Pollution
Pollution is the damaging and undesirable change in the physical or biological features of environment (air, land or water), than can adversely affect all aspects of human life or other desirable species. In other words, pollution is the unfavorable alteration of the environment due to damaging addition of any materials or energy in it.
Pollution is the most CHA Practical ecological crisis for today’s world. There is pollution of air, water, land by different material pollutants. Addition of damaging amounts of energy to the environment is called non-material pollutions such as radiations pollution and noise pollution.
Air Pollution
When concentration of harmful substances gases or particulate matter increases in the air beyond their normal amounts the air is said to be polluted. Air pollution is the most common type of pollution, particularly in industrial urban areas. Air pollution is basically caused by burning of fossil fuels such as coal, petrol and natural gas. Some air pollution is also produced by industrial and agricultural activity etc. Particular pollutants include carbon particles, lead, asbestos particles, mineral dust, pollen grains, resins etc. The common gaseous pollutants are Carbon monoxide, CO₂, SO₂ oxides of nitrogen, chlorine etc. Air pollution has both pathological as well as effect on climate.
1. Pathalogical Effects of Air Pollution
Air pollution is the cause of many respiratory diseases like bronchits, cough, asthma, sorc throats, eye irritation, lung cancer and many nervous disorders. Carbonmonoxide (CO), is a poisonous gas and reduces the oxygen carrying capacity of the blood. In low quantities it causes nausea, head aches and sluggishness. Large levels of CO in blood may result in death. SO₂ irritates lining of respiratory tract, causing cough, bronchitis, asthma, lung cancer etc. Lead is added to air from automobile exhausts and is absorbed by the blood. It causes lead poisoning, which produces anaemia, stomach pains, kidney failure. It may also damage the nervous system and cause many nervous disorders. Asbestos particles are the main cause of lung cancer in the workers.
2. Environmental Effects of Air Pollution on Climate
Air pollution considerably affects the local as well as global weather and climate. Following are some of the major effects of air pollution on the environment
i. Photochemical Smog
In simple terms, smog is the mixture of air and smoke. Burning of fossil fuels at high temperature by vehicles and industry, releases nitrogen oxides (NO₂). With the energy supplied by the sunligh, the NO₂ combines with hydrocarbons (methane, ethane etc) to form secondary pollutants called photochemical oxidants. Presence of those pollutants scatter the light and a hazy milky smog is formed. Which is called the photochemical smog. It is very harmful for human health causes irritation of respiratory tract and lungs, head aches and breathing difficulties, which may even prove fatal.
ii. Acid Rains
Burning of fossil fuel by transport vehicles and industries produce pollutants such as SO₂, NO₂, CO₂. In this atmosphere these gases mix with the moisture of the air and gradually from dilute acids, which fall to the ground with rain. Such rains are called acid rains. Acid rains cause many respiratory diseases in humans. Acid rains also increase the acidity of the soil and water thus damaging crops and aquatic life. Corrosive action of H₂SO4 damages the buildings, statues and structures of historical and cultural importance.
iii. Green House Efect (Global Warming)
CO₂ plays an important role in regulating the earth’s surface temperature. Layer of CO₂ in upper atmosphere allows the sun rays to pass through atmosphere and reach the earth as short wave electromagnetic radiation. However, it partially prevents the long wave infra red heat radiation from escaping to outer space. Thus the globe is kept warm. Due to excessive burning of fossil fuels, the amount of CO₂ in atmosphere has become abnormally high. It holds back the increasing quantities of the heat waves and therefore the atmosphere gets over heated. This phenomenon is called green house effect. The possible effects of global warming are
- Melting of the polar ice which in turn would raise the sea level flooding vast coastal areas.
- Early melting of shows in the mountains would flood large areas of farmland.
- Warming of atmosphere can cause heavy rains and strong hurricanes and storms.
iv. Depletion of Ozone Layer
There is a protective layer of Ozone in the upper layers of the atmosphere. It acts as a shield and reduces the penetration of harmful ultraviolet rays of the sun. This ozone layer can be broken by release of chlorine atoms at high altitude. The main source of chlorine atoms is a group of industrially produced compounds called Chlorofluorocarbon (CFC). These chemicals are used as refrigerator and also in pressurised acrosol cans CFCs get accomodated in greater amounts at high altitudes (stratosphere). Under normal conditions these compounds are inert, but at high altitudes they release chlorine atoms due to action of intense short wave ultraviolet radiation from the sun. Chlorine atoms then react with Ozone molecules and convert them to oxygen. (Each atom of chlorine reacts with about 1,00,000 molecules of ozone). Reduction in Ozone layer allows greater ultraviolet radiation to reach the earth. It is thought that this intensified radiation can cause significant increase in skin cancer and other adverse effects associated with ultraviolet radiation.
