Key Idea: Topic 4.4 focuses on how water pollution damages ecosystems and health, especially through bioaccumulation and biomagnification, and how pollution can be managed using prevention, treatment, and policy.
☠️ Bioaccumulation vs biomagnification (must be crystal clear)
Bioaccumulation: Build-up of a toxin in **one organism** over time. Absorbed faster than it can be broken down/excreted. Example: mercury building up in one fish.
Biomagnification: Toxin concentration increases **up a food chain**. Top predators get the highest dose. Example: plankton → fish → seals → top predators (including humans).
High marks: use a simple food chain and explicitly state why top predators have the highest concentration (many prey eaten + toxins stored, often fat-soluble/persistent).
🧪 Pollutants that biomagnify
- Heavy metals (mercury, lead, cadmium)
- POPs (DDT, PCBs, dioxins)
- Often persistent + fat-soluble + not easily excreted
🧰 Pollution management (best answers show layers)
- Prevention (best value): reduce pollution at source
- Catch/stop nutrients: riparian buffers, precision farming, cover crops, phosphate-free detergents
- Treatment: improved wastewater treatment, constructed wetlands
- Policy: legal limits, polluter pays, fines, subsidies, education
Strong responses explain HOW each strategy reduces pollution (not just listing).
1) Define bioaccumulation and biomagnification. 2) Name 2 pollutants that biomagnify. 3) Give 3 management strategies and explain how they work.