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
25
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/2950920.html
相关试题推荐
[originaltext]W:Doyouthinkyoucangiveanexactdefinitionof"management",
[originaltext]M:I’vejustfoundthemostusefuldeviceatthenewoutdoorstor
Ausefuldefinitionofanairpollutantisacompoundaddeddirectlyorindi
Ausefuldefinitionofanairpollutantisacompoundaddeddirectlyorindi
Althoughrecentyearshaveseensubstantialreductionsinnoxiouspollutants
Althoughrecentyearshaveseensubstantialreductionsinnoxiouspollutants
Althoughrecentyearshaveseensubstantialreductionsinnoxiouspollutants
Althoughrecentyearshaveseensubstantialreductionsinnoxiouspollutants
Althoughrecentyearshaveseensubstantialreductionsinnoxiouspollutants
Althoughrecentyearshaveseensubstantialreductionsinnoxiouspollutants
随机试题
[audioFiles]2017m5s/audio_ezfj_044_201705[/audioFiles]StrangeFestivals
Thefirstaid(急救)youlearnfromacourseisnotquitelikereality.Mosto
Iamhonoredtobeheretoday,【L1】______HarvardatthiscelebrationoftheC
A.相同,相反 B.相反,相同 C.相同,相同 D.相反,相反
某慢性低氧血症患者出现代谢性酸中毒和高钾血症,但血压正常。分析该患者血钾增高的原
头孢哌酮A.氨基糖苷类B.β-内酰胺类C.四环素类D.大环内酯类E.多烯多肽类
A.淡绿色 B.白色 C.淡蓝色 D.淡黄色 E.淡红色第二类精神药品处
近年来随着房地产市场的不断发展,房地产已成为最主要、最广泛、最重要,也是人们最看
某桥主梁高度170cm,桥面铺装层共厚20cm,支座高度(含垫石)15cm,采用
A.散脉 B.芤脉 C.濡脉 D.弱脉 E.代脉脉来浮大中空的是
最新回复
(
0
)