Chapter 7 Flashcards
a. Define acid deposition.
b. Explain the causes and formation of acid deposition.
c. Describe two effects of acid deposition on the natural environment.
a. Acid deposition: The falling of acidic compounds (wet or dry) from the atmosphere to Earth’s surface, primarily as sulfuric acid (H₂SO₄) and nitric acid (HNO₃).
b. Causes & formation:
Burning fossil fuels (coal, oil) releases SO₂ and NOₓ.
These gases react with water vapor/oxygen in the atmosphere to form H₂SO₄ and HNO₃.
Transported by wind, then deposited via rain (wet deposition) or particles (dry deposition).
c. Effects on environment:
Aquatic ecosystems: Lowers pH of water bodies, killing fish and amphibians.
Forests: Leaches nutrients from soil, damages leaves (needle loss in conifers).
Describe wet and dry acid deposition.
Wet deposition: Acidic compounds dissolve in rain/snow/fog (e.g., acid rain).
Dry deposition: Acidic particles/gases settle directly on surfaces (soil, plants, buildings).
Outline the formation of acid deposition.
Emission: SO₂ and NOₓ released from factories/vehicles.
Transport: Winds carry gases over long distances.
Chemical reaction: Gases react with water/oxygen to form H₂SO₄ and HNO₃.
Deposition: Falls as rain (wet) or particles (dry).
Describe the impacts of acid deposition on:
a. Aquatic ecosystems
b. Vegetation
c. Humans
d. Structures
a. Aquatic ecosystems: Kills fish/algae by lowering pH; releases toxic metals (e.g., aluminum).
b. Vegetation: Damages leaves, leaches soil nutrients (e.g., calcium).
c. Humans: Respiratory issues (inhaled particles), contaminated drinking water.
d. Structures: Corrodes buildings/statues (e.g., limestone, marble).
Describe the causes and contents of photochemical smog.
Causes: Sunlight reacts with NOₓ (from vehicles) and VOCs (paints, gasoline).
Contents: Ozone (O₃), peroxyacyl nitrates (PANs), nitrogen dioxide (NO₂).
Describe the impacts of photochemical smog on:
a. Eyes
b. Respiratory systems
c. Crop yields
d. Plastics/rubber
a. Eyes: Irritation, watering.
b. Respiratory: Asthma, lung damage (ozone inflames airways).
c. Crops: Reduces photosynthesis (ozone damages leaves).
d. Plastics/rubber: Cracks and degrades materials.
Describe strategies for managing air pollution.
Renewable energy: Solar/wind reduce fossil fuel use.
Emission reduction: Catalytic converters (vehicles), scrubbers (factories).
Laws: Clean Air Acts, vehicle emission standards.
Public transport: Fewer cars = less NOₓ/VOCs.
How does ozone depletion occur, and why is it worst over Antarctica?
Process: CFCs release chlorine atoms, which destroy ozone (O₃ → O₂).
Antarctic factors:
Polar vortex: Isolates cold air, prolonging depletion.
Polar stratospheric clouds (PSCs): Provide surfaces for chlorine reactions.
Temperature: Cold speeds up ozone-destroying reactions.
How is ozone depletion measured?
In Dobson Units (DU). 1 DU = 0.01 mm thickness of ozone layer if compressed to Earth’s surface. Normal = 300 DU; Antarctic “hole” = <100 DU.
State the type of radiation absorbed by ozone and two impacts of ozone depletion on humans.
Radiation: UV-B (ultraviolet-B).
Human impacts:
Skin cancer (melanoma).
Cataracts (eye damage).
Why was the Rowland-Molina hypothesis (CFCs cause ozone depletion) initially rejected?
Industry lobbies denied CFC dangers (profitable chemicals).
Scientific skepticism (lack of Antarctic data in 1970s).
Delayed observation of ozone hole (proof came later).
Describe strategies to reduce ozone layer damage.
Montreal Protocol (1987): Phased out CFCs.
Alternatives: HCFCs (less ozone-depleting).
Bans: CFCs in aerosols/refrigerants.
What are the impacts of alternative gases (HCFCs, F-gases)?
HCFCs: Still ozone-depleting (but less than CFCs).
F-gases (e.g., HFCs): No ozone harm, but potent greenhouse gases (worse than CO₂).
