Environmental Change: Climate Change and Pollution
Pollution is any undesirable change in physical, chemical or biological characteristics of air, land, water or soil. Agents that bring about such an undesirable change are called as pollutants.
Pollution is often classed as point source or nonpoint source pollution. A point source is a single, identifiable source of pollution, such as a pipe or a drain. Industrial wastes are commonly discharged to rivers and the sea in this way. Non-point sources of pollution are often termed ‘diffuse’ pollution and refer to those inputs and impacts which occur over a wide area and are not easily attributed to a single source. For example as water from rainfall and snowmelt flows over and through the landscape, it picks up and carries contaminants from many different sources. This is called Non-Point Source pollution.
5.9.1. AIR POLLUTION
Air pollution is the introduction of particulates, biological molecules, or other harmful materials into Earth's atmosphere, causing damage, diseases and death to living organisms. Industry and transport are the largest sources of air pollutants and emission of these pollutants results in high levels of particles and soot in the air and can cause smog to form. Air pollutants can be either gases or aerosols (particles or liquid droplets suspended in the air). They change the natural composition of the atmosphere and can cause damage to natural water bodies and the land.
Air pollution has both natural and human sources:
Natural air pollution
Dust from natural sources, usually large areas of land with little or no vegetation
Methane, emitted by various sources.
Radon gas from radioactive decay within the Earth's crust.
Smoke and carbon monoxide from wildfires
Vegetation, in some regions, emits environmentally significant amounts of Volatile organic compounds (VOCs) on warmer days. These VOCs react with primary anthropogenic pollutants—specifically, NOx, SO2, and anthropogenic organic carbon compounds — to produce a seasonal haze of secondary pollutants. Black gum, poplar, oak and willow are some examples of vegetation that can produce abundant VOCs. The VOC production from these species results in ozone levels up to eight times higher than the low-impact tree species.
Volcanic activity, which produces sulfur, chlorine, and ash particulates
Stationary sources include smoke stacks of power plants, factories and waste incinerators, as well as furnaces and other types of fuel-burning heating devices. In developing and poor countries, traditional biomass burning is the major source of air pollutants; traditional biomass includes wood, crop waste and dung.
Mobile sources include motor vehicles, marine vessels, and aircraft.
Fumes from paint, hair spray, varnish, aerosol sprays and other solvents
Waste deposition in landfills, which generate methane. Methane is also an asphyxiant and may displace oxygen in an enclosed space. Asphyxia or suffocation may result if the oxygen concentration is reduced to below 19.5% by displacement.
Military resources, such as nuclear weapons, toxic gases, germ warfare and rocketry
Particulate matter from mining activities.
Types of Pollutants
1. Primary Pollutants: These are emitted directly into the air from sources at the Earth’s surface. Examples are greenhouse gasses.
2. Secondary Pollutants: The regional gases can also react chemically in the atmosphere to form other compounds which are known as secondary pollutants. One of the main results of secondary pollution is photochemical smog.
Apart from gasses, the second type of pollutant is Particulate matter which consists of a wide range of liquid and solid particles known scientifically as aerosols. The smallest of these particles are hazardous to human health. As with the gases, particles can be directly emitted into the air or can form from gases. For example such particles from wood-burning can cause a brown haze over the region and larger particles may interfere with plant growth because they deposit on the leaves.
National Carbonaceous Aerosols Programme (NCAP)
India launched the Black Carbon Research Initiative as part of the National Carbonaceous Aerosols Programme (NCAP). This is a joint initiative of several government ministries and leading research institutions.
Black carbon (BC) is the result of incomplete combustion of fossil fuels, biofuel, and biomass. It consists of elemental carbon in several forms. Black carbon warms the atmosphere due to its absorption and by reducing albedo when deposited on snow and ice. Life time of black carbon in the atmosphere is only a few days to weeks, compared to CO2 which has an atmospheric lifetime of more than 100 years.
Aerosols are suspended particulates in the atmosphere and have implications for climate and health through different mechanisms Direct and indirect climate forcing by aerosols depend on the physical and chemical properties of the composite aerosol, which consist mainly of sulfates, carbonaceous material, sea salt and mineral particles. Among the various aerosol types, black carbon aerosol assumes most importance due to its high absorption characteristics, which in turn depends on its production mechanism. Until the late nineties, sulfate aerosols had received most attention because of its scattering effects and its ability to act as Cloud Condensation Nucleus (CCN). Studies carried out during the late nineties, however, have identified carbonaceous aerosols as one of the most important contributors to aerosol forcing. Carbonaceous aerosols are the result of burning coal, diesel fuels, bio fuels and biomass burning.
Indoor Air Pollution
The air pollution types mentioned so far are also known as outdoor air pollution. Indoor air pollution is also a very important problem. The air within homes and other buildings can sometimes be more polluted than the outdoor air even in the largest and most industrialised cities. Indoor air quality is an important concern for the health and comfort of the occupants. Some of the sources of indoor air pollution are:
1. Radon: Radon is an invisible, radioactive atomic gas that results from the radioactive decay of radium, which may be found in rock formations beneath buildings or in certain building materials themselves. Radon is the second most frequent cause of lung cancer, after cigarette smoking.
2. Second-hand smoke: It is tobacco smoke which affects other people other than the 'active' smoker. It includes both a gaseous and a particulate phase, with particular hazards arising from levels of carbon monoxide and very small particulates.
3. Biological chemicals: They can arise from a host of means, like moisture induced growth of mould colonies and natural substances released into the air such as animal dander and plant pollen. They are allergens and aggravate asthama.
4. Volatile organic compounds (VOCs): They are emitted as gases from certain solids or liquids like paints and lacquers, pesticides, building materials and furnishings, office equipment, correction fluids, glues and adhesives, permanent markers, and photographic solutions.
