Types Of Pollution And Their Causes Environmental Sciences Essay
|✅ Paper Type: Free Essay||✅ Subject: Environmental Sciences|
|✅ Wordcount: 5427 words||✅ Published: 1st Jan 2015|
Pollution is the introduction of contaminants into a natural environment that causes discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat, or light. Pollutants, the elements of pollution, can be foreign substances or energies, or naturally occurring; when naturally occurring, they are considered contaminants when they exceed natural levels. Pollution is often classed as point source or nonpoint source pollution.
POINT SOURCE POLLUTION
A point source of pollution is a single identifiable localized source of air, water, thermal, noise or light pollution. A point source has negligible extent, distinguishing it from other pollution source geometries. The sources are called point sources because in mathematical modeling, they can be approximated as a mathematical point to simplify analysis. Pollution point sources are identical to other physics, engineering, optics andchemistry point sources except that their emissions have been labeled
Water pollution from an oil refinery wastewater discharge outlet
Noise pollution from a jet engine
Disruptive seismic vibration from a localized seismic study
Light pollution from an intrusive street light
Thermal pollution from an industrial process outfall
Radio emissions from an interference-producing electrical device
Types of air pollution sources which have finite extent are line sources, area sources and volume sources. Air pollution sources are also often categorized as either stationary or mobile.
NON POINT SOURCE POLLUTION
Non-point source (NPS) pollution is water pollution affecting a water body from diffuse sources, such as polluted runoff from agricultural areas draining into a river, or wind-borne debris blowing out to sea. Nonpoint source pollution can be contrasted with point source pollution, where discharges occur to a body of water at a single location, such as discharges from a chemical factory, urban runoff from a roadway storm drain, or from ships at sea.
NPS may derive from many different sources with no specific solution to rectify the problem, making it difficult to regulate. It is the leading cause of water pollution in the United States today, with polluted runoff from agriculture the primary cause.
Other significant sources of runoff include hydrological and habitat modification, and silviculture (forestry).
Contaminated stormwater washed off of parking lots, roads and highways, and lawns (often containing fertilizers and pesticides) is called urban runoff. This runoff is often classified as a type of NPS pollution. Some people may also consider it a point source because many times it is channeled into municipal storm drain systems and discharged through pipes to nearby surface waters. However, not all urban runoff flows through storm drain systems before entering waterbodies. Some may flow directly into waterbodies, especially in developing and suburban areas. Also, unlike other types of point sources, such as industrial discharge, wastewater plants and other operations, pollution in urban runoff cannot be attributed to one activity or even group of activities. Therefore, because it is not caused by an easily identified and regulated activity, urban runoff pollution sources are also often treated as true nonpoint sources as municipalities work to abate them.
MAJOR FORMS OF POLLUTION :::
The major forms of pollution are listed below along with the particular pollutants relevant to each of them:
Air pollution is the introduction of chemicals, particulate matter, or biological materials that cause harm or discomfort to humans or other living organisms, or damages the natural environment into the atmosphere.
The atmosphere is a complex dynamic 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.
Noise pollution (or environmental noise) is displeasing human, animal or machine-created sound that disrupts the activity or balance of human or animal life. The word noise comes from the Latin word nauseas, meaning seasickness.
The source of most outdoor noise worldwide is mainly construction and transpHYPERLINK “http://en.wikipedia.org/wiki/Transport”ortation systems, including motor vehicle noise, aircraft noise and rail noise. Poor urban planning may give rise to noise pollution, since side-by-side industrial and residential buildings can result in noise pollution in the residential area.
Indoor and outdoor noise pollution sources include car alarms, emergency service sirens, mechanical equipment, fireworks, compressed air horns, groundskeeping equipment, barking dogs, appliances,lighting hum, audio entertainment systems, electric megaphones, and loud people.
Soil contamination (soil pollution) is caused by the presence of xenobiotic (human-made) chemicals or other alteration in the natural soil environment. This type of contamination typically arises from the rupture of underground storage tanks, application of pesticides, percolation of contaminated surface water to subsurface strata, oil and fuel dumping, leaching of wastes fromlandfills or direct discharge of industrial wastes to the soil. The most common chemicals involved are petroleum hydrocarbons, solvents, pesticides, lead and other heavy metals. This occurrence of this phenomenon is correlated with the degree of industrialization and intensities of chemical usage.
The concern over soil contamination stems primarily from health risks, from direct contact with the contaminated soil, vapors from the contaminants, and from secondary contamination of water supplies within and underlying the soil. Mapping of contaminated soil sites and the resulting cleanup are time consuming and expensive tasks, requiring extensive amounts of geology,hydrology, chemistry and computer modeling skills.
