首页
登录
职称英语
A useful definition of an air pollutant is a compound added directly or indi
A useful definition of an air pollutant is a compound added directly or indi
游客
2023-08-23
32
管理
问题
A useful definition of an air pollutant is a compound added directly or indirectly by humans to the atmosphere in such quantities as to affect humans, animals, vegetation, or material adversely. Air pollution requires a very flexible definition that permits continuous change. When the first air pollution laws were established in England in the fourteenth century, air pollutants were limited to compounds that could be seen or smelled—a far cry from the extensive list of harmful substances known today. As technology has developed and knowledge of the health aspects of various chemicals has increased, the list of air pollutants has lengthened. In the future, even water vapour might be considered an air pollutant under certain conditions.
Many of the more important air pollutants, such as sulphur oxides, carbon monoxide, and nitrogen oxides, are found in nature. As the earth developed, the concentrations of these pollutants were altered by various chemical reactions; they became components in biogeochemical cycles. These reactions serve as an air purification scheme by allowing the compounds to move from the air to the water or soil. On a global basis, nature’ s output of these compounds dwarfs that resulting from human activities. However, human production usually occurs in a localized area, such as a city.
In this localized region, human output may be dominant and may temporarily overload the natural purification scheme of the cycles. The result is an increased concentration of noxious chemicals in the air. The concentrations at which the adverse effects appear will be greater than the concentrations that the pollutants would have in the absence of human activities. The actual concentration need not be large for a substance to be a pollutant; in fact the numerical value tells us little until we know how much of an increase this represents over the concentration that would occur naturally in the area. For example, sulphur dioxide has detectable health effects at 0.08 parts per million(ppm), which is about 400 times its natural level. Carbon monoxide, however, has a natural level of 0.1 ppm and is not usually a pollutant until its level reaches about 15 ppm. [br] According to the passage, what can we know about human-generated air pollution in cities?
选项
A、It is the most serious pollution in the environment.
B、It may overburden the natural system that purifies pollutants.
C、It will react harmfully with naturally occurring pollutants.
D、It will damage areas outside the localized regions.
答案
B
解析
细节题。根据human-generated air pollution将答案定位到第三段In thislocalized region,human output may be dominant and may temporarily overload thenatural purification scheme of the cycles.“在这些局部区域.污染物可能主要来自人类活动。而且可能会暂时超出自然循环的净化能力。”可知选项B是对原文的同义转述,其中overburden和原文的overload互为近义词。所以答案选B。
转载请注明原文地址:https://tihaiku.com/zcyy/2949360.html
相关试题推荐
Ausefuldefinitionofanairpollutantisacompoundaddeddirectlyorindi
Ausefuldefinitionofanairpollutantisacompoundaddeddirectlyorindi
Althoughrecentyearshaveseensubstantialreductionsinnoxiouspollutants
Althoughrecentyearshaveseensubstantialreductionsinnoxiouspollutants
Althoughrecentyearshaveseensubstantialreductionsinnoxiouspollutants
Althoughrecentyearshaveseensubstantialreductionsinnoxiouspollutants
Althoughrecentyearshaveseensubstantialreductionsinnoxiouspollutants
Ausefuldefinitionofanairpollutantisacompoundaddeddirectlyorindi
Ausefuldefinitionofanairpollutantisacompoundaddeddirectlyorindi
Ausefuldefinitionofanairpollutantisacompoundaddeddirectlyorindi
随机试题
(1)Firstthegoodnews-.9in10peoplesaidtheyweresatisfiedwiththeir
Healthfoodisageneraltermappliedtoallkindsoffoodsthatareconside
LearntoGiveUpWisely1.遇到困难,很多人会坚持,而有些人则会明智地放弃2.为什么很多时候应该明智地放弃3.我的观点
下列关于水泥稳定土和级配砂砾基层施工的说法中,表述正确的是()。A.应用摊铺机
系统方法论是项目评估方法论的理论基石。系统方法论的基本原则不包括()。A.
以下在银行间债券市场发行的非金融企业债务融资工具中,有待偿还余额不得超过企业净资
集体合同与劳动合同的区别在于()A:主体不同 B:内容不同 C:功能不同
与纸质发票相比,增值税电子专用发票的优点有()A.发票样式更简洁 B.领用方
高压接户线受电端的对地面距离不应小于()。 A.5m;B.4m;C.
关于施工段落的划分,错误的是()A.各段落之间工程量基本平衡 B.尽可能
最新回复
(
0
)