首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Fertilizer use has exploded, overloading plants worldwide, likely altering ecosystems for decades to centuries, scientists repor
Fertilizer use has exploded, overloading plants worldwide, likely altering ecosystems for decades to centuries, scientists repor
admin
2017-12-07
43
问题
Fertilizer use has exploded, overloading plants worldwide, likely altering ecosystems for decades to centuries, scientists report Thursday. In the journal Science, a review led by Donald Canfield of the University of Southern Denmark found that fertilizer use worldwide increased 800% from 1960 to 2000. "Given the rising costs of synthetic fertilizer production, this overuse is not only economically expensive, but also initiates a series of large-scale environmental impacts," says the review.
Fundamentally, nitrogen from fertilizers has led to an explosion in "dead zones" in seas and oceans, upsetting a cycle of nutrients balanced with growth that has lasted for billions of years, the authors find. As well, the excess nitrogen is forming large amounts of nitrous oxide (一氧化二氨), a powerful greenhouse gas in wetlands, adding to climate change. Agriculture today produces about a quarter of the nitrous oxide in the atmosphere.
"The effects of humans have been profound. In the last few decades we have doubled the worldwide biological availability of nitrogen, an element that often limits growth of plants and algae," says Thomas Jordan of the Smithsonian Environmental Research Center in Edgewater, Md., who was not part of the review. The review, "is a very careful analysis of the nitrogen cycle by three of the world authorities in this area," says biochemist Robert Blankenship of Washington University in St Louis, who also was not part of the review. "The concerns they raise for how the nitrogen cycle is now significantly out of balance are important and need to be addressed by changing agricultural practices. The world’s food supply depends directly on nitrogen application in the form of fertilizer, but current practices are such that much of the applied nitrogen ends up in rivers and eventually in the ocean where it causes serious problems."
"Natural feedbacks driven by microorganisms will likely produce a new steady state over time scales of many decades," say the review authors. "However, because of the projected increase in human population through at least 2050, there will be demand for an increase in fixed nitrogen for crops to feed this population." And that will mean a lot more dead zones, they warn, like the one that blooms yearly, m 2010 about the size of New Jersey, in the Gulf of Mexico.
"Several new approaches and a much wider use of more sustainable time-honored practices, however, can decrease nitrogen use substantially," they conclude. The rising cost and environmental toll of fertilizers will increase demand for less use on farms, they add. "However, even with management, the future cycle will likely be different from the one that preceded the Industrial Revolution."
It is concluded in the review that______.
选项
A、the use of nitrogen will become sustainable
B、the use of nitrogen will disappear from farms
C、the demand for nitrogen will decrease
D、the demand for nitrogen will increase
答案
C
解析
最后一段第1句中的decrease…substantially和第2句中 increase demand for less use都表明研究人员认为将来对氮的需求将会下降。因此,本题应选C。
转载请注明原文地址:https://kaotiyun.com/show/9aU7777K
0
大学英语六级
相关试题推荐
出国留学,一般指一个人到另一个国家继续接受教育的行为。出国留学能够丰富知识、开阔视野,同时也可以培养人的独立性。如今,中国已成为世界上最大的留学生生源国(sourcecountry),从1978年至2012年,中国的留学生大约有265万人,而且未来每年将
Forthispart,youareallowed30minutestowriteashortessayentitledTheImpactofOnlineSocialNetworks.Youressayshoul
Thelevelofdiscriminationhasvariedenormouslyinthehistoryofhumansocieties,fromgenocidewhereethnicsarekilledoff
Nottoomanydecadesagoitseemed"obvious"bothtothegeneralpublicandtosociologiststhatmodemsocietyhaschangedpeopl
FeedingtheMassesaLoadofManureTheGreenRevolutionMyth,NormanBorlaug,andWorldHunger[A]Mostpeopledon’tkno
Individualsandbusinesseshavelegalprotectionforintellectualpropertytheycreateandown.Intellectualproperty【C1】______f
Teenagersarespendingmoremoneythanever.Justlastyear,31.6millionteensspent155billion,accordingtotheNorthbrook,
Peoplecannowavoidhavingtosortthroughalbumsfromseveraldifferentfriendswhentryingtoreliveparties,weddingsandot
Inthissection,youaregoingtoreadapassagewithtenstatementsattachedtoit.Eachstatementcontainsinformationgiveni
随机试题
中国人群疾病谱的特点是
在注射剂生产中,一般注射剂的过滤与除菌过滤常用滤膜的孔径分别为
引起水痘一带状疱疹的病原体是与鼻咽癌的发生有关的是
甲乙丙丁作为股东,设立了蓝天有限责任公司。章程中约定:甲以货币30万元出资,乙以实物10万元作价出资,丙以专利权10万元作价出资,丁以实物10万元作价出资。公司成立一年后戊加入。下列有关该各股东出资责任的说法正确的是:()
根据《城市道路绿化规划与设计规范》的规定,交通岛周边的植物配置宜增强导向作用,应该()
下列各项因素中,影响企业持有的以摊余成本计量的金融资产的摊余成本的有()。
信度系数(r)()。
新生儿能以面部表情和身体活动等方式对下列几种基本味道作出反应()。
1898年维新变法失败后,在形式上唯一未被顽固派废除的新设学堂是()。
Notationgavewesternmusicameansofwrittenrecord,butatfirstonlyforakindofmusic,chant,thatwasbelievedtohaveo
最新回复
(
0
)