EDUCATION HOLE PRESENTS
ENGINEERING CHEMISTRY
Unit-III
Environmental Pollution......................................................................................................
Environmental Pollution
Pollution is the introduction of contaminants into the natural environment that cause adverse
chan...
countries, said that humans have been the primary cause of global warming since 1950. Humans
have ways to cut greenhouse g...
• Industrial/commercial supply: waters suitable for industrial and commercial uses with or
without treatment.
Recreational...
Control measures for thermal pollution
The following methods can be adapted to control high temperature caused by thermal ...
Sources of Air Pollution
The pollution of air can be caused by natural processes or by human activities. The sources of ai...
when they are converted to less harmful product carbon dioxide and a harmless product
water.
2. Absorption: In this method...
2. Pesticides and fertilizers should be applied on croplands only in recommended dose,
prescribed by Indian Standard Insti...
A quarter of the oil creates a ripple effect that is larger than 2 acres in diameter. One liter of fuel
pollute a million ...
sink. Oil absorbent arms are 5 “and 8″ in diameter with a length of 10 Ft or 20 Ft Cleaning up the
oil can be achieved by ...
Solutions for Land Pollution
o Make people aware about the concept of Reduce, Recycle and Reuse.
o Reduce the use of pesti...
fewer extreme weather events). Climate change is caused by factors such as biotic processes,
variations in solar radiation...
atmosphere, especially CO2, according to NASA. CO2 and other greenhouse gases act like a
blanket, absorbing IR radiation a...
Ozone layer formation
Over two billion years ago, early aquatic organisms called blue-green algae began using energy
from ...
Impact of water and air borne diseases on human health
Waterborne diseases
• Droughts can cause increased concentrations o...
Toxic wastes
Toxic waste is waste material that can cause death, injury or birth defects to living creatures. It
spreads q...
Nuclear hazards
The world's nuclear fleet creates about 10,000 metric tons of high-level spent nuclear fuel each
year. Hig...
Nuclear power plants use the energy of radiation to convert water to steam, which is then used to
generate electricity.
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  1. 1. EDUCATION HOLE PRESENTS ENGINEERING CHEMISTRY Unit-III
  2. 2. Environmental Pollution.......................................................................................................... 3 Causes of pollution...........................................................................................................................3 Control measures for water pollution...............................................................................................4 Water quality use designations ............................................................................................................................4 Recreational activities include..............................................................................................................................5 Aquatic life habitats..............................................................................................................................................5 Water pollution control criteria............................................................................................................................5 Control measures for thermal pollution ...........................................................................................6 Air pollution ............................................................................................................................ 6 Sources of Air Pollution.........................................................................................................................................7 Prevention And Control of Air Pollution ...............................................................................................................7 Soil Pollution ........................................................................................................................... 8 Control of Marine pollution..............................................................................................................9 Land pollution ....................................................................................................................... 11 Causes of Land Pollution ................................................................................................................ 11 Solutions for Land Pollution................................................................................................................................12 Noise pollution ...................................................................................................................... 12 Climate change .............................................................................................................................. 12 Greenhouse effect.......................................................................................................................... 13 Global warming..................................................................................................................... 13 Acid rain......................................................................................................................................... 14 The Effects of Acid Rain ......................................................................................................................................14 Ozone layer formation........................................................................................................................................15 Ozone layer depletion.........................................................................................................................................15 Impact of water and air borne diseases on human health .............................................................. 16 Waterborne diseases..........................................................................................................................................16 Air borne diseases.......................................................................................................................... 16 Toxic wastes................................................................................................................................... 17 Carcinogens ................................................................................................................................... 17 Nuclear hazards ............................................................................................................................. 18 Natural Radiation................................................................................................................................................18 Man-Made Radiation..........................................................................................................................................18