Water Pollution
Any contamination of fresh water or marine is called water pollution. Major sources of water pollution are
1. Domestic Waste or Sewerage
2. Industrial Waste
3. Agricultural Waste
1. Pollution of Water by Sewerage
Sewerage may include faccal matter, dissolved organic matter such as carbohydrates, urea etc, inorganic substances like nitrates, phosphates, detergents , insecticides etc. Both surface and soil water can be polluted by the sewage. Most of the components of sewage are biodegradable and are decomposed by natural processes, but when their intake exceeds the decomposing capacity of the environment, water becomes polluted. Some of the ill effects of sewage pollution are
- It is responsible for water borne diseases like Typhoid, Amoebic dysentery, hepatitis, cholera etc. Harmful chemicals present in sewage also damage the tissues of the body can cause several diseases.
- Organic pollutants in sewage provide favorable medium for bacterial growth, which consume the oxygen of water. As a result fishes and other useful animals are killed for lack of oxygen.
- Anaerobic conditions also produce bad smelling compounds such as H₂S₂ which make the water unfit for human consumption.
2. Pollution of Water by Industrial Waste
Most of the streams and lakes are polluted by industrial wastes which include metals like lead, copper, mercury acids, alkalis, cyanides, arsenic, chlorine and many other toxic materials. These pollutants cause death to aquatic life and are also harmful for humans when they drink polluted water. These toxic substances cause various diseases of kidney, liver and nervous system. Some of which may prove fatal.
3. Pollution of Water by Agricultural Waste
Fertilizers, insecticides and pesticides and poultry feed contain many harmful components such as chlorine, nitrates etc, which contaminate soil and surface water. In rivers and streams they kill the aquatic life. Chlorine reduces the reproductive rate of aquatic animals. High nitrite concentration in drinking water converts hemoglobin in the blood to methemoglobin, which reduces blood’s oxygen carrying capacity.
Pollution by Oil
Oil is the main pollutant of marine water. Leakage from oil tankers and off shore oil wells kills many marine animals and plants.
Entrophication Or Algal Bloom
Natural lakes are divided into two types on the basis of production of organic matter. Entrophic lakes are shallow and contain high amount of nutrients. As a result phytoplankton growth is very high. This leads to increased number of heterotrophs which consume oxygen for respiration. Therefore, oxygen content of such lakes is reduced. The olgatrophic lakes are deeper and contain fewer amounts of nutrients. Therefore phytoplankton growth is poor and lesser number of heterotrophs are present and the oxygen content is high. Addition of agriculture waste, sewage, factory waste, increases the inorganic nutrients of the lakes. This over-enrichment is called entrophication. It causes algal bloom or explosive growth of small photosynthetic organisms such as algae. As the algae die, the activity of decomposers increase and they consume more and more oxygen. Deficiency of oxygen results in massive death of useful organisms such as fishes.
Land Pollution
The land can be polluted by deposition of solid waste and by harmful chemicals and hazardous waste.
1. Deposition of Solid Waste
Increase in population and rapid urbanisation has resulted in creation of enormous amounts of solid waste. It includes house hold garbage, hospital waste usually contaminated with various germs, agricultural, animal and industrial waste, dead animals and plants and host of other substances. If this refuse is dumped in open places without any pre-treatment, it pollutes the land. Wastes from hospitals carry germs of many dangerous diseases and the organic matter in the refuse provide favorable conditions for their growth and multiplication. These dumping sites also provide favourable breeding grounds for flies, rats and other vectors for pathogenic organisms. All these factors together pose a grave threat to the health of the population. Huge amounts of solid waste pose economic problems also because their proper disposal is very costly.
2. Harmful Chemicals and Hazardous Wastes
The land is also polluted by many harmful chemicals such as fertilizers, pesticides, insecticides which contain poisonous components. Most of the these pollutants are bio-nondegradable and stay in the soil for long periods. Solid wastes which cause human illness and death are called hazardous wastes. They include substances like mercury, cadmium, lead, nuclear wastes. They can ultimately end up in human body through food, water and radiation and cause dangerous disorders including cancer. These substance also interfere with biochemical cycles, thus decreasing the fertility of the soil.
Non-Material Pollution
Non-material pollution is the addition of damaging amount of energy to the environment. It includes radiation pollution, noise pollution, thermal pollution.
1. Radiation Pollution
Radiation, in the sense of pollution, comes from radio-active isotopes of such substances as Uranium, Radium, Thorium, Plutonium etc., which are used in nuclear reactors, atomic explosions, x-ray plants and other such devices. These radiation can penetrate tissues and organs of man and accumulate there. They may cause diseases like Leukaemia, bone tumour, cancer of many organs. Radiations also increases the mutation rate in the germ cells, which can produce genetic abnormalities in future generations.
2. Noise Pollution
Noise is the unwanted sound which the recipient does not like and which can adversely affect a person mentally, physically or aesthetically. Noises above 80 decibels are considered loud, uncomfortable and is harmful for human health. Noise is produced by motor vehicles, aeroplanes, machines, radio, TV, loud speakers. Loud noise is the serious threat to man’s physical and mental health. It affects mental peace, distracts the concentration and thus affects the quality and work output. Calm and quiet environment is a must for any creative and scholarly work. Loud noise is responsible for many disorders of cardrovascular and nervous system. People having continuously in environment of loud sound show symptoms of nervous stress, such as irritation, high blood pressure, headaches, sleeplessness, fatigue and depression. Persistent noise damages the internal car and may lead to impairment of hearing or even permanent deafness.
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