Environmental Pollution Environmental pollution can be defined as

Environmental Pollution Environmental pollution can be defined as any undesirable change in the physical, chemical or biological characteristics of any component of the environment ( air, water, soil), which can cause harmful effects on various form of life or property. Pollutant are defined as matter or energy which leads to undesirable changes in the environment. Pollutants include solid, liquid or gaseous substances present in greater than natural abundance produced due to human activity, which have a detrimental effect on our environment. From an ecological perspective pollutants can be classified as follows: 1) Degradable or non-persistent pollutants: These can be rapidly broken down by natural processes. Eg: domestic sewage, discarded vegetables etc. 1) Slowly degradable or persistent pollutants: Pollutants that remain in the environment for many years in an unchanged condition and take decades or longer to degrade. Eg: DDT and most plastics. 1) Non-degradable pollutants: These cannot be degraded by natural processes. Once they are released into the environment they are difficult to eradicate and continue to accumulate. Eg: toxic elements like lead or mercury.

Environmental Pollution could be of various types: 1) Air Pollution: Air pollution occurs due to the presence of certain substances (including the normal constituent in excess) in concentration which can cause undesirable effects on human health, property and structure. These substance include gases, particulate matter, radioactive substances etc. Classification of Air Pollutants: Based upon their origin air pollutant are classified into two type: a) Primary Pollutants: Pollutants that are emitted directly from identifiable sources are produced both by natural events (for example, dust storms and volcanic eruptions) and human activities (emission from vehicles, industries, etc. ). There are five primary pollutants that together contribute about 90 percent of the global air pollution. These are carbon oxides (CO and CO 2), nitrogen oxides, sulfur oxides, volatile organic compounds (mostly hydrocarbons) and suspended particulate matter.

Major primary pollutant: 1) Particulate matter: Particulates are small pieces of solid material (for example, smoke particles from fires, bits of asbestos, dust particles and ash from industries) dispersed into the atmosphere. The effects of particulates range from soot to the carcinogenic (cancer causing) effects of asbestos, dust particles and ash from industrial plants that are dispersed into the atmosphere. Some definition: a) Aerosol : General term for particles suspended in air. Example: Sprays from pressurized cans a) Mist : Aerosol consisting of liquid droplets. Example: Sulfuric acid mist a) Dust : Aerosol consisting of solid particles that are blown into the air or are produced from larger particles by grinding them down. Example : Dust storm

d ) Smoke: Aerosol consisting of solid particles or a mixture of solid and liquid particles produced by chemical reaction such as fires. Example: Cigarette smoke, smoke from burning garbage. e) Fume : It applies specifically to aerosols produced by condensation of hot vapors of metals. Example: Zinc/lead fumes f) Plume : Geometrical shape or form of the smoke coming out of a chimney. g) Fog : Aerosol consisting of water droplets. h) Smog : Term used to describe a mixture of smoke and fog. 2) Hydrocarbon: Hydrocarbons are a group of compounds consisting of carbon and hydrogen atoms. They either evaporate from fuel supplies or are remnants of fuel that did not burn completely. They act as precursor for the production of secondary pollutant. 3) Nitrogen oxides: Nitrogen oxides are found in vehicular exhausts. Nitrogen oxides are significant, as they are involved in the production of secondary air pollutants such as ozone. They are also important component of acid rain.

4) Sulfur oxides: are produced when sulfur containing fossil fuels are burnt. They are major source of increase acidity in the atmospheric rain, a phenomenon known as acid rain. 5) Carbon monoxide: is a colorless, odorless and toxic gas produced when organic materials such as natural gas, coal or wood are incompletely burnt. Vehicular exhausts are the single largest source of carbon monoxide. Carbon monoxide is however not a persistent pollutant. Natural processes can convert carbon monoxide to other compounds that are not harmful. 6) Carbon dioxide: It is a component of atmospheric system and currently make 0. 038 per cent of the atmosphere. It is important for maintaining the biotic system as source of carbon. However during past decade its concentration is increasing in atmosphere due to burning of fossils fuel and land use changes. It shows property of green house gas, thereby results into a phenomenon known as global warming. Beside these primary pollutant there are certain pollutant which are not a natural component of atmosphere, however it is introduced by human activities, such as CFC, MIC (methyl isocyanate).

b) Secondary Pollutant: Pollutants that are produced in the atmosphere when certain chemical reactions take place among the primary pollutants are called secondary pollutants. Eg: sulfuric acid, nitric acid, carbonic acid, etc. Some more example of Secondary pollutant: a) Tropospheric Ozone: The majority of tropospheric ozone formation occurs when nitrogen oxides (NOx), carbon monoxide (CO) and volatile organic compounds (VOCs), such as xylene, react in the atmosphere in the presence of sunlight. NOx, CO, and VOCs are called ozone precursors.

b) Peroxyacetyl nitrate (PAN): Acyl peroxy nitrates, or Peroxyacyl nitrates (also known as APNs, or PANs), are powerful respiratory and eye irritants present in photochemical smog. CH 3 C(O)OO· + NO 2 → CH 3 C(O)OONO 2 General equation: Hydrocarbons + O 2 + light → Cx. Hy. C(O)OO· + NO 2 → Cx. Hy. C(O)OONO 2 Sources of Air Pollutants: It is mainly divided into two types: a) Natural sources: The natural sources of air pollution are volcanic eruption, forest fire, sea salt sprays, biological decay, pollen grains of flowers, spore etc. Radioactive material present in earth crust are the sources of radioactivity in the atmosphere. a) Man-made (Anthropogenic sources): it include thermal power plant, industrial units, vehicular emissions, fossil fuel burning, agricultural activities etc.

Human can be affected by both indoor or outdoor air pollution. The most important indoor air pollutant is radon gas ( causing lung cancer) a 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 (bricks, concrete, tiles etc) themselves. Beside radon carbon monoxide, sulphur dioxide and hydrocarbon released due to incomplete combustion of fossil fuel, wood for cooking purpose are other major air pollutant. Fate of pollutant in the atmosphere: • Once pollutants enter the troposphere they are transported downwind, diluted by the large volume of air, transformed through either physical or chemical changes or are removed from the atmosphere by rain during which they are attached to water vapor that subsequently forms rain or snow that falls to the earth’s surface. • However this transportation and dilution of air pollutant depend strongly upon the metrological condition prevailing in that area. In an unstable atmosphere with high wind speed dispersion and dilution rate of pollutant are much higher compare to a stable atmosphere.

Stable atmosphere: If we (somehow) lift the parcel: It will cool at the dry adiabatic lapse rate. The parcel will find itself cooler than the environmental (sounding) temperature. At the same pressure, a cooler parcel will be more dense than the environment. Being denser, the parcel will descend back to where it came from. STABLE!

Unstable atmosphere: If we (somehow) lift the parcel: It will cool at the dry adiabatic lapse rate. The parcel will find itself warmer than the environmental (sounding) temperature. At the same pressure, a warmer parcel will be less dense than the environment. Being less dense, the parcel will ascend and move farther from where it came from. UNSTABLE!

Temperature Inversion: • Although the temperature of air relatively near the earth’s surface normally decreases with increasing altitude, certain atmospheric conditions can result in the opposite condition—increasing temperature with increasing altitude. Such conditions are characterized by high atmospheric stability and are known as temperature inversions. Because they limit the vertical circulation of air, temperature inversions result in air stagnation and the trapping of air pollutants in localized areas. Frontal inversion: An inversion can form from the collision of a warm air mass (warm front) with a cold air mass (cold front). The warm air mass overrides the cold air mass in the frontal area, producing the inversion. Radiation inversions: It is the most common form of surface inversion and occurs when the earth's surface cools rapidly. As the earth cools, so does the layer of air close to the surface. If this air cools to a temperature below that of the air above, it becomes very stable, and the layer of warmer air impedes any vertical motion. Radiation inversions usually occur in the late evening through the early morning under clear skies with calm winds, when the cooling effect is greatest.