  3. 3. Environmental Pollution Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of chemical substances or energy, such as noise, heat or light. Pollutants, the components of pollution, can be either foreign substances/energies or naturally occurring contaminants. Pollution is often classed as point source or nonpoint source pollution. Although environmental pollution can be caused by natural events such as forest fires and active volcanoes, use of the word pollution generally implies that the contaminants have an anthropogenic source that is, a source created by human activities. Pollution has accompanied humankind ever since groups of people first congregated and remained for a long time in any one place. Indeed, ancient human settlements are frequently recognized by their pollutants shell mounds and rubble heaps, for instance. Pollution was not a serious problem as long as there was enough space available for each individual or group. However, with the establishment of permanent settlements by great numbers of people, pollution became a problem, and it has remained one ever since. Causes of pollution Air pollution comes from both natural and human-made (anthropogenic) sources. However, globally human-made pollutants from combustion, construction, mining, agriculture and warfare are increasingly significant in the air pollution equation. Motor vehicle emissions are one of the leading causes of air pollution. China, United States, Russia, India Mexico, and Japan are the world leaders in air pollution emissions. Principal stationary pollution sources include chemical plants, coal-fired power plants, oil refineries, petrochemical plants, nuclear waste disposal activity, incinerators, large livestock farms (dairy cows, pigs, poultry, etc.), PVC factories, metals production factories, plastics factories, and other heavy industry. Agricultural air pollution comes from contemporary practices which include clear felling and burning of natural vegetation as well as spraying of pesticides and herbicides. About 400 million metric tons of hazardous wastes are generated each year. The United States alone produces about 250 million metric tons. Americans constitute less than 5% of the world's population, but produce roughly 25% of the world’s CO2, and generate approximately 30% of world’s waste. In 2007, China has overtaken the United States as the world's biggest producer of CO2, while still far behind based on per capita pollution - ranked 78th among the world's nations. In February 2007, a report by the Intergovernmental Panel on Climate Change (IPCC), representing the work of 2,500 scientists, economists, and policymakers from more than 120
  4. 4. countries, said that humans have been the primary cause of global warming since 1950. Humans have ways to cut greenhouse gas emissions and avoid the consequences of global warming, a major climate report concluded. But to change the climate, the transition from fossil fuels like coal and oil needs to occur within decades, according to the final report this year from the UN's Intergovernmental Panel on Climate Change (IPCC). Some of the more common soil contaminants are chlorinated hydrocarbons (CFH), heavy metals (such as chromium, cadmium– found in rechargeable batteries, and lead–found in lead paint, aviation fuel and still in some countries, gasoline), MTBE, zinc, arsenic and benzene. In 2001 a series of press reports culminating in a book called Fateful Harvest unveiled a widespread practice of recycling industrial byproducts into fertilizer, resulting in the contamination of the soil with various metals. Ordinary municipal landfills are the source of many chemical substances entering the soil environment (and often groundwater), emanating from the wide variety of refuse accepted, especially substances illegally discarded there, or from pre-1970 landfills that may have been subject to little control in the U.S. or EU. There have also been some unusual releases of polychlorinated dibenzodioxins, commonly called dioxins for simplicity, such as TCDD. Control measures for water pollution Water pollution refers to the qualitative state of impurity or uncleanliness in hydrologic waters of a certain region, such as a watershed. It results from an occurrence or process which causes a reduction in the utility of the earth’s waters, especially as related to human health and environmental effects. The pollution process stresses the loss of purity through contamination, which further implies intrusion by or contact with an outside source as the cause. The term tainted is applied to extremely low levels of water pollution, as in their initial corruption and decay. Defilement is the result of pollution and suggests violation or desecration. Water quality use designations The ultimate goal in the control of water pollution would be zero discharge of pollutants to water bodies; however, complete achievement of this objective is usually not cost effective. The preferred approach is to set limitations on waste disposal discharges for the reasonable protection of human health and the environment. Although these standards may vary widely in different jurisdictions, use designations for specific bodies of water are commonly the basis, as briefly addressed below. Water supplies include: • public water supply: waters which with conventional treatment will be suitable for human consumption • agricultural supply: waters suitable for irrigation and livestock watering without treatment
  5. 5. • Industrial/commercial supply: waters suitable for industrial and commercial uses with or without treatment. Recreational activities include • bathing waters: waters which during certain seasons are suitable for swimming as approved for water quality along with protective conditions and facilities • primary contact: waters which during certain seasons are suitable for full body contact recreation such as swimming, canoeing and underwater diving with minimal threat to public health as a result of water quality • secondary contact: waters which during certain seasons are suitable for partial body contact recreation such as, but not limited to, wading, with minimal threat to public health as a result of water quality. Public water resources are categorized as water bodies which lie within park systems, wetland, wildlife areas, wild, scenic and recreational rivers and publicly owned lakes, and waters of exceptional recreational or ecological significance. Aquatic life habitats Typical designations will vary according to climates, but relate to conditions in water bodies for supporting and maintaining certain aquatic organisms, especially various species of fish. For example, use designations in a temperate climate as subdivided in regulations for the State of Ohio Environmental Protection Agency (EPA) are listed below without detailed descriptions: • warmwater • limited warmwater • exceptional warmwater • modified warmwater • seasonal salmonid • coldwater • limited resource water. Water pollution control criteria Natural waters and wastewaters are characterized in terms of their physical, chemical and biological composition. The principal physical properties and the chemical and biological constituents of wastewater and their sources are a lengthy list, reported in a textbook by Metcalf and Eddy (1991). Analytical methods for these determinations are given in a widely used manual entitled Standard Methods for the Examination of Water and Waste Water by the American Public Health Association (1995).
