Download ACID PRECIPITATION

ACID PRECIPITATION
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ACIDS & BASES

•
Acid – loses a H+ when dissolved in H2O
•
organic (contain C) e.g. amino acids or acetic acid
(CH3COOH)
inorganic like HCl or H2SO4

Base – releases OH- when dissolved in water
•
eg. NaOH or NaHCO3

amount of acidity is measured on pH scale
 low pH (< 7) indicates acidity
 high pH (> 7) indicates alkalinity (basic)
 pH of 7 is neutral
Deposition

source: pollution associated with burning of
fossil fuels; leads to acid deposition.

Wet Deposition - acids with a pH below 5.6 are
removed from the atmosphere in the form of
rain, snow, sleet, and mist.

Dry Deposition - particles such as volcanic ash,
sulphates, and nitrates are deposited onto a
surface and then converted into acids when they
contact water.
Acid Deposition
Sulphur dioxide (SO2)
 sulphur
from coal burning power plants is
the greatest amount of SO2 entering the
atmosphere
 need to reduce sulphur emissions
 best way: conserve energy or use
alternative sources
3 ways to reduce sulphur emissions from coal-fired
plants:
1.Wash the sulphur from the coal before
combustion
2.Wash the sulphur from the smoke before it
leaves the smokestacks
3.Remove the sulphur after combustion by using
scrubbers - sprays a mixture of water and
limestone (basic) into the smokestack
Nitrogen Oxides (NOX)
 from
vehicle emissions and burning coal
 catalytic converters on vehicles help to
reduce the emissions of carbon monoxide,
hydrocarbons, and the nitrogen oxides
 ON vehicles have to pass an emissions
test every two years
Movie
Govt. policies

Canada-Wide Acid Rain strategy:
•
implemented in 1991
• targeted reduction by 50% in most provinces
• 1990-2000 AP decreased by 60% in some eastern
provinces

•
Canada – US Clean Air Quality Agreement:
US emissions declined by 27% between 1991-1996.
Changes in SO2 1990-2000
Acid Rain in Canada
THE EAST:
 Canadian Shield & East Coast provinces
(Ontario, Quebec, Nova Scotia, New Brunswick)
are hardest hit
 their water and soil systems can't neutralize the
effects of the acid rain
 > 150 lakes are “dead” and 48 000 are at risk of
acid rain destruction
 > 90% of the acid deposition in eastern Canada
originates from emissions in the US Midwest
THE WEST
 western provinces are relatively unharmed
 soils are more alkaline - able to neutralize
acid rain
 lower levels of industrialization and natural
factors such as eastwardly moving
weather patterns (moves the air pollution
to the east)
Natural Acid Precipitation
Volcanic Fog “vog” (SO2)
Lightning (NOx)
Recap Movie Clip