Subsidence inversions: It takes place in hill area, where cooler surface air tends to flow into valleys at night, where it is overlain by warmer, less dense air. , often accompanied by radiation inversions, can become very widespread. marine inversion is produced during the summer months when cool air laden with moisture from the ocean blows onshore and under warm, dry inland air. Illustration of pollutants trapped in a temperature inversion.

Impact of Temperature Inversion: Due to temperature inversion condition, environment become more stable thereby prevent dispersal and dilution of air pollutant from localized areas. One major air pollution scenario due to temperature inversion condition is London Smog (winter of 1952). The weather in Greater London had been unusually cold for several weeks leading up to the event. Because of the cold weather, households were burning more coal than usual to keep warm. The smoke from approximately one million coal-fired stoves, in addition to the emissions from local industry, was released into the atmosphere. Thousands of tons of black soot, tar particles, and sulfur dioxide had accumulated in the air from the heavy coal combustion. Estimates of PM 10 concentrations during December, 1952, range between 3, 000 and 14, 000 μg/m³ with the high range being approximately 50 times higher than normal levels at the time. PM 10 is particulate matter less than 10 micrometers in diameter. Due to temperature inversion condition the thick, smoke-polluted air to be trapped under the inversion. The following 114 hours in London experienced visibility less than 500 meters with 48 hours below 50 meters visibility. The smog-related deaths were primarily attributed to pneumonia, bronchitis, tuberculosis, and heart failure.

Effect of air pollution: Air pollution has adverse effects on living organisms and materials. 1) Effects on human health: • Air pollutants especially particulate matter( PM) is related to respiratory disease in human being. Particles come in a wide range of sizes. Those less than 10 micrometers in diameter (PM 10) are so small that they can get into the lungs, potentially causing serious health problems. Suspended particulates can cause damage to lung tissues and diseases like asthma, chronic bronchitis and emphysema( damage of air sacs leading to loss of lung elasticity and acute shortness of breath. Metal in form of PM like lead, Asbestos etc also cause cancer or affect vital organs like kidney, liver, spleen etc. • Carbon monoxides combine with hemoglobin of blood to form carboxyhaemoglobin, due to which oxygen carrying capacity to various part of the body decrease which may results into suffocation, dizziness, unconsciousness and even death. • Hydrocarbon emission from vehicle or industrial units ( benzene, formaldehyde etc. ) may results into mutation, reproductive problem or even cancer.

2) Effects on Plant: Air pollution affects plant by entering through stomata (leaf pores through which gases diffuse), destroy chlorophyll and affect photosynthesis. Gaseous pollutant like SO 2, ozone etc can leads to necrosis( dead areas of leaf), chlorosis( yellowing of leaf due to reduction of chlorophyll), abscission ( dropping of leaves). 3) Effects on aquatic life: Air pollutants (SOx and NOx) when mix up with rain can results into acid rain which reduces the p. H of fresh water lakes especially in the higher latitude. This reduction in p. H has adverse effect on aquatic biotic life. 4) Effects on materials: Metal parts of building, vehicle, bridges, wires and railway tracks are affected due to corrosion by particulate matter which further get accerlated in presence of SO 2 and moisture. Acid rain also affect the structure made up of marble and limestone. Example: Yellowing of Tajmahal in Agra. Ozone in the atmosphere can cause cracking of rubber tyres. Beside these effect, air pollutants also leads to stratospheric Ozone depletion which results into increase UV-rays exposure on earth surface and Global warming due to green house gases are major environmental problem.

Control of Air Pollution: Air pollution can be controlled by applying various measures such as: 1) Zonation in landuse pattern: Industries should be set up far away from the residential areas and Industries should be located in places so as to minimize the effects of pollution after considering the topography and the wind directions. 2) Dilution of emission: It can be done by increasing stack height, beyond inversion layer. Wind current will disperse the pollutant. 3) Low Sulphur coal in industries to reduce emission of SOx from coal burning. 4) Installment of pollutant control equipment such as cyclones, bag house filters etc to reduce pollutant emission from industry. 5) Establish vehicular emission norm to reduce emission from vehicles, regular tuning of engines, installing catalytic converters, engine modification to have fuel efficient (lean) mixture to reduce CO and hydrocarbon emission, slow and cooler burning of fuels to reduce NOx emission( Honda Technology). 6) Using mass transport system, bicycles etc.

Bharat stage emission standards are emission standards instituted by Government of India to regulate the output of air pollutants from internal combustion engine equipments, including motor vehicles. The standards and the timeline for implementation are set by the Central Pollution Control Board under the Ministry of Environment & Forests.

Air Pollution control through pollution control equipment: 1) Particulate matter: Many devices are available for removal of particulate matter and choice of which depend upon characteristics of particulate matter, flow rate, collection efficiency, costs etc. a) Cyclone: These are employed for large size particle. The gas with particle in it enters tangentially at the top of cylinder and spin forming a vortex. Due to centrifugal force, particle strike the wall of cylinder.

b) Bag house filter: It contain large number of filter bags made of fabric. Dirty gas is passed through the filter bags which leaves the bags through their pores. The dust particle get deposited on the inner surface of the bag filters and may form a cake which can be removed by shaking. c) Wet scrubber: Dirty gas is passed through water in the chamber or water is sprayed on the gas. Particles are made wet and are removed from the gas stream which leaves from the top of scrubber.

d) Electrostatic precipitator: It can be plate type or cylinder type. Vertical wires are placed between the parallel plates or wires is hung along the axis of the cylinder. Higher negative voltage is applied to the wire. Dust particle while passing from the lower end get negatively charged and are collected on the positively charges surface. Electrostatic precipitators utilize electric energy and can efficiently remove even submicroscopic particles. 2) Gaseous pollutant: Gaseous pollutant can be reduced by physical absorption on porous solid materials like activated charcoal, silica gel etc. Effluent gases can be absorbed in liquid absorbent, example: SO 2 absorbed in ammonia solution.

Air quality monitoring: The Central Pollution Control Board (CPCB) initiated its own national Ambient Air Quality Monitoring (NAAQM) program in 1985. Ambient air quality standards in India developed by the Central Pollution Control Board

Legal aspects of air pollution control in India: The Air (Prevention and Control of Pollution) Act was legislated in 1981. The Act provided for prevention, control and abatement of air pollution. In areas notified under this Act no industrial pollution causing activity could come up without the permission of the concerned State Pollution Control Board. To regulate vehicular pollution the Central Motor Vehicles Act of 1939 was amended in 1989. Following this amendment the exhaust emission rules for vehicle owners were notified in 1990 and the mass emission standards for vehicle manufacturers were enforced in 1991 for the first time. The mass emission norms have been further revised for 2000.

Water Pollution When the quality or composition of water changes directly or indirectly as a result of man’s activities such that it becomes unfit for any purpose it is said to be polluted. Water pollution can be defined as alteration in physical, chemical or biological characteristics of water making it unsuitable for the designated use in its natural state. Source of water pollution: Water pollution can be divided into two broad category depending upon source nature: Point sources: When a source of pollution can be readily identified because it has a definite source and place where it enters the water it is said to come from a point source. Eg. Municipal and Industrial Discharge Pipes. 2) Non-point sources: When a source of pollution cannot be readily identified, such as agricultural runoff, atmospheric deposition , etc, they are said to be non-point sources of pollution.