  6. 6. Control measures for thermal pollution The following methods can be adapted to control high temperature caused by thermal discharges: 1. Cooling towers: Use of water from water systems for cooling systems for cooling purposes, with subsequent return to the water way after passage through a condenser, is called cooling process. Cooling towers transfer heat from hot water to the atmosphere by evaporation. Cooling towers are of two types: (i) Wet cooling tower: Hot water coming out from the condenser (reactor) is allowed to spray over baffles. Cool air, with high velocity, is passed from sides, which takes away the heat and cools the water. (ii) Dry cooling tower: Here, hot water is allowed to flow in long spiral pipes. Cool air with the help of a fan is passed over these hot pipes, which cools down hot water. This cool water can be recycled. 2. Cooling ponds: Cooling ponds are the best way to cool thermal discharges. Heated effluents on the surface of the water in cooling ponds maximise dissipation of heat to the atmosphere and minimise the water area and volume. The warm water wedhe acts like a cooling pond. 3. Spray ponds: The water coming out from condensers is allowed to pass into the ponds through sprayers. Here water is sprayed through nozzles as fine droplets. Heat from the fine droplets gets dissipated to the atmosphere. 4. Artificial lakes: Artificial lakes are man made water bodies that offer once-through cooling. The heated effluents can be discharged into the lake at one end and water for cooling purposes may be withdrawn from the other end. The heat is eventually dissipated through evaporation. Air pollution Air pollution is the introduction of chemicals, particulates, biological materials, or other harmful materials into the Earth's atmosphere, possibly causing disease, death to humans, damage to other living organisms such as food crops, or the natural or built environment. The atmosphere is a complex natural gaseous system that is essential to support life on planet Earth. Stratospheric ozone depletion due to air pollution has long been recognized as a threat to human health as well as to the Earth's ecosystems. Indoor air pollution (see Airlog) and urban air quality are listed as two of the world’s worst toxic pollution problems in the 2008 Blacksmith Institute World's Worst Polluted Places report.
  7. 7. Sources of Air Pollution The pollution of air can be caused by natural processes or by human activities. The sources of air pollution are classified into two groups: 1. Natural Sources 2. Man made sources Natural Sources of Air Pollution: They are dust storms, forest fires, ash from smoking volcanoes, decay of organic matters and pollen grains floating in air. Manmade Sources of Air Pollution: They are population explosion, deforestation, urbanization and industrialization, whose effects can be explained as follows: 1. Burning of fuels like wood, cow dung cakes, coal and kerosene in homes pollute the air. 2. Exhaust gases emitted by motor vehicles which pollute the air are the major source of air pollution in big cities. 3. Industries pollute air by releasing various types of pollutants such as sulphur dioxide, oxides of carbon, nitrogen oxide, chlorine, asbestos dust and cement dust. 4. Thermal power plants pollute air by emitting sulphur dioxide and fly-ash. 5. Nuclear power plants pollute air by releasing radioactive rays. 6. Use of fertilisers and pesticides in agriculture pollute the air. 7. Mining activities releases particulate matter into the air and pollutes it. 8. Indiscriminate cutting of trees and clearing of forests increases the amount of carbon dioxide in the atmosphere and thereby pollutes it. 9. Use of chlorofluorocarbons in refrigeration, fire extinguishers and aerosol sprayers pollutes air by depleting the ozone layer. 10. Smoking pollutes air by emitting carbon monoxide and nicotine. Prevention And Control of Air Pollution Different techniques are used for controlling air pollution caused by 'gaseous pollutants' and that caused by 'particulate pollutants'. • Methods of controlling gaseous pollutants: The air pollution caused by gaseous pollutants like hydrocarbons, sulphurdioxide, ammonia, carbon monoxide, etc can be controlled by using three different methods-Combustion, Absorption and Adsorption. 1. Combustion: This technique is applied when the pollutants are organic gases or vapours. The organic air pollutants are subjected to 'flame combustion or catalytic combustion'