5. Carbon monoxide: Sources of carbon monoxide are tobacco smoke, space heaters using fossil fuels, defective central heating furnaces, and automobile exhaust.6. Bacteria: Many bacteria of health significance found in indoor air and on indoor surfaces.
6. Ozone: Ozone is produced by ultraviolet light from the Sun hitting the Earth's atmosphere, lightning, certain high-voltage electric devices and as a by-product of other types of pollution.
Sources of indoor air pollutants are of many types and this is a serious problem particularly in poor countries where the standard of living is low.
Many air fresheners employ carcinogens, volatile organic compounds and known toxins such as phthalate esters in their formulas. Most of the products that have been studied contain chemicals that can aggravate asthma and affect reproductive development
Emissions and their Quantification
Burning fuels such as coal, oil, gas and petrol to produce energy and to power vehicles causes the emission of many different chemical species into the atmosphere.
Large amounts of both gases and particles are emitted into the air when coal is burnt in power stations. The gases emitted include sulphur dioxide (SO2), nitrogen oxides (NOx), carbon monoxide (CO) and carbon dioxide(CO2) and the dust contains heavy metals such as lead (Pb), zinc (Zn) and cadmium (Cd). The exhaust gasses from petrol engines contain Carbon Monoxide and Nitrogen Oxides, hydrocarbons, some Sulphur Dioxide and solid particles. Diesel Engines emit less toxic gasses but may emit more particles.
Metallurgy is the main industrial source of air pollution delivering primarily sulphur dioxide (SO2) and highly toxic heavy metal containing dust. Steel works emit large amounts of carbon monoxide (CO), and aluminum works produce lots of fluorine which is very harmful to living organisms.
Particles not only come from the combustion of fossil fuels but also from the road surface and from the car tyres and the brakes. Most cars are now equipped with catalytic converter which significantly reduce the amount of pollutants being emitted. However the numbers of cars globally is still rising and vehicles are still an important source of air pollution. The catalysts in catalytic converters are made up of heavy metals including platinum, palladium and rhodium. Increasing numbers of cars and therefore catalytic converters mean that levels of these metals are increasing in the atmosphere.
Emission factor is a representative value that attempts to relate the quantity of a pollutant released to the atmosphere with an activity associated with the release of that pollutant. These factors are usually expressed as the weight of pollutant divided by a unit weight, volume, distance, or duration of the activity emitting the pollutant (e. g., kilograms of particulate emitted per megagram of coal burned). Such factors facilitate estimation of emissions from various sources of air pollution.
Negative Effects of Air Pollution
Air pollution has an impact on both local and global scales. Harmful substances which are emitted into the atmosphere in one country are transported by the wind and cross over national borders. Global negative effects of air pollution include the enhanced greenhouse effect and the ozone hole. Smog and acid rain are the best known local effects and smog, in particular, affects people living in urban areas. Air pollution is a threat to our health and can also cause economic losses.
It is detrimental to human health causing major respiratory disorders. Hay fever, asthma and bronchitis are caused due to air pollution. Sulphur dioxide is responsible for cough, spasm of larynx and reddening of the eye due to irritation of membranes in the eye. Haemorrhage and pulmonary disorders are resulted even with very low concentrations of ozone. Beryllium causes berylliosis. Dusts, grits and smokes cause tuberculosis and silicosis whereas heavy metals are carcinogenic in nature and develop dermatitis and ulcers of skin. Nickel may cause lung cancer.
The forage crops are sometimes contained with metallic pollutants, such as, lead, arsenic and molybdenum in mining and thermal power plants area due to air pollution. The domestic animals feeding on contaminated fodder suffer from different diseases. Air contaminated with ozone causes pulmonary changes, oedema and haemorrhage in dogs, cats, and rabbits. Animals feeding on fluoride compound containing fodder may suffer from fluorosis. Cattle and sheep are most frequently affected animals. Hypoplasia of dental enamel and bone lessening are the other effects caused due to excessive fluoride in the body.
Plants are affected by various air pollutants. Excessive sulphur dioxides make the cells inactive and finally are killed. At lower concentrations, brownish red colour of leaf, choruses and necrosis take place. Tomato is affected by ammonia and radish, cucumber and soybean are affected due to hydrogen sulphite. Ethylene causes epinasty and early maturation of plants. In India in 2014, it was reported that air pollution by black carbon and ground level ozone had cut crop yields in the most affected areas by almost half in 2010 when compared to 1980 levels.
Materials and atmosphere
Increase in carbon dioxide concentration increases the temperature of the earth. Depletion of ozone layer due to fluorocarbon of aerosol causes the exposure of U. V. radiation which is lethal. Different metals, such as iron, aluminum and copper are corroded when exposed to contaminated air. Building and other materials are disfigured by deposition of soot.
The word "smog" is the combination of the words smoke and fog. It was invented around 1911 by the physician Harold Des Voeux. There are two kinds of smog:
1. London type smog: Burning coal leads to emissions of Carbon Dioxide, Sulphur Dioxide and dust. When these pollutants mix with fog, droplets of highly corrosive Sulphuric Acid are produced in the air. It occurs at very cold temperatures.
2. Los Angeles type or Photochemical Smog: This type of smog forms on sunny days and is the result of emissions from traffic. Nitrogenous oxides from car exhausts and hydrocarbons react in the presence of sunlight to produce a noxious mixture of aerosols and gasses.
Secondary pollutants: Derived from Primary Air Pollutants. In bright sunlight, nitrogen, nitrogen oxides, oxygen and hydrocarbons undergo photochemical reaction. As a result, powerful oxidants – Ozone, Aldehydes, Sulphuric acid, Peroxy acetyl nitrate (PAN), Peroxides, etc. are produced. They form photochemical Smog.
