环境污染〖中英文对照〗

什么是污染
随着工业革命的到来，它所引起的环境污染也正惊人地增长。我们把污染定义为空气、水、陆地的物理、化学或生物特性的一种不利变化，这种变化可危害人或其它活的有机体的健康、生存或活动。主要有四种污染--陆地上的废弃物、水污染（既可是海洋的也可以是内陆湖泊的水）、大气污染和噪音污染。
什么是陆地污染
有许多物质都能对陆地产生污染。主要的污染物分为两类：可降解的和不可降解的。可降解的污染物如DDT和放射性物质。DDT的分解虽缓慢，但最终可被完全破坏，或被减少到无害的水平。例如：土壤中的DDT要分解到原来施用水平的25%，通常需要花四年的时间。一些能放射出有害射线的放射性物质，如碘-131可衰变为无害的污染物。其它可降解的污染物，如核电厂产生的钚-239可维持在其有害水平上达数千万年。
不可降解的污染物不能被自然过程所分解，例如：汞、铅及其化合物以及一些塑料均是不可降解的污染物。必须从根本上防止这些物质进入空气、水和土壤，或者必须把它们彻底清除出环境，使它们的含量低于有害的水平。　
什么是水体污染
水体污染有多种形式。它是水体被下列污染物所污染：城市污水和工业废水；从农场和饲养场流失的化肥和粪肥；充满泡沫的溪流；由于暴雨、耕作、建筑和采矿而被冲刷的土壤沉积物；来自核电站的放射性排泄物；电厂和工厂的热水；漂流在全球海洋中的塑料小球；从服用避孕药的妇女的尿液进入供水系统的女性荷尔蒙。
虽然科学家们已开发了高灵敏度的测量仪器，但测定水质仍然是十分困难的。水中有大量的能相互作用的化学物质，其中大多数化学物质仅以微量存在。目前已商品化的大约有三万种化学物质，并且每年大约还要新增一千种化学物质。这些化学物质中的大多数迟早要进入河流、湖泊和海洋。另外，不同的生物对各种污染物的耐受范围及阈值都不尽相同。更有甚者，虽然一些污染物可在水中被稀释到无害的水平或被一些生物或自然过程分解成无害的形式，但一些其它的污染物（如DDT、一些放射性物质和汞的化合物）会被生物富积在各种生物体中。
什么是空气污染
空气污染通常被定义为：空气中含有一种或多种化学物质，并且其浓度高到足以伤害到人类，动、植物或其它一些物质。空气中的污染物可以分为两大类，一类主要的污染物是直接混入空气中并且其浓度达到有害程度的化学物质。它既可以是空气的一种组成物，如：超过正常含量的二氧化碳；也可以是空气中不常见的物质，如铅的化合物。另一类污染物则

是通过大气组分间所发生的化学反应而形成的有害化学物质。
我们常常将空气污染与烟囱和汽车联系在一起，但事实上火山、森林火灾、沙暴、沼泽、海洋和植物都会带来一些我们认为是大气污染物的化学物质。这些“自然污染物”通常都广泛分散在地球的各个角落，因而很难累积到有害的程度。但是，一旦它们累积了起来，例如火山爆发，这些污染物一般就只能通过自然气候和化学循环来进行消除。
什么是噪音污染
当更多的人生活得越来越接近，并且人们更多地使用机械来制造休闲时，人们发现他们的休闲、甚至他们的工作时间已经被机械的副产物—噪音所损害。
控制噪音的技术难点常常来自于该问题的主、客观两方面。你可以根据一个速度表上指针的读数来定义一辆机动车的超速，但是你可以用这种方法来定义噪音超标吗? 你会发现使用任何已有的“噪音表”，一些已被判断为发出同样大小噪音的车辆在表上可显示出相当大的偏差。
虽然解决噪声的理想方法是在将其消灭在其起源处，但这在很多情况下是不可能的。另一个措施就是在噪音传到耳朵前就将其吸收。大多数的噪音问题可通过有效地降低接收噪音处的声压水平来得到最好的解决。餐厅里的轻音乐可以掩盖陶器的碰撞声和邻桌的交谈声。电话亭里风扇的噪音可用来掩盖来自隔壁电话亭的话音干扰。通常噪声问题的解决办法就是在其声源处或是在其传播途中降低其声压水平。
ENVIRONMENTAL POLLUTION
　
With the coming of the Industrial Revolution the environmental pollution increased alarmingly. Pollution can be defined as an undesirable change in the physical, chemical, or biological characteristics of the air, water, or land that can harmfully affect health, survival, or activities of humans or other living organisms. There are four major forms of pollution - waste on land, water pollution (both the sea and inland waters), pollution of the atmosphere and pollution by noise.
Land can be polluted by many materials. There are two major types of pollutants: degradable and nondegradable. Examples of degradable pollutants are DDT and radioactive materials. DDT can decompose slowly but eventually are either broken down completely or reduced to harmless levels. For example, it typically takes about 4 years for DDT in soil to be decomposed to 25 percent of the original level applied. Some radioactive materials that give off harmful radiation, such as iodine-131, decay to harmless pollutants. Others, such as plutonium-239 produced by nuclear power plants, remains at harmful levels for thousands to hundreds of thousands of years.
Nondegradable pollutants are not broken down by natural processes. Examples of nondegradable pollutants are me