It is in North America and Western Europe that the extent of contaminated land is most well known, with many of countries in these areas having a legal framework to identify and deal with this environmental problem; this however may well be just the tip of the iceberg with developing countries very likely to be the next generation of new soil contamination cases.
Radioactive contamination, also called radiological contamination, is radioactive substances on surfaces, or within solids, liquids or gases (including the human body), where their presence is unintended or undesirable, or the process giving rise to their presence in such places.
Also used less formally to refer to a quantity, namely the activity on a surface (or on a unit area of a surface).
Contamination does not include residual radioactive material remaining at a site after the completion of decommissioning.
The term radioactive contamination may have a connotation that is not intended.
The term radioactive contamination refers only to the presence of radioactivity, and gives no indication of the magnitude of the hazard involved.
Radioactive contamination is typically the result of a spill or accident during the production or use of radionuclides (radioisotopes), an unstable nucleus which has excessive energy. Contamination may occur from radioactive gases, liquids or particles. For example, if a radionuclide used in nuclear medicine is accidentally spilled, the material could be spread by people as they walk around. Radioactive contamination may also be an inevitable result of certain processes, such as the release of radioactive xenon in nuclear fuel reprocessing. In cases that radioactive material cannot be contained, it may be diluted to safe concentrations. Nuclear fallout is the distribution of radioactive contamination by a nuclear explosion.
Thermal pollution is the degradation of water quality by any process that changes ambient water temperature.
A common cause of thermal pollution is the use of water as a coolant by power plants and industrial manufacturers. When water used as a coolant is returned to the natural environment at a higher temperature, the change in temperature (a) decreases oxygen supply, and (b) affects ecosystem composition. Urban runoff–stormwater discharged to surface waters from roads and parking lots–can also be a source of elevated water temperatures.
When a power plant first opens or shuts down for repair or other causes, fish and other organisms adapted to particular temperature range can be killed by the abrupt rise in water temperature known as ‘thermal shock’.
SOURCES AND CAUSES
Air pollution comes from both natural and man made sources. Though globally man 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, 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 worldHYPERLINK “http://en.wikipedia.org/wiki/World’s_population”‘HYPERLINK “http://en.wikipedia.org/wiki/World’s_population”s population, but produce roughly 25% of the world’s COHYPERLINK “http://en.wikipedia.org/wiki/Carbon_dioxide”2, and generate approximately 30% of world’s waste. In 2007, China has overtaken the United States as the world’s biggest producer of CO2.
In February 2007, a report by the Intergovernmental Panel on Climate Change (IPCC), representing the work of 2,500 scientists from more than 130 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 in order 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).
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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.
Pollution can also be the consequence of a natural disaster. For example, hurricanes often involve water contamination from sewage, and petrochemical spills from ruptured boats or automobiles. Larger scale and environmental damage is not uncommon when coastal oil rigs or refineries are involved. Some sources of pollution, such as nuclear power plants or oil tankers, can produce widespread and potentially hazardous releases when accidents occur.
In the case of noise pollution the dominant source class is the motor vehicle, producing about ninety percent of all unwanted noise worldwide.
Adverse air quality can kill many organisms including humans. Ozone pollution can cause respiratory disease, cardiovascular disease, throat inflammation, chest pain, andcongestion. Water pollution causes approximately 14,000 deaths per day, mostly due to contamination of drinking water by untreated sewage in developing countries. An estimated 700 million Indians have no access to a proper toilet, and 1,000 Indian children die of diarrhoeal sickness every day. Nearly 500 million Chinese lack access to safe drinking water. 656,000 people die prematurely each year in China because of air pollution. In India, air pollution is believed to cause 527,700 fatalities a year. Studies have estimated that the number of people killed annually in the US could be over 50,000.
Oil spills can cause skin irritations and rashes. Noise pollution induces hearing loss, high blood pressure, stress, and sleep disturbance. Mercury has been linked to developmental deficits in children and neurologic symptoms. Older people are majorly exposed to diseases induced by air pollution. Those with heart or lung disorders are under additional risk. Children and infants are also at serious risk. Lead and other heavy metals have been shown to cause neurological problems. Chemical and radioactive substances can cause cancerand as well as birth defects.
Pollution has been found to be present widely in the environment. There are a number of effects of this:
Biomagnification describes situations where toxins (such as heavy metals) may pass through trophic levels, becoming exponentially more concentrated in the process.
Carbon dioxide emissions cause ocean acidification, the ongoing decrease in the pH of the Earth’s oceans as CO2 becomes dissolved.
