Natural pollutants for example include, those caused by erosion and volcanic eruptions, and are heavily outweighed by human pollutants. Figure 1.1, shows the cities that emit the most amount of pollutants into the air, Mexico City, Beijing and Delhi, are the biggest contributors, Asian cities also emit more than other continents.
Human activities are the main cause of pollution and acid rain. Over the past few decades, humans have released so many different chemicals into the air that they have changed the mix of gases in the atmosphere. Power plants release the majority of sulphur dioxide and much of the nitrogen oxides when they burn , such as coal, to produce electricity. In addition, the from cars, trucks, and buses releases nitrogen oxides and sulphur dioxide into the air. These pollutants cause acid rain and increase air pollution greatly.
The following pollutants are the cause and greatest contributors towards air pollution and acid rain:
Carbon monoxide: Carbon monoxide is a colourless, odourless gas that is produced by the burning of carbon based fuels such as petrol, diesel, and wood. Carbon monoxide along with carbon dioxide are the biggest contributing pollutants to the atmosphere.
Carbon dioxide: Carbon dioxide is the greenhouse gas emitted as a result of human activities such as the burning of coal, oil, and natural gases.
Lead: Lead is present in petrol, diesel, lead batteries, paints, hair dye products, etc. Lead affects children in particular. It can cause nervous system damage and digestive problems and, in some cases, cause cancer.
Nitrogen oxide: Nitrogen oxide causes smog and acid rain. It is produced from burning fuels including petrol, diesel, and coal.
Sulphur dioxide: Sulphur dioxide is a gas produced from burning coal, mainly in thermal power plants. Some industrial processes, such as production of paper and smelting of metals, produce sulphur dioxide. It is a major contributor to smog and acid rain.
Acid rain is caused by a chemical reaction that begins when like sulphur dioxide and nitrogen oxides are released into the air. These substances can rise very high into the atmosphere, this is usually pushed along by large smokestacks like that in figure 1, which pushes the pollutants higher into the air where they can mix and react with water, oxygen, and other chemicals to form more , known as acid rain. Sulphur dioxide and nitrogen oxides dissolve very easily in water and can be carried very far by the wind. As a result, the two pollutants can travel long distances where they become part of the rain, sleet, snow, and fog and form acid rain, this process is described below.
Consequences of pollution and acid rain
Pollution and acid rain causes many problems to the plant and animal life, furthermore it can cause significant problems to human beings, such as respiratory diseases and cancer. The toxins released into the air by polluted rain cause a huge problem in the form of acid rain. The chemicals in acid rain react with any object they come in contact with. Acids are corrosive chemicals that react with other chemicals by giving up hydrogen atoms. Acid rain has been linked to widespread environmental damage, including soil and plant degradation, depleted life in lakes and streams, and erosion of man made structures.
In soil, acid rain dissolves and washes away nutrients needed by plants. It can also dissolve toxic substances, such as aluminium and mercury, which are naturally present in some soils, freeing these toxins to pollute water or to poison plants that absorb them
By removing useful nutrients from the soil, acid rain slows the growth of plants, especially trees. It also attacks trees more directly by eating holes in the waxy coating of leaves, causing brown dead spots. If many such spots form, a tree loses some of its ability to make food through .
Acid rain falls and drains into streams, lakes, and marshes. Where there is snow cover in winter, local waters grow suddenly more acidic when the snow melts in the spring. The chemicals of acid rain, once entered into a water body can harm the organisms in it as shown in figure 1.6.
The effect of acid rain on wildlife can be quite hazardous. If a population of one plant or animal is adversely affected by acid rain, animals that feed on that organism may also suffer. Ultimately, an entire may become endangered.
Acid rain and the dry deposition of acidic particles can disfigure buildings, statues, automobiles, and other structures made of stone, metal, or any other material exposed to weathering for long periods, as shown in figure 1.7.
Treatment of pollution and acid rain
Air pollution and acid rain can best be curtailed by reducing the amount of sulphur dioxide, nitrogen oxides and carbon dioxide released by power plants, motorized vehicles, and factories. The simplest way to cut these emissions is to use less energy from fossil fuels. Everybody can also help restrain air pollution and acid rain, by buying energy efficient appliances, take public transport and using energy wisely. Electric companies can help cut pollution by switching to cleaner energy. Cleaner energy includes, wind power, solar power and hydraulic power, this contrasts with coal, oil and gas which can be very dangerous to the environment. Petrol used by the ever increasing number of vehicles can also be changed to be more environmentally friendly; this includes the introduction of hybrid cars which release almost no toxins into the air.
Liming is a way of reducing acidic levels in areas that have been effected by acid rain, this is done by powdered limestone being added to the effected area, thus almost immediately reducing acidic levels. This reduces acidic levels but unfortunately temporarily.
These are a few things that can be done by you to minimise air pollution:
About half of the air pollution comes from the exhausts of vehicles. Two important ways to reduce air pollution are to drive less and to drive wise. Ways of smarter driving include:
- Public transport.
- Walk or ride a bicycle.
- Carpool.
Many household products release toxins into the air, ways of minimizing this include:
- Use products with a water base, or contain a high level of water.
- Large scale painting should be done with a brush not a sprayer.
- Use an electric mower.
Wise energy usage helps to reduce air pollution
- Turn off the lights when you leave a room.
- Replace energy hungry incandescent lights with fluorescent lighting.
- Add insulation to your home.
- Dry your clothes on a clothesline.