ENVIRONMENTAL POLLUTION
Pollution is the introduction of contaminants into the environment that cause harm or discomfort to humans or other living organisms, or that damage the environment. India has been ranked as the seventh most environmentally hazardous country in the world. Brazil is the worst, United States is second worst and China is third. Singapore has been found to be the best.
There are three major types of environmental pollution:
Air Pollution
Water Pollution
Soil Pollution
Air Pollution
Some of the most important air pollutants are Sulphur dioxide, nitrogen dioxide, carbon monoxide, ozone, volatile organic compounds (VOCs) and airborne particles. Radioactive pollutants are the most destructive ones specially when produced by nuclear explosions. Carbon dioxide and water vapour present in the atmosphere, strongly absorb a large fraction of the earth’s emitted radiation. This absorbed radiation is partly re-emitted to the earth’s surface. The net result is that the earth’ surface gets heated up by a phenomenon called the Greenhouse Effect.
Deforestation and combustion of fossil fuels (oil, gas, coal) have a cumulative effect on the net increase in carbon dioxide content. Forests are the areas where a great deal of photosynthesis occurs, which helps in maintaining a balance in the atmospheric carbon dioxide level.
Trees and animals contribute large quantities of hydrocarbons (mainly methane) to the atmosphere. Harmful effects of hydrocarbon pollution are due to the photochemical reactions in which they are involved. Large quantities of automobile exhausts in the atmosphere exposed to intense sunlight leads to the formation of photochemical oxidants. This gives rise to photochemical smog (Characterised by brown, hazy fumes) which irritates the eyes and lungs, leads to the cracking of rubber and extensive damage of plant life. Smog is a combination of smoke and fog. Smog containing high levels of sulphur dioxide is called reducing smog. Peroxyacyl nitrate (PAN) is a potent eye irritant found in photochemical smog.
Oxides of nitrogen and sulphur entering the atmosphere are converted into nitric acid and sulphuric acid respectively. They combine with hydrochloric acid from HCl emission to generate acidic precipitation known as acid rain. Acid rain is now a major pollution problem in some areas. It causes extensive damage to buildings and sculptural materials of marble, limestone, slate, mortar, etc. It is harmful for aquatic plants and animals, and causes soil acidification.
Small solid particles and liquid droplets are collectively called particulates. These are present in large amounts in the atmosphere and sometimes pose a serious air-pollution problem. Examples of processes which inject particulate matter into the atmosphere: volcanic eruptions, blowing of soil and dust by wind, formation of fly ash from power plants, smelters and mining operations, and smoke from incomplete combustion processes. Airborne asbestos (a fibrous silicate mineral) and toxic metals like beryllium are carcinogenic. Fine particles (less than 3 microns) are the worst causes of lung damage. Coal miners’ black-lung disease, and asbestos workers’ pulmonary fibrosis are associated with the accumulation of such small particles. Very fine particulate matter, which is less than 2.5 microns in size, is called PM 2.5 and is known to cause diabetes and cardiovascular diseases.
Air in Delhi is choking with pollutant PM 2.5. Any kind of combustion, especially of vehicular origin, contains this particle. If PM 2.5 is not regulated it will increase the number of patients suffering from asthma and lung cancer. It brings about lead deposition in the lungs. Particulates accelerate corrosion of metals and cause damage to buildings, sculptures, paints, etc. Particulates in the atmosphere reduce visibility and influence the climate through the formation of clouds, rain and snow.
Burning CNG has the highest rates of potentially hazardous carbonyl emissions. Retrofitted CNG car engines emit 30% more methane than original CNG engines. Almost all CNG car engines in India are retrofitted. Coal pollution kills more than 300,000 people every year. Nitrogen and sulphur oxides emitted by aircrafts, at an altitude of 35,000 ft, combine with other gases in the atmosphere to create harmful pollutants.
Vehicle emission is responsible for 70% of the air pollution in India. Bangalore is called the asthma capital of India. The levels of suspended particulate matter are above permissible limits in Mumbai.
