Environmental Pollution Global Environmental Issues And Control Measures PDF

# Environmental Pollution Global Environmental Issues And Control Measures ## 3.1 Environmental Pollution ### Introduction: According to Odum (1971), pollution is "an undesirable change in the characteristics of air, water, and land that harmfully affect the life and also create health hazards for...

# Environmental Pollution Global Environmental Issues And Control Measures ## 3.1 Environmental Pollution ### Introduction: According to Odum (1971), pollution is "an undesirable change in the characteristics of air, water, and land that harmfully affect the life and also create health hazards for all living organisms on the globe". According to Southwick (1976), Pollution can be defined as "the unfavorable (or) alteration of the environment caused by human activities and causing harm to human beings". ### Types of Pollution: Basically, pollution is of two types viz., 1. **Natural Pollution**: This type of pollution is limited in its occurrence generally from natural hazards like volcanic eruptions, emissions of natural gas, soil erosion, ultraviolet rays, cosmic rays, etc. 2. **Manmade Pollution**: Most of the pollution is man-made only. However, pollution is usually categorized as: * Air pollution * Water pollution * Thermal pollution * Noise pollution * Land and soil pollution * Radioactive pollution * Marine pollution ## 3.1.1 Air Pollution Air pollution may be described as "the imbalance in quality of air so as to cause adverse effects on the living organisms existing on earth". Pollution is due to the presence of undesirable substances of sufficient quantity which exists in the environment. The substance or energy which causes pollution is called a pollutant. ### Types of Air Pollutants: Pollutants may be classified according to origin and state of matter. #### a) According to Origin: Air pollutants are divided into two categories as primary and secondary. 1. **Primary air pollutants** are those which are emitted directly into the atmosphere. * Eg: C, CO, CO2, SOx, N, S, H, NOx, CFC's etc. 2. **Secondary air pollutants** are those which are produced in the air by the interaction among the primary air pollutants or by reaction with atmospheric constituents. * Eg: Ozone (O3), Smog, Para Acetyl Nitrate (PAN), Acid Rain, Aerosols. #### b) According to State of Matter: Air pollutants include fine solids, liquids, and gases. Dust, Smoke, Fumes etc are examples of solid particles whereas fog is an example of liquid particles. ## Primary Pollutants 1. **Carbon Monoxide**: It is a colorless, odorless, poisonous gas that is produced by the incomplete burning of carbon-based fuels (coal, petrol, diesel, and wood) which comes from the automobile industries, exhaust devices. About 70% of CO emissions are from the transport sector. When the air is polluted with CO, human blood is likely to be deprived of oxygen and leads to coma and death. In mild dosages, it leads to headaches. 2. **Oxides of Sulfur**: SO2 is a gas produced from burning of coal, mainly in thermal power plants. Some industries such as paper mills produce SO2. It is injurious not only to men and plants, but it also attacks rapidly a few rocks such as limestone, marbles, electric contacts, etc. It can even dissolve nylon. Paper absorbs SO2 causing the paper to become brittle and fragile. SO2 polluted air leads to corrosion of metals such as Fe, Zn, Cu, steel etc... SO2 is a major contributor to smog and acid rain. Sulphur trioxide is more irritant than SO2 because it combines immediately with water to form sulfuric acid. 3. **Oxides of Nitrogen**: Combustion of coal, oil, natural gas and gasoline which produces upto 50 ppm of Nitrogen. NOx are also produced when fossil fuels are burned especially in power plants and motor vehicles. NO2 poisoning results in SILOFILTER disease. High levels of NO2 exposure causes cough and make the human beings feel short of breath. People who are exposed to NO2 for a long time have a higher chance of getting respiratory infections. NOx compounds contribute to the formation of Ozone. Similarly, when nitrogen oxide combines with SOx to form acid rain. 4. **Chloro Fluoro Carbons**: CFC's (also known as Freon) are non-toxic. They contain Carbon, Fluorine, and Chlorine atoms. The five main CFCs are: * CFC-11 (Trichloro Fluoro Methane CFC13) * CFC-12 (Dichloro Fluoro Methane CF2C12) The major uses of CFCs are as coolants in refrigerators and in air conditioners; as solvents in cleaners particularly for electronic circuit boards etc... CFCs are the main cause of ozone depletion. CFCs have a lifetime in the atmosphere of about 20 to 100 years, and as a result one free chlorine atom from a CFC molecule