Exploring Oceans 3. How and in what ways do human activities pollute oceans?

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  • Created by: DanBish
  • Created on: 08-05-22 21:54
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  • How and in what ways do human activities pollute oceans?
    • Spread and effects of pollution
      • Spread
        • In 1992, a container holding thousands of plastic bath toys was swept off a ship in the Pacific
          • This has inadvertently advanced understanding of the operation of ocean currents, as we can follow the toys
        • Marine debris can enter the oceans from: rivers, beaches, discarding off ships in storms
      • Effects
        • Marine debris can be persistent, potentially over many decades
        • Can pose physical dangers to ships, as well as damage to ecosystems
        • Larger marine creatures, like seals and sharks, can be entangled in discarded fishing nets and drown
        • Many plastics do not biodegrade, instead breaking down into micro-plastics through photo-degredation
          • This plastic are shipped around the world in vast quantities, and being so small and light can be easily spilled and dispersed
    • Accumulation of plastic - Great Pacific Garbage Patch
      • Causation
        • The great pacific garbage patch is a concentration of pollution in a gyre
          • A gyre is a system of circular currents, formed by wind patterns and the rotation of the planet
        • There are some locations with high concen-trations of relatively large debris - visible - although most pollution is micro-plastics, and isn't visible to the naked eye
        • Formed by plastics and micro-plastics being caught in the North Pacific gyre, and being deposited in two principle areas of accumulation, one east and one west, with a lower-density zone just to the north
      • Impacts
        • Large pieces of plastic can become wrapped around animals such as seals, and strangle or drown them
        • Smaller pieces are ingested by fish and birds.
        • The plastic interferes with digestion, both physically and chemically
        • Not only do the chemicals in plastics, but the pollutants they attract also harm organisms
        • If chemicals / pollutants enter the marine food chain, then it could be transferred to humans through eating marine life

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