  8. 8. when they are converted to less harmful product carbon dioxide and a harmless product water. 2. Absorption: In this method, the polluted air containing gaseous pollutants is passed through a scrubber containing a suitable liquid absorbent. The liquid absorbs the harmful gaseous pollutants present in air. 3. Adsorption: In this method, the polluted air is passed through porous solid adsorbents kept in suitable containers. The gaseous pollutants are adsorbed at the surface of the porous solid and clean air passes through. • Methods of controlling particulate emissions: The air pollution caused by particulate matter like dust, soot, ash, etc, can be controlled by using fabric filters, wet scrubbers, electrostatic precipitators and certain mechanical devices. 1. Mechanical Devices: It works on the basis of following: • Gravity: In this process, the particulate settle down by the action of gravitational force and get removed. • Sudden change in the direction of air flow: It brings about separation of particles due to greater momentum. 2. Fabric Filters: The particulate matter is passed through a porous medium made of woven or filled fabrics. • The particulate present in the polluted air are filtered and gets collected in the fabric filters , while the gases are discharged. • The process of controlling air pollution by using fabric filters is called 'bag filtration'. 3. Wet Scrubbers: They are used to trap SO2, NH3 and metal fumes by passing the fumes through water. 4. Electrostatic Precipitators: When the polluted air containing particulate pollutants is passed through an electrostatic precipitator, it induces electric charge on the particles and then the aerosol particles get precipitated on the electrodes. Soil Pollution The following measures may be suggested to control soil pollution: 1. Development of such pesticides should be encouraged, which may save crops from pests and rodents but should not contaminate soil with toxic chemicals.
  9. 9. 2. Pesticides and fertilizers should be applied on croplands only in recommended dose, prescribed by Indian Standard Institution experts. It will help in reducing the level of water and soil pollution caused through these chemicals. 3. There should be sufficient duration between the harvesting of crops and time of last spray of pesticides. This will help in reducing contamination of pesticides, directly to the crop. It will also cause less contamination of chloride and other chemicals to the soil. 4. There must be arrangement for educating farmers regarding the proper use of pesticides and fertilizers. Only those fertilizers could be used for growing crops, which are deficient in soils. 5. After every two or three years soils percentage should be analyzed, so that it can be observed that what is the percentage of nutrients in the soils. This will help in maintaining the required amount of nutrient in the soils. 6. Waste water from industries should not be used for irrigation without eliminating toxic chemicals from the effluent. This will also reduce the concentration of unwanted substances in the soil. 7. Garbage should not be disposed of on cultivated land without covering it with the soils. 8. Soil conservation practices should also be adopted so as to avoid loss of valuable nutrients through soil erosion. In addition to this, government should encourage research programmers examining the effects of pesticides and fertilizers on soils and human beings. This will help in devising suitable measures to control soil pollution and restore its fertility. Control of Marine pollution Oil spills are harmful to aquatic plants and animals, including fish, birds and people. Oil will affect the roads and drinking water. Gasoline and oil contain carcinogenic substances known to cause cancer. Marine oil pollution are man-made threats to the lakes and streams as quickly as possible. These are issued to small recreational vessels leak larger, heavier oil in commercial vessels. Manage these potentially dangerous leaks, it is essential to the waterways as quickly as possible. Prevention of oil pollution control, bilge-water disposal, fuel and oil spill cleanup, the Federal Water Pollution Control Act of 1972 and the Oil Pollution Act 1990 prohibits any discharge of oil at or near the navigable waters of the United States. This includes the discharge of the film, sheen, discoloration, sludge or emulsion caused at or below the water surface. The discharge of these species could lead to stiff civil penalties.
