the nitrogen that enters the cow's mouth is excreted out the back end."

Last year, a study supported by American beef producers found that their industry's environmental impact has decreased over the past thirty years. Jude Capper at Washington State University reported that by producing more beef from fewer animals, the industry cut its carbon footprint by eighteen percent.

The nitrogen calculator is currently designed for people in the United States, Germany and the Netherlands. Another online calculator will be designed for India.

标签:voa special
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2012-04-19 20:59 编辑:pliny
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