Ways in which people are polluting the Earth

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Ways in which people are polluting the Earth
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Problems associated with the burning of fuels

• Incomplete combustion
• the presence of impurities in fuels

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Major pollutants in car exhaust
Sulphur dioxide
Unburned hydrocarbons
Dark smoke
Nitrogen oxides
Carbon monoxide
Lead compounds
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Carbon monoxide Dark smoke

• A hydrocarbon fuel burns incompletely to form
  carbon monoxide
• CO combines with red blood cells to form a stable
  compound, thus competing with oxygen for
  hemoglobin

• Incomplete burning of hydrocarbon produces dark
  smoke which contains mainly carbon particles
  which remain suspended in the air for a long time
• It causes the reduction of visibility.

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Unburned hydrocarbons Lead compounds
Unburned hydrocarbons such as benzene may cause
cancer.

• Without additives, straight-run petrol (mainly
  straight-chain alkanes) tends to burn with lower
  efficiency.
• Lead compounds are added to raise the efficiency
  of burning of petrol
• Lead compounds have harmful effects on red blood
  cells and brain cells. Children are more easily
  affected.

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Nitrogen dioxide

• High temperatures reached during the burning of
  fuels inside the car engine cause the oxidation
  of nitrogen.
• N2(g) O2(g) 2NO(g)
• 2NO(g) O2(g) 2NO2(g)
• NO2 dissolves in rainwater to form acid rain
  2NO2(g) H2O(l) HNO3 HNO2
• Nitrogen oxides together with unburned
  hydrocarbons form photochemical smog

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Air pollution from industry

• Factories and power stations use either coal or
  low grade petroleum as fuels, both of which
  contain sulphur.
• The smoke from incinerators contains large
  amounts of sulphur dioxide upon burning paper
  waste containing sulphur.
• Like nitrogen oxides, it causes acid rain

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The effects of acid rain include

• Forests are seriously damaged
• Rivers and lakes become more acidic, killing
  marine organisms
• Speed up the corrosion of metalwork and may lead
  to the release of lead and copper compounds into
  plumbing systems
• Cause damage to stonework (limestone or marble,
  CaCO3)

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The Greenhouse Effect

• CO2 in the atmosphere acts like the glass of a
  greenhouse. It allows high energy radiation from
  the sun to penetrate the atmosphere and warms the
  earths surface. The high energy radiation is
  re-radiated as IR. The low energy IR is trapped
  by the carbon dioxide, keeping the earth warm.
• Human activities put too much CO2 into the
  atmosphere and overheating of the earth occurs
  because of the greenhouse effect.
  The problem is known as global warming.

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Methods of reducing air pollution

• The SAR Government introduced unleaded petrol in
  1991 increased the tax on leaded petrol. Using
  unleaded petrol in cars reduces the level of lead
  compounds in the air
• Catalytic converters in car exhaust systems can
  change nitrogen oxide and carbon monoxide into
  harmless nitrogen and carbon dioxide
  2NO(g) 2CO(g) N2(g) 2CO2(g)
  
• The excess CO unburned hydrocarbons are mixed
  with air through an inlet in the converter. The
  gases are oxidized to water carbon dioxide
  2C8H18(g)25O2(g) 16CO2 18H2O(l)

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• Cars with catalytic converters must run on
  unleaded petrol because lead compounds stop these
  catalysts working
• Scrubbers in power plants reduce up to 95 of
  sulphur dioxide emissions
• in dry scrubbing, powdered CaCO3 used becomes CaO
  CO2 in the combustion chamber. The CaO then
  reacts with SO2, forming calcium sulphite which
  are washed away as a slurry
  CaO(s)
  SO2(g) CaSO3(s)
• Wet scrubbing removes sulphur dioxide by the
  reaction of calcium hydroxide which is formed by
  dissolving CaO in water.
• Ca(OH)2(aq) SO2(g) CaSO3(s)
  H2O(l)
• Electrostatic precipitators remove 99 of the
  particulates which pass through a strong electric
  field
• Using fuels with a sulphur content less than 0.5

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Government policy against air pollution

• 2 million people are exposed to undesirable
  levels of sulphur dioxide nitrogen dioxide
• 3 million people are exposed to high levels of
  particulates
• The SAR government controls air pollution through
• legislation
• monitoring investigation
• planning

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• The EPD(86) ensures the implementation of air
  pollution control laws
• the Air Pollution Control Ordinance which
  identifies air control zones where air quality
  objectives (AQO) are defined so that action is
  taken to improve the air quality
• factory owners have to install scrubbers/precipita
  tors use low-sulphur fuel Unleaded petrol is
  used in cars
• catalytic converter is used only with unleaded
  petrol
• transfer stations are built to replace
  incinerators
• police spot-check cars to examine their exhaust
  gases
• 9 air-quality monitoring stations are set up in
  HK air quality studies are conducted in selected
  places
• Development schemes have to undertake an EIA

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Oil Spillage water pollution

• Oil clogs the feathers of sea birds,preventing
  them from flying or swimming. It also interferes
  with the insulation provided by the feathers, so
  that the birds may die of cold. Birds trying to
  clean their feathers with their beaks may be
  poisoned.
• Oil floats on water and blocks the oxygen supply
  to marine organisms.
• Water current carries away the oil after
  emulsifying it with detergents(wind/wave may
  disperse the oil)

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Renewable energy sources
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Uses of plastics
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