Source of water pollution can be different for both ground water and surface water. Ground water Pollution: While surface water pollution are highly visible and often get a lot of media attention, a much greater threat to human life comes from our groundwater being polluted which is used for drinking and irrigation. Major source of ground water pollution are: a) Urban run-off of untreated or poorly treated waste water and garbage. Industrial waste storage located above or near aquifers. Agricultural practices such as the application of large amounts of fertilizers and pesticides, animal feeding operations, etc. in the rural sector. Leakage from underground storage tanks containing gasoline and other hazardous substances. e) Leachate from landfills. f) Poorly designed and inadequately maintained septic tanks.

Beside these sources of ground water pollution, high metal concentration in ground water in some part of country is also very serious environmental issue. The high Arsenic concentration in ground water in West Bengal is known today as the worst case of groundwater pollution. The arsenic poisoning was first noticed by K C Saha, former professor of dermatology at the School of Tropical Medicine, Kolkata when he began to receive patients with skin lesions that resembled the symptoms of leprosy which was in reality not leprosy. Since all the patients were from the district of 24 -Parganas, Saha along with others began to look for the cause and found it to be arsenic toxicity. There are two theories that have been put forth to explain this unusually high content of arsenic in groundwater. a) According to the first hypothesis, arsenic probably originates in the Himalayan headwaters of the Ganga and the Brahmaputra rivers and has been lying undisturbed beneath the surface of the region’s deltas for thousands of years in the thick layers of fine alluvial mud across the banks of these rivers.

The mud in these areas is thicker, wider and flatter than almost anywhere else on earth. It can thus take hundreds or thousands of years for underground water to percolate through the mud before reaching the sea and thus it absorbs arsenic for a long period. b) Other researchers feel that the excess amount of arsenic in groundwater can be contributed to by the high rate of groundwater extraction. Their hypothesis called the pyrite oxidation thesis describes how arsenic can get mobilized in the groundwater. In this hypothesis arsenic is assumed to be present in certain minerals (pyrites) that are deposited within the aquifer sediments. Due to the lowering of the water table below the deposits, arsenopyrite which is oxidized in a zone of the aquifer called the Vadose zone releases arsenic adsorbed on iron hydroxide. During the subsequent recharge period, iron hydroxide releases arsenic into groundwater. Arsenicosis or arsenic toxicity develops after two to five years of exposure to arsenic contaminated drinking water depending on the amount of water consumption and the arsenic concentration in water. Initially the skin begins to darken (called diffuse melanosis) which later leads to spotted melanosis when darkened sports begin to appear on the chest, back and limbs. At a later stage leucomelanosis sets in and the body begins to show black and white spots.

Surface water pollution: The major source of surface water pollution are: Sewage: Domestic waste mostly dumped into the nearby surface water bodies through drain and sewers are major source of pollution especially near the big cities. Industrial effluents: waste emerging out of industrial units are major source of toxic chemicals, acids, alkalis, metallic salts, organic material to the surface water bodies. Synthetic detergents: They are used in washing and cleaning processes in domestic and industrial unit and are major source of phosphate to surface water bodies. Agrochemicals: Chemicals like fertilizers, pesticides and insecticides applied in the agricultural land or urban garden areas washed away with rainwater and surface runoff from these area are major pollution source. Oil: Oil spillage into sea-water during drilling and shipment transport are major source of water pollution.

6) Waste heat: Thermal pollution occurs when industry returns the heated water to a water source. The warm water not only decreases the solubility of oxygen but changes the breeding cycles of various aquatic organisms. The state of India’s rivers Urbanization, industrialization, excess withdrawal of water, agricultural run-off, improper agricultural practices and various religious and social practices all contribute to river pollution in India. Waters from the Ganga and the Yamuna are drawn for irrigation through the network of canals as soon as these rivers reach the plains reducing the amount of water that flows downstream. What flows in the river is water from small nalas, and streams that carry with them sewage and industrial effluents. Sewage and municipal effluents account for 75% of the pollution load in rivers while the remaining 25% is from industrial effluents and non-point pollution sources. In 1985, India launched the Ganga Action plan (GAP) the largest ever river clean-up operation in the country. The GAP Phase II in 1991 included cleaning operations for the tributaries of the Ganga, ie; the Yamuna, Gomti and the Damodar. Thus the Yamuna Action Plan (YAP), Gomti Action Plan and the Damodar Action plan were added.

In 1995 the National River Conservation plan( NRCP) was launched. Under this all the rivers in India were taken up for clean-up operations. In most of these plans, attempts have been made to tap drains, divert sewage to sewage treatment plants before letting out the sewage into the rivers. NRCP is scheduled to be completed by March 2005. The approved cost for the plan is Rs. 772. 08 crores covering 18 rivers in 10 states including 46 towns. The cost is borne entirely by the Central Government and the Ministry of Environment and Forests is the nodal agency that co-ordinates and monitors the plan. Under this plan the major activities include treating the pollution load from sewer systems of towns and cities, setting up of Sewage treatment plants, electric crematoria, low cost sanitation facilities, riverfront development, afforestation and solid waste management. Water pollutants are classified into different class depending upon their nature: 1) Oxygen demanding waste: These are organic wastes that can be decomposed by aerobic (oxygen requiring) bacteria. Large populations of bacteria use up the oxygen present in water to degrade these wastes.

The amount of oxygen required to break down a certain amount of organic matter is called the biological oxygen demand (BOD). The amount of BOD in the water is an indicator of the level of pollution. If too much organic matter is added to the water all the available oxygen is used up. This causes fish and other forms of oxygen dependent aquatic life to die. 2) Disease-causing agents: It include bacteria, viruses, protozoa and parasitic worms that enter water from domestic sewage and untreated human and animal wastes. Human wastes contain concentrated populations of coliform bacteria such as Escherichia coli and Streptococcus faecalis. These bacteria are not harmful in low numbers. Large amounts of human waste in water, increases the number of these bacteria which cause gastrointestinal diseases. 3) Inorganic plant nutrients: These are water soluble nitrates and phosphates that cause excessive growth of algae and other aquatic plants. The excessive growth of algae and aquatic plants due to added nutrients is called eutrophication. While excess fertilizers cause eutrophication, pesticides cause bioaccumulation and biomagnification. At each link in the food chain these chemicals which do not pass out of the body are accumulated and increasingly concentrated resulting in biomagnification of these harmful substances.

4) Water soluble inorganic chemicals: It includes acids, salts and compounds of toxic metals such as mercury and lead. High levels of these chemicals can make the water unfit to drink, harm fish and other aquatic life, reduce crop yields and accelerate corrosion of equipment that use this water. The disease called Minamata disease occurred due to consumption of methyl mercury contaminated fish caught from Minamata bay in Japan. The disease claimed 50 lives and permanently paralysed over 700 persons. Pollution from hevy metal cadmium had caused the disease Itai-Itai in the people of Japan. This disease was caused by cadmium contaminated rice. In this disease bones, liver, kidney, lungs, pancreas and thyroid are affected. 5) organic chemicals: It include oil, gasoline, plastics, pesticides, cleaning solvents, detergent and many other chemicals. These are harmful to aquatic life and human health. 6) Sediment of suspended matter: These are insoluble particles of soil and other solids that become suspended in water. This occurs when soil is eroded from the land. High levels of soil particles suspended in water, interferes with the penetration of sunlight. This reduces the photosynthetic activity of aquatic plants and algae disrupting the ecological balance of the aquatic bodies.

