3.c. The pattern of global ocean currents can disperse and concentrate pollution

Question 1

Explain marine debris and why it is a problem

Answer 1

• plastics, metals, rubber, paper and other items that enter the marine environment everyday, creating a widespread pollution probem
• enters oceans via rivers, from beaches and from dumping by ships at sea
• it is a long term, persistant problem, posing threats to ships and wildlife

Question 2

Why are plastics such a big problem to the ocean

Answer 2

• most serious impact from plastics as do not biodegrade but break down into smaller pieces- microplastics. this process is called photodegradation
• plastics start as manufactured pellets known as ‘nurdles’. They are shipped around the world in vast quantities and are easily spilled and dispersed
• have been found in every ocean and along coastlines

Question 3

Case study of accumulation of plastic in an ocean gyre- Great Pacific Patch- key info

Answer 3

• an ocean gyre is a system of circular currents formed by wind patterns
• accumulation of debris in North Pacfic Gyre has lead to the term ‘Great Pacific Garbage Patch’
• the use of this name has lead to the assumption that the patch is a large+continuous area of debris
• much is plastic and exists at the surface and is suspended below the surface for several metres
• most of garbage is micro plastics
• two principles of accumulation- east and west, with lower density zone just to the north

Question 4

Case study of accumulation of plastic in an ocean gyre- Great Pacific Patch- problems

Answer 4

• larger plastic pieces can become wrapped around animals and drown them
• smaller pieces injested by birds. Plastic then interfers with digestion
• once pollutants is in the food chain there is the risk of it being transferred to humans
• marine debris is pollution and plastic debris is still being found in oceans
• problem likely to become more serious
• the problem is how we dispose of it