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
23
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] It can be inferred from the first paragraph that______.
选项
A、water vapour is an air pollutant in localized areas
B、the definition of an air pollutant will continue to change
C、a substance becomes an air pollutant only in cities
D、most air pollutants today can be seen or smelled
答案
B
解析
细节题。根据文章第一段Air poilution requires a very flexible definition thatpermits continuous change.“空气污染物的定义要求具有灵活性以适应不断的变化”和B选项“空气污染物的定义会继续发生变化”的表达一致。所以答案选B。
转载请注明原文地址:https://tihaiku.com/zcyy/2949358.html
相关试题推荐
Ausefuldefinitionofanairpollutantisacompoundaddeddirectlyorindi
Ausefuldefinitionofanairpollutantisacompoundaddeddirectlyorindi
Ausefuldefinitionofanairpollutantisacompoundaddeddirectlyorindi
Althoughrecentyearshaveseensubstantialreductionsinnoxiouspollutants
Althoughrecentyearshaveseensubstantialreductionsinnoxiouspollutants
Althoughrecentyearshaveseensubstantialreductionsinnoxiouspollutants
Althoughrecentyearshaveseensubstantialreductionsinnoxiouspollutants
Althoughrecentyearshaveseensubstantialreductionsinnoxiouspollutants
Althoughrecentyearshaveseensubstantialreductionsinnoxiouspollutants
Ausefuldefinitionofanairpollutantisacompoundaddeddirectlyorindi
随机试题
有一垂直放置的渐缩管,内径由d1=300mm渐缩至d2=150mm,水从下而上自
劳力型心绞痛的典型心电图改变是A.ST-T呈鱼钩样降低,T波倒置 B.ST段抬
春秋战国时期,社会经济发展比现在落后,但当时诸子峰起、百家争鸣,是中华文化史上的
2009~2012年间全国商品进出口总额最高年份,矿产品进出口总额比
站用交流电源系统精益化评价细则交接试验报告,没有资料的,扣();0.05分$;$
每年评价变电站数量为管辖范围内变电站总数的()。二分之一$;$三分之一$;$四分
坐在湖边,思如走马,不觉时光之过,一瞥眼间,忽见身畔石壁上隐隐似有彩色流动,凝神
具有明显舒张肾血管、增加肾血流量的作用的药物是A.肾上腺素 B.异丙肾上腺素
2020年度中国公民张某取得如下收入: (1)每月工资7000元,已
根据税务行政法制的规定,下列税务行政处罚,需要采取听证程序的是()。A.对
最新回复
(
0
)