  10. 10. A quarter of the oil creates a ripple effect that is larger than 2 acres in diameter. One liter of fuel pollute a million gallons of water. Gasoline and other petroleum negative impact on the marine environment and should be included. To prevent pollution of the sea, absorbent bilge pads to receive petroleum products, but no water. When the bilge water is Bilge Booms - Reduces the tree with not saturated with oil they should be removed. If not properly disposed of the main sources of marine pollution they collect oil, antifreeze and transmission fluids. If the bilge pump is activated, the liquid is pumped into the water. Solution: a bilge bilge, the oil tank or sump fluctuations. - Replace oil absorbent inserts under the engine - Replace oil absorbent materials contaminated with highly saturated - Keep your engine tuned: Check for leaking seals, gaskets and hoses. - Change oil filters are often - Do not allow oily bilge pump or displayed in or near water Bilge sink rails not yet saturated. Bilge arms can float indefinitely. Bilge rails can be kept to the public, free of dust and impervious to both rot and mildew. They come with loops a rope for easy installation and confirm. Bilge rails is available in three sizes. Problem: Motor Boat of the Oil Spill Fuel is spilled while the gas engine. Sometimes there is a backsplash out of fuel, or a vent valve in the overflow. Harmful to aquatic organisms such spills. If a leak is not a snake in the water. Much better use of oil absorbent sweep to clear the spillage Solution: oil-absorbing Sweep If the use of fuel oil spilled into the water-absorbing Sweep. Oil Absorbent Sweep purpose built hinges. A large absorbent surface made of a large spills, absorb or surface sheen. This is a great way to clean oil spills in the water. Never use soap or detergent oil distribution. The cleaners will bring roads and non-biodegradable. Detergents is a major source of pollution. Solution 2: Oil Absorbent Booms Oil absorbent booms and perfect offshore oil industry based on strong mesh screens Bund Encasing the outer skin, a highly sorbent polypropylene filler. A nylon rope and steel hardware ensure long life and easy retrieval. Water repellent and oil-absorbent Booms are not yet saturated
  11. 11. sink. Oil absorbent arms are 5 “and 8″ in diameter with a length of 10 Ft or 20 Ft Cleaning up the oil can be achieved by using sorbents, gels and foams. Land pollution When we talk about air or water pollution, the reactions garnered are stronger. This is because we can see the effects caused by the pollutants and their extent very clearly. It is normal human psychology to believe in what you see first hand. Our land on the other hand is living a nightmare too. We may not be able to see the effects with clarity, but land is being polluted and abused constantly and we are unable to calculate the damages incurred. Land Pollution has come to become one of the serious concerns that we collectively battle. Causes of Land Pollution 1. Deforestation and soil erosion: Deforestation carried out to create dry lands is one of the major concerns. Land that is once converted into a dry or barren land, can never be made fertile again, whatever the magnitude of measures to redeem it are. Land conversion, meaning the alteration or modification of the original properties of the land to make it use-worthy for a specific purpose is another major cause. This hampers the land immensely. Also there is a constant waste of land. Unused available land over the years turns barren; this land then cannot be used. So in search of more land, potent land is hunted and its indigenous state is compromised with. 2. Agricultural activities: With growing human population, demand for food has increased considerably. Farmers often use highly toxic fertilizers and pesticides to get rid off insects, fungi and bacteria from their crops. However with the overuse of these chemicals, they result in contamination and poisoning of soil. 3. Mining activities: During extraction and mining activities, several land spaces are created beneath the surface. We constant hear about land caving in; this is nothing but nature’s way of filling the spaces left out after mining or extraction activity. 4. Overcrowded landfills: Each household produces tonnes of garbage each year. Garbage like aluminum, plastic, paper, cloth, wood is collected and sent to the local recycling unit. Items that can not be recycled become a part of the landfills that hampers the beauty of the city and cause land pollution. 5. Industrialization: Due to increase in demand for food, shelter and house, more goods are produced. This resulted in creation of more waste that needs to be disposed of. To meet the demand of the growing population, more industries were developed which led to deforestation. Research and development paved the way for modern fertilizers and chemicals that were highly toxic and led to soil contamination.
  12. 12. Solutions for Land Pollution o Make people aware about the concept of Reduce, Recycle and Reuse. o Reduce the use of pesticides and fertilizers in agricultural activities. o Avoid buying packages items as they will lead to garbage and end up in landfill site. o Ensure that you do not litter on the ground and do proper disposal of garbage. o Buy biodegradable products. o Do Organic gardening and eat organic food that will be grown without the use of pesticides. o Create dumping ground away from residential areas. Noise pollution Follow the below given steps for controlling and preventing noise pollution. • Control of Noise pollution at Source • Noise producing industries, railway stations, aerodrome, etc. should be located far away from the residential areas. • We should play various music systems such as stereos, television, etc. at low volume. • We should not use loud speakers during night. Even during time they should be used at low volumes. • Various machines should be well maintained so that they produce less sound. • It is observed that certain persons blow horns of their vehicles unnecessarily, or remove silencers of the exhaust pipes of vehicles. Such practices produce lot of noise and should be avoided. • Laws should be framed so that the persons producing unnecessary noise are punished. Control of Noise Pollution by obstructing the path of Noise • By constructing soundproof buildings, the menace of sound pollution can be minimized. • Plants also help in controlling noise pollution because they absorb high frequency sound waves. Thus, planting trees along the roads help in controlling noise pollution. Climate change Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions, or in the distribution of weather around the average conditions (i.e., more or