The emission of greenhouse gases leads to global warming which affects ecosystems in many ways.
Invasive species can out compete native species and reduce biodiversity. Invasive plants can contribute debris and biomolecules (allelopathy) that can alter soil and chemical compositions of an environment, often reducing native species competitiveness.
Nitrogen oxides are removed from the air by rain and fertilise land which can change the species composition of ecosystems.
Smog and haze can reduce the amount of sunlight received by plants to carry out photosynthesis and leads to the production of tropospheric ozone which damages plants.
Soil can become infertile and unsuitable for plants. This will affect other organisms in the food web.
Sulphur dioxide and nitrogen oxides can cause acid rain which lowers the pH value of soil.
POLLUTION CONTROL ::
Pollution control is a term used in environmental management. It means the control of emissions and effluents into air, water or soil. Without pollution control, the waste products from consumption, heating, agriculture, mining, manufacturing, transportation and other human activities, whether they accumulate or disperse, will degrade the environment. In the hierarchy of controls, pollution prevention and waste minimization are more desirable than pollution control.
Recycling involves processing used materials (waste) into new products to prevent waste of potentially useful materials, reduce the consumption of fresh raw materials, reduce energy usage, reduce air pollution (from incineration) and water pollution (from landfilling) by reducing the need for “conventional” waste disposal, and lower greenhouse gas emissions as compared to virgin production. Recycling is a key component of modern waste reduction and is the third component of the “Reduce, Reuse, Recycle” waste hierarchy.
Recyclable materials include many kinds of glass, paper, metal, plastic, textiles, and electronics. Although similar in effect, the composting or other reuse of biodegradable waste – such as food or garden waste – is not typically considered recycling. Materials to be recycled are either brought to a collection center or picked up from the curbside, then sorted, cleaned, and reprocessed into new materials bound for manufacturing.
In a strict sense, recycling of a material would produce a fresh supply of the same material-for example, used office paper would be converted into new office paper, or used foamed polystyrene into new polystyrene. However, this is often difficult or too expensive (compared with producing the same product from raw materials or other sources), so “recycling” of many products or materials involves their reuse in producing different materials (e.g., paperboard) instead. Another form of recycling is the salvage of certain materials from complex products, either due to their intrinsic value (e.g., lead from car batteries, or goldfrom computer components), or due to their hazardous nature (e.g., removal and reuse of mercury from various items). Critics dispute the net economic and environmental benefits of recycling over its costs, and suggest that proponents of recycling often make matters worse and suffer from confirmation bias. Specifically, critics argue that the costs and energy used in collection and transportation detract from (and outweigh) the costs and energy saved in the production process; also that the jobs produced by the recycling industry can be a poor trade for the jobs lost in logging, mining, and other industries associated with virgin production; and that materials such as paper pulp can only be recycled a few times before material degradation prevents further recycling. Proponents of recycling dispute each of these claims, and the validity of arguments from both sides has led to enduring controversy.
A number of different systems have been implemented to collect recyclates from the general waste stream. These systems lie along the spectrum of trade-off between public convenience and government ease and expense. The three main categories of collection are “drop-off centres”, “buy-back centres” and “curbside collection”.
Drop-off centres require the waste producer to carry the recyclates to a central location, either an installed or mobile collection station or the reprocessing plant itself. They are the easiest type of collection to establish, but suffer from low and unpredictable throughput. Buy-back centres differ in that the cleaned recyclates are purchased, thus providing a clear incentive for use and creating a stable supply. The post-processed material can then be sold on, hopefully creating a profit. Unfortunately government subsidies are necessary to make buy-back centres a viable enterprise, as according to the United States Nation Solid Wastes Management Association it costs on average US$50 to process a ton of material, which can only be resold for US$30.
Curbside collection encompasses many subtly different systems, which differ mostly on where in the process the recyclates are sorted and cleaned. The main categories are mixed waste collection, commingled recyclables and source separation. A waste collection vehicle generally picks up the waste.
At one end of the spectrum is mixed waste collection, in which all recyclates are collected mixed in with the rest of the waste, and the desired material is then sorted out and cleaned at a central sorting facility. This results in a large amount of recyclable waste, paper especially, being too soiled to reprocess, but has advantages as well: the city need not pay for a separate collection of recyclates and no public education is needed. Any changes to which materials are recyclable is easy to accommodate as all sorting happens in a central location.
In a Commingled or single-stream system, all recyclables for collection are mixed but kept separate from other waste. This greatly reduces the need for post-collection cleaning but does require public education on what materials are recyclable.
