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
2016-12-18
39
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(一氧化二氮), 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 Eclgewater, 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, in 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句中的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/tXF7777K
0
大学英语六级
相关试题推荐
在历代学者、学生及校友的共同努力下,香港大学经历了时间与转变的考验,成为一所充满动力的学府。这旱的毕业生除了加入政府服务行业或投身香港的不同机构外,还在海外开创事业。诚然,大学是任何社会中最历久不衰的机构之一,也是社会的灵魂,为大家带来希望。今天
Forthispart,youareallowed30minutestowriteashortessayentitledTheImportanceofDetailsbycommentingontheremark
Overacenturyago,AlfredRussellWallacewrotethat"weliveinazoologicallyimpoverishedworld,fromwhichallthehugest,
I’vetwicebeentocollege-admissionswars,andasIsurveythebattlefield,somethingdifferentishappening.It’sone-upmanshi
Thefirststeptodefeatinganenemyistopindownhisexactidentityandhowheoperates.Hypertension—chronic,abnormallyrai
A、Problemsinportmanagement.B、Improvementofportfacilities.C、Delayedshipmentofgoods.D、Shortageofcontainerships.D对话
OntheImportanceofBeingGrateful1.感恩对于每个人的成长至关重要2.现在心存感恩的人却在逐渐减少,原因是……3.我们应该怎样做
Teenagerswillbetoldto"standupfortheirelders"onpublictransport—orrisklosingtheirrighttofreetravel.LondonMayo
Teenagerswillbetoldto"standupfortheirelders"onpublictransport—orrisklosingtheirrighttofreetravel.LondonMayo
随机试题
关于质量监督工作正确的说法是().
行政诉讼期间,不停止具体行政行为的执行。但有()情形之一的,停止具体行政行为的执行。
患者男,9岁,两颗上颌中切牙受硬物撞击,牙齿酸痛,上、下牙咬合时有不适感,牙齿未见脱位,但釉质表面有裂纹。临床及X线检查,牙根组织未见明显折断,牙周间隙稍增宽。最恰当的诊断是
以下大疱病中具有显著瘙痒的是
要约人确定了承诺期限的要约仍可撤销。()
决定某一房地产价格状况水平高低的供求状况主要是()。
到某一游览点后,若有个别旅游者希望不按规定的线路游览而要求自由游览或摄影时。若环境许可,导游人员可满足其要求。
下列社会工作者面临的伦理困境中,属于“价值介入与客观性的矛盾”类型的有()。
下列关于《诗经》的表述,不正确的是()。
被誉为意大利文艺复兴“三杰”的是()。
最新回复
(
0
)