您現(xiàn)在的位置: Language Tips> Audio & Video> Normal Speed News  
   
 





 
Fireworks industry studying more eco-friendly pyrotechnics
[ 2008-07-04 11:04 ]

 

Download

As July 4th approaches, Americans look to the skies. Throughout the country, fireworks will be launched in celebration of the nation's independence. But what goes up must come down. Reporter Eric Libby looks at the environmental issues surrounding fireworks, and efforts to develop "greener" pyrotechnics.

Take a group of reactive chemicals, shoot them high into the air, and watch them explode in a very loud, very smoky, and very hot spectacle. This sounds like the exact opposite of an environmentally friendly, or green, activity. So researchers are actively assessing the impact of fireworks and working to make them safer for the environment.

Among the chemicals used in fireworks, perchlorates have drawn attention. These compounds provide the oxygen that fuels the explosion. Hydrogeologist David Jewett of the Environmental Protection Agency points to an EPA study measuring perchlorates in an Oklahoma lake after fireworks displays from 2004 to 2006. "They saw a peak in perchlorate concentrations within 12 or 14 hours after the fireworks display," says Jewett. "But then those concentrations decreased back to background levels over a time period of 20 to 80 days."

Studies have linked perchlorates to impaired thyroid function. While Julie Heckman, executive director of the American Pyrotechnics Association, acknowledges the potential health risks of perchlorates, she says their use in fireworks does not pose a danger to the public. "The position of the fireworks industry," Heckman explains, "is [that] the amount of pyrotechnic composition containing perchlorate is pretty nominal in terms of what other industries use or discharge. Look at the military, [which is the] biggest contributor," she adds.

She notes that U.S. government regulations prohibit fireworks from containing even more-toxic substances such as lead and arsenic. Another concern is the use of so-called heavy metals to give fireworks their colors. In particular, barium - which is responsible for the color green - is extremely poisonous in some forms. Mike Hiskey describes how his pyrotechnics company, DMD Systems, is addressing these concerns. "We base all our mixes on nitrocellulose, which burns very cleanly, with basically no smoke, (in)to carbon dioxide, water, and nitrogen. We can reduce the amount of heavy metals in there by quite a bit, like almost an order of magnitude," Hiskey adds. "In addition to that, all of our outdoor pyro contains no perchlorate."

Hiskey says there is growing interest in green fireworks, especially from indoor concert promoters and the Disney Company, one of the world's largest users of fireworks. Scientists at Germany's Ludwig Maximilian University of Munich are searching for ways to completely replace barium in fireworks. Graduate student Karina Tarantik says it's difficult to produce the color green with safer ingredients like copper compounds.

"If chlorine combines with copper you get blue color and no green. Or if the temperature is too high of the combustion you get more red or yellow flame color. So, [it is] quite difficult," she cautions.

Tarantik says the hardest color to make "green" is, in fact, green. Thankfully, the most important colors on the 4th of July are red, white, and blue.

(Source: VOA 英語點津姍姍編輯)

 
英語點津版權說明:凡注明來源為“英語點津:XXX(署名)”的原創(chuàng)作品,除與中國日報網(wǎng)簽署英語點津內(nèi)容授權協(xié)議的網(wǎng)站外,其他任何網(wǎng)站或單位未經(jīng)允許不得非法盜鏈、轉載和使用,違者必究。如需使用,請與010-84883631聯(lián)系;凡本網(wǎng)注明“來源:XXX(非英語點津)”的作品,均轉載自其它媒體,目的在于傳播更多信息,其他媒體如需轉載,請與稿件來源方聯(lián)系,如產(chǎn)生任何問題與本網(wǎng)無關;本網(wǎng)所發(fā)布的歌曲、電影片段,版權歸原作者所有,僅供學習與研究,如果侵權,請?zhí)峁┌鏅嘧C明,以便盡快刪除。
相關文章 Related Story
 
 
 
本頻道最新推薦
 
Walking in the US first lady's shoes
“準確無誤”如何表達
英國新晉超女蘇珊大媽改頭換面
豬流感 swine flu
你有l(wèi)ottery mentality嗎
翻吧推薦
 
論壇熱貼
 
別亂扔垃圾。怎么譯這個亂字呀?
橘子,橙子用英文怎么區(qū)分?
看Gossip Girl學英語
端午節(jié)怎么翻譯?
母親,您在天堂還好嗎?

 

精品无码久久久久久尤物,99视频这有这里有精品,国产UU精品无码视频,女同精品一区二区网站