Bhopal gas tragedy was the greatest industrial disaster in the world that took place at a Union Carbide pesticide plant in the Indian city of Bhopal, Madhya Pradesh. On 3rd December, 1984 (midnight), the plant accidentally released methyl isocyanate (MIC) gas. Within a week about 10,000 people died, 1,000 became blind while more than 1 lakh continued to suffer from various disorders. This was the deadliest man made environmental disaster in history.
On 14 July 2010, chlorine gas leaked from the Sewri industrial area on land owned by the Mumbai Port Trust and approximately 76 people were treated in hospital. Rice crop yields in Southern India are decreasing as brown clouds are increasingly blocking the sunlight. The brilliant white of the famous Taj Mahal is slowly fading to a sickly yellow. The Supreme Court ordered the closure of more than 200 factories to save the Taj Mahal from being polluted by fumes.
There has been a drastic fall in the number of butterflies in the Western Himalayas, famous for their biodiversity. In areas of Himachal Pradesh, and Jammu and Kashmir, the population of 50% of the 288 species has declined more than half in just 10 years. Over 700 million people in India suffer from high levels of indoor air pollution as 75% homes use biomass fuel like wood, crop residue and dung cakes.
Excessive ultraviolet radiation coming from the sun through the ozone layer in the upper atmosphere, which is eroded by some air pollutants, may cause skin cancer in wildlife and damage to trees and plants. Ozone in the lower atmosphere may damage lung tissues of animals, and adversely affect plant respiration and photosynthesis.
Water Pollution
Water pollutants include insecticides and herbicides, food processing waste, pollutants from livestock operations, volatile organic compounds (VOCs), heavy metals, chemical waste, disease causing agents, sewage, Detergents, oil, sediments and radioactive materials. Beryllium, boron, cadmium, chromium, cyanide, lead, mercury, selenium, silver, sulphide, vanadium and zinc are some of the toxic water pollutants.
Waterborne diseases caused by polluted drinking water are typhoid, amoebiasis, giardiasis, ascariasis, hookworm, hepatitis, encephalitis, gastroenteritis and Diarrhoea. Conditions related to water polluted by chemicals are cancer, hormonal problems, and damage to liver, kidney, nervous system and DNA. Water polluted by mercury can lead to Parkinson’s disease, Alzheimer’s disease, heart disease, etc.
According to a United Nations report released on 22 March 2010 on World Water Day, contaminated and polluted water kills more people than all forms of violence including wars. 80% of urban waste in India ends up in rivers.
The river Ganga is dying slowly due to unchecked pollution. Samples taken from the river Ganga near Varanasi showed that levels of fecal coliform, a dangerous bacterium that comes from untreated sewage, were some 3,000 per cent higher than what is considered safe for bathing.
Chemical contamination in water can cause declines in frog biodiversity. Persistent organic pollutants (POPs) may cause declines, deformities and death of fish life. Plants and animals may be killed by too much sodium chloride (ordinary salt) in water. Plants may be killed by herbicides in water. Water pollution may disrupt photosynthesis in aquatic plants.
Soil Pollution
Soil pollutants include hydrocarbons, solvents and heavy metals. Soi contamination causes cancer. Lead in soil damages the brain, and mercury leads to kidney damage. It causes headache, nausea, fatigue, eye irritation, skin rashes, and depression of the central nervous system. It may alter plant metabolism and reduce crop yields. It can alter the metabolism of microorganisms. Trees and plants may absorb soil contaminants and pass them up the food chain. This may lead to increased mortality rates and even animal extinction.
Fossil Fuel Pollution
Fossil fuels (oil, gas, coal) are used in vehicles, power-generating plants, and in the manufacture of products like plastics, solvents, detergents, lubricating oils, etc. Fossil fuels contribute to soil contamination and water pollution.
When oil is transported by pipelines, an oil leak from the pipeline may occur and pollute the soil, and subsequently the groundwater. When oil is transported by tankers in an ocean, an oil spill may occur and pollute ocean water. Transport and power-generating plants are the biggest sources of fossil fuel pollution. Fossil fuel combustion is also a major source of carbon dioxide emissions (air pollution) and perhaps the most important cause of global warming.
