Pollution
Pollution is the introduction of
contaminants into an environment that causes instability, disorder, harm or
discomfort to the ecosystem i.e. physical systems or living organisms.[1] 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. The
Blacksmith Institute issues annually a list of the world's worst polluted
places. In the 2007 issues the ten top nominees are located in
Official acknowledgement
The earliest known writings concerned with
pollution were Arabic medical treatises written between the 9th and 13th
centuries, by physicians such as al-Kindi (Alkindus), Qusta ibn Luqa (Costa ben Luca), Muhammad ibn Zakarīya Rāzi (Rhazes), Ibn Al-Jazzar, al-Tamimi, al-Masihi, Ibn Sina (Avicenna), Ali ibn Ridwan, Ibn
Jumay, Isaac Israeli ben
Solomon, Abd-el-latif, Ibn
al-Quff, and Ibn al-Nafis. Their works covered a number of subjects related to
pollution such as air contamination, water contamination, soil contamination,
solid waste mishandling, and environmental assessments of certain
localities.[3]
King Edward I of England banned the burning of
sea-coal by proclamation in London in 1272, after its smoke had become a
problem.[4][5] But the fuel was so common in England that this earliest of
names for it was acquired because it could be carted away from some shores by
the wheelbarrow. Air pollution would continue to be a problem in
It was the industrial revolution that gave birth
to environmental pollution as we know it today. The emergence of great
factories and consumption of immense quantities of coal and other fossil fuels
gave rise to unprecedented air pollution and the large volume of industrial
chemical discharges added to the growing load of untreated human waste.
Modern
awareness
Early Soviet poster, before the modern
awareness: "The smoke of chimneys is the breath of Soviet Russia"
Pollution became a popular issue after WW2, when
the aftermath of atomic warfare and testing made evident the perils of
radioactive fallout. Then a conventional catastrophic event The Great Smog of
Pollution began to draw major public attention
in the
Bad bouts of local pollution helped increase
consciousness. PCB dumping in the
The development of nuclear science introduced
radioactive contamination, which can remain lethally radioactive for hundreds
of thousands of years.
Nuclear weapons continued to be tested in the
Cold War, sometimes near inhabited areas, especially in the earlier stages of
their development. The toll on the worst-affected populations and the growth
since then in understanding about the critical threat to human health posed by
radioactivity has also been a prohibitive complication associated with nuclear
power. Though extreme care is practiced in that industry, the potential for
disaster suggested by incidents such as those at Three Mile Island and
International catastrophes such as the wreck of
the Amoco Cadiz oil tanker off the coast of
Growing evidence of local and global pollution
and an increasingly informed public over time have given rise to
environmentalism and the environmental movement, which generally seek to limit
human impact on the environment.
[edit]
Forms of pollution
The major forms of pollution are listed below
along with the particular pollutants relevant to each of them:
Air
pollution, the release of chemicals and particulates into the
atmosphere. Common gaseous air pollutants include carbon monoxide, sulfur
dioxide, chlorofluorocarbons (CFCs) and nitrogen oxides produced by industry
and motor vehicles. Photochemical ozone and smog are created as nitrogen oxides
and hydrocarbons react to sunlight. Particulate matter, or fine dust is
characterized by their micrometre size PM10 to PM2.5.
Water
pollution, by the release of waste products and contaminants
into surface runoff into river drainage systems, leaching into groundwater,
liquid spills, wastewater discharges, eutrophication
and littering.
Soil contamination occurs when chemicals are
released by spill or underground leakage. Among the most significant soil
contaminants are hydrocarbons, heavy metals, MTBE,herbicides,
pesticides and chlorinated hydrocarbons.
Littering
Radioactive contamination, resulting from 20th
century activities in atomic physics, such as nuclear power generation and
nuclear weapons research, manufacture and deployment. (See alpha emitters and
actinides in the environment.)
Noise
pollution, which encompasses roadway noise, aircraft noise,
industrial noise as well as high-intensity sonar.
Light
pollution, includes light trespass, over-illumination and
astronomical interference.
Visual
pollution, which can refer to the presence of overhead power
lines, motorway billboards, scarred landforms (as from strip mining), open
storage of trash or municipal solid waste.
Thermal
pollution, is a temperature change in natural water bodies
caused by human influence, such as use of water as coolant in a power plant.
