Unit 3.3 - Oceans - Ocean Pollution

Question 1

What are the 3 ways in which pollution enters the ocean?

Answer 1

Terrestrial run-off transports polluting substances into rivers and the sea, including fertilizers, pesticides, oil, industrial waste, sewage, and litter. Waste disposal includes treated sewage water with plastic microbeads and household waste. Oil spills result from shipping accidents and extraction activities, such as the 2010 BP Deepwater Horizon spill in the Gulf of Mexico.

Question 2

Describe the process of eutrophication.

Answer 2

Nitrate fertilisers are carried by run-off water from farmland into rivers and then transported towards coastal water. The nutrient–enriched waters initially experience a growth in marine life. Tiny organisms flourish, creating an explosion of life called an algal bloom. For a variety of reasons, the algae use up most of the water’s oxygen. Marine animal species suffocate in the de-oxygenated water. Around twenty major ‘marine dead zones’ exist in the world’s coastal margins, with Japan and the Gulf of Mexico particularly badly-affected.

Question 3

What are Garbage Patches?

Answer 3

Large amounts of plastics have entered the oceans since the 1950s and 1960s.
Over time, ocean gyres have helped to concentrate levels of plastic waste in marine areas to create ocean garbage patches.
The North Pacific garbage patch covers an area of 1.6 million km2 and may contain 2 trillion small (or microscopic) pieces of plastic.

Question 4

How are stakeholders working to tackle ocean pollution problems at different geographic scales.

Answer 4

• UNCLOS mandates all states to protect marine environments.
• EU’s Marine Strategy Framework Directive mandates ‘good environmental status’ of marine environments.
• State governments set their own rules, like UK’s phase-out of microbeads and introduction of charge for throwaway carrier bags.
• Local action against plastic, like Modbury’s campaign, highlights harm to sea creatures.
• NGOs like Friends of the Earth and Greenpeace raise plastic pollution issue.
• Boyan Slat’s ‘Ocean Clean-up’ aims to develop technologies to remove plastic from oceans.