Pollution

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Pollution
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What is pollution?
The term pollution refers to the adverse
environmental effects of gaseous, aqueous and
solid waste generation and disposal. As legally
defined, pollution is the introduction by people
into environment of substances or energy which is
liable to cause hazards to human health, harm to
living resources and ecosystem damage to
structure and amenity, or interference to
legitimate uses of the environment.In essence,
pollution is most often the result of the
overloading of natural systems, which may in the
normal course of events be able to recycle
effluents.
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Pollution is commonly associated with
unmanaged wastes for which there are no adequate
procedures for effective treatment and/or
disposal although managed wastes can also provide
pollutants as a result of imperfect or inadequate
management. The use of the term energy in the
formal definition above demonstrates that
pollution can also actively be caused by the
introduces of unwanted noise, heat or visual
intrusion into the natural or human environment.
Management systems for solid, liquid and gaseous
wastes have traditionally followed two basic
principles associated with their disposal into
the natural environment dispersal and
containment.
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Until recently, waste management was largely
carried out using the principle of
dilute-and-disperse, which sought to minimize
environment impacts of a wide range of substances
by diluting the waste through introducing it into
the land, sea or atmosphere. This principle
assumes that slid, liquid and gaseous wastes can
most easily be dealt with by using the natural
recycling processes of the environment, and that
their dilution would mitigate against the
concentration of harmful substances which would
lead to pollution of land, sea and air.
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This principle has most often been used in the
disposal of waste gases into the atmosphere, and
the disposal of domestic sewage, industrial
liquids and other aqueous wastes into the marine
environment through sewage outfalls. Dumping of
solid materials such as estuarine dredging and
inert building waste at sea also demonstrates the
principle, as here it is hoped that the coastal
and marine processes will prevent its
concentration at any one place. The idea is sound
provided that the rate of waste delivery to the
chosen environment does not exceed the ability of
that environment to recycle or redistribute the
waste deposited within it.
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Unfortunately, the dilute-and-disperse principle
frequently leads to pollution. The problem is
illustrated by the creation of smog in our
major cities in the late nineteenth and twentieth
centuries, comprising dense clouds of
particulate-rich atmospheric pollution, which
posed significant hazards to human health. A
famous example is the London pea-souper of
December 1952, which resulted in 4000 deaths,
mostly from respiratory disease. This crisis was
primary a result of the combination of
atmospheric conditions- stagnant, uncirculating
air, heavy cloud cover and high humidity -with
the widespread burning of fossil fuels for
domestic heating, needed in the cold, foggy
weather, which led to the accumulation of
particulate-rich smoke and sulphur dioxide.
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Today, management policies are mostly based upon
the containment of waste in safe repositories
from which there should be no direct source of
pollution. This principle is based on the idea
that wastes should be concentrated-and-contained
in cities where there is little or no chance of
pollution into the natural world. Although this
is clearly desirable in principle it rarely
happens in practice, since most containment
barriers and liners will eventually be
compromised by physical, chemical or biological
action or through the ingress of ground and
meteoric waters. This principle is most often
associated with the management of solid and
liquid waste products, the best examples being
sanitary landfill operations and radioactive
waste disposal repositories. The principle is
less easily applied to gaseous wastes which
cannot be easily contained, and are usually
treated before being released into the
atmosphere.
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Water Pollution
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i.Causes of Water Pollution
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• Marine life is affected because the level of
  dissolved oxygen at which fish and other animals
  can be sustained is approaching the threshold.
  Beaches are affected because the tides carry
  harbor water to the beaches on Castle Peak Road
  and east coast of Hong Kong Island. Human and
  livestock waste has also contaminated rivers.

• As the population grew rapidly over the past four
  decades, sewage services did not keep up. In the
  New Territories, houses were built without proper
  sewerage connections and livestock farmers were
  allowed to dump their waste untreated into rivers
  and streams.

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• Sewage from illegal connections, car oil, or pet
  and other animal waste, which can all pollute
  rivers, streams and bays.

• The polluted flows of the Pearl River Delta,
  which affect Hong Kong, are a more serious and
  complicated problem because of the thousands of
  sources of effluent. Discussions will be
  necessary on how to tackle this enormous problem.

Deterioration in water quality in Hong Kong may
be caused by (1)  livestock waste (from pigs and
poultry), (2)  oil spillage (from ships), (3) 
residues of pesticides (from farms), (4)detergents
in sewage(from commercial and domestic
wastewater), industrial effluents (from dyeing
and electroplating factories)
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ii. Effects of Water Pollution on the
Environment

• Tolo harbour was heavily polluted with human and
  livestock waste, and oxygen-gobbling red tides
  were choking marine life including fish farms.

• Other waste bodies in the New Territories were
  also heavily polluted, especially by livestock
  waste.

• Shing Mun River, for example, the unacceptable
  levels of bacteria remain a concern because they
  pose a health risk to anyone using the river for
  recreation and are expensive to clean up.

