ACID PRECIPITATION

ACID PRECIPITATIONACID PRECIPITATIONmoviemovie

ACIDS & BASESACIDS & BASES Acid – loses a HAcid – loses a H++ when dissolved in H when dissolved in H22OO• organic (contain C) e.g. amino acids or acetic acid organic (contain C) e.g. amino acids or acetic acid

(CH(CH33COOH)COOH)

• inorganic like HCl or Hinorganic like HCl or H22SOSO44

Base – releases OHBase – releases OH-- when dissolved in water when dissolved in water• eg. NaOH or NaHCOeg. NaOH or NaHCO33

amount of acidity is measured on pH scaleamount of acidity is measured on pH scale low pH (< 7) indicates acidity low pH (< 7) indicates acidity high pH (> 7) indicates alkalinity (basic)high pH (> 7) indicates alkalinity (basic) pH of 7 is neutralpH of 7 is neutral

DepositionDeposition source: pollution associated with burning of fossil source: pollution associated with burning of fossil

fuels; leads to acid deposition. fuels; leads to acid deposition.

Wet Deposition -Wet Deposition - acids with a pH below 5.6 are acids with a pH below 5.6 are removed from the atmosphere in the form of rain, removed from the atmosphere in the form of rain, snow, sleet, and mist. snow, sleet, and mist.

Dry Deposition -Dry Deposition - particles such as volcanic ash, particles such as volcanic ash, sulphates, and nitrates are deposited onto a sulphates, and nitrates are deposited onto a surface and then converted into acids when they surface and then converted into acids when they contact water. contact water.

Acid Deposition Acid Deposition

Sulphur dioxide (SOSulphur dioxide (SO22) )

sulphur from coal burning power plants is sulphur from coal burning power plants is the greatest amount of SOthe greatest amount of SO22 entering the entering the

atmosphere atmosphere need to reduce sulphur emissions need to reduce sulphur emissions best way: conserve energy or use best way: conserve energy or use

alternative sourcesalternative sources

3 ways to reduce sulphur emissions from coal-fired 3 ways to reduce sulphur emissions from coal-fired plants:plants:

1.1.Wash the sulphur from the coal before Wash the sulphur from the coal before combustion combustion

2.2.Wash the sulphur from the smoke before it Wash the sulphur from the smoke before it leaves the smokestacks leaves the smokestacks

3.3.Remove the sulphur after combustion by using Remove the sulphur after combustion by using scrubbers - sprays a mixture of water and scrubbers - sprays a mixture of water and limestone (basic) into the smokestack limestone (basic) into the smokestack

Nitrogen Oxides (NONitrogen Oxides (NOXX))

from vehicle emissions and burning coalfrom vehicle emissions and burning coal catalytic converters on vehicles help to catalytic converters on vehicles help to

reduce the emissions of carbon monoxide, reduce the emissions of carbon monoxide, hydrocarbons, and the nitrogen oxides hydrocarbons, and the nitrogen oxides

ON vehicles have to pass an emissions ON vehicles have to pass an emissions test every two years test every two years

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Govt. policiesGovt. policies Canada-Wide Acid Rain strategy:Canada-Wide Acid Rain strategy:• implemented in 1991implemented in 1991• targeted reduction by 50% in most provincestargeted reduction by 50% in most provinces• 1990-2000 AP decreased by 60% in some eastern 1990-2000 AP decreased by 60% in some eastern

provincesprovinces Canada – US Clean Air Quality Agreement:Canada – US Clean Air Quality Agreement:• US emissions declined by 27% between 1991-1996.US emissions declined by 27% between 1991-1996.

Changes in SOChanges in SO22 1990-2000 1990-2000

Acid Rain in CanadaAcid Rain in CanadaTHE EAST:THE EAST: Canadian Shield & East Coast provinces Canadian Shield & East Coast provinces

(Ontario, Quebec, Nova Scotia, New Brunswick) (Ontario, Quebec, Nova Scotia, New Brunswick) are hardest hitare hardest hit

their water and soil systems can't neutralize the their water and soil systems can't neutralize the effects of the acid rain effects of the acid rain

> 150 lakes are “dead” and 48 000 are at risk of > 150 lakes are “dead” and 48 000 are at risk of acid rain destruction acid rain destruction

> 90% of the acid deposition in eastern Canada > 90% of the acid deposition in eastern Canada originates from emissions in the US Midwest originates from emissions in the US Midwest

THE WESTTHE WEST western provinces are relatively unharmed western provinces are relatively unharmed soils are more alkaline - able to neutralize soils are more alkaline - able to neutralize

acid rain acid rain lower levels of industrialization and natural lower levels of industrialization and natural

factors such as eastwardly moving factors such as eastwardly moving weather patterns (moves the air pollution weather patterns (moves the air pollution to the east) to the east)

Natural Acid PrecipitationNatural Acid Precipitation

Volcanic Fog “vog” (SO(SO22))Volcanic Fog “vog” (SO(SO22))Lightning (NOx)Lightning (NOx)

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