  13. 13. fewer extreme weather events). Climate change is caused by factors such as biotic processes, variations in solar radiation received by Earth, plate tectonics, and volcanic eruptions. Certain human activities have also been identified as significant causes of recent climate change, often referred to as "global warming". Scientists actively work to understand past and future climate by using observations and theoretical models. A climate record extending deep into the Earth's past has been assembled, and continues to be built up, based on geological evidence from borehole temperature profiles, cores removed from deep accumulations of ice, floral and faunal records, glacial and periglacial processes, stable-isotope and other analyses of sediment layers, and records of past sea levels. More recent data are provided by the instrumental record. General circulation models, based on the physical sciences, are often used in theoretical approaches to match past climate data, make future projections, and link causes and effects in climate change. Greenhouse effect Greenhouse effect is a process by which thermal radiation from a planetary surface is absorbed by atmospheric greenhouse gases, and is re-radiated in all directions. Since part of this re- radiation is back towards the surface and the lower atmosphere, it results in an elevation of the average surface temperature above what it would be in the absence of the gases. Solar radiation at the frequencies of visible light largely passes through the atmosphere to warm the planetary surface, which then emits this energy at the lower frequencies of infrared thermal radiation. Infrared radiation is absorbed by greenhouse gases, which in turn re-radiate much of the energy to the surface and lower atmosphere. The mechanism is named after the effect of solar radiation passing through glass and warming a greenhouse, but the way it retains heat is fundamentally different as a greenhouse works by reducing airflow, isolating the warm air inside the structure so that heat is not lost by convection. If an ideal thermally conductive blackbody was the same distance from the Sun as the Earth is, it would have a temperature of about 5.3 °C. However, since the Earth reflects about 30% of the incoming sunlight, this idealized planet's effective temperature (the temperature of a blackbody that would emit the same amount of radiation) would be about −18 °C. The surface temperature of this hypothetical planet is 33 °C below Earth's actual surface temperature of approximately 14 °C. The mechanism that produces this difference between the actual surface temperature and the effective temperature is due to the atmosphere and is known as the greenhouse effect Global warming Since the dawn of the Industrial Revolution in the early 1800s, the burning of fossil fuels like coal, oil and gasoline have greatly increased the concentration of greenhouse gases in the
  14. 14. atmosphere, especially CO2, according to NASA. CO2 and other greenhouse gases act like a blanket, absorbing IR radiation and preventing it from escaping into outer space. The net effect is the gradual heating of Earth's atmosphere and surface, a process known as global warming. Atmospheric CO2 levels have increased by more than 40 percent since the beginning of the Industrial Revolution, from about 280 parts per million (ppm) in the 1800s to 400 ppm today. The last time Earth's atmospheric levels of CO2 reached 400 ppm was during the Pliocene Epoch, between 5 million and 3 million years ago, according to the University of California, San Diego's Scripps Institution of Oceanography. Acid rain Acid rain is a result of air pollution. When any type of fuel is burnt, lots of different chemicals are produced. The smoke that comes from a fire or the fumes that come out of a car exhaust don't just contain the sooty grey particles that you can see - they also contains lots of invisible gases that can be even more harmful to our environment. Power stations, factories and cars all burn fuels and therefore they all produce polluting gases. Some of these gases (especially nitrogen oxides and sulphur dioxide) react with the tiny droplets of water in clouds to form sulphuric and nitric acids. The rain from these clouds then falls as very weak acid - which is why it is known as "acid rain". Acidity is measured using a scale called the pH scale. This scale goes from 0 to 14. 0 is the most acidic and 14 is the most alkaline (opposite of acidic). Something with a pH value of 7, we call neutral, this means that it is neither acidic nor alkaline. Very strong acids will burn if they touch your skin and can even destroy metals. Acid rain is much, much weaker than this, never acidic enough to burn your skin. Rain is always slightly acidic because it mixes with naturally occurring oxides in the air. Unpolluted rain would have a pH value of between 5 and 6. When the air becomes more polluted with nitrogen oxides and sulphur dioxide the acidity can increase to a pH value of 4. Some rain has even been recorded as being pH2. The Effects of Acid Rain Acid rain can be carried great distances in the atmosphere, not just between countries but also from continent to continent. The acid can also take the form of snow, mists and dry dusts. The rain sometimes falls many miles from the source of pollution but wherever it falls it can have a serious effect on soil, trees, buildings and water. Forests all over the world are dying, fish are dying. In Scandinavia there are dead lakes, which are crystal clear and contain no living creatures or plant life. Many of Britain's freshwater fish are threatened, there have been reports of deformed fish being hatched. This leads to fish-eating birds and animals being affected also. Is acid rain responsible for all this? Scientists have been doing a lot of research into how acid rain affects the environment.