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Livestock waste When an excessive amount of
organic matter is discharged into water, the
existing aquatic micro-organisms will grow and
multiply rapidly. The oxygen dissolved in water
is rapidly depleted. Because of the lack of
oxygen, anaerobic micro-organisms begin to break
down partially the organic matter, releasing
foul-smelling and toxic gases like CH4, NH3 and
H2S. As a result, the aquatic organisms will die.
Residues of pesticides Pesticides cause
immediate toxic effects on aquatic life and may
accumulate along the food chain until a toxic
level is reached. E.g. the once widely used
organochlorine insecticide, DDT, is fairly inert
and persistent in the environment, and thus
causes much ecological damage. Its use has been
banned in many parts of the world including Hong
Kong.
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Oil spillage The effects of oil spillage may
include the following
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i.Oil clogs the feathers of sea birds and
prevents them from flying or swimming, oil
interferes with the insulation provided by the
feathers, so the birds may die of cold or
pneumonia. Birds trying to clean their feathers
with the beak may be poisoned through ingestion.
u  ii.As oil is immiscible with water and
floats on water, it blocks the oxygen supply
to the sea water.
iii.As oil is toxic, it kills marine life.
iv.On beaches, oil drives away holiday-makers and
spoils recreation resorts.
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Industrial effluents The toxic materials
present in industrial effluents vary with the
industry involved. They may contain toxic metal
ions of Cd, Cr, Cu, Hg, Ni, Pb and Zn cyanides,
polychlorinated hydrocarbons (e.g.
polychlorinated biphenyl, PCB), organic solvents,
acids and bases.
²       Detergents in sewage u  Detergents may
speed up the eutrophication (because the
phosphates in some detergents are nutrients to
algae ) u Detergents may cause foaming in rivers
and lakes (because some synthetic detergents with
branched hydrophobic chains cannot be biodegraded
within a short time)
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Pollution Control in Hong Kong
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The Role of EPD
The Environment Protection Department (EDP) was
established in 1986. It is responsible for
1.Formulating policy proposals on environmental
protection
2.Monitoring environmental quality
3.Enforcing environmental legislation
4.Drawing up plans for the treatment and disposal
of wastes
5.Advising on the environment implications of
town plans and major developments
6.Providing a centralized service to handle
complaints and enquiries
The EPD and other concerned groups have made
efforts to raise the general environmental
awareness of the public and to keep the public
informed of environmental matters.
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Treatment
The problems of sewage-sludge disposal are
becoming increasingly great for a number of
reasons. As with most environment problems,
increased populations and the desire for higher
standards of living have converted a relatively
small-scale problem into a major resources
conflict. This is summarized below.
Problems How to dispose of human
excreta. Solution Collect the wastes and spread
them on land. Problems Pathogenic bacteria,
viruses, parasites cause endemic diseases.
Pollution of watercourses causes diseases. Larger
population centers make collection and disposal
more difficult. The smell of the collected
material may be offensive. Solutions Build a
system of water closets and sewers.
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Problems The untreated sewer effluent uses up
the dissolved oxygen in rivers, killing all
higher aquatic life-forms. The smell and visible
appearance of rivers deteriorates. The
contamination of water supplies of downriver
communities occurs. Solution Build sewage
treatment plants. Problems The cost increases
very rapidly as the type of treatment is uprated
from primary to secondary to tertiary. The final
water quality depends upon the degree of
treatment. The solids still have to be disposed
of. Solution The solids can be dumped on land,
as they contain useful nitrogen, phosphorus,
potassium and organic matter, to replace
fertilizers. Problems Urban and industrial areas
produce sludge with high toxic-metal contents.
Therefore only limited amounts can be applied
without damaging crops or consumers, and they may
still contain pathogenic organisms..
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Solution The solids could be dumped in the sea
away from coast. Problems The toxic contents
will affect marine organisms. Solution The
sludge could be incinerated. Problems This is
costly because a lot of energy is needed to
remove water before the sludge will burn. Air
pollution may occur if gases not properly
cleaned. Ash will contain even higher
concentrations of toxic metals and must be dumped
in special sites to prevent pollution of
watercourses. Solution Reduce the population
reduce the industrial contamination of the
effluent use smaller quantities of potentially
toxic compounds. Maximum the use of natural
systems to detoxify contaminants and remove other
toxic substances by treatment, preferably at
source where their concentration is highest and
other impurities lowest..
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Suggestions
Proper sewers and treatment plants, and
effective laws and regulations had to be brought
in urgently.
People use less water, for instance by not
leaving taps running or using low-flow showers
and other devices, it could open enough capacity
in the existing system so fewer new sewers and
treatment plants are needed. It could also save
on pumping and chemical costs at treatment
plants.
The tiny bacteria and other pollutants in
Hong Kong's waste do not pose an immediate
threat. But they must be removed. In the long
run, they affect not only marine life, but
people's quality of life.
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Actions
The harbour and all other eaters are now
Water Control Zones- and disposal of chemical
waste, such as nickel, chromium and copper, has
been controlled since 1993, with the opening of
the Chemical Waste Treatment Plant on Tsing Yi
and the introduction of regulations under the
Waste Disposal Ordinance.The multi-billion-dollar
Strategic Sewage Disposal Strategy (SSDS) is
intended to collect sewage from around the
harbour, transport it by deep tunnels to a sewage
treatment plant on Stonecutters Island.
Conclusion
Clean harbours and rivers are important
for recreation, sport and public health.Community
support will be crucial, not only in the things
people can do in their daily lives but in their
understanding of the problem.
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END