Source separation is the other extreme, where each material is cleaned and sorted prior to collection. This method requires the least post-collection sorting and produces the purest recyclates, but incurs additional operating costs for collection of each separate material. An extensive public education program is also required, which must be successful if recyclate contamination is to be avoided.
Source separation used to be the preferred method due to the high sorting costs incurred by commingled collection. Advances in sorting technology (see sorting below), however, have lowered this overhead substantially-many areas which had developed source separation programs have since switched to comingled collection.
Once commingled recyclates are collected and delivered to a central collection facility, the different types of materials must be sorted. This is done in a series of stages, many of which involve automated processes such that a truck-load of material can be fully sorted in less than an hour. Some plants can now sort the materials automatically, known as single-stream recycling. A 30 percent increase in recycling rates has been seen in the areas where these plants exist.
Initially, the commingled recyclates are removed from the collection vehicle and placed on a conveyor belt spread out in a single layer. Large pieces of corrugated fiberboard and plastic bags are removed by hand at this stage, as they can cause later machinery to jam.
Next, automated machinery separates the recyclates by weight, splitting lighter paper and plastic from heavier glass and metal. Cardboard is removed from the mixed paper, and the most common types of plastic, PET (#1) and HDPE (#2), are collected. This separation is usually done by hand, but has become automated in some sorting centers: a spectroscopic scanner is used to differentiate between different types of paper and plastic based on the absorbed wavelengths, and subsequently divert each material into the proper collection channel.
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Strong magnets are used to separate out ferrous metals, such as iron, steel, and tin-plated steel cans (“tin cans”). Non-ferrous metals are ejected by magnetic eddy currents in which a rotating magnetic field induces an electric current around the aluminium cans, which in turn creates a magnetic eddy current inside the cans. This magnetic eddy current is repulsed by a large magnetic field, and the cans are ejected from the rest of the recyclate stream.
Finally, glass must be sorted by hand based on its color: brown, amber, green or clear.
GREEN HOUSE GASES AND GLOBAL WARNING
Carbon dioxide, while vital for photosynthesis, is sometimes referred to as pollution, because raised levels of the gas in the atmosphere are affecting the Earth’s climate. Disruption of the environment can also highlight the connection between areas of pollution that would normally be classified separately, such as those of water and air. Recent studies have investigated the potential for long-term rising levels of atmospheric carbon dioxide to cause slight but critical increases in the acidity of ocean waters, and the possible effects of this on marine ecosystems.
Global warming is the increase in the average temperature of Earth’s near-surface air and oceans since the mid-20th century and its projected continuation. According to the 2007 Fourth Assessment Report by the Intergovernmental Panel on Climate Change (IPCC), global surface temperature increased 0.74 ± 0.18 °C (1.33 ± 0.32 °F) during the 20th century. Global dimming, a result of increasing concentrations of atmospheric aerosols that block sunlight from reaching the surface, has partially countered the effects of warming induced by greenhouse gases.
Climate model projections summarized in the latest IPCC report indicate that the global surface temperature is likely to rise a further 1.1 to 6.4 °C (2.0 to 11.5 °F) during the 21st century. The uncertainty in this estimate arises from the use of models with differing sensitivity to greenhouse gas concentrations and the use of differing estimates of future greenhouse gas emissions. An increase in global temperature will cause sea levels to rise and will change the amount and pattern of precipitation, probably including expansion of subtropical deserts. Warming is expected to be strongest in the Arcticand would be associated with continuing retreat of glaciers, permafrost and sea ice. Other likely effects include changes in the frequency and intensity of extreme weather events, species extinctions, and changes in agricultural yields. Warming and related changes will vary from region to region around the globe, though the nature of these regional variations is uncertain. As a result of contemporary increases in atmospheric carbon dioxide, the oceans have become more acidic; a result that is predicted to continue.
The scientific consensus is that anthropogenic global warming is occurring. Nevertheless, political and public debate continues. The Kyoto Protocol is aimed at stabilizing greenhouse gas concentration to prevent a “dangerous anthropogenic interference”. As of November 2009, 187 states had signed and ratified the protocol.
The greenhouse effect is the process by which absorption and emission of infrared radiation by gases in the atmosphere warm a planet’s lower atmosphere and surface. It was proposed by Joseph Fourierin 1824 and was first investigated quantitatively by Svante Arrhenius in 1896. The question in terms of global warming is how the strength of the presumed greenhouse effect changes when human activity increases the concentrations of greenhouse gases in the atmosphere.
