Acid Rain

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Acid Rain
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What is acid rain?
Any ppt ?pH value lt 5.6 ? acid rain
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Introduction

• 1) Wet deposition
• ? acidic rain, fog snow
• a) Rainout incorporation of materials into
• cloud drops
• b) Washout when materials below the
• cloud are swept out by
  rain
• or snow as it falls

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• 2) Dry deposition
• ? acidic gases particles
• a) Atmospheric pollutants directly contact with
• the ground, vegetation and buildings
• b) Gravitational settling

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Causes of acid rain

• Main sources
• 1) Sulphur dioxides (SO2)
• a) Natural
• - volcanoes
• - sea spray
• - rotting of vegetation
• plankton (????)
• b) Human
• ? burning of fossil fuels
• (coal, oil natural gas) in
• power plants
• factories
• ? releases sulphur into the
• air
• ? combines with oxygen
• ? SO2

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SO2 Emissions from Canada the USA in 1998

• e.g. In 1998, U.S. SO2
• emissions were 6
• times greater than
• Canada's.

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• 2) Nitrogen oxides (NOX)
• ? combustion of fossil fuels in motor
  vehicles, residential and commercial furnaces,
  industrial and electrical-utility boilers and
  engines
• e.g.
• a) In HK, 8500 tonnes of SO2, 43200 tonnes of
  NO2 5900 tonnes of particulates are emitted
  annually from the fleet of some 424000 licensed
  vehicles
• b) In UK, power stations are responsible for 71
  of SO2, 32 of NO2 33 of CO2 emission

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NOx Emissions from Canada the USA in 1998
e.g. In 1998, by comparison, U.S. NOX
emissions was 11 times more than
Canada's. .
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Formation of acid rain

• SO2 NOX
• ?mixed with moisture
• ?sulphuric acid (H2SO4)
• nitrate acid(HNO3)
• ?dissolved in rain
• ?falls onto the ground as acid rain

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Area affected by acid rain
West Europe
East N. America
SE China
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Reasons

• 1)?no. of cities
• 2)?population
• 3)?power plants
• 4)?industries
• 5)?traffic
• ? pollutants are produced

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Regional pollution in Scandinavia

• ??level of industrialization in UK
• ??emission of SO2
• ? Westerlies blow the pollutants from the
• west of U.K. to Scandinavia and the rest
• of Europe
• ? Scandinavia has been receiving acid rain
• for at least a century

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Effects of acid rain

• A. Positive effects (local and short term)
• 1) improves visibility
• 2) dissolves some of the atmospheric pollutants
  poisonous to plants
  and animals
• 3) washes away dust on the leaves of the urban
  plants and revitalize photosynthesis
• 4) cools the hot concrete surface

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• B) Negative effects
• 1) Aquatic ecosystem
• ? lake acidification
• ? fish kills
• ? stock depletion
• e.g. In Sweden, 14,000 lakes cannot support
  sensitive aquatic life and 2,200 show no signs of
  life at all.

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• 2) Forest destruction
• Acid rain causes release of metals, e.g.
  Al, from soil
• ? rots plant roots,
• attacks leaves
• ? forest are destroyed
• e.g. a) In UK, 70 of beech trees
  80 of yew trees have
• been hit by acid rain.
• b) 54 of all trees in Germany
• have been hit by acid rain.
• c) In some Chinese provinces
• like Maocaoba, over 90 of the pine
  trees are dead.

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• 3) Crop yield drops
• ?? acidity
• e.g. Acid rain in China causes 260 million in
  crop damages in the Hunan province alone.
• 4) Human health
• ? contaminated fish drinking water supplies
  passed on to
• people through the food chain
• e.g.
• a) Sweden, 1000 lakes with high concentration
  of mercury esp. Pregnant womens fetuses (??) are
  sensitive to mercury poisoning
• b) Sweden, drinking water with high levels of
  copper causes diarrhea (?? ) in young children ?
  harms liver, kidneys
• c) Norway, aluminum from acid rain ? pre-smile
  dementia (??)
• d) N. America Canada, in 1982, 51000 people die
  from Sulfur pollution
• e) Others respiratory problems, asthma(??), dry
  coughs brain damage

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• 5) Material and visibility
• ? corrodes buildings, monuments,
• bridges and highways
• ? reducing the life expectancy
• of properties infrastructure
• e.g.
• a) In Europe, structures like The Acropolis in
  Greece and
• Renaissance buildings in Italy, as well as
  several churches and
• cathedrals have suffered visible damage.
• b) In the Yucatan peninsula in Mexico, and in
  places in South America, ancient Mayan Pyramids
  are being destroyed by acid rain.
• .

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Solution

• 1) Legislation
• Examples
• a) In HK , Air Pollution Control Regulation (Fuel
  Restriction) has been very successful SO2 have
  been reduced by about 40 on average.
• b) In HK, between 1992-97, emissions of SO2 NOx
  were reduced by banning the use of high sulphur
  fuels, using natural gas for power generation. As
  a result, the total amount of SO2 emitted was
  reduced by 54 in 1992 -97, and NOx emitted was
  educed by 44 in 1992 -97.
• .

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• 2) Economic Emission Strategy
• e.g.
• In USA, the Emission Trading Policy (1982) sold
• the right to pollute
• But, strict controls
• ? ? production costs may drive industries to area
• where there is less control

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• 3) Installation of advanced anti-pollution
  equipments
• e.g.
• Power plants in H.K. have adopted flue-gas
• desulphrization to?SO2 emission by 90 and water
• injection techniques to?Nox emission by 75

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• 4) Education
• i) encourage people to adopt waste reduction
• and recycling programmes should be
  launched
• ? ?pollutants emitted from incineration
• ii) encouragement and promotion towards
• environmental conservation

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• 5) Transport
• i) Construct mass transport system which is more
• efficient uses cleaner fuel
• e.g. MTR, KCR
• ii) Encourage drivers to turn off engine while
  waiting
• iii) Encourage drivers to install catalytic
  converter to reduce NOx emission
• e.g. By the end of 1998, 75 of petrol cars were
  fitted with 3-way catalytic converters and using
  unleaded petrol
• iv) Encourage people to use unleaded petrol, LPG
  and
• bio-diesels
• e.g. No diesel taxi will be allowed after 2006
• v) Encourage people to use public transport
  instead of
• driving their own car

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• 6) Better and proper city planning
• i) Highly polluting industries should be
  separated
• from residential zones by buffer.
• ii) Highly polluting industries should be
  relocated to
• less populated areas.
• iii) Highly polluting industries must be
  carefullt sited
• e.g. Power plants in Tsing Yi, Lamma I sland
  Tap
• Shek Kok are all located at the western
  side of
• H.K., which are the downwind sides of the
  urban
• area since the prevailing wind is easterly
• Yet, it is sometimes criticized that the
  city
• planners are simply shifting pollution
  problem
• from one part of the city to the other.

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Conclusion

• Whether it is effective, depends on
• 1) availability of capital
• 2) advanced technology
• 3) inter-departmental coordination
• 4) cooperation among government,
• 
  industrialists and
• citizens