Photochemical smog contains tropospheric ozone, formaldehyde, ketones and PAN (peroxyacetyl nitrates). Normal tropospheric ozone levels are less than 0.04 ppm but ozone levels can be as high as 12 ppm in these smogs. The substances in these smogs are irritating to eyes and can damage respiratory system. They also affect vegetation. This type of smog is rather common now in large cities.
Clean rain is slightly acidic naturally but when the pH of rain falls below 5.6, we call it acid rain. Emissions of the two air pollutants, nitrogen oxides (NOx) and sulphur dioxide (SO2) are the main reasons for acid rain formation. Nitrogen oxides (NOx = NO + NO2) and sulphur dioxide (SO2) are emitted during fossil fuel combustion and then undergo reactions with water in the air to form the nitric acid (HNO3) and the sulphuric acid (H2SO4) found in acid rain.
Acid rain affects all elements of the environment, surface- and ground-water, soils and vegetation. It negatively affects food chains, reduces biodiversity and damages our world as discussed below:
When soil becomes acidified, essential nutrients such as calcium (Ca) and magnesium (Mg) are leached out before the trees and plants can use them to grow. This reduces the soil's fertility. In addition, acidification may release1 aluminium from the soil. At high concentrations, aluminium is toxic and damages plant roots. This reduces the plants ability to take up nutrients such as phosphorus, eventually leading to death.
It leads to acidification of water bodies. Some 14,000 Swedish lakes, located in acidic crystalline rocks, have been affected by acidification with widespread damage to plant and animal life as a consequence.
Acid precipitation does not usually kill trees directly. Acid deposition destroys the surfaces of the leaves of trees and plants. This damage causes uncontrolled water loss and slows photosynthesis. It reduces the rate at which leaf litter decomposes, causes the death of useful microorganisms present in tree roots and reduces the rate at which soil organisms (including bacteria) respire.
Soil acidification releases metals that can harm microorganisms in the soil as well as birds and mammals higher up in the food chain. The most sensitive groups include fish, lichens, mosses, certain fungi and small aquatic organisms. Some organisms may be completely eliminated, reducing biodiversity.
Acid rain also disturbs the natural cycles of sulphur and nitrogen.
Toxic hotspots are locations where emissions from specific sources such as water or air pollution may expose local populations to elevated health risks, such as cancer. Urban, highly populated areas around pollutant emitters such as old factories and waste storage sites are often toxic hotspots. Some toxic hotspots in India are Bhopal, Pantacheru, AP and Eloor in Cochin.
Some of the effective methods to Control Air Pollution are as follows:
When pulverized coal is burnt in the boiler of a thermal power station, a part of ash falls down at the bottom of the boiler and is known as bottom ash. Whereas, the major portion of the ash comes out along with the flue gases and is collected through electro static precipitator or filter bags or other means before allowing the exhaust gases to escape through chimney. This is called Fly Ash.
Fly Ash is categorised as hazardous waste and therefore, pollution control standards require that it be captured prior to release. However, it has found number of uses. The most common use of fly ash is as a replacement for Portland cement used in producing concrete. Concrete made with fly ash is stronger and more durable than traditional concrete. Fly ash concrete is easier to pour, has lower permeability, and resists alkali-silica reaction, which results in a longer service life
1. Source Correction Methods:
Industries are major contributors towards air pollution. Formation of pollutants can be prevented and their emission can be minimized at the source itself. By carefully investigating the early stages of design and development in industrial processes e.g., those methods which have minimum air pollution potential can be selected to accomplish air-pollution control at source itself. Some of these source correction methods are:
(i) Substitution of raw materials:
(a) Low sulphur fuel which has less pollution potential can be used as an alternative to high Sulphur fuels, and,
(b) Comparatively more refined liquid petroleum gas (LPG) or liquefied natural gas (LNG) can be used instead of traditional high contaminant fuels such as coal.
(ii) Process Modification:
(a) If coal is washed before pulverization, then fly-ash emissions are considerably reduced.
(b) If air intake of boiler furnace is adjusted, then excess Fly-ash emissions at power plants can be reduced.
(iii) Modification of Existing Equipment:
(a) Smoke, carbon-monoxide and fumes can be reduced if open hearth furnaces are replaced with controlled basic oxygen furnaces or electric furnaces.
(b) In petroleum refineries, loss of hydrocarbon vapours from storage tanks due to evaporation, temperature changes or displacement during filling etc. can be reduced by designing the storage tanks with floating roof covers.
(c) Pressurising the storage tanks in the above case can also give similar results.
(iv) Maintenance of Equipment: An appreciable amount of pollution is caused due to poor maintenance of the equipment which includes the leakage around ducts, pipes, valves and pumps etc. Emission of pollutants due to negligence can be minimized by a routine checkup of the seals and gaskets.
2. Pollution Control Equipment:
Sometimes pollution control at source is not possible by preventing the emission of pollutants. Then it becomes necessary to install pollution control equipment to remove the gaseous pollutants from the main gas stream.
Pollution control equipment’s are generally classified into two types:
Control Devices for Particulate Contaminants:
(1) Gravitational Settling Chamber: For removal of particles exceeding 50 μm in size from polluted gas streams, gravitational settling chambers are put to use. The gas stream polluted with particulates is allowed to enter from one end. The particulates having higher density obey Stoke’s law and settle at the bottom of the chamber from where they are removed ultimately.
(2) Cyclone Separators (Reverse flow Cyclone): Instead of gravitational force, centrifugal force is utilized by cyclone separators, to separate the particulate matter from the polluted gas.