7) Water soluble radioactive isotopes: These can be concentrated in various tissues and organs as they pass through food chains and food webs. Ionizing radiation emitted by such isotopes can cause birth defects, cancer and genetic damage. 8) Hot water: Water is used for cooling purpose in Thermal power plant and other industries. Thermal pollution occurs when industry returns the heated water to a water source. This heated water, which is at least 15 o. C higher than the normal is discharged back into the water body. The warm water not only decreases the solubility of oxygen but changes the breeding cycles of various aquatic organisms. Control of water pollution: Non-point sources are difficult to control in respect to point sources, discharge from point sources can be controlled by using different treatment process. Non-point pollution can be reduced by reducing use of chemical fertilizer, pesticides and insecticides applied to agricultural field. By reducing the amount of surface runoff by lining the street with percolating materials and prevent the mixing of storm water with the sewer water to avoid overflowing of sewer line.

Municipal waste water treatment Plant: The municipal waste water treatment plant are deigned to reduced the BOD and suspended solid load from the domestic sewage. Some of the treatment plant also use advanced treatment (tertiary) for removal of nutrients such as nitrogen and phosphate.

Primary treatment: These treatment plants use physical processes such as screening and sedimentation to remove pollutants that will settle, float or, that are too large to pass through simple screening devices. This includes, stones, sticks, rags, and all such material that can clog pipes. A screen consists of parallel bars spaced 2 to 7 cms apart followed by a wire mesh with smaller openings. After screening the wastewater passes into a grit chamber. The detention time is chosen to be long enough to allow lighter, organic material to settle. From the grit chamber the sewage passes into a primary settling tank (also called as sedimentation tank) where the flow speed is reduced sufficiently to allow most of the suspended solids to settle out by gravity. Primary treatment normally removes about 35 percent of the BOD and 60 percent of the suspended solids. Secondary treatment: There are three commonly used approaches: trickling filters, activated sludge process and oxidation ponds. Secondary treatment can remove at least 85 percent of the BOD.

Trickling filter: It consists of a rotating distribution arm that sprays liquid wastewater over a circular bed of ‘fist size’ rocks or other coarse materials. The spaces between the rocks allow air to circulate easily so that aerobic conditions can be maintained. The individual rocks in the bed are covered with a layer of slime, which consists of bacteria, fungi, algae, etc. which degrade the waste trickling through the bed. Trickling filter

Activated sludge process: The sewage is pumped into a large tank and mixed for several hours with bacteria rich sludge and air bubbles to facilitate degradation by microorganisms. The water then goes into a sedimentation tank where most of the microorganisms settle out as sludge. This sludge is then broken down in an anaerobic digester where methane-forming bacteria slowly convert the organic matter into carbon dioxide, methane and other stable end products.

Oxidation ponds These are large shallow ponds approximately 1 to 2 meters deep where raw or partially treated sewage is decomposed by microorganisms. They are easy to build and manage and accommodate large fluctuations in flow and can provide treatment at a much lower cost. They however require a large amount of land hence can be used where land is not a limitation. Advanced sewage treatment: This involves a series of chemical and physical process that removes specific pollutants left in the water after primary and secondary treatment. Sewage treatment plant effluents contain nitrates and phosphates in large amounts. These contribute to eutrophication. Thus advanced treatment plants are designed to specifically remove these contaminants. Chlorination of water is generally done to kill harmful bacteria and some viruses. Advanced treatment plants are very expensive to build and operate and hence are rarely used.

Thermal Pollution It is defined as presence of waste heat in the water which can cause undesirable changes in the natural environment. Causes of thermal pollution: Heat producing industries i. e. , thermal power plant, nuclear power plants, refineries, steel mills, etc are the major sources of thermal pollution. Power plants heat water to convert it into steam, to drive the turbines that generate electricity. For efficient functioning of the steam turbines, the steam is condensed into water after it leaves the turbines. This condensation is done by taking water from a water body to absorb the heat. This heated water, which is at least 15 o. C higher than the normal is discharged back into the water body. Effect of Thermal Pollution: 1) The dissolved oxygen concentration (DO) of water is decreased as the solubility of oxygen in water is decreased at high temperature.

2) Toxicity of pesticides, detergents and chemicals in the effluent increases with increase in temperature. 3) The composition of flora and fauna changes because the species sensitive to increased temperature due to thermal shock will be replaced by temperature tolerant species. 4) Metabolic activities of aquatic organisms increase at high temperature and require more oxygen, whereas oxygen level falls under thermal pollution. 5) Discharge of heated water near the shores can disturb spawning and can even kill young fishes. 6) Fish migration is affected due to formation of various thermal zones. Control of Thermal Pollution: Thermal pollution are control by using following majors: 1) Cooling ponds: Water from condenser is stored in ponds where natural evaporation cools the water which can then be recirculated or discharged in nearby water body.

Cooling ponds 2) Spray Ponds: The water from condenser is received in spray ponds. Here the water is sprayed through nozzles where fine droplets are formed. Heat from these fine droplet is dissipated to the atmosphere.

3) Cooling towers: It can be of two types: Wet cooling tower: Hot water is sprayed over baffles. Cool air entering from sides take away the heat and cools the water. This cool water can be recycled or discharged. Dry cooling tower: The heated water flow through pipes. Air is passed over these hot pipes with fans. It is costlier than wet cooling tower.

Wet Cooling Tower

Marine Pollution Marine pollution can be defined as the introduction of substances to the marine environment directly or indirectly by man resulting in adverse effects such as hazards to marine biota, obstruction of marine activities and lowering the quality of sea water. Sources of Marine Pollution: 1) The municipal waste and sewage from residences and hotels in coastal towns are directly discharged into the sea. 1) Pesticides and fertilizers from agriculture which are washed off the land by rain, enter water courses and eventually reach the sea. 3) Petroleum and oils washed off from the roads normally enter the sewage system but storm water overflows carry these materials into rivers and eventually into the seas. 4) Oil release due to Ship accidents and accidental spillages at sea can be very damaging to the marine environment.

5) Offshore oil exploration and extraction also pollute the seawater to a large extent. Pollution due to oil: Oil pollution of the sea normally attracts the greatest attention because of its visibility. There are several sources though which the oil can reach the sea. Tanker operations: After a tanker has unloaded its cargo of oil it has to take on seawater as ballast for the return journey. This ballast water is stored in the cargo compartments that previously contained the oil. load-on-top system and ‘crude oil washing’ are used to reduced the amount of oil in the ballast water. 2) Dry docking: All ships need periodic dry docking for servicing, repairs, cleaning the hull, etc. During this period when the cargo compartments are to completely emptied, residual oil finds its way into the sea. 3) Bilge and fuel oils : This generate in the process of emptying fuel tanker. 4) Tanker accidents: Tanker accidents are major source of oil-spillage in the sea.

5) Offshore oil production: Oil that is extracted from the seabed contains some water. Even after it is passed through oil separators the water that is discharged contains some oil, which adds to marine pollution. Uncontrolled release of oil from the wells can be catastrophic events resulting in oil pollution. Effects of marine pollution: When liquid oil is spilled on the sea it spreads over the surface of the water to form a thin film called an oil slick. The rate of spreading and the thickness of the film depends on the sea temperature and the nature of the oil. Oil slicks damage marine life to a large extent. Salt marshes, mangrove swamps are likely to trap oil and the plants, which form the basis for these ecosystems thus suffer. If liquid oil contaminates a bird’s plumage its water repellent properties are lost. Water thus penetrates the plumage and displaces the air trapped between the feathers and the skin. This air layer is necessary as it provides buoyancy and thermal insulation. Birds often clean their plumage by preening and in the process consume oil which depending on its toxicity can lead to intestinal, renal or liver failure.