Pollutants
A pollutant is a waste material that pollutes
air, water or soil. Three factors determine the severity of a pollutant: its
chemical nature, the concentration and the persistence.
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.[9][10][11]
About 400 million metric tons of hazardous
wastes are generated each year.[14] The United States alone produces about 250
million metric tons.[15] Americans constitute less than 5% of the world's
population, but produce roughly 25% of the world’s CO2,[16] and generate
approximately 30% of world’s waste.[17][18] In 2007, China has overtaken the
United States as the world's biggest producer of CO2.[19]
In February
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
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.
[edit]
Effects
[edit]
Human health
Overview of main health effects on humans from
some common types of pollution.[22][23][24]
Adverse air quality can kill many organisms
including humans. Ozone pollution can cause respiratory disease, cardiovascular
disease, throat inflammation, chest pain, and congestion. 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.[25] Nearly 500
million Chinese lack access to safe drinking water.[26] 656,000 people die
prematurely each year in China because of air pollution. In
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 cancer and as well as birth defects.
[edit]
Environment
Pollution has been found to be present widely in
the environment. There are a number of effects of this:
Nitrogen oxides are removed from the air by rain
and fertilise land which can change the species
composition of ecosystems.
Soil can become infertile and unsuitable for
plants. This will affect other organisms in the food web.
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.
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.
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.
Regulation
and monitoring
To protect the environment from the adverse
effects of pollution, many nations worldwide have enacted legislation to regulate
various types of pollution as well as to mitigate the adverse effects of
pollution.
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.
[edit]
Pollution control devices
Dust collection systems
Cyclones
Electrostatic precipitators
Baghouses
Scrubbers
Baffle spray scrubber
Cyclonic spray scrubber
Ejector venturi
scrubber
Mechanically aided scrubber
Spray tower
Wet scrubber
Sewage treatment
API oil-water separators.
Sedimentation (water treatment)
Dissolved air flotation (DAF)
Activated sludge biotreaters
Biofilters
Powdered activated carbon treatment
Vapor recovery systems
Perspectives
The earliest precursor of pollution generated by
life forms would have been a natural function of their existence. The attendant
consequences on viability and population levels fell within the sphere of
natural selection. These would have included the demise of a population locally
or ultimately, species extinction. Processes that were untenable would have
resulted in a new balance brought about by changes and adaptations. At the
extremes, for any form of life, consideration of pollution is superseded by
that of survival.
For humankind, the factor of technology is a
distinguishing and critical consideration, both as an enabler and an additional
source of byproducts. Short of survival, human concerns include the range from
quality of life to health hazards. Since science holds experimental
demonstration to be definitive, modern treatment of toxicity or environmental
harm involves defining a level at which an effect is observable. Common
examples of fields where practical measurement is crucial include automobile
emissions control, industrial exposure (eg
Occupational Safety and Health Administration (OSHA) PELs),
toxicology (eg LD50), and medicine (eg medication and radiation doses).
"The solution to pollution is
dilution", is a dictum which summarizes a traditional approach to
pollution management whereby sufficiently diluted pollution is not
harmful.[30][31] It is well-suited to some other modern, locally-scoped
applications such as laboratory safety procedure and hazardous material release
emergency management. But it assumes that the dilutant
is in virtually unlimited supply for the application or that resulting
dilutions are acceptable in all cases.
Such simple treatment for environmental
pollution on a wider scale might have had greater merit in earlier centuries
when physical survival was often the highest imperative, human population and
densities were lower, technologies were simpler and their byproducts more
benign. But these are often no longer the case. Furthermore, advances have
enabled measurement of concentrations not possible before. The use of
statistical methods in evaluating outcomes has given currency to the principle
of probable harm in cases where assessment is warranted but resorting to
deterministic models is impractical or unfeasible. In addition, consideration
of the environment beyond direct impact on human beings has gained prominence.
Yet in the absence of a superseding principle,
this older approach predominates practices throughout the world. It is the
basis by which to gauge concentrations of effluent for legal release, exceeding
which penalties are assessed or restrictions applied. The regressive cases are
those where a controlled level of release is too high or, if enforceable, is
neglected. Migration from pollution dilution to elimination in many cases is
confronted by challenging economical and technological barriers.
Greenhouse gases and global
warming
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.