rcury, lead and some of their compounds and some plastics. Nondegradable pollutants must be either prevented from entering the air, water, and soil or kept below harmful levels by removal from the environment.
Water pollution is found in many forms. It is contamination of water with city sewage and factory wastes; the runoff of fertiliser and manure from farms and feed lots; sudsy streams; sediment washed from the land as a result of storms, farming, construction and mining; radioactive discharge from nuclear power plants; heated water from power and industrial plants; plastic globules floating in the world’s oceans; and female sex hormones entering water supplies through the urine of women taking birth control pills.
Even though scientists have developed highly sensitive measuring instruments, determining water quality is very difficult. There are a large number of interacting chemicals in water, many of them only in trace amounts. About 30,000 chemicals are now in commercial production, and each year about 1,000 new chemicals are added. Sooner or later most chemicals end up in rivers, lakes, and oceans. In addition, different organisms have different ranges of tolerance and threshold levels for various pollutants. To complicate matters even further, while some pollutants are either diluted to harmless levels in water or broken down to harmless forms by decomposers and natural processes, others (such as DDT, some radioactive materials, and some mercury compounds) are biologically concentrated in various organisms1.
Air pollution is normally defined as air that contains one or more chemicals in high enough concentrations to harm humans, other animals, vegetation, or materials. There are two major types of air pollutants. A primary air pollutant is a chemical added directly to the air that occurs in a harmful concentration. It can be a natural air component, such as carbon dioxide, that rises above its normal concentration, or something not usually found in the air, such as a lead compound. A secondary air pollutant is a harmful chemical formed in the atmosphere through a chemical reaction among air components.
We normally associate air pollution with smokestacks and cars, but volcanoes, forest fires, dust storms, marshes, oceans, and plants also add to the air chemicals we consider pollutants. Since these natural inputs are usually widely dispersed throughout the world, they normally don’t build up to harmful levels. And when they do, as in the case of volcanic eruptions, they are usually taken care of by natural weather and chemical cycles2.
As more people live closer together, and as they use machines to produce leisure, they find that their leisure, and even their working hours, become spoilt by a byproduct of their machines – namely, noise,
The technical difficulties to control noise often arise from the subjective-objective nature of the problem. You can define the excessive speed o

f a motor-car in terms of a pointer reading on a speedometer. But can you define excessive noise in the same way? You find that with any existing simple “noise-meter”, vehicles which are judged to be equally noisy may show considerable difference on the meter.
Though the ideal cure for noise is to stop it at its source, this may in many cases be impossible. The next remedy is to absorb it on its way to the ear. It is true that the overwhelming majority of noise problems are best resolved by effecting a reduction in the sound pressure level at the receiver. Soft taped music in restaurants tends to mask the clatter of crockery and the conversation at the next table. Fan noise has been used in telephone booths to mask speech interference from adjacent booths. Usually, the problem is how to reduce the sound pressure level, either at source or on the transmission path.