6. Pollution and Natural Resources

Pollution is the introduction of harmful substances into the environment. Understanding types, sources, and effects is a frequent GED® topic.

Types of pollution:

• Air pollution — burning fossil fuels releases CO₂, sulfur dioxide (SO₂), and nitrogen oxides (NOₓ). SO₂ and NOₓ dissolve in rainwater to form acid rain, which damages forests and aquatic ecosystems.
• Water pollution — industrial waste, agricultural runoff (fertilizers containing nitrogen and phosphorus), and sewage contaminate lakes, rivers, and groundwater.
• Eutrophication — excess nutrients (especially from fertilizer runoff) cause algae to bloom explosively. When the algae die, bacteria decompose them and use up all the oxygen, creating dead zones where fish cannot survive.
• Soil pollution — pesticides, heavy metals, and plastic waste degrade farmland and groundwater.
• Plastic pollution — plastics break into microplastics that enter food chains.

Natural resources:

• Renewable — replenish naturally within a human lifetime: solar energy, wind, water (hydro), wood (if forests are managed), geothermal.
• Nonrenewable — form over millions of years and are used far faster than they form: coal, oil, natural gas (fossil fuels), uranium.

Fossil fuels formed from ancient organisms buried under pressure. They are carbon-rich and release CO₂ when burned — the main driver of climate change.

⚠️ Common misconception: nuclear power is a renewable resource. Uranium (the fuel) is nonrenewable; nuclear power just produces no direct CO₂ emissions while operating.

💡 Tip: Eutrophication questions on the GED® often show a graph with rising nutrient levels followed by a drop in dissolved oxygen — trace cause → algae bloom → oxygen depletion → fish die.