Control measures for oil pollution: The natural process of emulsification of oil in the water can be accelerated through the use of chemical dispersants which can be sprayed on the oil. The oil pollution control has physical strategy i. e. mechanical booms or barriers are spread around an oil slick to check it progress. Natural material like peat moss, straw, sawdust, and pine bark can be used as dispersants. Bioremediation is fast emerging technology for cleaning the clean oil spill by using strain of microbes which decomposes oil. Control of marine pollution: Toxic pollutant from industries and sewage treatment plant should not be discharged in coastal area. Run off from non-point sources should be prevented to reach coastal area. Ecological sensitive coastal area should be protected from oil-drilling activiteis. Oil Ballast should not be dumped to the sea.

Soil Pollution Soil is a thin covering over the land consisting of a mixture of minerals, organic material, living organisms, air and water that together support the growth of plant life. Sources of soil pollution: Dumping of domestic and industrial waste on soil surface results into soil pollution. Domestic waste include garbage, rubbish material like glass, plastic, metallic can, paper, fibers etc. Industrial wastes are effluent discharged from industries and type of contaminant are dependent upon the type of Industry present. For example: paper and pulp industry mostly generate organic waste, Thermal power plant generate fly ash, or precipitate forms during treatment of pollutant gas produced due to combustion processes. • Application of fertilizers and Insecticides into agricultural land are other important category of soil pollution. Persistent pesticides once applied are effective for a long time. However as they do not break down easily they tend to accumulate in the soil and in the bodies of animals in the food chain.

• Soil also receive excreta from animals and humans. The sewage sludge contain many pathogenic organism, bacteria, viruses and intestinal worm which cause pollution in the soil. • The source of radioactive substances in soil are explosion of radioactive devices, radioactive waste discharged from industries and laboratories, aerial fall out etc. The main isotopes are radium, uranium, thorium, strontium etc. Effects of soil pollution: • Sewage and industrial effluents which pollute the soil ultimately affect human health. One example is Itai-Itai disease which occurs due to consumption of Cd containing rice. The chemical discharge on soil such as acid and alkali also affects the soil fertility. • Some of the persistent toxic chemicals target the non-target organisms, soil flora and fauna and reduced soil fertility. These chemical accumulates in food chain and ultimately affect human health. • Radioactive fallout on soil are source of radio-isotopes which enter the food chain. Some of these replace essential elements in the body and cause abnormalities. Example: strontium-90 instead of calcium gets deposited in the bones and tissue.

• Nitrogen and phosphorous from fertilizers in soil reach nearby water bodies with agricultural run-off and cause eutrophication. Control of Soil Pollution: • Effluent should be properly treated before discharging them on the soil. • Solid waste should be properly collected and disposed off by appropriate method. • Biodegradable organic waste( cattle waste, human faeces) should be used for generation of biogas. • Microbial degradation of biodegradable substances is also employed for reducing soil pollution.

Nuclear Hazards Radioactive substances undergo natural radioactive decay in which unstable isotopes spontaneously give out fast moving particles, high energy radiation or both, at fixed rate until a new stable isotope is formed. The isotopes release energy either in the form of gamma rays high energy electromagnetic radiation), or ionization particles i. e. alpha particles and beta particles.

Penetrating power of alpha, beta and gamma particle

Sources of Radioactivity: It can be both natural or man made sources: 1) Natural sources: It includes cosmic rays from outer space, radioactive radon-222, soil, rocks, air, water and food , which contain one or more radioactive substances. 2) Anthropogenic sources: It includes nuclear power plants, nuclear accidents, nuclear weapon testing, X-rays, diagnostic kits, research laboratories etc. Effect of Radiations: Ionization radiations can affect living organisms by causing harmful changes in body cells and also damage at genetic level. Genetic damage: It includes mutation in the DNA, thereby affecting genes and chromosome. The damage can be transmitted up to several generation. Somatic damage: it includes burns, miscarriage, eye cataract and cancer of bone, thyroid, lungs and skin. Example: Radioactive iodine (I 131) accumulates in thyroid gland causes cancer. Strontium-90 accumulates in the bones and causes leukemia or cancer of bone marrow.

The damage cause by different type of radiation depends on the penetration power. The Alpha particles cannot penetrate the skin to reach internal organs whereas beta particles can damage the internal organs. Greater threat is posed by radioisotopes with intermediate half-lives as they have long time to find entry inside the human body. The radioactive material present in the earth crust or fall down as dry deposition from atmosphere enters the crop grown there and ultimately in Human beings. Radionuclide enters the water bodies such as ground water by coming in contact with the radionuclide bearing rocks. Control of Nuclear Pollution: Siting of nuclear power plants should be carefully done after studying long term and short term effects. Proper disposal of wastes from research laboratory and hospital involving in the use of radioisotopes should be done. Complete ban on Nuclear weapon testing should be imposed.

Solid waste management Change in the standard of living of ever increasing population has resulted in an increase in the quantity and variety of waste generated. Management of solid waste has, therefore become very important in order to minimize the adverse effect of solid wastes. Solid waste( waste other than liquid and gaseous) can be classified as municipal (MSW), industrial, agricultural, mining waste and sewage sludge. Sources of solid waste: Waste from homes( Domestic waste) : It can contain food waste such as vegetable and meat material, left over food, egg shells, etc which is classified as wet garbage as well as paper, plastic, tetrapacks, plastic cans, newspaper, glass bottles, cardboard boxes, aluminum foil, metal items, wood pieces, etc. which is classified as dry garbage. Biomedical waste: It includes anatomical wastes, pathological wastes, infectious waste etc.

3) Construction/ demolition waste: includes debris and rubbles, wood, concrete etc. 4) Horticulture waste and waste from slaughter houses: include vegetable part, residual and remains of slaughtered animals, respectively. The MSW can be divided into biodegradable wastes( that can be degraded by micro-organism) and non-biodegradable wastes( can not degrade). 5) Industrial waste: The type of waste generated varies depending upon the type of industry for example: Mining industry solid waste will contain loose earth material, Thermal power plant will produce solid waste in form of fly ash and slurry produce during the treatment of flue gas. In Europe and North America the environmental laws are very strict regarding solid waste disposal, thereby these countries started exporting their solid waste to less developed countries like Asian and African countries for dumping.

Effects of Solid waste: Municipal solid wastes heap up on the road due to improper disposal system. These type of dumping allows biodegradable materials to decompose under uncontrolled and unhygienic conditions. This produces foul smell and breeds various types of insects and infectious organisms besides spoiling the aesthetics of the site. Industrial solid wastes are sources of toxic metals and hazardous wastes, which may spread on land can cause changes in physico-chemical and biological characteristics thereby affecting productivity of soils. Toxic metals can also leach or percolate to contaminate the ground water. If MSW get mixed with industrial waste , this make segregation and disposal of waste very difficult. Burning of some of the solid material produce dioxins, furans and polychlorinated biphenyls, which have the potential to cause various type of ailments including cancer.

Management of solid waste: An integrated waste management strategy includes three main components. For waste management stress is on three R’S’- Reduce, reuse and recycle before destruction and safe disposal of solid waste. 1) Source reduction: is one of the fundamental ways to reduce waste. This can be done by using less material when making a product, reuse of products on site, designing products or packaging to reduce their quantity. On an individual level we can reduce the use of unnecessary items while shopping, buy items with minimal packaging, avoid buying disposable items and also avoid asking for plastic carry bags. 2) Recycling of materials: is reusing some components of the waste that may have some economic value. Metal, paper, glass and plastics are recyclable. Mining of new aluminum is expensive and hence recycled aluminum has a strong market and plays a significant role in the aluminum industry. Paper recycling can also help preserve forests as it takes about 17 trees to make one ton of paper. Crushed glass (cullet) reduces the energy required to manufacture new glass by 50 percent. The problems associated with recycling are either technical or economical.

