1/30/2012 1 Acid Deposition Acid rain, snow, fog, and dry deposition 1 Acid Deposition • Is the process by which acidic particles leave the atmosphere • Can be – Wet deposition in the form of rain, sleet, snow, fog, hail – Dry deposition, includes acidic gases and particles 2 pH scale 3 • Measure of acidity/alkalinity of solution • 7 = neutral • Less than 7 = acidic • More than 7 = alkaline • Logarithmic scale – Change from 7 to 6 means 10X more acidic pH scale 4 Rain is naturally acidic • pH of about 5.6 • CO 2 + H 2 O H 2 CO 3 – Naturally occurring or anthropogenic CO 2 combines with water to form carbonic acid • Any precipitation with a pH of less than 5.6 is considered acidic. Formation of Acids • Primary pollutants (SO 2 , NO x , particulates) as discussed earlier • Primary pollutants converted to secondary pollutants • Secondary pollutants may deposit directly (dry deposition) or react with water in atmosphere to form acid (wet deposition) 5 Conversion of SO 2 to acid Primary: S + O 2 SO 2 Secondary: SO 2 + O 2 SO 3 SO 2 + H 2 O H 2 SO 3 2H 2 SO 3 + O 2 2H 2 SO 4 SO 3 + H 2 O 2H 2 SO 3 23 April 2009 Acid-Rain.ppt 6 Conversion of NO to acid Primary: N 2 + O 2 2NO Secondary:2NO + O 2 2NO 2 3NO 2 + H 2 O 2HNO 3 + NO 4NO + O 2 + H 2 O 4HNO 2 23 April 2009 Acid-Rain.ppt 7 8 Areas prone to acid deposition 9 • In the US: Northeastern States & Ohio Valley
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acid deposition - homeworknow.com · Acid-Rain.ppt 10 Some statistics • Most acidic precipitation recorded in Wheeling, WV, with a pH of 1.5 • Los Angeles often has fogs with
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1/30/2012
1
Acid DepositionAcid rain, snow, fog, and dry
deposition
1
Acid Deposition
• Is the process by which acidic particles leave
the atmosphere
• Can be
– Wet deposition in the form of rain, sleet, snow,
fog, hail
– Dry deposition, includes acidic gases and particles
2
pH scale
3
• Measure of acidity/alkalinity of solution
• 7 = neutral
• Less than 7 = acidic
• More than 7 = alkaline
• Logarithmic scale– Change from 7 to 6 means
10X more acidic
pH scale
4
Rain is naturally acidic
• pH of about 5.6
• CO2 + H2O � H2CO3
– Naturally occurring or anthropogenic CO2
combines with water to form carbonic acid
• Any precipitation with a pH of less than 5.6 is considered acidic.
Formation of Acids
• Primary pollutants (SO2, NOx, particulates) as discussed earlier
• Primary pollutants converted to secondary pollutants
• Secondary pollutants may deposit directly (dry deposition) or react with water in atmosphere to form acid (wet deposition)
5
Conversion of SO2 to acid
Primary: S + O2 � SO2
Secondary: SO2 + O2 � SO3
SO2 + H2O � H2SO3
2H2SO3 + O2 � 2H2SO4
SO3 + H2O � 2H2SO3
23 April 2009 Acid-Rain.ppt 6
Conversion of NO to acid
Primary: N2 + O2 � 2NO
Secondary:2NO + O2 � 2NO2
3NO2 + H2O � 2HNO3 + NO
4NO + O2 + H2O � 4HNO2
23 April 2009 Acid-Rain.ppt 7 8
Areas prone to acid deposition
9
• In the US: Northeastern States & Ohio Valley
1/30/2012
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Areas prone to acid deposition• Outside the US: Eastern Europe, Russia, China