Acid Deposition and Its Effects

Acid Deposition
  • Types of Acid Deposition
    • Wet Deposition: Acid falls as liquid (rain, snow)
    • Dry Deposition: Acid falls as solid particles (ash, dust)
pH Scale and Acidity
  • pH Values:
    • 0: Battery acid
    • 1: Sulfuric acid
    • 2: Strong acids
    • 3: Lemon juice, Vinegar
    • 4: Acid rain (4.2-4.4)
    • 5: Healthy lakes (6.5), Bananas (5.0-5.3)
    • 6: Clean rain (5.6) and neutral (7)
    • 8: Milk (6.5-6.8)
    • 14: Liquid drain cleaner
Natural Acidity of Rain
  • Clean rain has a pH of approximately 5.6.
  • Natural acids in rain originate from:
    • Volcanic emissions (SO₂)
    • Cellular respiration (CO₂) producing carbonic acid
    • Lightning (NOx)
Fossil Fuels and Acid Rain
  • Burning fossil fuels (coal, oil) releases SO₂.
  • The smelting of ores releases SO₂ too.
  • Combustion creates heat that allows N₂ to react with O₂ to generate NOx.
Oxides and Their Deposition
  • SO₂ and NOx are emitted from:
    • Industrial processes
    • Transportation
    • Power stations
    • Urban environments
  • Can lead to acid formation when oxidized in the atmosphere.
Impact of Acid Rain
  • Leaching of Nutrients:
    • Essential ions like Calcium (Ca), Magnesium (Mg), and Potassium (K) are lost, affecting soil fertility.
  • Aluminum Release:
    • Increased acidity makes Al soluble, harming aquatic life. Leads to fish suffocation by gill damage.
Effects on Aquatic Life
  • Fish species tolerance varies:
    • Tolerant (pH < 6): Brown bullhead, yellow perch
    • Sensitive: Atlantic salmon, walleye - generally killed below pH 5.2
Effects on Vegetation
  • Acid rain leads to:
    • Loss of chlorophyll in leaves
    • Decreased growth and increased susceptibility to disease
  • Young trees may show rapid growth due to pollution nutrients, but are often less resilient.
Human Health Effects
  • Dry deposition of acids can cause respiratory illnesses such as asthma and bronchitis.
Geographic Areas of Concern
  • Most affected areas include:
    • Eastern United States
    • South Western Canada
    • Eastern Europe
    • East Coast of China
Prevention Measures
  • Techniques for reducing acid rain include:
    • Using gas desulfurization in power plants.
    • Reducing automotive emissions.
    • Implementing emissions trading for industry.
Examples of Mitigation
  • Neutralization by spreading lime in affected lakes
  • Regulators, like the US EPA's Acid Rain program, influence emissions standards.
Interaction with Ecosystems
  • Run-off from acidified forests can carry acidity to nearby aquatic ecosystems, affecting biodiversity and productivity.
  • Loss of trees can impact shade and increase water temperature, further crippling aquatic life.
Conclusion
  • Strongly acidic environments pose a threat to various ecosystems, necessitating continued efforts for mitigation and education on the impacts of acid deposition.