Collection, sorting and transport account for about 90 percent of the cost of paper recycling. The processes of pulping, deinking and screening wastepaper are generally more expensive than making paper from virgin wood or cellulose fibers. 3) Disposal: It is done most commonly through a sanitary landfill or through incineration. Sanitary landfill: is a depression in an impermeable soil layer that is lined with an impermeable membrane. The three key characteristics of a municipal sanitary landfill that distinguish it from an open dump are: Solid waste is placed in a suitably selected and prepared landfill site in a carefully prescribed manner. The waste material is spread out and compacted with appropriate heavy machinery. The waste is covered each day with a layer of compacted soil.

The problem with older landfills are associated with groundwater pollution. Pollutants seeping out from the bottom of a sanitary landfill (leachates) very often percolate down to the groundwater aquifer. Advanced sanitary landfill sites are equipped with suitable bottom liners and leachate collection systems along with the installation of monitoring systems to detect groundwater pollution. it has become increasingly difficult to find suitable land filling sites that are within economic hauling distance and very often citizens do not want landfills in their vicinity.

Incineration: is the process of burning municipal solid waste in a properly designed furnace under suitable temperature and operating conditions. For complete oxidation the waste must be mixed with appropriate volumes of air at a temperature of about 815 o C for about one hour. Incineration can reduce the municipal solid waste by about 90 percent in volume and 75 percent in weight. The risks of incineration however involve air quality problems and toxicity and disposal of the fly and bottom ash produced during the incineration process. Vermicomposting: Vermicomposting is a simple biotechnological process of composting, in which certain species of earthworms are used to enhance the process of waste conversion and produce a better end product. It is a mesophilic process, utilizing microorganisms and earthworms that are active at 10– 32°C. The process is faster than composting; because the material passes through the earthworm gut, a significant transformation takes place, whereby the resulting earthworm castings (worm manure) are rich in microbial activity and plant growth regulators, and fortified with pest repellence attributes as well!

Noise pollution Sound is a form of energy which is emitted by a vibrating body and on reaching the ear causes the sensation of hearing through nerves. Sounds produced by all vibrating bodies are not audible. The frequency limits of audibility are from 20 HZ to 20, 000 HZ. A type of sound may be pleasant to someone and at the same time unpleasant to others. The unpleasant and unwanted sound is called noise. The discrimination and differentiation between sound and noise also depends upon the habit and interest of the person/species receiving it, the ambient conditions and impact of the sound generated during that particular duration of time. There could be instances that, excellently rendered musical concert for example, may be felt as noise and exceptional music as well during the course of the concert! The intensity of sound is measured in sound pressure levels (SPL) and common unit of measurement is decibel, d. B. The SPL is logarithmic ratio of the sound pressure to a reference pressure. If the sound levels are measured in terms of pressure, then, sound pressure level, LP is given by,

LP = 20 Log 10 (P/Po) d. B(A) The Lp is measured against a standard reference pressure, Po = 2 x 10 -5 N/m 2 which is equivalent to zero decibels. The sound pressure is the pressure exerted at a point due to a sound producing source. Addition of sound levels: The effective sound levels form two or more sources cannot be simply added algebraically.

Sources of noise The sources of noise may be domestic (movement of utensils, cutting and peeling of fruits/vegetables etc. ) natural (shores, birds/animal shouts, wind movement, sea tide movement, water falls etc. ), commercial (vendor shouts, automobiles, aeroplanes, marriages, laboratory, machinery etc. ) industrial (generator sets, boilers, plant operations, trolley movement, transport vehicles, pumps, motors etc. ).

Effects of noise pollution on physical health The most direct harmful effect of excessive noise is physical damage to the ear and the temporary or permanent hearing loss often called a temporary threshold shift (TTS). Permanent loss, usually called noise induced permanent threshold shift (NIPTS) represents a loss of hearing ability from which there is no recovery. Some of the adverse effects are summarized below: Annoyance: It creates annoyance to the receptors due to sound level fluctuations. The aperiodic sound due to its irregular occurrences causes displeasure to hearing and causes annoyance. Physiological effects: The physiological features like breathing amplitude, blood pressure, heart-beat rate, pulse rate, blood cholesterol are effected. Loss of hearing: Long exposure to high sound levels cause loss of hearing. This is mostly unnoticed, but has an adverse impact on hearing function. Human performance: The working performance of workers/human will be affected as they'll be losing their concentration.

Nervous system: It causes pain, ringing in the ears, feeling of tiredness, thereby effecting the functioning of human system. Sleeplessness: It affects the sleeping there by inducing the people to become restless and loose concentration and presence of mind during their activities. Damage to material : The buildings and materials may get damaged by exposure to infrasonic / ultrasonic waves and even get collapsed. The variations in the emission of noise levels in a particular environment can be assessed from the statistical distribution of noise levels in that environment. To draw a statistical distribution curve, terms like L 10, L 50 and L 90 play an important role. The Sound levels exceeding 10%, 50% and 90% of the total time intervals during a particular period are designated as L 10, L 50 and L 90 respectively. The equivalent noise levels, Leq can also be calculated as Leq = L 50 + (L 10 - L 90)2 / 60

Permitted noise levels A standard safe time limit has been set for exposure to various noise levels. Beyond this ‘safe’ time continuing exposure over a period of a year will lead to hearing loss.

Noise Pollution during Diwali: There has been a great concern over the noise levels generated during Diwali. Noise generated by various firecrackers is beyond the permissible noise levels of 125 decibels as per the Environmental Protection (second Amendment) Rules, 1999. Supreme Court in a Writ petition(civil) of 1998 concerning noise pollution had passed the following direction as an interim measure: The manufacture, sale or use of fire-crackers generating noise level exceeding 125 d. B(AI) or 145 d. B(C)pk at 4 meter distance from the point of bursting shall be prohibited. The use of firecrackers shall not be permitted except between 6. 00 p. m. and 10. 00 p. m. Fire crackers shall not be used at any time in silence zones( Silence zone in an area comprising not less that 100 meters around hospitals, education institutions, courts, religious places or any other area which is declared as such by the competent authority).

Noise Control techniques There are four fundamental ways in which noise can be controlled: Reduce noise at the source, Block the path of noise, Increase the path length Protect the recipient. In general, the best control method is to reduce noise levels at the source. Noise Control at Source: The noise pollution can be controlled at the source of generation itself by employing techniques like. Reducing the noise levels from domestic sectors: The domestic noise coming from radio, tape recorders, television sets, mixers, washing machines, cooking operations can be minimized by their selective and judicious operation. Maintenance of automobiles: Regular servicing and tuning of vehicles will reduce the noise levels. Fixing of silencers to automobiles, two wheelers etc. , will reduce the noise levels. Control over vibrations: The vibrations of materials may be controlled using proper foundations, rubber padding etc. to reduce the noise levels caused by vibrations.