(3) Fabric Filters (Baghouse Filters): In a fabric filter system, a stream of the polluted gas is made to pass through a fabric that filters out the particulate pollutant and allows the clear gas to pass through.
(4) Electrostatic Precipitators: Electrically charged particulates present in the polluted gas are separated from the gas stream under the influence of the electrical field.
(5) Wet Collectors (Scrubbers): In wet collectors or scrubbers, the particulate contaminants are removed from the polluted gas stream by incorporating the particulates into liquid droplets.
3. Diffusion of Pollutants in Air:
Dilution of the contaminants in the atmosphere can be accomplished through the use of tall stacks which penetrate the upper atmospheric layers and disperse the contaminants so that the ground level pollution is greatly reduced. The height of the stacks is usually kept 2 to 21/2 times the height of nearby structures.
Dilution of pollutants in air depends on atmospheric temperature, speed and direction of the wind. The disadvantage of the method is that it is a short term contact measure which in reality brings about highly undesirable long range effects because they are less noticeable near their original source whereas at a considerable distance from the source these very contaminants eventually come down in some form or another.
Plants contribute towards controlling air-pollution by utilizing carbon dioxide and releasing oxygen in the process of photosynthesis. This purifies the air (re-moval of gaseous pollutant—CO2) for the respiration.
Gaseous pollutants like carbon monoxide are fixed by some plants, namely, Coleus Blumeri, Ficus variegata and Phascolus Vulgaris. Species of Pinus, Quercus, Pyrus, Juniperus and Vitis depollute the air by metabolising nitrogen oxides. Plenty of trees should be planted especially around those areas which are declared as high-risk areas of pollution.
This method of controlling air pollution can be adopted at the planning stages of the city. Zoning advocates setting aside of separate areas for industries so that they are far removed from the residential areas. The heavy industries should not be located too close to each other.
New industries, as far as possible, should be established away from larger cities (this will also keep a check on increasing concentration of urban population in a few larger cities only) and the locational decisions of large industries should be guided by regional planning. The industrial estate of Bangalore is divided into three zones namely light, medium and large industries. In Bangalore and Delhi very large industries are not permitted.
Air pollution in India
Air pollution in India is a serious issue with the major sources being fuelwood and biomass burning, fuel adulteration, vehicle emission and traffic congestion. The Air (Prevention and Control of Pollution) Act was passed in 1981 to regulate air pollution and there have been some measurable improvements. However, the 2013 Environmental Performance Index ranked India 155 out of 178 countries.
The ambient air quality is monitored by the Central Pollution Control Board in association with various State Pollution Control Boards, Pollution Control Committees for Union Territories and NEERI across the country, including in 35 metro cities in terms of Sulphur Dioxide (SO2), Nitrogen Dioxide (NO2) and PM10 (particulate matter less than 10 micron) under National Air Monitoring Programme (NAMP. The basic guidelines to prevent air pollution arising due to transport sector, industry sector, energy sector, etc. in metro cities, are followed by different organs of the Administration and concerned organisations.
The steps being taken include, inter alia, strengthening of public transport, supply of cleaner fuel as per Auto Fuel Policy, use of beneficiated coal in thermal power plants, more stringent mass emission norms for new vehicles in select cities, ‘Pollution Under Control’ certificate system for in-use vehicles, strict implementation of emission & effluent norms in air and water polluting industries, etc. with a view to contain pollution in the cities. Concerned authorities implement city-specific Ambient Air Quality Improvement Programme for 17 identified cities. The Central Government has very recently established a National Ambient Noise Monitoring Network in seven cities, namely, Delhi, Mumbai, Kolkata, Lucknow, Bengaluru, Chennai and Hyderabad, to begin with, for systematic monitoring of ambient noise on 24 X 7 basis and for creation of baseline data.
Bharat Stage emission standards
The standards, based on European regulations were first introduced in 2000. Progressively stringent norms have been rolled out since then. All new vehicles manufactured after the implementation of the norms have to be compliant with the regulations. Since October 2010, Bharat stage III norms have been enforced across the country. In 13 major cities, Bharat stage IV emission norms for cars have been in place since April 2010. Government has announced that all two-wheelers, three-wheelers and four-wheelers will have to comply with Bharat Stage IV (BS IV) norms from April 1, 2017. It has announced plans to skip BS V norms and directly implement BS VI norms by April 2020. However, compliance with the norms leads to increase in the cost of the vehicles.
National Air Quality Index (AQI) It has been launched for monitoring the quality of air in major urban centres across the country on a real-time basis and enhancing public awareness for taking mitigative action. The AQI has been at present launched for 10 cities -- Delhi, Agra, Kanpur, Lucknow, Varanasi, Faridabad, Ahmedabad, Chennai, Bangalore and Hyderabad. Government proposes to extend the measurement of air quality to 22 state capitals and 44 other cities with a population exceeding one million. There are six AQI categories, namely: Good, Satisfactory, Moderately polluted, Poor, Very poor and Severe.
The index considers eight pollutants -- PM10, PM2.5, NO2, SO2, CO, O3, NH3 and Pb). The likely health implications of the six categories would also be provided with a colour code.
With this step, India has joined the global league of countries like the US, China, Mexico and France that have implemented smog alert systems.
5.9.2. WATER POLLUTION
Water pollution may be defined as the presence of undesirable substances (organic, inorganic, biological or radioactive) in water and such physical factors as heat, which make it unfit and harmful for use by the human beings, animals and marine life.
Marine water pollution has assumed greater significance because in the present age of technology and large scale industrialization, the coastal areas of oceans and seas are most vulnerable to pollution. These areas receive direct discharges from the rivers, which carry a large amount of dissolved and particulate matter. The oceans and seas are being used as endless dustbins for wastes.