Naturally occurring greenhouse gases have a mean warming effect of about 33 °C (59 °F). The major greenhouse gases are water vapor, which causes about 36-70 percent of the greenhouse effect;carbon dioxide (CO2), which causes 9-26 percent; methane (CH4), which causes 4-9 percent; and ozone (O3), which causes 3-7 percent. Clouds also affect the radiation balance, but they are composed of liquid water or ice and so have different effects on radiation from water vapor.
Human activity since the Industrial Revolution has increased the amount of greenhouse gases in the atmosphere, leading to increased radiative forcing from CO2, methane, tropospheric ozone, CFCs andnitrous oxide. The concentrations of CO2 and methane have increased by 36% and 148% respectively since 1750. These levels are much higher than at any time during the last 650,000 years, the period for which reliable data has been extracted from ice cores. Less direct geological evidence indicates that CO2 values higher than this were last seen about 20 million years ago. Fossil fuel burning has produced about three-quarters of the increase in CO2 from human activity over the past 20 years. Most of the rest is due to land-use change, particularly deforestation.
Over the last three decades of the 20th century, GDP per capita and population growth were the main drivers of increases in greenhouse gas emissions. CO2 emissions are continuing to rise due to the burning of fossil fuels and land-use change. Emissions scenarios, estimates of changes in future emission levels of greenhouse gases, have been projected that depend upon uncertain economic,sociological, technological, and natural developments. In most scenarios, emissions continue to rise over the century, while in a few, emissions are reduced. These emission scenarios, combined with carbon cycle modelling, have been used to produce estimates of how atmospheric concentrations of greenhouse gases will change in the future. Using the six IPCC SRES “marker” scenarios, models suggest that by the year 2100, the atmospheric concentration of CO2 could range between 541 and 970 ppm. This is an increase of 90-250% above the concentration in the year 1750. Fossil fuel reserves are sufficient to reach these levels and continue emissions past 2100 if coal, tar sands or methane clathrates are extensively exploited.
The destruction of stratospheric ozone by chlorofluorocarbons is sometimes mentioned in relation to global warming. Although there are a few areas of linkage, the relationship between the two is not strong. Reduction of stratospheric ozone has a cooling influence. Substantial ozone depletion did not occur until the late 1970s. Ozone in the troposphere (the lowest part of the EarthHYPERLINK “http://en.wikipedia.org/wiki/Atmosphere_of_Earth”‘HYPERLINK “http://en.wikipedia.org/wiki/Atmosphere_of_Earth”s atmosphere) does contribute to surface warming.
8 most polluted cities in India :::
Number of people affected: 2,600,000
Type of pollutant: Hexavalent chromium and other metals
Source of pollution: Chromite mines and processing
Hexavalent chromium is: a nasty heavy metal used for stainless steel production and leather tanning that is carcinogenic if inhaled or ingested.
In Sukinda, which contains one of the largest open cast chromite ore mines in the world, 60% of the drinking water contains hexavalent chromium at levels more than double international standards. An Indian health group estimated that 84.75% of deaths in the mining areas — where regulations are nonexistent — are due to chromite-related diseases. There has been virtually no attempt to clean up the contamination.
Sukinda has been listed in the Top 10 most polluted places in the world by the US-based Blacksmith Institute.
Labourers work at a road construction site near Vapi
Number of people potentially affected: 71,000
Type of pollutant: Chemicals and heavy metals
Source of pollution: Industrial estates
If India’s environment is on the whole healthier than its giant neighbor China’s, that’s because India is developing much more slowly. But that’s changing, starting in towns like Vapi, which sits at the southern end of a 400-km-long belt of industrial estates. For the citizens of Vapi, the cost of growth has been severe: levels of mercury in the city’s groundwater are reportedly 96 times higher than WHO safety levels, and heavy metals are present in the air and the local produce. “It’s just a disaster,” says Fuller.
Vapi has been listed in the Top 10 most polluted places in the world by the US-based Blacksmith Institute.
Mandi Gobindgarh, Punjab
Number of people affected: 155,416
Type of pollutant: High dust and smoke particulate
Source of pollution: Industrial units
Gobindgarh in Punjab, also known as ‘Loha mandi’, recorded suspended particulate matter (microscopic particles in the air such as dust and smoke) level of 252 micrograms per cubic metre in 2007, 320 percent higher than the national standard level of 60 micrograms.
Known for its iron and steel factories, it is one of the most polluted city in the country. The population in Gobindgarh shows a higher prevalence of symptoms of angina and cardiovascular disease.
A ragpicker rows boat in polluted Gomti river in Lucknow
Number of people affected: 30 lakh
Type of pollutant: High dust and smoke particulate
Source of pollution: Industrial units, vehicles
Vehicular emissions are the main cause of air pollution in Lucknow. In recent years there has been a rapid rise in vehicular
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