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
2014-12-18
26
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 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, 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."
What happens to the "dead zones" year by year?
选项
A、The sizes of such zones keep expanding.
B、The human population in such zones keeps increasing.
C、There is an increasing demand for crops in such zones.
D、Microorganisms grow well in such zones.
答案
A
解析
该句中的blooms表明在墨西哥湾的“死区”每年的面积都在扩大。而该句开头部分又表明,以后会有更多与墨西哥湾“死区”相似的dead zones的出现,这暗示dead zones的面积每年都会扩大。因此,本题应选A。
转载请注明原文地址:https://kaotiyun.com/show/wum7777K
0
大学英语六级
相关试题推荐
Ourape-menforefathershadnoobviousnaturalweaponsinthestruggleforsurvivalintheopen.Theyhadneitherthepowerfult
How"SecondBrain"InfluencesMoodandWeil-BeingAsOlympiansgoforthegoldinVancouver,eventhesteeliestarelikelyt
How"SecondBrain"InfluencesMoodandWeil-BeingAsOlympiansgoforthegoldinVancouver,eventhesteeliestarelikelyt
A、Researchingwaystoincreasegrainoutput.B、Studyingtheliferulesofplantsandinsects.C、Reducingoreveneliminatingthe
A、Todescribewayspestscandamageplants.B、Toexaminethelifecycleofcornplants.C、Toexplainhowcornplantsdevelop.D、
AsSesameStreet(芝麻街)kicksoffits40thanniversaryseasonTuesday,withfirstladyMichelleObamaandBroadwaystarLin-Manuel
A、Attherestaurant.B、Atthebusstation.C、Atthetravelagency.D、Atthelaundry.C场景推断题。男士说自己对对方导游的服务质量的投诉石沉大海;女士解释说员工可能是因为太
随机试题
工程项目施工成本管理的基础工作包括()。
Forthispart,youarerequiredtowriteacompositiononthetopicTheDamageofE-wastebasedontheoutlinegivenbelow.Plea
以下不是肉瘤组织学特点的是
开始进行产前系列检查时间为
按照功能的标准化可以将其分为()。
根据著作权法及相关规定,关于录音录像制作者的权利义务,下列哪些说法是正确的?
班集体的每个学生都来自不同的社区和家庭,拥有各自不同的社会知识与经验背景。这从一定程度上有助于促进学生()的形成。
依法律规定,下列不得作为保证人的有()。
“许多事情我们可以讲一千个理由、一万个理由,但老百姓吃不上饭,就没有理由。‘民以食为天’”。这段话表明( )
名胜古迹
最新回复
(
0
)