Prohibition on usage of loud speakers: By not permitting the usage of loudspeakers in the habitant zones except for important meetings / functions. Now-a-days, the urban administration of the metro cities in India, is becoming stringent on usage of loudspeakers. Maintenance of machines: Proper lubrication and maintenance of machines, vehicles etc. will reduce noise levels. Similarly is the case of machines. Proper handling and regular maintenance is essential not only for noise control but also to improve the life of machine. Control in the transmission path The change in the transmission path will increase the length of travel for the wave and get absorbed/refracted/radiated in the surrounding environment. The available techniques are briefly discussed below. Installation of barriers: Installation of barriers between noise source and receiver can attenuate the noise levels. For a barrier to be effective, its lateral width should extend beyond the line-of-sight at least as much as the height. The barrier may be either close to the source or receiver, subject to the condition that, R <<D or in other words, to increase the traverse length for the sound wave.

Design of building: The design of the building incorporating the use of suitable noise absorbing material for wall/door/window/ceiling will reduce the noise levels.

Green belt development: Green belt development can attenuate the sound levels. The degree of attenuation varies with species of greenbelt. The statutory regulations direct the industry to develop greenbelt four times the built-up area for attenuation of various atmospheric pollutants, including noise. Using protection equipment: The usage of protective equipment and the worker's exposure to the high noise levels can be minimised by – Job rotation: By rotating the job between the workers working at a particular noise source or isolating a person, the adverse impacts can be reduced. Exposure reduction: Regulations prescribe that, noise level of 90 d. B (A) for more than 8 hr continuous exposure is prohibited. Persons who are working under such conditions will be exposed to occupational health hazards. Hearing protection: Equipment like earmuffs, ear plugs etc. are the commonly used devices for hearing protection. Attenuation provided by ear-muffs vary widely in respect to their size, shape, seal material etc. Literature survey shows that, an average noise attenuation up to 32 d. B can be achieved using earmuffs.

Hazardous wastes are those that can cause harm to humans or the environment. Wastes are normally classified as hazardous waste when they cause or significantly contribute to an increase in mortality or an increase in serious irreversible or incapacitating reversible illness or pose a substantial present or potential hazard to human health or the environment when improperly treated, stored, transported or disposed of. A waste is classified as a hazardous waste if it exhibits any of the four primary characteristics based on the physical or chemical properties of toxicity, reactivity, ignitability and corrosivity. Toxic wastes: are those substances that are poisonous even in very small or trace amounts. Some may have an acute or immediate effect on humans or animals causing death or violent illness. Others may have a chronic or long term effect slowly causing irreparable harm to exposed persons. Reactive wastes: are those that have a tendency to react vigorously with air or water, are unstable to shock or heat, generate toxic gases or explode during routine management. For example, gunpowder, nitroglycerine, etc.

3) Ignitable wastes: are those that burn at relatively low temperatures (less than 60° C) and are capable of spontaneous combustion during storage, transport or disposal. For example, gasoline, paint thinners, and alcohol. 4) Corrosive wastes: are those that destroy materials and living tissue by chemical reaction. For example, acids and bases. 5) Infectious wastes: include human tissue from surgery, used bandages and hypodermic needles, microbiological materials, etc. 6) Radioactive waste: is basically an output from the nuclear power plants and can persist in the environment for thousands of years before it decays appreciably. Environmental problems and health risks caused by hazardous wastes: As most of the hazardous wastes are disposed of on or in land the most serious environmental effect is contaminated groundwater. Pesticides are used increasingly to protect and increase food production. Today we have an alternative to the excess use of pesticides through the use of Integrated Pest Management (IPM).

• Lead, mercury and arsenic are hazardous substances which are often referred to as heavy metals. Most of the lead taken up by people and wildlife is stored in bones. Lead can affect red blood cells by reducing their ability to carry oxygen and shortening their life span. Lead may also damage nerve tissue which can result in brain disease. • PCBs (Polychlorinated biphenyls) are resistant to fire and do not conduct electricity very well which makes them excellent materials for several industrial purposes. PCBs are concentrated in the kidneys and liver and thus cause damage. They cause reproductive failure in birds and mammals. • Vinyl chloride is a chemical that is widely used in the manufacture of plastic. After a long continuous exposure (one to three years) in humans, vinyl chloride can cause deafness, vision problems, circulation disorders and bone deformities. Vinyl chloride can also cause birth defects. • Today the most common methods for disposing off hazardous wastes are land disposal and incineration. Although toxic wastes cannot be entirely eliminated, technologies are available for minimizing, recycling and treating wastes.

ROLE OF AN INDIVIDUAL IN PREVENTION OF POLLUTION A small effort made by each individual at his own place will have pronounced effect at the global level. It is aptly said, ‘ Think globally act locally’. Each individual should change his or her lifestyle in such a way as to reduce environmental pollution. Few of the suggestion are as follows: Lay greater emphasis on pollution prevention than pollution control. Use ecofriendly products. example: use CFC free refrigerators, use the chemical derived from peaches and plums to clean computer chips and circuit board instead of CFCs. Reduce the dependency on fossil fuel especially coal or oil, promote the use of non-conventional source of energy such as solar energy, biomass energy etc. Promote Reuse and Recycling wherever possible and reduce the production of waste. Improve energy efficiency to reduce the amount of waste energy. Save electricity by not wasting it. Shut off the lights and fans when not needed.

• Do not litter the roads and surroundings just because the sweeper from the Municipal Corporation will clean it up. Take care to put trash into dustbins or bring it back home with you where it can be appropriately disposed. • Try to avoid asking for plastic carry bags when you buy groceries or vegetables or any other items. Use your own cloth bag instead. • Try to lobby and push for setting up garbage separation and recycling programs in your localities. • Advocate organic farming by asking your grocery store to stock vegetables and fruits grown by an organic method. This will automatically help to reduce the use of pesticides. • Reduce the use of wood and paper products wherever possible. Manufacturing paper leads to pollution and loss of forests which releases oxygen and takes up carbon dioxide. Try to recycle paper products and use recycled paper wherever possible. • Set up a compost bin in your garden or terrace and use it to produce manure for your plants to reduce use of fertilizers.

DISASTER MANAGEMENT: FLOODS, EARTHQUAKES, CYCLONES, LANDSLIDES The Indian subcontinent is very vulnerable to droughts, floods, cyclones, earthquakes, landslides, avalanches and forest fires. Among the 36 states and Union territories in the country, 22 are prone to disasters. Among all the disasters that occur in the country, floods are the most frequently occurring natural disasters, due to the irregularities of the Indian monsoon. Approximately 40 million hectares of land in the country has been identified as being prone to floods. Major floods are mainly caused in the Ganga-Brahmaputra-Meghna basin which carries 60 percent of the total river flow of our country. India has a long coastline of 5700 kms, which is exposed to tropical cyclones arising in the Bay of Bengal and the Arabian sea. The Indian Ocean is one of the six major cyclone prone regions of the world. In India, cyclones occur usually between April and May and also between October and December. Earthquakes are considered to be one of the most destructive natural hazards. About 50 to 60 percent of India is vulnerable to seismic activity of varying intensities. Most of the vulnerable areas are located in the Himalayan and sub. Himalayan regions.

From management to mitigation of disasters Till very recently the approach towards dealing with natural disasters has been post disaster management involving problems such as evacuation, warnings, communications, search and rescue, fire-fighting, medical and psychiatric assistance, provision of relief, shelter, etc. Natural occurrences such as floods, earthquakes, cyclones, etc. will always occur. They are a part of the environment that we live in. However destruction from natural hazards can be minimized by the presence of a well functioning warning system combined with preparedness on part of the community that will be affected. Disaster management is a multidisciplinary area in which a wide range of issues that range from forecasting, warning, evacuation, search and rescue, relief, reconstruction and rehabilitation are included. It is also multi-sectoral as it involves administrators, scientists, planners, volunteers and communities. These roles and activities span the pre-disaster, during disaster and post disaster plans. The early warning systems for a range of natural hazards are available at present however they are not enough to ensure communities are safe from disasters. This is where disaster mitigation can play an important role.

