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
2019-09-18
41
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."
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://jikaoti.com/ti/TzIFFFFM
0
大学英语六级
相关试题推荐
Oncetheydecidedtohavechildren,MiShelandCarlMeissnertackledthenextbigissue:Shouldtheytrytohaveagirl?Itwas
A、Becausetherobesofthemanandthewomanaretoodetailed.B、Becauseitiswhiteandmuchsmallerthantheoriginal.C、Becau
A、Ithaslinkedoptimismwithreducedriskofdeathfromcardiovasculardisease.B、Itoffersusabestwaytopreventdisease.C
A、FriendshipsbetweenAmericansusuallyextenddeeplyintotheirfamilies.B、FriendshipsbetweenAmericansusuallylastforall
TheUnitedStateshasamajorproblemonitshands.Theonlywaytosolveitisthrougheducation.Negroes(黑人)shouldknowabout
Whenwetalkaboutintelligence,wedonotmeantheabilitytogetagoodscoreonacertainkindoftest,oreventheabilityt
GermanChancellor(首相)OttoVonBismarckmaybemostfamousforhismilitaryanddiplomatictalent,buthislegacy(遗产)includesman
Atattoomaygiveparentsofchildrenwithfoodallergiessomepeaceofmindwhentheysendtheirkidsofftoschool.Yes,atat
It’sperhapstheworld’smostfamousunderwaterattraction,immortalizedinfilmandinlegend:theTitanic.Butnowexpertssay
A、Hisformerheadmaster.B、Hisformerclassmate.C、Hisformerclosestfriend.D、Hisformerlunchlady.D①选项都是指人的名词,预测问题与人物相关。②问题
随机试题
简述ICU的组成。
下列叙述错误的是()
药品生产企业应当几日内完成获知的死亡病例的调查报告?()
在各种危险源中,能够造成物的障碍或人的失误的可能的环境因素有()。
会计按其报告对象不同分为()。
下列税金中,不应计入存货成本的是()。
根据我国有关法律规定,在公司制企业中,对本单位会计工作负责的单位负责人应当是( )
甲公司欠乙公司300万元货款。后甲公司将部分优良资产分享出去另成立丙公司,甲、丙公司在分立协议中约定,该笔债务由甲、丙公司按3:7比例分担,但甲、丙公司未与乙公司达成债务清偿协议。债务到期后。乙公司要求甲公司清偿300万元,遭到拒绝。根据公司法律制度的规定
1999年11月,美国国会通过(),允许金融持股公司及其下属子公司对银行、证券、保险兼业经营,美国金融重新进入混业时代。
给定程序MODI1.C中函数fun的功能是:计算正整数num的各位上的数字之积。例如,若输入:252,则输出应该是:20。若输入:202,则输出应该是:0。请改正程序中的错误,使它能得出正确的结果。注意:不要改动main函数,
最新回复
(
0
)