Sources of Water Pollution
Major sources of water pollution are as below:
Domestic Sewage: Human beings use water for drinking, cooking, bathing, washing clothes, gardening, recreation, etc. The discharged water has soluble and insoluble, organic and inorganic matter. It includes detergents, toxic heavy metals and even pathogens. In the municipal drains the domestic sewage is mixed up with garbage from urban and rural settlements. This highly polluted water is discharged into rivers, lakes and ponds. Thus the domestic waste and garbage are the main source of water pollution.
Industrial Waste: The industrial wastes are most harmful of all water pollutants as they contain toxic metals (lead, mercury, zinc, copper, chromium and cadmium) and toxic non-metals (arsenic, acids, alkalis, cellulose fibers, coloring and bleaching materials, petrochemicals, etc.). These pollutants are continuously discharged in the water bodies either directly or from waste dumps.
Agricultural Waste: Water pollution caused by agriculture is mainly an outcome of fertilizers and agricultural chemicals such as insecticides and herbicides that runoff into streams and lakes. They are rich in many nutrients and lead to phenomenon like eutrophication.
Off-shore Oil Drilling: This pollution is mainly due to the loss of oil during off-shore exploration, oil drilling and extraction of mineral oil, leakage of oil and natural gas from under-water pipelines and oil spills from oil tankers. The waste oil also reaches the oceans and seas due to leakage during loading and unloading of oil tankers, run off from the roads at seaports and washing of oil tankers.
Thermal Pollution: Most of the large-scale industrial units, thermal power plants, nuclear power plants, oil refineries, etc., are located along the banks of rivers. These industries use large quantities of fresh water for cooling purposes. The hot water is generally discharged in the rivers. This increases the temperature of river water by about 10 Degree Celsius, and this leads to thermal pollution of water. This has a harmful effect on the aquatic organisms, such as fishes and algae. The increase in temperature of river water also decreases the level of dissolved oxygen, which results in the release of foul and toxic gases.
Effects of Water Pollution
The pollution of fresh and marine water has harmful effects on the environment, human health and other organisms. Effects of different Sources of water pollution can be discussed as under:
The domestic waste and sewage has the following effects:
It can cause infectious diseases, such as typhoid, cholera, dysentery, jaundice, etc.
The presence of pathogens make it unfit for domestic use.
The reduced oxygen level causes foul smell.
The industrial wastes have the following effects:
The water cannot be used for domestic purposes.
It has caused extinction of a number of marine species.
It includes toxic metals (lead, mercury, zinc, copper, cadmium and chromium) and toxic non-metals (arsenic, petrochemicals, acids, alkalis) whose effects can be:
1. The accumulation of lead in human body damages the nervous system, kidney, liver and brain. The children and pregnant women are most affected by lead poisoning.
2. Mercury and its compounds can cause abdominal problems, headache, chest pain and diarrhea.
3. Zinc can cause renal damage and vomiting.
4. Copper can cause hypertension, dizziness and drowsiness.
5. The accumulation of chromium can cause diseases like cancer and disorder of nervous system.
6. Arsenic can cause liver cirrhosis, lung cancer, kidney damage, gastrointestinal disorder and skin problems.
The agricultural wastes have the following effects:
The water becomes turbid due to suspended impurities and is unfit for domestic use.
It causes respiratory and vascular damage by restricting the amount of oxygen that reaches the brain.
It can cause precipitation of proteins in the body resulting in the damage of the liver.
It reacts with respiratory system and causes acute suffocation by blocking the respiratory tract.
The marine pollution has the following effects:
The nuclear wastes are disposed off in sealed containers in the deep seas. The leakage can cause serious damage to flora and fauna in marine habitat.
Oil spills cause frequent death of plankton, fish, coral reef, sea food and marine birds. The oil spreads on water and forms a layer, which is harmful for marine life. Some chemicals in the oil form a black layer on the surface which can coat the feathers of birds and fur of marine mammals. All of them die or drown. When the oil spill reaches the coast, it affects fishing activities and tourism.
Fresh Water Depletion and Contamination
Fresh water is naturally occurring water on Earth's surface in ice sheets, ice caps , glaciers, icebergs, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and other total dissolved solids.
Global freshwater consumption rose six-fold in the last century, at more than twice the rate of population growth. Yet for many of the world’s poor, one of the greatest environmental threats to health remains lack of access to safe water and sanitation. Over 1 billion people globally lack access to safe drinking-water supplies, while 2.6 billion lack adequate sanitation; diseases related to unsafe water, sanitation and hygiene result in an estimated 1.7 million deaths every year
Poor access to sufficient quantities of water also can be a key factor in water-related disease, and is closely related to ecosystem conditions. About one-third of the world's population lives in countries with moderate to high water stress, and problems of water scarcity are increasing, partly due to ecosystem depletion and contamination. Two out of every three persons on the globe may be living in water-stressed conditions by the year 2025, if present global consumption patterns continue.
Water ecosystems both replenish and purify water resources essential to human health and well-being. But the sustainability of many such ecosystems has been impacted by development and land use changes involving: elimination of marshes and wetlands; the diversion of surface water or alteration of flows; increased exploitation of underground aquifers; and contamination of water by waste and discharges from industry and transport, as well as from household and human waste.
The absolute quantity and the diversity of pollutants reaching freshwater systems have increased since the 1970s. These include not only biological contaminants, e.g. microorganisms responsible for traditional water-borne diseases, but also heavy metals and synthetic chemicals, including fertilizers and pesticides. Depending on the type of contaminant and degree of exposure, acute or chronic health impacts may result, along with impacts on the environment.
