Hello there!

To start the discussion on plastic pollution, today’s blog entry would discuss the types of plastics found in the environment. We can categorise plastics primarily into 4 groups according to their size, namely megaplastic, macroplastic, mesoplastic, and microplastic.

Megaplastic

Larger size plastics visualised by the naked eye is known as Megaplastic. Usually found in sizes of more than a meter, these larger plastic fragments would then convert into microplastics within the environment (Thushari & Senevirathna, 2020).

Macroplastic

Similar to megaplastics, microplastic can be seen by the naked eye as well. Examples of macroplastics include plastic bottles. In sizes of up to a meter, microplastics in the open environment are exposed to chemical, biological, physical, and mechanical processes and change the typical properties of plastics such as structure and integrity. As a result, large plastics degrade into minute plastic fragments in the environment.

The Fundamental forces leading to the degradation of macroplastics are ultra-violet (UV) radiation, also known as photo degradation, and wave abrasion physically (Andrady, 2011). During photo-degradation of plastics, large plastics are subjected to UV rays, leading to the oxidation of polymer plastic and breakdown of structural integrity. The plastic fragments with reduced structural integrity are further exposed to physical and mechanical forces such as wave turbulence and abrasion. Finally, macroplastics rapidly convert into minute particles during the degradation process. This process continues until plastics become microscopic in size, forming microplastics.

Mesoplastic

Mesoplastics possess an intermediate size range between visible macroplastic and minute microscopic plastics, with a size of less than 2.5cm. Examples of mesoplastics include resin pellets which are 5 to 10mm in size (UNEP, 2015).

Microplastic

Known as plastic litter, microplastics are observable only using a microscope as they are less than 5mm in size. Microplastics can be classified into two groups, namely primary microplastic and secondary microplastic. Primary microplastics are plastic debris manufactured with a microscopic size range and are mainly used in manufacturing cosmetics such as cleansers and shower gels. Secondary plastics are defined as the plastic debris resulting after the breakdown of macroplastic in the terrestrial environment and ocean through the process of photo degradation and wave abrasion, as covered earlier (Thushari & Senevirathna, 2020).

Feeling a little lost? Apologies. This crash course of plastic sizes found in the environment would be useful in understanding more about plastic pollution in future blog entries. See you next week!

References

Andrady, A. L. (2011). Microplastics in the marine environment. Marine Pollution Bulletin, 62(8), 1596–1605. https://doi.org/10.1016/j.marpolbul.2011.05.030

Thushari, G. G. N., & Senevirathna, J. D. M. (2020). Plastic pollution in the marine environment. Heliyon, 6(8), e04709. https://doi.org/10.1016/j.heliyon.2020.e04709

UNEP. (2015, July). Plastics and microplastics factsheet. UNEP. Retrieved January 16, 2022, from https://wedocs.unep.org/bitstream/handle/20.500.11822/28420/Microplas-en.pdf?sequence=1&isAllowed=y – :~:text=Mesoplastics%20are%20large%20plastic%20particles,breakdown%20of%20macroplastics%20%5B1%5D.