Climate change is a change in the statistical
distribution of weather over periods of time that range from decades to
millions of years. It can be a change in the average weather or a change in the
distribution of weather events around an average (for example, greater or fewer
extreme weather events). Climate change may be limited to a specific region, or
may occur across the whole Earth. It can be caused by recurring, often cyclical
climate patterns such as El Niño-Southern Oscillation, or come in the
form of more singular events such as the Dust Bowl.
In recent usage, especially in the context of
environmental policy, climate change usually refers to changes in modern
climate. It may be qualified as anthropogenic climate change, more generally
known as "global warming" or "anthropogenic global warming"
(AGW).
For information on temperature measurements over
various periods, and the data sources available, see temperature record. For
attribution of climate change over the past century, see attribution of recent
climate change.
Causes
Factors that can shape climate are climate forcings. These include such processes as variations in
solar radiation, deviations in the Earth's orbit, mountain-building and
continental drift, and changes in greenhouse gas concentrations. There are a
variety of climate change feedbacks that can either amplify or diminish the
initial forcing. Some parts of the climate system, such as the oceans and ice
caps, respond slowly in reaction to climate forcing because of their large
mass. Therefore, the climate system can take centuries or longer to fully
respond to new external forcings.
Plate
tectonics
Over the course of millions of years, the motion
of tectonic plates reconfigures global land and ocean areas and generates topography.
This can affect both global and local patterns of climate and atmosphere-ocean
circulation.
The position of the continents determines the
geometry of the oceans and therefore influences patterns of ocean circulation.
The locations of the seas are important in controlling the transfer of heat and
moisture across the globe, and therefore, in determining global climate. A
recent example of tectonic control on ocean circulation is the formation of the
Isthmus of Panama about 5 million years ago, which shut off direct mixing
between the Atlantic and
More locally, topography can influence climate.
The existence of mountains (as a product of plate tectonics through
mountain-building) can cause orographic
precipitation. Humidity generally decreases and diurnal temperature swings
generally increase with increasing elevation. Mean temperature and the length
of the growing season also decrease with increasing elevation. This, along with
orographic precipitation, is important for the
existence of low-latitude alpine glaciers and the varied flora and fauna along
at different elevations in montane ecosystems.
The size of continents is also important.
Because of the stabilizing effect of the oceans on temperature, yearly
temperature variations are generally lower in coastal areas than they are
inland. A larger supercontinent will therefore have more area in which climate
is strongly seasonal than will several smaller continents and/or island arcs.
Solar
output
Variations in solar activity during the last
several centuries based on observations of sunspots and beryllium isotopes.
The sun is the predominant source for energy
input to the Earth. Both long- and short-term variations in solar intensity are
known to affect global climate.
Early in Earth's history the sun emitted only
70% as much power as it does today. With the same atmospheric composition as
exists today, liquid water should not have existed on Earth. However, there is
evidence for the presence of water on the early Earth, in the Hadean and Archeaneons, leading to what is known as the faint young
sun paradox.[ Hypothesized solutions to this paradox include a vastly different
atmosphere, with much higher concentrations of greenhouse gases than currently exist.Over the following approximately 4 billion years, the
energy output of the sun increased and atmospheric composition changed, with
the oxygenation of the atmosphere being the most notable alteration. The
luminosity of the sun will continue to increase as it follows the main
sequence. These changes in luminosity, and the sun's ultimate death as it
becomes a red giant and then a white dwarf, will have large effects on climate,
with the red giant phase possibly ending life on Earth.
Solar output also varies on shorter time scales,
including the 11-year solar cycle[and longer-term modulations.[ The 11-year
sunspot cycle produces low-latitude warming and high-latitude cooling over
limited areas of statistical significance in the stratosphere with an amplitude
of approximately 1.5°C. But although "variability associated with the
11-yr solar cycle has a significant influence on stratospheric temperatures.