Biological oxygen demand (BOD) is the amount of dissolved oxygen needed (i. e., demanded) by aerobic biological organisms to break down organic material present in a given water sample at certain temperature over a specific time period. BOD can be used to gauge the effectiveness of wastewater treatment plants. Pristine rivers, where there is very little microbial growth have very less values of BOD (~1mg/L); untreated sewerage, which has high nutrients, and therefore, supports high micro-organism growth, has values ranging from 200-600mg/L.
P.S. - Dissolved oxygen depletion is most likely to become evident during the initial aquatic microbial population explosion in response to a large amount of organic material. If the microbial population deoxygenates the water, however, that lack of oxygen imposes a limit on population growth of aerobic aquatic microbial organisms resulting in a longer term food surplus and oxygen deficit.
One of the main problems affecting coastal waters is the high levels of nitrogen and phosphorous based pollutants entering the water. These pollutants come mainly from human activities. Excessive discharge of nutrients into coastal water results in accelerated phytoplankton growth. Eutrophication is defined as ‘enhanced plankton growth due to excess supply of nutrients’. Large growths of phytoplankton are known as blooms and these large blooms can have undesirable effects.
Major problems associated with eutrophication are:
● These blooms occur throughout the water and prevent light reaching the waters below. This stops the growth of plants deeper in the water and reduces biological diversity.
● When the blooms are really large, this bacterial decomposition can use up so much oxygen in the deep
waters that there isn't enough left for fish to breathe and they have to swim away or else they die. Animals living on the sea floor can't easily move away and they also die.
● Excess nutrients can sometimes encourage the growth of phytoplankton species which produce harmful toxins. These toxins may cause the death of other species including fish in fish farms.
● Large phytoplankton blooms can cause huge ugly foams on beaches. These blooms are not toxic but temporarily ruin the beach, reducing its recreational value.
1. Sewage treatments: Adequate care should be taken to ensure that effective sewage treatment process is in place and that contaminated water does not get mixed with the environment. In order to prevent water pollution, human and animal excreta should be prevented from mixing with its sources. Construction of pit toilet and proper sewage treatments can offer some solution to this problem.
Sewage contains large amounts of organic matter and microbes. Many of which are pathogenic. Treatment of waste water is done by the heterotrophic microbes naturally present in the sewage. This treatment is carried out in two stages:
Primary treatment: These treatment steps basically involve physical removal of particles- large and small- from the sewage through filtration and sedimentation. These are removed in stages; initially, floating debris is removed by sequential filtration. Then the grit (soil and small pebbles) are removed by sedimentation. All solids that settle form the primary sludge, and the supernatant forms the effluent. The effluent from the primary settling tank is taken for secondary treatment.
Secondary treatment or Biological treatment: The primary effluent is passed into large aeration tanks where it is constantly agitated mechanically and air is pumped into it. This allows vigorous growth of useful aerobic microbes into flocs (masses of bacteria associated with fungal filaments to form mesh like structures). While growing, these microbes consume the major part of the organic matter in the effluent. This significantly reduces the BOD (biochemical oxygen demand) of the effluent. BOD refers to the amount of the oxygen that would be consumed if all the organic matter in one litre of water were oxidised by bacteria. The sewage water is treated till the BOD is reduced. The BOD test measures the rate of uptake of oxygen by micro-organisms in a sample of water and thus, indirectly, BOD is a measure of the organic matter present in the water. Greater the BOD of waste-water, more is its polluting potential.
Once the BOD of sewage or waste water is reduced significantly, the effluent is then passed into a settling tank where the bacterial 'flocs' are allowed to sediment. This sediment is called activated sludge. A small part of the activated sludge is pumped back into the aeration tank to serve as the inoculum. The remaining major part of the sludge is pumped into large tanks called anaerobic sludge digesters. Here, other kinds of bacteria, which grow anaerobically, digest the bacteria and the fungi in the sludge. During this digestion, bacteria produce a mixture of gases such as methane, hydrogen sulphide and carbon dioxide. These gases form biogas and can be used as source of energy as it is inflammable. The effluent from the secondary treatment plant is generally released into natural water bodies like rivers and streams.
2. Prevent river water to get polluted: The flowing water of the river cannot be cleaned easily by natural process. Since, a large number of external substances are discharged into the water, the river water becomes polluted. This may cause diseases to the people using river water. Thus, every effort should be made to prevent the river water to get contaminated. People should not be allowed to throw wastes into the river water.
3. Treatment of wastes before discharge: Factories are expected to treat its effluent wastes prior to discharge. Toxic material must be treated chemically and converted into harmless materials. If possible, factories should try to recycle the treated water.
4. Strict adherence to water laws: Laws and legislation relating to pollution should be strictly followed by all. People should be made aware that adherence to water laws is in their own interest.
5. Treatment of drainage water: In cities, a huge amount of water is put into drains every day. The water that flows through the city drainage system should be properly treated. Harmful pollutants be removed, before they are introduced into reservoirs. If this water allowed going into water reservoirs without treatment, it will pollute them.
6. Keep the pond water clean and safe: Washing, bathing of cattle in the pond that is used by human should not be done. Washing of dirty clothes and bathing of cattle make the pond water dirty and unsuitable for human use. If these ponds are continually misuses, then it may lead of severe consequences.
7. Routine cleaning: Ponds, lakes and wells meant for human use should be routinely cleaned and treated, so
that it remains fit for human use. It is an essential step that should not be avoided. A system of regular testing of pond and lake water can be introduced to ensure the safety of the water.
8. Don’t pour insecticides in sinks and toilets: Never pour household insecticides, medicines, etc. down the sink, drain or toilet. At homes, people often throw wastes and old medicines into the bathroom toilet. This practice is discouraged for the reason that the chemical compounds of medicines, insecticides, etc., when mixed with other chemicals, may result in formation of harmful substances.