can do a lot of damage. ## Secondary Pollutants: 1. **Ozone (O3) / Ozone layer Depletion**: Ozone consists of oxygen molecules which contain three oxygen atoms. It is not emitted directly into the air but produced in the atmosphere when oxygen combines with oxygen radical (O) in the presence of sunlight. Ozone protects us from ultraviolet radiation and other harmful rays. It is observed that over the last few years, many manmade processes release gases into the atmosphere causing drastic depletion of the ozone layer. The chlorine atoms cause depletion of ozone slowly and holes are formed in the ozone layer. Ozone reacts with tissues and cause for breathing and decrease the working ability of the lungs, chest pains and coughing. It lowers the human body resistance power and leads to cold; pneumonia also. 2. **Smog**: Smog is a combination of smoke and fog or various gases when they react in the presence of sunlight. The effects of smog on human health cause for respiratory irritation to the eyes, diseases related to nose, throat, bronchitis, pneumonia, headache, nerves, liver, and kidneys. The first smog related deaths were recorded in London in 1873, when it killed 500 people. In 1892, December. London had worst experiences causing 1000 deaths. In the 1940s, severe smog began covering the cities of Los Angeles in USA. 3. **Acid Rain**: Acid rain has become one of the most important global environmental problems and poses significant adverse impact on soils, rivers, lakes, forests, and monuments. The phenomenon occurs when SOx and NOx from the burning of fossil fuels such as Petrol, Diesel, Coal etc combine with water vapor in the atmosphere and fall as rain or snow or fog. Natural sources like volcanoes, forest fires, etc also contribute SOx and NOx. Increased urban and industrial activities cause air pollution resulting in the rise of the concentration of SO2 and NOx. Sulphur dioxide and NO2 combine with water vapor in the atmosphere to produce sulphuric acid and Nitric acid respectively and results in acid rain. Some of the examples are: * Europe and parts of W Asia have experienced rain with a water pH range of 4.5 to 5.0 (acidic) in 1958. ## Air Pollution Effects, Prevention, and Control Measures: Human beings breathe 22,000 times a day on average, inhaling 16 kg of air. The atmosphere constitutes a protective cover of gases surrounding the earth which sustains life and saves it from unfriendly environments. The atmosphere consists of several layers viz. Troposphere, Stratosphere, Mesosphere, Thermosphere & Exosphere. The lower atmosphere i.e., the troposphere contains 70% of gaseous components of major, minor, and traces. Ultraviolet radiation from the sun is absorbed by ozone in the stratosphere which is so called ozone layer located between 17-26 kms above sea level. ### Effects of Air Pollution: The effects of pollution may be direct and affect certain organisms. The effects of pollution may possess a hazard or nuisance. Long continued pollution even affects the evolution of a species and eliminates organisms that cannot tolerate certain pollutants and favor others who can eat. Air pollution causes deaths, impairs health, reduces visibility and brings vast economic losses. It can also cause intangible losses to historic monuments such as Taj Mahal. Finally, Air pollution can affect the environment on a global scale. ### Prevention and Control of Air Pollution: * Inputs that do not contain the pollutants. * Operating processes to minimize the generation of the pollutants. * Replacing the process with one does not generate the pollutant. * Removing the pollutants from the process. * Substitution of raw materials. ## 3.1.2 Water Pollution The hydrosphere in the universe contains water in the form of oceans, rivers, lakes, tanks, and many other water sources. Water sources in the world are of two types: * Marine water bodies * Freshwater bodies. Water is a good solvent for many substances. Because of this property, water cannot exist in its pure form at many parts of the world. Water pollution is mainly because of sewage, industrial disposals i.e., effluents. ### Parameters of Water Pollution: Chemical examination of water (tests): pH; Biological Oxygen Demand (BOD), Dissolved Oxygen (DO), etc are some of the chemical tests to find the stage of pollution of water. 