AP Environmental Science Unit 8 Cheatsheet: Aquatic and Terrestrial Pollution

Point Source: Single, identifiable origin

• Smokestack, waste discharge pipe, factory outlet
• Easier to regulate and trace

Nonpoint Source: Diffuse, multiple origins

• Pesticide spraying, urban runoff, agricultural fertilizer
• Harder to identify and control

Each organism has an optimum range for environmental factors to maintain homeostasis.

Outside optimum range:

• Physiological stress
• Limited growth and reproduction
• Death (extreme cases)

Aquatic examples:

• Oil spills: Hydrocarbons kill organisms; coating feathers/fur prevents insulation
• Sediment: Reduces light, disrupts habitats, affects predators
• Heavy metals: Industrial/mining runoff contaminates groundwater and drinking water

Eutrophication: Water enriched in nutrients (N, P) from agricultural runoff or wastewater.

Sequence:

1. Algal bloom occurs
2. Algae dies; bacteria decompose it, consuming O₂
3. Dissolved O₂ drops → hypoxic conditions
4. Fish and organism die-offs

Oxygen Sag Curve: DO drops near pollution source, reaches minimum downstream, recovers with distance.

Thermal pollution: Warm water holds less dissolved oxygen than cold water, compounding eutrophication.

Compare: Oligotrophic waters = low nutrients, stable algae, high DO.