In the previous post, we had briefly discussed about how cheap and chemically inert plastic products can contribute to environmental pollution. To fully understand the impact of plastic pollution, this week’s post will go into greater detail on how plastic pollution harms the marine environment.

Quick Recap from last week:

  1. More than 1 type of plastic (HDPE, PVC, Polycarbonate, etc)
  2. Plastics take a long time to biodegrade.
  3. Through photodegradation and other weathering processes, plastics break down into numerous small plastic fragments. They tend to bioaccumulate in marine animals.
  4. Even when plastics biodegrade, they tend to produce toxic by-products that harms living organisms.


  1. How do plastics end up in the oceans? (Jambek et al., 2015)
    It is estimated that 275 million metric tons of plastic waste was generated by 192 coastal countries in 2010. approximately 4.8 million to 12.7 million metric tons of these plastic waste entered the ocean.Plastic wastes originate from two main sources:
    – Dumping activities in the water. Discharge from ocean vessels, military operations, ship casualties and oil rigs.
    – Land-based sources. Mismanaged waste produced by coastal populations.Jambek et al. (2015) defines mismanged waste as material that is either littered or inadequately disposed. Inadequately disposed waste  includes disposal in dumps or uncontrolled landfill which are unable to fully contain the waste. Mismanaged waste enter the ocean via inland waterways, wastewater outflows, and transport by wind or tides.

    Creek in Manilla

    Inadequately Disposed Waste Flowing in a Creek in Manilla, Philippines, March 01 2009. Photo: Francis R. Malasig

  2. Magnitude of Plastic Pollution in the World today. (Eriksen et al., 2014)

Eriken et al. (2014) estimated that more than 5 trillion plastic pieces weighing over 250,000 tons are currently afloat at sea. Eriken et al. verified their hypothesis that ocean margins are area of plastic migration, while subtropical gyres (large system of circular ocean currents formed by global wind patterns and forces created by Earth’s rotation) are areas of accumulation.

Plastic debris accumulates because they do no biodegrade. Because the plastic waste items are highly buoyant, they get moved throughout the world’s ocean by the prevailing winds and surface currents. Eriksen et al discovered that the total amount of plastics determined for the southern hemisphere is similar to that of the northern hemisphere. This is unexpected as inputs of plastic waste is substantially higher in the more affluent north. Plastic pollution is thus equally distributed through oceanic current.

According to a Greenpeace report “Plastic Debris in the World’s Oceans“, 70% of the plastic mass eventually sinks, damaging life on the seabed. The rest either continue to float in the ocean seas, accumulate as garbage patch in gyres, or washed ashore onto someone’s beach.

It is believed that there is a great pacific garbage patch in the central North Pacific Ocean. The pacific trash vortex is a gyre of marine debris that spans between 700,000 km sq to 15,000,000 km sq (for reference, Singapore only has a land area of 712 km sq).

In the next post, we’ll investigate the consequences of having so much plastic waste in the ocean. Cya


Eriksen, M., Lebreton, L. C., Carson, H. S., Thiel, M., Moore, C. J., Borerro, J. C., … & Reisser, J. (2014). Plastic pollution in the world’s oceans: more than 5 trillion plastic pieces weighing over 250,000 tons afloat at sea. PloS one, 9(12), e111913.

Jambeck, J. R., Geyer, R., Wilcox, C., Siegler, T. R., Perryman, M., Andrady, A., … & Law, K. L. (2015). Plastic waste inputs from land into the ocean.Science, 347(6223), 768-771.