Mitigation means lessening the negative impact of the natural hazards. It is defined as sustained action taken to reduce long term vulnerability of human life and property to natural hazards. The main elements of a mitigation strategy are as follows: a) Risk assessment and Vulnerability analysis: This involves identification of hot spot areas of prime concern, collection of information on past natural

natural hazards, information of the natural ecosystems and information on the population and infrastructure. Once this information is collected a risk assessment should be done to determine the frequency, intensity, impact and the time taken to return to normalcy after the disaster. The use of Geographical Information Systems (GIS) a computer program can be a valuable tool in this process as the primary data can be easily updated and the corresponding assessments can be made. Applied research and technology transfer There is a need to establish or upgrade observation equipment and networks, monitor the hazards properly, improve the quality of forecasting and warning, disseminate information quickly through the warning systems and undertake disaster simulation exercises. Public awareness and training One of the most critical components of a mitigation strategy is the training to be imparted to the officials and staff of the various departments involved at the state and the district level. The success of a mitigation strategy will depend to a large extent on the inter-sectional, inter-departmental coordination and efficient teamwork.

Institutional mechanisms The most important need at the National level is to strengthen or develop the capacity to undertake disaster mitigation strategies. The National Disaster Management Authority (NDMA) establish in 1999 perform such a task. Incentives and resources for mitigation To a very large extent the success of mitigation programs will depend upon the availability of continued funding. There is thus a need to develop mechanisms to provide stable sources of funding for all mitigation programs. Landuse planning and regulations Long term disaster reduction efforts should aim at promoting appropriate land -use in the disaster prone areas. Special maps for Costal regulation zones, earthquake prone region and river flood plain should be prepared and introduced into land use planning. Hazard resistant design and construction In areas that are prone to disasters protection can be enhanced by careful selection of sites and the way the buildings are built.

Structural and constructional reinforcement of existing buildings It is also possible to reduce the vulnerability of existing buildings through minor adaptations or alterations thereby ensuring their safety. This can be done by insertion of walls on the outside of the building, buttresses, walls in the interior of the building, portico fill-in-walls, specially anchored frames, covering of columns and beams, construction of new frame system etc. Floods and mitigation measures Floods can be caused by natural, ecological or anthropogenic factors either individually or as a combined result. Anthropogenic activities such as deforestation and shifting cultivation can also contribute to floods. The mitigation measures for floods include both structural and non-structural measures. Structural measures includes: Reservoirs for impounding monsoon flows to be released in a regulated manner after the peak flood flow passes. Prevention of over-bank spilling by the construction of embankments and floodwalls. Improvement of flow conditions in the channel and anti-erosion measures.

The non-structural measures include: 1) Flood plain management such as Flood Plain Zoning and Flood Proofing including Disaster Preparedness 1) Maintaining wetlands 1) Flood forecasting and warning services Earthquakes and mitigation measures Earthquakes occurs due to sudden movements of earth’s crust. The earth crust has several tectonic plates of solid rock which slowly moves along with their boundaries. Some time due to friction fracture formation take place along the boundaries or fault line within the plate.

The severity of an earthquake is generally measured by its magnitude on Richte Scale:

Mitigation measures: The critical factors responsible for the high seismic risk in India has prioritized six sets of critical interventions; as the six pillars of earthquake management. They are to: Ensure the incorporation of earthquake-resistant design features for the construction of new structures. Facilitate selective strengthening and seismic retrofitting of existing priority and lifeline structures in earthquake-prone areas. Improve the compliance regime through appropriate regulation and enforcement. Improve the awareness and preparedness of all stakeholders. Introduce appropriate capacity development interventions for effective earthquake management (including education training, R&D, and documentation). Strengthen the emergency response capability in earthquake-prone areas.

Cyclones and mitigation measures Tropical cyclones are the worst natural hazards in the tropics. They are large revolving vortices in the atmosphere extending horizontally from 150 to 1000 km and vertically from the surface to 12 to 14 km. These are intense lowpressure areas. Strong winds spiraling anti clockwise in the Northern Hemisphere blow around the cyclone center at the lower level. They generally move 300 to 5000 km per day over the ocean. While moving over the ocean they pick up energy from the warm water of the ocean and some of them grow into a devastating intensity. One of the requirement formation of tropical cyclones is that the sea surface temperature (SST) should be above 26°C.

On an average about 5 to 6 tropical cyclones form in the Bay of Bengal and the Arabian Sea every year out of which 2 to 3 may be severe. More cyclones form in the Bay of Bengal than in the Arabian Sea. The main dangers from cyclones are very strong winds, torrential rains and high storm tides. Most of the causalities are caused by coastal inundation by storm tides. This is often followed by heavy rainfall and floods. Storm surges cause the greatest destruction. mitigation measures: Some of the mitigation methods are as follows: Installation of early warning systems: Such systems fitted along the coastlines can greatly assist forecasting techniques thus helping in early evacuation of people in the storm surge areas. Developing communication infrastructure: Communication plays a vital role in cyclone disaster mitigation and yet this is one of the first services that gets disrupted during cyclones. Amateur Radio has today emerged as a second line unconventional communications systems and is an important tool for disaster mitigation.

3) Developing shelter belts: Shelter belts with plantations of trees can act as effective wind and tide breakers. Apart from acting as effective windbreakers and protecting soil crops from being damaged they prevent soil erosion. 4) Developing community cyclone shelters: Cyclone shelters at strategic locations can help minimizing the loss of human life. In the normal course these shelters can be used as public utility buildings. 5) Construction of permanent houses: There is a need to build appropriately designed concrete houses that can withstand high winds and tidal waves. 6) Training and education: Public awareness programs that inform the population about their response to cyclone warnings and preparedness can go a long way in reducing causalities. 7) Land use control and settlement planning: No residential and industrial units should be ideally permitted in the coastal belt of 5 km from the sea as it is the most vulnerable belt.

Landslides and mitigation measures Landslides occur as a result of changes on a slope, sudden or gradual, either in its composition, structure, hydrology or vegetation. The changes can be due to geology, climate, weathering, land-use and earthquakes. Landslides are recurring phenomena in the Himalayan region. In the recent years however intensive construction activity and the destabilizing forces of nature have aggravated the problem.

Type of Land slide: The term "landslide" describes a wide variety of processes that result in the downward and outward movement of slope-forming materials including rock, soil, artificial fill, or a combination of these. The materials may move by falling, toppling, sliding, spreading, or flowing. The various types of landslides can be differentiated by the kinds of material involved and the mode of movement.

LANDSLIDE CAUSES: It can be characterize into three major type: Geological: It can be due to presence of weak or sensitive materials, sheared, jointed, or fissured materials, contrast in permeability and/or stiffness of materials etc. . Morphological causes: It can be due to Tectonic or volcanic uplift, Fluvial, wave, or glacial erosion of slope toe or lateral margins, Vegetation removal (by fire, drought) etc. Human causes: It is mainly due to Mining, Deforestation, Irrigation, Drawdown (of reservoirs) etc.

mitigation measures: Some of the mitigation measures are: preventing the exposure of population and facilities to landslides. Developmental programs that involve modification of the topography, exploitation of natural resources and change in the balance load on the ground should not be permitted in the landslide prone region. Some critical measures that could be undertaken to prevent further landslides are drainage measures, erosion control measures such a bamboo check dams, terracing, jute and coir netting. Rock fall control measures such as grass plantation, vegetated dry masonry wall, retaining wall and most importantly preventing deforestation and improving afforestation.