  15. 15. Ozone layer formation Over two billion years ago, early aquatic organisms called blue-green algae began using energy from the Sun to convert molecules of water (H2O) and carbon dioxide (CO2) and recombine them into organic compounds and molecular oxygen (O2). This solar energy conversion process is known as photosynthesis. Some of the photosynthetically created oxygen began to accumulate in the atmosphere, touching off a massive ecological disaster with respect to early existing anaerobic organisms. As oxygen in the atmosphere increased, CO2 decreased. High in the atmosphere, some oxygen (O2) molecules absorbed energy from the Sun's ultraviolet (UV) rays and split to form single oxygen atoms. These atoms combined with molecular oxygen (O2) to form ozone (O3) molecules, which are very effective at absorbing UV rays. The thin layer of ozone that surrounds Earth acts as a shield, protecting the planet from irradiation by UV light. The amount of ozone required to shield Earth from biologically lethal UV radiation, wavelengths from 200 to 300 nanometers (nm), is believed to have been in existence 600 million years ago. At this time, the oxygen level was approximately 10% of its present atmospheric concentration. Prior to this period, life was restricted to the ocean. The presence of ozone enabled organisms to develop and live on the land. Ozone layer depletion The ozone layer is a belt of naturally occurring ozone gas that sits 9.3 to 18.6 miles (15 to 30 kilometers) above Earth and serves as a shield from the harmful ultraviolet B radiation emitted by the sun. Ozone is a highly reactive molecule that contains three oxygen atoms. It is constantly being formed and broken down in the high atmosphere, 6.2 to 31 miles (10 to 50 kilometers) above Earth, in the region called the stratosphere. Today, there is widespread concern that the ozone layer is deteriorating due to the release of pollution containing the chemicals chlorine and bromine. Such deterioration allows large amounts of ultraviolet B rays to reach Earth, which can cause skin cancer and cataracts in humans and harm animals as well. Extra ultraviolet B radiation reaching Earth also inhibits the reproductive cycle of phytoplankton, single-celled organisms such as algae that make up the bottom rung of the food chain. Biologists fear that reductions in phytoplankton populations will in turn lower the populations of other animals. Researchers also have documented changes in the reproductive rates of young fish, shrimp, and crabs as well as frogs and salamanders exposed to excess ultraviolet B. Chlorofluorocarbons (CFCs), chemicals found mainly in spray aerosols heavily used by industrialized nations for much of the past 50 years, are the primary culprits in ozone layer breakdown. When CFCs reach the upper atmosphere, they are exposed to ultraviolet rays, which causes them to break down into substances that include chlorine. The chlorine reacts with the oxygen atoms in ozone and rips apart the ozone molecule.
  16. 16. Impact of water and air borne diseases on human health Waterborne diseases • Droughts can cause increased concentrations of effluent pathogens, overwhelming water treatment plants and contaminating surface water. Older water treatment plants are particularly at risk. • Changes in ocean and coastal ecosystems, including changes in pH, nutrient and contaminant runoff, salinity, and water security, that can cause degradation of fresh water, particularly in areas where much of the population uses untreated surface water for daily consumption and activities. • Increased frequency of intense extreme weather events can cause flooding of water and sewage treatment facilities, increasing the risk of waterborne diseases. • Indirectly, the lack of water can cause pressure on agricultural productivity, crop failure, malnutrition, starvation, population displacement, and resource conflict. • Changes can occur in the distribution and concentrations of chemical contaminants in coastal and ocean waters through the release of contaminants previously locked in polar ice she Air borne diseases Climatic factors such as absolute humidity have been associated with risk of lower respiratory tract infection. Respiratory syncytial virus (RSV) is one of the most important viral respiratory pathogens especially for infants. The epidemic activity of RSV infection is related to meteorological conditions and thus to latitude: persistently high temperature and humidity results in epidemic peaks in summer and early autumn, while in temperate climates RSV infection peaks in the winter. A causal link with temperature seems inconsistent based on these climatic data, but the RSV infection season in England and Wales has ended earlier and its duration has shortened as the climate has become warmer. Seasonality has been documented for a number of other respiratory infections including tuberculosis, and seasonal fluctuations of El Niño-southern oscillation in California are associated with the impact of influenza epidemics (hospital admissions or mortality profiles;) but a direct link to climate change has not been established. Furthermore, increased use of cooling towers during heat waves might increase the risk for exposure to Legionella spp, although appropriate public health measures should be able to contain this risk. On the basis of the articles reviewed here, it is not possible to draw conclusive inferences about the link between airborne diseases and climate change, but it might shorten the transmission season.
