Year 9 Science · Unit 2 · Lesson 18

Microplastics, Sources, Pathways and Bioaccumulation

Challenge Worksheet

Name

Date

Class

Learning Goals

Critically evaluate claims about the Great Pacific Garbage Patch and microplastic pollution
Apply understanding of photodegradation and biomagnification to multi-step reasoning questions
Identify and correct scientific errors in statements about microplastics and their environmental impact

Go Deeper

Evaluate the claim

Someone claims…

"The microplastics problem isn't that serious for Australia, the Great Pacific Garbage Patch is in the North Pacific, far from us. Anyway, UV light breaks down plastic over time so it eventually disappears. And microplastics only affect sea creatures that live in the water, not fish you eat, because the plastic doesn't get absorbed into the flesh, it stays in the gut and you don't eat that part."

(a) This claim contains at least TWO factual errors about Australia's exposure to microplastic pollution. Identify them and explain what the evidence from the lesson actually shows.

Challenge 3 marks

(b) The claim states UV light causes plastic to "eventually disappear." Using your knowledge of photodegradation, explain precisely why this is misleading. What does UV light actually do to plastic, and why does this make the situation worse rather than better?

Challenge 3 marks

(c) The claim suggests microplastics only affect fish in their gut (which is discarded). Using the 2022–2023 research evidence mentioned in the lesson, explain why this is incorrect for both fish and humans.

Challenge 2 marks

Show What You Know

1. A state government is deciding between two policies to reduce microplastic pollution in NSW waterways: Policy Aban all synthetic fibre clothing. Policy Brequire all washing machines sold in NSW to include a microfibre-capture filter. Using your knowledge of microplastic sources and pathways, evaluate which policy would be more practical and effective. Consider at least TWO factors beyond just the amount of microplastics captured.

Challenge 4 marks

2. CSIRO researchers found that the oldest plastic fragments on the Cocos (Keeling) Islands beach were manufactured in the 1960s, over 60 years old, and were still present as polymer fragments rather than having mineralised. Explain why this finding is important evidence for the scientific argument that UV photodegradation does NOT solve the microplastics problem. In your answer, use the terms "photodegradation", "mineralise", and "microplastic".

Challenge 4 marks

Wrap Up

In one sentence, what was the main idea of this lesson?