...there is still no consensus on the exact magnitude and spatial
structure".[These stratospheric variations are consistent with the idea
that excess equatorial heating can drive thermal winds. In the near-surface
troposphere, there is only a small change in temperature (on the order of a
tenth of a degree, and only statistically significant in limited areas
underneath the peaks in stratospheric zonal wind speed) due to the 11-year
solar cycle. Solar intensity variations are considered to have been influential
in triggering the Little Ice Age,[15] and for some of the warming observed from
1900 to 1950. The cyclical nature of the sun's energy output is not yet fully
understood; it differs from the very slow change that is happening within the
sun as it ages and evolves, with some studies pointing toward solar radiation
increases from cyclical sunspot activity affecting global warming.[
Orbital variations
Slight variations in Earth's orbit lead to
changes in the seasonal distribution of sunlight reaching the Earth's surface
and how it is distributed across the globe. There is very little change to the
area-averaged annually-averaged sunshine; but there can be strong changes in
the geographical and seasonal distribution. The three types of orbital
variations are variations in Earth's eccentricity, changes in the tilt angle of
Earth's axis of rotation, and precession of Earth's axis. Combined together,
these produce Milankovitch cycles which have a large
impact on climate and are notable for their correlation to glacial and
interglacial periods,[18] their correlation with the advance and retreat of the
Volcanism
Volcanism is a process of conveying material
from the crust and mantle of the Earth to its surface. Volcanic eruptions,
geysers, and
Eruptions large enough to affect climate occur
on average several times per century, and cause cooling (by partially blocking
the transmission of solar radiation to the Earth's surface) for a period of a
few years. The eruption of
Volcanoes are also part of the extended carbon
cycle. Over very long (geological) time periods, they release carbon dioxide
from the Earth's crust and mantle, counteracting the uptake by sedimentary
rocks and other geological carbon dioxide sinks. According to the US Geological
Survey, however, estimates are that human activities generate more than 130
times the amount of carbon dioxide emitted by volcanoes.[24]
Ocean
variability
A schematic of modern thermohaline
circulation
The ocean is a fundamental part of the climate system.
Short-term fluctuations (years to a few decades) such as the El
Niño–Southern Oscillation, the Pacific decadal oscillation, the North
Atlantic oscillation, and the Arctic oscillation, represent climate variability
rather than climate change. On longer time scales, alterations to ocean
processes such as thermohaline circulation play a key
role in redistributing heat by carrying out a very slow and extremely deep
movement of water, and the long-term redistribution of heat in the world's
oceans.
Human influences
Anthropogenic factors are human activities that
change the environment. In some cases the chain of causality of human influence
on the climate is direct and unambiguous (for example, the effects of
irrigation on local humidity), whilst in other instances it is less clear.
Various hypotheses for human-induced climate change have been argued for many
years. Presently the scientific consensus on climate change is that human
activity is very likely the cause for the rapid increase in global average temperatures
over the past several decades.[25] Consequently, the debate has largely shifted
onto ways to reduce further human impact and to find ways to adapt to change
that has already occurred.[26]
Of most concern in these anthropogenic factors
is the increase in CO2 levels due to emissions from fossil fuel combustion,
followed by aerosols (particulate matter in the atmosphere) and cement
manufacture. Other factors, including land use, ozone depletion, animal
agriculture[27] and deforestation, are also of concern in the roles they play -
both separately and in conjunction with other factors - in affecting climate,
microclimate, and measures of climate variables.
Physical evidence for climatic change
Evidence for climatic change is taken from a
variety of sources that can be used to reconstruct past climates. Reasonably
complete global records of surface temperature are available beginning from the
mid-late 1800s. For earlier periods, most of the evidence is indirect—climatic
changes are inferred from changes in proxies, indicators that reflect climate,
such as vegetation, ice cores,[28] dendrochronology,
sea level change, and glacial geology.
Historical
and archaeological evidence
Climate change in the recent past may be
detected by corresponding changes in settlement and agricultural patterns.[29]
Archaeological evidence, oral history and historical documents can offer
insights into past changes in the climate. Climate change effects have been
linked to the collapse of various civilisations.[30]
Glaciers
Variations in CO2, temperature and dust from the
Vostok ice core over the last 450,000 years
Glaciers are considered among the most sensitive
indicators of climate change,[31] advancing when climate cools (for example,
during the period known as the Little Ice Age) and retreating when climate
warms. Glaciers grow and shrink, both contributing to natural variability and
amplifying externally forced changes. A world glacier inventory has been
compiled since the 1970s. Initially based mainly on aerial photographs and
maps, this compilation has resulted in a detailed inventory of more than
100,000 glaciers covering a total area of approximately 240,000 km2 and, in
preliminary estimates, for the recording of the remaining ice cover estimated
to be around 445,000 km2. The World Glacier Monitoring Service collects data
annually on glacier retreat and glacier mass balance From this data, glaciers
worldwide have been found to be shrinking significantly, with strong glacier
retreats in the 1940s, stable or growing conditions during the 1920s and 1970s,
and again retreating from the mid 1980s to present.[32] Mass balance data
indicate 17 consecutive years of negative glacier mass balance.