9. Public Awareness: Common public should be aware about the effect of water pollution. Voluntary organization should go door-to-door to educate the creating awareness about the environment. They should run environmental education centers. Students can impart health education to enable people to prevent water pollution.
Naturally decontaminating water
The cleaning occurs in two stages. Firstly, the conventional sedimentation, filtering and chlorine treatments are given. After this stage, lots of dangerous pollutants like dissolved heavy metals still remain. This water is then passed through large marshy area containing appropriate plants, algae, fungi and bacteria which neutralise, absorb and assimilate the pollutants. Hence, as the water flows through the marshes it gets purified naturally. The process of using fungal mycelia to filter toxic waste and microorganisms from water in soil is called Mycofiltration. Similarly use of plants to eliminate toxic waste from the water or other polluted medium is called phytoremediation. Many plants such as mustard plants, alpine pennycress, hemp, and pigweed have proven to be successful at hyperaccumulating contaminants at toxic waste sites. For bioremediation, read ahead.
Chlorine, Chloramine, Chlorine dioxide, Ozone and UV rays are commonly used as water disinfectant.
Bioamagnification, Bioaccumulation and Bioconcentration
Biomagnification (or Bioamplification) refers to an increase in the concentration of a substance as you move up the food chain. This often occurs because the pollutant is persistent, meaning that it cannot be, or is very slowly, broken down by natural processes. These persistent pollutants are transferred up the food chain faster than they are broken down or excreted.
In contrast, bioaccumulation occurs within an organism, where a concentration of a substance builds up in the tissues as it is absorbed faster than it is removed. Bioaccumulation often occurs in two ways, simultaneously: by eating contaminated food, and by absorption directly from water. This second case is specifically referred to as bioconcentration.
For example: phytoplankton and other microscopic organisms take up methylmercury and then retain it in their tissues. Here, mercury bioaccumulation is occurring: mercury concentrations are higher in the organisms than it is in the surrounding environment. As animals eat these smaller organisms, they receive their prey’s mercury burden. Because of this, animals that are higher in the food chain have higher levels of mercury than they would have due to regular exposure. With increasing trophic level, mercury levels are amplified.
5.9.3. POLLUTION DUE TO SOLID WASTES
All waste that we generate can be categorized into three types – bio-degradable, recyclable and the non-biodegradable. Solid wastes are generally composed of non-biodegradable and non-compostable biodegradable materials. The latter refer to solid wastes whose bio-deterioration is not complete; in the sense that the enzymes of microbial communities that feed on its residues cannot cause its disappearance or conversion into another compound.
Solid waste pollution is when the environment is filled with non-biodegradable and non-compostable biodegradable wastes that are capable of emitting greenhouse gases, toxic fumes, and particulate matters as they accumulate in open landfills. These wastes are also capable of leaching organic or chemical compositions to contaminate the ground where such wastes lay in accumulation. The concentration of solid wastes reacting to heat, moistures and air as they lay exposed to the environment also cause greenhouse gas emissions.
Irreparable computers and other electronic goods are known as electronic wastes (e-wastes). E-wastes are buried in landfills or incinerated. Over half of the e-wastes generated in the developed world are exported to developing countries, mainly to China, India and Pakistan, where metals like copper, iron, silicon, nickel and gold are recovered during recycling process. Unlike developed countries, which have specifically built facilities for recycling of e-wastes, recycling in developing countries often involves manual participation thus exposing workers to toxic substances present in e-wastes. Recycling is the only solution for the treatment of e-waste, provided it is carried out in an environment friendly manner.
The e-waste substances found in large quantities include epoxy resins, fiberglass, PCBs, PVC (polyvinyl chlorides), thermosetting plastics, lead, tin, copper, silicon, beryllium, carbon, iron and aluminium. Elements found in small amounts include cadmium, mercury, and thallium. Other elements are also present in trace amounts.
Burning is often used to treat the municipal solid waste. Burning reduces the volume of wastes, although it is generally not burn to completion and open dumps often serve as the breeding ground for rats and flies. Sanitary landfills adopted as the substitute for open-burning dumps. In a sanitary landfill wastes are dumped in a depression or trench after compaction and covered with dirt every day. Landfills are also not really much of a solution since the amount of garbage generation especially in the metros has increased so much that these sites are getting filled too. Also there is danger of seepage of toxic chemicals to the underground water resources.
A solution to all this can only be in human beings becoming more sensitive to environment issues. All waste should be sorted into three types (a) bio-degradable, (b) recyclable and (c) the non-biodegradable. What can be reused or recycled should be separated. The biodegradable materials can be put into deep pits in the ground and be left for natural breakdown. That leaves only the non-biodegradable to be disposed-off. The need to reduce our waste generation should be a priority and use of recyclable and biodegradable materials wherever possible be encouraged.
Regulation of E-Waste in India
As per the survey carried out by Central Pollution Control Board (CPCB) during the year 2005, 1,46,800 MT of e-waste was generated in the country. The Ministry of Environment & Forests has notified e-waste (Management and Handling) Rules, 2011 which have become effective from 1st May, 2012. These Rules provide for mandatory authorization of producer, collection center, dismantler and recycler of e-waste; registration of dismantler and recycler of e-waste from the State Pollution Control Board or Pollution Control Committee of Union territories; and ‘Extended Producer Responsibility’ under which producers will be responsible for collection and channelization of e-waste generated from the ‘end of life’ of their products to registered dismantler or recycler.
