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
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."
According to Robert Blankenship, the nitrogen cycle is out of balance because ______.
选项
A、nitrogen is applied in the form of fertilizer
B、much nitrogen ends up in seas and oceans
C、food supply depends directly on nitrogen
D、much nitrogen is applied in agriculture
答案
B
解析
第3段倒数第2句末尾的并列句and need to be addressed by changing agricultural practices表明氮循环的不平衡是因为agricultural practices不当所致,最后一句中的but current practices are such that…可知问题在于“大多数的氮渗入了河流中,最后流入大海”,这就是导致氮循环失衡的原因。因此,本题应选B。
转载请注明原文地址:https://kaotiyun.com/show/1aU7777K
0
大学英语六级
相关试题推荐
AstudyconductedbyanAustralianscienceagencyhasdiscoveredsignsthatthecountry’sancientAboriginesmayhavebeenthew
AmericansEugeneFama,LarsPeterHansenandRobertShillerwontheNobelPrizeforeconomicsonMondayfordevelopingmethodst
Internationalairlineshaverediscoveredthebusinesstravelers,themanorwomanwhoregularlyjetsfromcountrytocountryas
Internationalairlineshaverediscoveredthebusinesstravelers,themanorwomanwhoregularlyjetsfromcountrytocountryas
ConradHiltonreallywantedtobeabanker.Instead,hesuccessfullychangedthe【C1】______purchaseofaTexaslow-endhotelinto
Whenyouthinkaboutthegrowthofhumanpopulationoverthelastcenturyorso,itisalltooeasytoimagineitmerelyasani
Ablindbabyisdoublyhandicapped.Notonlyisitunabletosee,butbecauseitcannotreceivethevisualstimulusfromitsenv
Angerisaverycommonhuman【C1】______andatsometimeoranotherweallexperienceit.Fromyoungchildrentooldpeopleweall
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
A、Becausetheywantedtobeclosertothegovernment.B、BecauseTokyowasthehistoricalcommercialcapital.C、Becausethepopul
随机试题
虱绿蝇
产后腹痛之气血两虚证主要证候不包括
血淋与尿血的主要鉴别在于()
A.经常自汗不止B.睡时汗出,醒则汗止C.蒸蒸汗出D.头部热汗而黏E.半身汗出中焦湿热上蒸而汗出的特点是
A.成本效益分析B.成本效用分析C.用药频度分析D.药物利用指数分析E.流行病学分析分析用药剂量合理性的方法是()。
下列生活现象中,解释不正确的一项是:
过渡时期总路线的内容可以概括为“一化三改””一体两翼”,一化是工业化,这是主体;“三改”是指逐步实现国家对农业、手工业、资本主义工商业的社会主义改造,这是“两翼”。对于农业的改造我们党所遵循的阶级路线是()。
“他山之石,可以攻玉”这一名言是出自()。
用WAIT命令给内存变量输入数据时,内存变量获得的数据是()。
Accordingtothepassagemodemadvertisingis"authoritative"becauseofthewayit______.Theformofadvertisingwhichhass
最新回复
(
0
)