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Environmental Science
Microplastic Pollution
From Everyday Products to Food Webs
Related Labs
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Microplastic pollution is the spread of tiny plastic particles through air, soil, rivers, lakes, and oceans. These particles come from everyday products, broken plastic trash, synthetic clothing fibers, tire wear, and industrial plastic pellets. They matter because their small size makes them easy for organisms to ingest and hard to remove from the environment. Microplastics connect human consumption to ecosystem health, water quality, and food safety.
Key Facts
- Microplastics are plastic particles smaller than 5 mm in diameter.
- Primary microplastics are made small, while secondary microplastics form when larger plastics break apart.
- Particle concentration can be calculated as C = N / V, where C is particles per liter, N is number of particles, and V is water volume in liters.
- Microplastics can move by runoff, wastewater discharge, wind transport, ocean currents, and food web transfer.
- Ingestion rate can be estimated as R = C × F, where R is particles ingested per day, C is particles per liter, and F is liters filtered or consumed per day.
- Bioaccumulation describes buildup in one organism, while biomagnification describes increasing concentration at higher trophic levels.
Vocabulary
- Microplastic
- A microplastic is a plastic particle smaller than 5 millimeters that can persist in the environment.
- Primary microplastic
- A primary microplastic is manufactured at a small size, such as a resin pellet or some cosmetic bead.
- Secondary microplastic
- A secondary microplastic forms when larger plastic items fragment through sunlight, abrasion, and weathering.
- Bioaccumulation
- Bioaccumulation is the increase of a substance inside an organism over time when intake is greater than elimination.
- Trophic level
- A trophic level is a feeding position in a food web, such as producer, primary consumer, or predator.
Common Mistakes to Avoid
- Assuming all microplastics come from littered bottles is wrong because fibers from clothing, tire particles, paint flakes, and industrial pellets are also major sources.
- Treating biodegradable and compostable plastics as harmless is wrong because they may still fragment or persist if environmental conditions do not support full breakdown.
- Confusing bioaccumulation with biomagnification is wrong because bioaccumulation happens within one organism, while biomagnification happens across feeding levels.
- Counting only visible plastic pieces is wrong because many microplastics are too small to see clearly without filtration, staining, or microscopy.
Practice Questions
- 1 A water sample contains 240 microplastic particles in 12 liters of seawater. Calculate the particle concentration in particles per liter.
- 2 A filter-feeding mussel filters 4.0 liters of water per day in water containing 15 particles per liter. Estimate how many microplastic particles it may ingest in 7 days.
- 3 Explain why microplastic fibers from synthetic clothing can affect marine food webs even if the clothing is used far from the ocean.