Import and export of e-waste are regulated under Hazardous Waste (Management, Handling and Trans-boundary Movements) Rules, 2008. Under the Rules no permission for import of e-waste has been granted during last three years by the Ministry of Environment and Forests. However, permission for export of 10,575 MT of e-waste has been granted for export of e-waste to various countries viz. Belgium, Germany, Japan, Singapore Hong Kong, Sweden, UK and Switzerland
5.9.4. RADIATION POLLUTION
Radiation, that is given off by nuclear waste is extremely damaging to organisms, because it causes mutations at a very high rate. At high doses, nuclear radiation is lethal but at lower doses, it creates various disorders, the most frequent of all being cancer. Therefore, nuclear waste is an extremely potent pollutant and has to be dealt with utmost caution.
The natural sources of radiation pollution include cosmic rays, ultraviolet rays and infra-red rays, which reaches the earth from the sun and other heavenly bodies. It also includes radioactive rays from unstable atoms of uranium, thorium and radium. The human-made radiations come from the use of radioactive materials, which are widely used in the production of nuclear weapons, nuclear fuel and electric power.
It has been recommended that storage of nuclear waste, after sufficient pre-treatment, should be done in suitably shielded containers buried within the rocks, about 500 m deep below the earth’s surface.
Soil pollution is defined as the change in the physical, chemical and biological conditions due to the presence of various toxic materials. Harmful substances are added to the soil through the surface run-off or through leaching. Soils can be polluted by pathogenic organisms, organic and inorganic chemicals and toxic metals. Some of the toxic chemicals from the polluted soils may enter the food chain and then enter the body of humans and other organisms, causing serious health problems.
Sources of Soil Pollution
Industrial effluents like harmful gases and chemicals.
Use of chemicals in agriculture like pesticides, fertilizers and insecticides.
Improper or ineffective soil management system.
Unfavorable irrigation practices, especially over-irrigation.
Improper management and maintenance of septic system, sanitary waste leakage, release sewage into dumping grounds and nearby water bodies.
Toxic fumes from industries get mixed with rains causing acid rains.
Leakages of fuel from automobiles are washed off due to rains and are deposited in the nearby soil.
Use of pesticides in agriculture retains chemicals in the environment for a long time. These chemicals also effect beneficial organisms like earthworm in the soil and lead to poor soil quality.
Garbage blocks passage of water into the soil and affects its water holding capacity.
Unscientific disposal of nuclear waste contaminate soil and can cause mutations.
Consequences of soil pollution
Soil pollution causes huge disturbances in the ecological balance and health of living organisms at an alarming rate. Some the effects of soil pollution are:
Reduced soil fertility causes decrease in agricultural yield.
Loss of natural nutrients in soil.
Reduced nitrogen fixation.
Increased soil erosion.
Imbalance in the flora and fauna of the soil.
Increase in soil salinity, makes it unfit for cultivation.
Creation of toxic dust.
Foul odor due to industrial chemicals and gases.
Alteration in soil structure can lead to death of organisms in it.
Reducing the use of chemical fertilizer and pesticides.
Recycling paper, plastics and other materials.
Ban on use of plastic bags, which are a major cause of pollution.
Avoiding deforestation and promoting forestation.
Suitable and safe disposal of wastes including nuclear wastes.
Chemical fertilizers and pesticides should be replaced by organic fertilizers and pesticides.
Encouraging social and agro forestry programs.
Undertaking many pollution awareness programs.
It is a treatment that uses naturally occurring organisms to break down hazardous substances into less toxic or non-toxic substances. It uses microorganisms to degrade organic contaminants in soil, groundwater, sludge, and solids. The microorganisms break down contaminants by using them as an energy source or cometabolizing them with an energy source. When Fungi are used, it is called mycoremediation. Bioremediation may be conducted in situ or ex situ. It has been relied up on to clean oil spills in the recent past using the bacteria of family Pseudomonas and other bacteria like Alcanivorax or Methylocella Silvestris.
Not all contaminants are easily treated by bioremediation using microorganisms. For example, heavy metals such as cadmium and lead are not readily absorbed or captured by microorganisms. Phytoremediation is useful in these circumstances because plants are able to bioaccumulate these toxins in their above-ground parts, which are then harvested for removal. Genetic engineering has been used to create organisms designed for specific purposes. For e.g. bacterium Deinococcus radiodurans (the most radioresistant organism known) has been modified to consume and digest toluene and ionic mercury from highly radioactive nuclear waste. However, releasing GM organisms into the environment may be problematic as tracking them can be difficult; bioluminescence genes from other species may be inserted to make this easier.
5.9.5. NOISE POLLUTION
Sound, which is measured in decibels (dB), is a form of energy having wave motion. Any sound, which is unwanted or unpleasant to our ears, is called noise. Thus any undesirable sound which adversely affects the physical and mental health of its recipient is called noise pollution. The noise pollution can be due to natural processes or human activities. It is caused by industries, mining, transport vehicles, thunder, households, defence sector, loudspeakers, supersonic jet aircrafts and others. Loud noise can cause impairment of hearing or total deafness.
It causes anxiety and stress reaction and in extreme cases, fright.
There is increase in heart rate.
Increase in cholesterol and blood pressure due to constriction of blood vessels.
Stomach disorders and digestive spasm.
Dilation of pupil of the eye.
It also interferes with peace of mind, behaviour and proper communication.
Nervousness, headache, irritability, fatigue and decrease in work efficiency can be caused due to noise pollution.
It also affects the development of embryo in mother's womb.
Effects on Wildlife: It can lead to changes in the delicate balance in predator and prey detection, interferes with the sounds of communication and in the relations to reproduction and navigation and overexposure to noise can lead to temporary or permanent loss of hearing.
Green Mufflers are barriers grown near noisy places to reduce the impact of noise. Normally 4 to 5 rows of green plants are grown near the noisy places like highways or industrial areas so that they obstruct the sound noise.