Pollution is the introduction of contaminants into the natural environment that changes the physical, chemical or biological characteristics of air, land, and water, which harmfully affect human life.
The pollutant is anything including a chemical, geochemical substance or a biological product that has undesired effects or adversely affects the usefulness of a resource
In the normal way there are two basic types of pollutants-
(i) Non-degradable pollutants: Non-degradable pollutants are those which either do not degrade or degrade extremely slowly in the natural environment. Such as aluminum cans, mercury salts, DDT, etc.
(ii) Biodegradable pollutants: Biodegradable pollutants Such as the domestic sewage which rapidly decomposed by the natural process or Some artificial System that enhance nature’s great capacity to decompose and recycle.
Different types of pollution are air pollution, acid rain, greenhouse effect, ozone depletion, water pollution, soil pollution, radioactive pollution, and noise pollution are given below:
★Release or occurrence of any foreign materials or gases in the atmosphere, which may be harmful to man, animals, and vegetation, etc., is known as air pollution.
★Important sources of air pollution are power and heat generating system, producing the large quantity of waste gases, use of insecticides and fungicides, etc.
★Motor vehicles alone contribute about 60% of air pollution in major cities like Mumbai, Delhi, Kolkata, and Chennai.
★Particulate air pollutant is any materials suspended in the atmosphere. They consist of fine solids or liquid droplets suspended in the air.
★One of the most harmful effects of smoke is the smog formation, which makes fog heavier and darker.
★Photochemical smog Hydrocarbons and nitrogen oxides, when mixed in the atmosphere formed ozone and complex organic gases in the presence of UV radiation in sunlight. This, in turn, causes photochemical smog. It comprising of O3, H2O2, PAN, etc.
★Smog is a mixture of smoke and fog arises from many sources including factories, oil refineries, etc.
★Photochemical smog is responsible for causing eye-watering ‘ and respiratory distress in human beings.
★Cigarette smoke, motor vehicles, industrial plants are the common sources of carbon monoxide (CO).
★Carbon monoxide is the most poisonous gas which causes suffocation because hemoglobin combines with CO.
Hb + CO -> Carboxyhaemoglobin
★Large amount of carbon monoxide, when inhaled leads to symptoms as laziness, exhaustion of body, headache, etc.
★Burning of fossil fuels is the main cause of sulfur dioxide pollution.
★ Sulfur dioxide causes different respiratory distress in animals.
The burning of fossil fuels mainly produces SO2 and NOx, which react with water to form sulphuric acid and nitric acid respectively. The acids, when precipitated as rain or snow, create acid rain.
SO2 (oxidised)→SO3 + H2O→H2SO4
NO (oxidized)→NO2 + H2O→HNO3
★Acid rain damages buildings and statues of limestone.
★Acid rain is also harmful to some aquatic forms.
★If there is an increase in CO2 concentration, then the thick layer of this gas prevents the heat from being re-radiated out. This thick CO2 layer thus functions like the glass panels of a greenhouse allowing the sunlight to filter through but preventing the heat from being re-radiated in outer space. This is so called greenhouse effect.
★ Carbon dioxide is chiefly produced by the burning of fossil fuels like coal, petroleum and natural gas.
★Carbon dioxide contributes the maximum to the greenhouse effect on earth.
★Green-house effect is related to global warming.
★Both methane (CH4) and chlorofluorocarbons (CFCs) are major greenhouse gases.
★Layer of the atmosphere (about 30-50 km above earth surface in the stratosphere) which provides a thermal blanket and radiation shield to the earth by absorbing much of the incoming shortwave radiation, which is very harmful to the living organism, especially in causing skin cancer contains the ozone.
★In 1975, atmospheric scientists first discovered the formation of the ozone hole, maximum over Antarctica.
★Chlorofluorocarbons and chlorofluoromethanes (CFMs) released into the stratosphere, where they dissociate to release free chlorine atom that causes depletion of ozone.
★The presence of some inorganic, organic, biological, radiological or physical foreign substances or particles, in the water that tends to degrade its quality, is called water pollution.
★Most of our water bodies as ponds, lakes, streams, rivers, sea, oceans have become polluted due to industrial growth, urbanization and other man-made problems.
The chief sources of water pollution are
★ It consists of excreta of animals.
★A major source of water pollution is raw or partially discharged sewage thrown into natural resources of water, e.g., rivers, lakes, streams, etc.