  17. 17. Toxic wastes Toxic waste is waste material that can cause death, injury or birth defects to living creatures. It spreads quite easily and can contaminate lakes, rivers, and the atmosphere. The term is often used interchangeably with “hazardous waste”, or discarded material that can pose a long-term risk to health or environment. Hazardous wastes are poisonous byproducts of manufacturing, farming, city septic systems, construction, automotive garages, laboratories, hospitals and other industries. The waste may be liquid, solid, or sludge and contain chemicals, heavy metals, radiation, dangerous pathogens, or other toxins. Even households generate hazardous waste from items such as batteries, used computer equipment, and leftover paints or pesticides. In the United States, the Environmental Protection Agency (EPA) and the state departments oversee the rules that regulate hazardous waste. The EPA requires that toxic waste be handled with special precautions and be disposed of in designated facilities around the country. Also, many cities in the United States have collection days where household toxic waste is gathered. Some materials that may not be accepted at regular landfills are ammunition, commercially generated waste, explosives/shock sensitive items, hypodermic needles/syringes, medical waste, radioactive materials, and smoke detectors. Carcinogens A carcinogen is any substance, radionuclide, or radiation that is an agent directly involved in causing cancer. This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive substances are considered carcinogens, but their carcinogenic activity is attributed to the radiation, for example gamma rays and alpha particles, which they emit. Common examples of non-radioactive carcinogens are inhaled asbestos, certain dioxins, and tobacco smoke. Although the public generally associates carcinogenicity with synthetic chemicals, it is equally likely to arise in both natural and synthetic substances. Carcinogens are not necessarily immediately toxic, thus their effect can be insidious. Cancer is any disease in which normal cells are damaged and do not undergo programmed cell death as fast as they divide via mitosis. Carcinogens may increase the risk of cancer by altering cellular metabolism or damaging DNA directly in cells, which interferes with biological processes, and induces the uncontrolled, malignant division, ultimately leading to the formation of tumors. Usually, severe DNA damage leads to apoptosis, but if the programmed cell death pathway is damaged, then the cell cannot prevent itself from becoming a cancer cell
  18. 18. Nuclear hazards The world's nuclear fleet creates about 10,000 metric tons of high-level spent nuclear fuel each year. High-level radioactive waste management concerns management and disposal of highly radioactive materials created during production of nuclear power. The technical issues in accomplishing this are daunting, due to the extremely long periods radioactive wastes remain deadly to living organisms. Of particular concern are two long-lived fission products, Technetium-99 (half-life 220,000 years) and Iodine-129 (half-life 15.7 million years), which dominate spent nuclear fuel radioactivity after a few thousand years. The most troublesome transuranic elements in spent fuel are Neptunium-237 (half-life two million years) and Plutonium-239 (half-life 24,000 years). Consequently, high-level radioactive waste requires sophisticated treatment and management to successfully isolate it from the biosphere. This usually necessitates treatment, followed by a long-term management strategy involving permanent storage, disposal or transformation of the waste into a non-toxic form. Governments around the world are considering a range of waste management and disposal options, usually involving deep-geologic placement, although there has been limited progress toward implementing long-term waste management solutions. This is partly because the timeframes in question when dealing with radioactive waste range from 10,000 to millions of years, according to studies based on the effect of estimated radiation doses. Natural Radiation Natural radiation is a by-product of processes and materials created when the earth was formed. The sun on which we all depend for heat and light produces very highly charged particles called cosmic rays. We are exposed continuously to this radiation every day. Not many people realize that we all have radiation sources within our bodies, usually in the form of potassium. Radioactive potassium occurs naturally in the earth and is therefore present in trace amounts in the food we eat and the water we drink. Additionally, radioactivity from uranium and thorium is found in rocks and soil. For example, radon gas is a source of radiation that results from the decay of uranium found in the earth. Radon gas has recently been identified as a concern because it can penetrate through the foundation of homes. Recent studies show that radon gas contributes more than half of our radiation exposure each year. Man-Made Radiation Our environment contains many sources of radiation. Some of these sources are natural in origin, either originating from the sun or from radioactive materials that have resided in the earth since its formation. Other sources are man-made. X-ray machines are used for dental and medical purposes, television sets are used for entertainment and microwave ovens are used to cook foods.
  19. 19. Nuclear power plants use the energy of radiation to convert water to steam, which is then used to generate electricity.

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