1. **pH**: The value of pH gives the degree of acidity or alkalinity of polluted water. Determination of pH is important in calculating the coagulant (thick or thin) dose. 2. **Biological Oxygen Demand (BOD)**: It is defined as the quantity of oxygen utilized by microorganisms at a temperature of 20°C, generally measured for 5 days. When water is polluted by unwanted materials, naturally the O2 content gets reduced and that water becomes not fit for consumption either by human beings or animals or plants. Living organisms require water with some quantity of sustainable oxygen in it. That oxygen is necessary for living organisms is generally called BOD. If there is a reduction in the oxygen content of water, it becomes unfit for biological consumption because there is a change in BOD. ## 3.1.3 Soil Pollution ### Definition: Soil pollution is defined as the build-up in soils of persistent toxic compounds, chemicals, salts, radioactive materials, or disease-causing agents, which have adverse effects on plant growth and animal health. Soil is the thin layer of organic and inorganic materials that covers the Earth's rocky surface. The organic portion, which is derived from the decayed remains of plants and animals, is concentrated in the dark uppermost topsoil. The inorganic portion made up of rock fragments, was formed over thousands of years by physical and chemical weathering of bedrock. Productive soils are necessary for agriculture to supply the world with sufficient food. ### There are many different ways that soil can become polluted, such as: * Seepage from a landfill * Discharge of industrial waste into the soil * Percolation of contaminated water into the soil * Rupture of underground storage tanks * Excess application of pesticides, herbicides or fertilizer * Solid waste seepage The most common chemicals involved in causing soil pollution are: * Petroleum hydrocarbons * Heavy metals * Pesticides * Solvents ### Types of Soil Pollution * Agricultural Soil Pollution and pollution due to urban activities * i) Pollution of surface soil * ii) Pollution of underground soil * Soil pollution by industrial effluents and solid wastes * i) Pollution of surface soil * ii) Disturbances in soil profile ## 3.1.4 Marine Pollution Pollution of oceans is damaging the marine environment and is becoming a major problem. The marine environment is interesting for various reasons such as seafood; navigation; adventure; tourism etc., Marine pollution is harmful and its danger can be identified in a variety of ways. ### Sources & causes of marine pollution: Marine pollution originates from one of two sources - the land or the sea which are explained below: ### Marine Oil Pollution: Oil is basically an important pollutant which destroys the marine environment. The various sources of oil pollution are: * Run-off oil from streets; * Disposal of lubricants from machines; * Off shore oil and gas exploitation from off-shore drilling; * Blowouts at off-shore drilling rigs; * Oil escaping under high pressure from a bore hole in the ocean floor. Waste chemicals, mud and accumulation of toxic substances in the ocean in the form of mercury, dioxin, PCBs, PAHs (Poly Aromatic Hydrocarbons), radioactivity; benzene; xylene (colorless, flammable liquids) and heavy metals such as lead; copper; nickel, mercury also cause for marine pollution during the off shore drilling activities. Both dumping and exploitation of ocean resources cause ocean pollution also. PAHs: It is a chemical compound and organic pollutant. These occur in oil, coal and tar deposits and are produced as byproducts of fuel burning. PAHs are lipophilic meaning they mix more easily in oil than water. Eg for PAHs are: Acenaphthene; Anthracene; Benzopyrene; Chrysene; Coronene; Fluorene; Pyrene. ## 3.1.5 Noise Pollution ### Introduction: Everyone knows that sound is a form of energy that is capable of causing disturbances in human beings. Ears are the hearing organs in human beings. A thin membrane is called Tympanum (or) ear drum receives the vibrations produced by sound to a limited extent. Human ear is capable of perceiving about 85 decibels of sound. Beyond the limit, the ear drum cannot bear sound. In nature, we hear different types of sounds. Sound is a kind of vibration which travels through air, water, and are sensed by the ear. This is from music, speech, etc from radio / television / computers etc., one thing in this matter is that we can increase the volume of sound or decrease as per our taste whereas, a noise is a sound which cannot be heard clearly and only mixed sounds will be heard. For eg: in an office one is talking on mobile, phone ringing another side, ring tones in some person's hands, loud conversations with one and another etc., this is called noise. One cannot increase or decrease the volume of noise. In general, a sound is a vibration from a particular machine, place or material which can be heard clearly whereas a noise is a mixed vibrations that will come to us from all directions. A sound can be clear and can be able to hear, whereas a noise will not be clear and cannot be heard.