4.10.6Additional lessons
The Effects of Pollution — IB Biology SL Revision Notes & Topical Questions
5 min read 4 parts Lesson 140 of 142
Curriculum Equation Key قوانين الرقم الهيدروجيني والاتزان الأيوني - pH & Acid-Base Equilibrium FormulasFast Exam Solution
pH = -log[H⁺] | pOH = -log[OH⁻] | pH + pOH = 14 | [H⁺][OH⁻] = 10⁻¹⁴
Word Equation & Conditions: الرقم الهيدروجيني = -لوغاريتم تركيز أيون الهيدروجين | pH + pOH = 14
Location & Specifications: الاتزان الأيوني، كيمياء 3 ثانوي، التحصيلي، و AP Chemistry.
Part 1 of 4Biomagnification
Persistence is the key propertya pollutant that breaks down quickly cannot build up through a food chain.
Definition
- Definition The increase in concentration of a persistent, non-biodegradable pollutant in the tissues of organisms at successively higher trophic levels.
Bioaccumulation
- Bioaccumulation The build-up of a pollutant within a single organism over its lifetime;
- biomagnification refers to increase between trophic levels.
Why it happens
- Why it happens Each predator eats many contaminated prey, and because the pollutant is not broken down or excreted it accumulates.
Top predators
- Top predators Animals at the top of a food chain therefore receive the highest doses and suffer the greatest harm.
| Term | Meaning |
|---|---|
| Bioaccumulation | Build-up within one organism |
| Biomagnification | Increase along a food chain |
Part 2 of 4Case Studies
Two well-known cases show how a pollutant moves through trophic levels and what harm it does.
1
DDT, a persistent insecticide, washed from sprayed crops into waterways and was taken up by plankton.
2
Small fish eating plankton accumulated DDT, and larger fish and birds that ate them gained still higher concentrations.
3
In birds of prey, DDT caused thin eggshells that broke under the incubating parent, so fewer chicks hatched.
4
Mercury released by coal burning and gold mining is changed by microorganisms into methylmercury, which builds up in fish.
5
Large predatory fish such as tuna and swordfish contain the highest mercury levels, which can harm human consumers.
Part 3 of 4Plastic Pollution
Plastics persist for decades and break into ever smaller pieces, so they affect land, rivers and oceans alike.
Plastic Pollution
Macroplastics
- Macroplastics Items larger than 5 mm, such as bags, bottles and fishing nets, which can entangle animals or be swallowed.
Microplastics
- Microplastics Fragments smaller than 5 mm formed when larger plastics are broken by waves and ultraviolet light.
Harm to wildlife
- Harm to wildlife Animals mistake plastic for food, fill their stomachs with it and may starve, and some release toxins as it breaks down.
Science communication
- Science communication Clear public information about these effects has changed behaviour, such as reducing packaging and improving recycling.
Entanglement
- Entanglement Fishing lines and netting trap animals such as turtles and seabirds, causing injury, drowning or starvation.
Part 4 of 4Exam Checklist & Tips
4.10.6 – Key Points for the Exam
- Biomagnification Increase in concentration of a pollutant along a food chain.
- Persistent pollutant A pollutant that does not break down easily in the environment.
- Microplastic A plastic fragment less than 5 mm in length.
- Bioaccumulation Build-up of a substance in an organism over time.
- Methylmercury A toxic organic form of mercury produced by microorganisms that readily accumulates in fish.
- Macroplastic A plastic item larger than 5 mm.
Common Mistakes
- Using bioaccumulation and biomagnification as if they are the same term.
- Claiming pollutants magnify because predators eat more energy;
- it is because the pollutant is not broken down.
- Saying plastics are quickly biodegradable.
- Forgetting to name the trophic level when describing where concentration is highest.
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