Environmental Pollution

Pollution is the release of harmful substances (pollutants) into the environment (air, water, or land) in quantities that are harmful to living organisms and the ecosystem. Understanding the chemistry behind these pollutants is crucial for JAMB candidates.

1. Types and Sources of Pollutants

Pollutants can be classified based on the medium they affect or their chemical nature.

• Air Pollutants: Substances like Carbon Monoxide (CO), Sulphur Dioxide (SO₂), Oxides of Nitrogen (NO_x), Hydrogen Sulphide (H₂S), Chlorofluorocarbons (CFCs), and particulate matter (dust).
• Water Pollutants: Domestic sewage, industrial effluents, oil spills, and agricultural run-offs (fertilizers and pesticides).
• Soil Pollutants: Solid wastes, heavy metals, and non-biodegradable materials like plastics.

2. Air Pollution: Key Gases and Effects

• Carbon Monoxide (CO): Formed by the incomplete combustion of carbon-containing fuels. It is dangerous because it binds with hemoglobin to form carboxyhemoglobin, reducing the blood's oxygen-carrying capacity.
• Sulphur Dioxide (SO₂): Produced from burning coal and smelting ores. It causes respiratory irritation and reacts with water vapor to form acid rain (H₂SO₃/H₂SO₄).
• Oxides of Nitrogen (NO, NO₂): Formed from internal combustion engines at high temperatures. They contribute to acid rain and photochemical smog.
• Chlorofluorocarbons (CFCs): Used in aerosols and refrigerants. They migrate to the stratosphere and cause the depletion of the ozone layer (O₃), leading to increased UV radiation.
• Hydrogen Sulphide (H₂S): Produced from decaying organic matter and industrial processes. It has a 'rotten egg' smell and is toxic.

3. Water Pollution

• Sewage: Untreated sewage dumped into water bodies leads to Eutrophication. This process involves the enrichment of water with nutrients (nitrates and phosphates), leading to excessive algae growth, oxygen depletion, and death of aquatic life.
• Oil Spillage: Occurs during drilling or transportation. Oil forms a layer on water, preventing oxygen dissolution and suffocating marine life.

4. Soil Pollution and Biodegradability

• Biodegradable Pollutants: Substances that can be broken down by microorganisms (e.g., paper, food waste, sewage).
• Non-biodegradable Pollutants: Substances that persist in the environment for long periods (e.g., plastics, glass, DDT, heavy metals like Lead and Mercury).

5. Control Measures

Pollution control involves legislative action, waste management (Reduce, Reuse, Recycle), treatment of industrial waste before disposal, and use of lead-free petrol or catalytic converters in vehicles.