Percentage of advancing glaciers in the
The most significant climate processes since the
middle to late Pliocene (approximately 3 million years ago) are the glacial and
interglacial cycles. The present interglacial period (the Holocene) has lasted
about 11,700 years.[33] Shaped by orbital variations, responses such as the
rise and fall of continental ice sheets and significant sea-level changes
helped create the climate. Other changes, including Heinrich events, Dansgaard–Oeschger events and the
Younger Dryas, however, illustrate how glacial
variations may also influence climate without the forcing effect of orbital
changes.
Glaciers leave behind moraines that contain a
wealth of material - including organic matter that may be accurately dated -
recording the periods in which a glacier advanced and retreated. Similarly, by tephrochronological techniques, the lack of glacier cover
can be identified by the presence of soil or volcanic tephra
horizons whose date of deposit may also be precisely ascertained.
Vegetation
A change in the type, distribution and coverage
of vegetation may occur given a change in the climate; this much is obvious. In
any given scenario, a mild change in climate may result in increased
precipitation and warmth, resulting in improved plant growth and the subsequent
sequestration of airborne CO2. Larger, faster or more radical changes, however,
may well[weasel words] result in vegetation stress, rapid plant loss and
desertification in certain circumstances.[34]
Ice cores
Analysis of ice in a core drilled from a ice
sheet such as the Antarctic ice sheet, can be used to show a link between
temperature and global sea level variations. The air trapped in bubbles in the
ice can also reveal the CO2 variations of the atmosphere from the distant past,
well before modern environmental influences. The study of these ice cores has
been a significant indicator of the changes in CO2 over many millennia, and
continues to provide valuable information about the differences between ancient
and modern atmospheric conditions.
Dendroclimatology
Dendroclimatology
is the analysis of tree ring growth patterns to determine past climate
variations. Wide and thick rings indicate a fertile, well-watered growing
period, whilst thin, narrow rings indicate a time of lower rainfall and
less-than-ideal growing conditions.
Pollen analysis
Palynology
is the study of contemporary and fossil palynomorphs,
including pollen. Palynology is used to infer the
geographical distribution of plant species, which vary under different climate
conditions. Different groups of plants have pollen with distinctive shapes and
surface textures, and since the outer surface of pollen is composed of a very
resilient material, they resist decay. Changes in the type of pollen found in
different sedimentation levels in lakes, bogs or river deltas indicate changes
in plant communities; which are dependent on climate conditions.[35][36]
Insects
Remains of beetles are common in freshwater and
land sediments. Different species of beetles tend to be found under different
climatic conditions. Given the extensive lineage of beetles whose genetic
makeup has not altered significantly over the millennia, knowledge of the
present climatic range of the different species, and the age of the sediments
in which remains are found, past climatic conditions may be inferred.[37]
Sea
level change
Global sea level change for much of the last
century has generally been estimated using tide gauge measurements collated
over long periods of time to give a long-term average. More recently, altimeter
measurements — in combination with accurately determined satellite orbits —
have provided an improved measurement of global sea level
change.
ENVIRONMENTAL PROTECTION IN
We are living in the time of rapid
scientific and technological progress, which is
accompanied by an increasing consumption of the world's natural resources. Such
vital sources of life as air, water, minerals as well as fauna and flora are being
wasted and destroyed.
The Government worked out the
rules for the use of the Earth's atmosphere.
Total emissions of smoke in the atmosphere have fallen by over 85 per cent
since 1960.
The Government is committed to the
elimination of chlorofluorocarbons
which damage the ozone layer. They also
contribute to the green-house effect, which leads to global warming and a rise in
sea levels.
There are nearly 500,000
protected buildings and 7,000 conservation areas
of architectural or historical interest in
The Government attaches great
importance to the protection of national parks (they cover 9 per cent of the
total land area of
Under such strict
regime the mineral and other resources of the oceans and seas would become reserves not only for use by
this generation but the following
generations as well.