★ The industries that cause pollution are printing, electroplating, soap manufacture, rubber, plastics etc.
★ Caustic soda and chlorine factories release heavy metals, such as mercury, cadmium, chromium, copper, lead, etc.
★Mercury poisoning occurred in Minamata city, Japan in 1953, where more than 100 persons died or suffered serious nerve damage from eating fish taken from Minamata Bay.
★Cadmium poisoning is called Itai-Itai (ouch-ouch) in Japan.
Effect of Heavy Metal Water Pollution on Man
★Adding a large amount of inorganic fertilizers to crop fields results in fertilizer pollution.
★ Nitrite poisoning or methemoglobinemia occurs in infants and farm animals by poisoning of nitrite.
★Eutrophication It means the enrichment of nutrients by human activity.
★Eutrophic it refers to lakes that are highly productive in terms of organic matter formed and well supplied with nutrients.
★Biological Oxygen Demand (BOD) is the amount of oxygen required for biological oxidation by microbes in any unit volume of water.
★The greater the amount of organic matter in water, higher the BOD.
★The excessive use of pesticides causes water pollution by penetrating through the soil and getting dissolved in soil water.
★Spraying of DDT on crops produces pollution of air soil and water.
★Biological amplification (magnification) Increase in the concentration of a persistent chemical by the organisms at successive trophic levels in a food chain.
★Biological monitoring Direct measurement of changes in the biological component of habitat based on the evaluation of the number and/or distribution of organisms or species.
★Soil is the most important component of the Earth.
All the plants grow over Earth’s crust (soil).
★ These plants serve as food for herbivore animals, thus supports the animals living on earth.
★Any foreign substance (organic pollutants) that enters the soil will adversely affect soil productivity.
★Three types of soil pollutants may be found in nature
(a) Pollutants that are washed out of the atmosphere when came in contact with it, may pollute the soil and Create soil pollution.
(b) Pesticides, insecticides, and biocides, sprayed over the crops may find their way along with water to the soil.
(c) Nitrogenous fertilizers, mixed with soil to increase its productivity may sometimes have negative effects on the soil.
★One of the major soil pollution problems in large cities is the disposal of plastics.
★Plastic articles are non-biodegradable.
★An unstable atomic nucleus may undergo spontaneous disintegration or decay. This process produces radiation and the atoms that undergo disintegration are said to be radioactive.
★Radiation is energy, which travels in waves or particles.
★Radiation can be measured in Curies.
★Atmospheric radiation [natural and man-made sources), background radiation (cosmic rays, nucleotides such as Radium 223, Uranium 238, Carbon 14) and man-made radiation (X-rays, nuclear Weapon testing) etc are some of the major sources of ionizing radiations.
★Exposure of man of radiation may cause cancer, genetic damage, and infant mortality.
★The most outstanding danger at present for the survival of living beings on earth is a radiation hazard.
★Chernobyl disaster occurred in Ukraine, USSR 011 26th April 1986. It was an explosion at the nuclear power station releasing huge amount of radioactive substances into the atmosphere.
★Strontium-90, a radioactive pollutant causes bone cancer and degeneration of tissues in human beings.
★ Iodine-131, radioactive isotopes are used in the detection of thyroid cancer.
★Mothers who received abnormal doses of X-rays for diagnostic purposes during their pregnancy tend to produce Mongol children.
★Due to radioactive pollution, radiation stress leads to the reduction in species diversity at the ecosystem level.
★ Noise pollution means the unwanted sound dumped into the atmosphere.
★ The main sources of noise pollution are factories and industries, transportation (air, rail, and road), community and religious activities.
★There are two basic properties of sound
★ It is the strength of sensation of sound perceived by the individual.
★ It is measured in decibels (dB).
Sound Level at Various Sources
★Sounds beyond 80 dB can be safely regarded as pollution as it harms a hearing system.
★The World Health Organisation (WHO) has fixed 45 dB as the safe noise level for a city.
★ Loudness is also expressed in sones.
1 sone = loudness 0f 40 dB sound pressure at 1000 Hz.
★Number of vibrations per second.
★It is denoted as hertz (Hz).
★The noise has the adverse effect on man reducing hearing capacity, flushing the skin and constricting stomach muscles.
★Deafness can be caused due to continuous noise exposure.
★Noise also produces ulcers, headache, heart diseases, high blood pressure, nervousness, etc.